mariadb/sql/mysqld.h

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/* Copyright 2006-2008 MySQL AB, 2008-2009 Sun Microsystems, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
#ifndef MYSQLD_INCLUDED
#define MYSQLD_INCLUDED
#include "my_global.h" /* MYSQL_PLUGIN_IMPORT, FN_REFLEN, FN_EXTLEN */
#include "sql_bitmap.h" /* Bitmap */
#include "my_decimal.h" /* my_decimal */
#include "mysql_com.h" /* SERVER_VERSION_LENGTH */
#include "my_atomic.h" /* my_atomic_rwlock_t */
#include "mysql/psi/mysql_file.h" /* MYSQL_FILE */
#include "sql_list.h" /* I_List */
class THD;
struct handlerton;
class Time_zone;
struct scheduler_functions;
typedef struct st_mysql_const_lex_string LEX_CSTRING;
typedef struct st_mysql_show_var SHOW_VAR;
/*
This forward declaration is used from C files where the real
definition is included before. Since C does not allow repeated
typedef declarations, even when identical, the definition may not be
repeated.
*/
#ifndef CHARSET_INFO_DEFINED
typedef struct charset_info_st CHARSET_INFO;
#endif /* CHARSET_INFO_DEFINED */
#if MAX_INDEXES <= 64
typedef Bitmap<64> key_map; /* Used for finding keys */
#else
typedef Bitmap<((MAX_INDEXES+7)/8*8)> key_map; /* Used for finding keys */
#endif
/* Bits from testflag */
#define TEST_PRINT_CACHED_TABLES 1
#define TEST_NO_KEY_GROUP 2
#define TEST_MIT_THREAD 4
#define TEST_BLOCKING 8
#define TEST_KEEP_TMP_TABLES 16
#define TEST_READCHECK 64 /**< Force use of readcheck */
#define TEST_NO_EXTRA 128
#define TEST_CORE_ON_SIGNAL 256 /**< Give core if signal */
#define TEST_NO_STACKTRACE 512
#define TEST_SIGINT 1024 /**< Allow sigint on threads */
#define TEST_SYNCHRONIZATION 2048 /**< get server to do sleep in
some places */
/* Function prototypes */
void kill_mysql(void);
void close_connection(THD *thd, uint sql_errno= 0);
void handle_connection_in_main_thread(THD *thd);
void create_thread_to_handle_connection(THD *thd);
void unlink_thd(THD *thd);
bool one_thread_per_connection_end(THD *thd, bool put_in_cache);
void flush_thread_cache();
void refresh_status(THD *thd);
bool is_secure_file_path(char *path);
extern MYSQL_PLUGIN_IMPORT CHARSET_INFO *system_charset_info;
extern MYSQL_PLUGIN_IMPORT CHARSET_INFO *files_charset_info ;
extern MYSQL_PLUGIN_IMPORT CHARSET_INFO *national_charset_info;
extern MYSQL_PLUGIN_IMPORT CHARSET_INFO *table_alias_charset;
/**
Character set of the buildin error messages loaded from errmsg.sys.
*/
extern CHARSET_INFO *error_message_charset_info;
extern CHARSET_INFO *character_set_filesystem;
extern MY_BITMAP temp_pool;
extern bool opt_large_files, server_id_supplied;
extern bool opt_update_log, opt_bin_log, opt_error_log;
extern my_bool opt_log, opt_slow_log;
extern my_bool opt_backup_history_log;
extern my_bool opt_backup_progress_log;
extern ulonglong log_output_options;
extern ulong log_backup_output_options;
extern my_bool opt_log_queries_not_using_indexes;
extern bool opt_disable_networking, opt_skip_show_db;
extern bool opt_skip_name_resolve;
extern bool opt_ignore_builtin_innodb;
extern my_bool opt_character_set_client_handshake;
extern bool volatile abort_loop;
extern bool in_bootstrap;
Patch that refactors global read lock implementation and fixes bug #57006 "Deadlock between HANDLER and FLUSH TABLES WITH READ LOCK" and bug #54673 "It takes too long to get readlock for 'FLUSH TABLES WITH READ LOCK'". The first bug manifested itself as a deadlock which occurred when a connection, which had some table open through HANDLER statement, tried to update some data through DML statement while another connection tried to execute FLUSH TABLES WITH READ LOCK concurrently. What happened was that FTWRL in the second connection managed to perform first step of GRL acquisition and thus blocked all upcoming DML. After that it started to wait for table open through HANDLER statement to be flushed. When the first connection tried to execute DML it has started to wait for GRL/the second connection creating deadlock. The second bug manifested itself as starvation of FLUSH TABLES WITH READ LOCK statements in cases when there was a constant stream of concurrent DML statements (in two or more connections). This has happened because requests for protection against GRL which were acquired by DML statements were ignoring presence of pending GRL and thus the latter was starved. This patch solves both these problems by re-implementing GRL using metadata locks. Similar to the old implementation acquisition of GRL in new implementation is two-step. During the first step we block all concurrent DML and DDL statements by acquiring global S metadata lock (each DML and DDL statement acquires global IX lock for its duration). During the second step we block commits by acquiring global S lock in COMMIT namespace (commit code acquires global IX lock in this namespace). Note that unlike in old implementation acquisition of protection against GRL in DML and DDL is semi-automatic. We assume that any statement which should be blocked by GRL will either open and acquires write-lock on tables or acquires metadata locks on objects it is going to modify. For any such statement global IX metadata lock is automatically acquired for its duration. The first problem is solved because waits for GRL become visible to deadlock detector in metadata locking subsystem and thus deadlocks like one in the first bug become impossible. The second problem is solved because global S locks which are used for GRL implementation are given preference over IX locks which are acquired by concurrent DML (and we can switch to fair scheduling in future if needed). Important change: FTWRL/GRL no longer blocks DML and DDL on temporary tables. Before this patch behavior was not consistent in this respect: in some cases DML/DDL statements on temporary tables were blocked while in others they were not. Since the main use cases for FTWRL are various forms of backups and temporary tables are not preserved during backups we have opted for consistently allowing DML/DDL on temporary tables during FTWRL/GRL. Important change: This patch changes thread state names which are used when DML/DDL of FTWRL is waiting for global read lock. It is now either "Waiting for global read lock" or "Waiting for commit lock" depending on the stage on which FTWRL is. Incompatible change: To solve deadlock in events code which was exposed by this patch we have to replace LOCK_event_metadata mutex with metadata locks on events. As result we have to prohibit DDL on events under LOCK TABLES. This patch also adds extensive test coverage for interaction of DML/DDL and FTWRL. Performance of new and old global read lock implementations in sysbench tests were compared. There were no significant difference between new and old implementations. mysql-test/include/check_ftwrl_compatible.inc: Added helper script which allows to check that a statement is compatible with FLUSH TABLES WITH READ LOCK. mysql-test/include/check_ftwrl_incompatible.inc: Added helper script which allows to check that a statement is incompatible with FLUSH TABLES WITH READ LOCK. mysql-test/include/handler.inc: Adjusted test case to the fact that now DROP TABLE closes open HANDLERs for the table to be dropped before checking if there active FTWRL in this connection. mysql-test/include/wait_show_condition.inc: Fixed small error in the timeout message. The correct name of variable used as parameter for this script is "$condition" and not "$wait_condition". mysql-test/r/delayed.result: Added test coverage for scenario which triggered assert in metadata locking subsystem. mysql-test/r/events_2.result: Updated test results after prohibiting event DDL operations under LOCK TABLES. mysql-test/r/flush.result: Added test coverage for bug #57006 "Deadlock between HANDLER and FLUSH TABLES WITH READ LOCK". mysql-test/r/flush_read_lock.result: Added test coverage for various aspects of FLUSH TABLES WITH READ LOCK functionality. mysql-test/r/flush_read_lock_kill.result: Adjusted test case after replacing custom global read lock implementation with one based on metadata locks. Use new debug_sync point. Do not disable concurrent inserts as now InnoDB we always use InnoDB table. mysql-test/r/handler_innodb.result: Adjusted test case to the fact that now DROP TABLE closes open HANDLERs for the table to be dropped before checking if there active FTWRL in this connection. mysql-test/r/handler_myisam.result: Adjusted test case to the fact that now DROP TABLE closes open HANDLERs for the table to be dropped before checking if there active FTWRL in this connection. mysql-test/r/mdl_sync.result: Adjusted test case after replacing custom global read lock implementation with one based on metadata locks. Replaced usage of GRL-specific debug_sync's with appropriate sync points in MDL subsystem. mysql-test/suite/perfschema/r/dml_setup_instruments.result: Updated test results after removing global COND_global_read_lock condition variable. mysql-test/suite/perfschema/r/func_file_io.result: Ensure that this test doesn't affect subsequent tests. At the end of its execution enable back P_S instrumentation which this test disables at some point. mysql-test/suite/perfschema/r/func_mutex.result: Ensure that this test doesn't affect subsequent tests. At the end of its execution enable back P_S instrumentation which this test disables at some point. mysql-test/suite/perfschema/r/global_read_lock.result: Adjusted test case to take into account that new GRL implementation is based on MDL. mysql-test/suite/perfschema/r/server_init.result: Adjusted test case after replacing custom global read lock implementation with one based on MDL and replacing LOCK_event_metadata mutex with metadata lock. mysql-test/suite/perfschema/t/func_file_io.test: Ensure that this test doesn't affect subsequent tests. At the end of its execution enable back P_S instrumentation which this test disables at some point. mysql-test/suite/perfschema/t/func_mutex.test: Ensure that this test doesn't affect subsequent tests. At the end of its execution enable back P_S instrumentation which this test disables at some point. mysql-test/suite/perfschema/t/global_read_lock.test: Adjusted test case to take into account that new GRL implementation is based on MDL. mysql-test/suite/perfschema/t/server_init.test: Adjusted test case after replacing custom global read lock implementation with one based on MDL and replacing LOCK_event_metadata mutex with metadata lock. mysql-test/suite/rpl/r/rpl_tmp_table_and_DDL.result: Updated test results after prohibiting event DDL under LOCK TABLES. mysql-test/t/delayed.test: Added test coverage for scenario which triggered assert in metadata locking subsystem. mysql-test/t/events_2.test: Updated test case after prohibiting event DDL operations under LOCK TABLES. mysql-test/t/flush.test: Added test coverage for bug #57006 "Deadlock between HANDLER and FLUSH TABLES WITH READ LOCK". mysql-test/t/flush_block_commit.test: Adjusted test case after changing thread state name which is used when COMMIT waits for FLUSH TABLES WITH READ LOCK from "Waiting for release of readlock" to "Waiting for commit lock". mysql-test/t/flush_block_commit_notembedded.test: Adjusted test case after changing thread state name which is used when DML waits for FLUSH TABLES WITH READ LOCK. Now we use "Waiting for global read lock" in this case. mysql-test/t/flush_read_lock.test: Added test coverage for various aspects of FLUSH TABLES WITH READ LOCK functionality. mysql-test/t/flush_read_lock_kill-master.opt: We no longer need to use make_global_read_lock_block_commit_loop debug tag in this test. Instead we rely on an appropriate debug_sync point in MDL code. mysql-test/t/flush_read_lock_kill.test: Adjusted test case after replacing custom global read lock implementation with one based on metadata locks. Use new debug_sync point. Do not disable concurrent inserts as now InnoDB we always use InnoDB table. mysql-test/t/lock_multi.test: Adjusted test case after changing thread state names which are used when DML or DDL waits for FLUSH TABLES WITH READ LOCK to "Waiting for global read lock". mysql-test/t/mdl_sync.test: Adjusted test case after replacing custom global read lock implementation with one based on metadata locks. Replaced usage of GRL-specific debug_sync's with appropriate sync points in MDL subsystem. Updated thread state names which are used when DDL waits for FTWRL. mysql-test/t/trigger_notembedded.test: Adjusted test case after changing thread state names which are used when DML or DDL waits for FLUSH TABLES WITH READ LOCK to "Waiting for global read lock". sql/event_data_objects.cc: Removed Event_queue_element::status/last_executed_changed members and Event_queue_element::update_timing_fields() method. We no longer use this class for updating mysql.events once event is chosen for execution. Accesses to instances of this class in scheduler thread require protection by Event_queue::LOCK_event_queue mutex and we try to avoid updating table while holding this lock. sql/event_data_objects.h: Removed Event_queue_element::status/last_executed_changed members and Event_queue_element::update_timing_fields() method. We no longer use this class for updating mysql.events once event is chosen for execution. Accesses to instances of this class in scheduler thread require protection by Event_queue::LOCK_event_queue mutex and we try to avoid updating table while holding this lock. sql/event_db_repository.cc: - Changed Event_db_repository methods to not release all metadata locks once they are done updating mysql.events table. This allows to keep metadata lock protecting against GRL and lock protecting particular event around until corresponding DDL statement is written to the binary log. - Removed logic for conditional update of "status" and "last_executed" fields from update_timing_fields_for_event() method. In the only case when this method is called now "last_executed" is always modified and tracking change of "status" is too much hassle. sql/event_db_repository.h: Removed logic for conditional update of "status" and "last_executed" fields from Event_db_repository:: update_timing_fields_for_event() method. In the only case when this method is called now "last_executed" is always modified and tracking change of "status" field is too much hassle. sql/event_queue.cc: Changed event scheduler code not to update mysql.events table while holding Event_queue::LOCK_event_queue mutex. Doing so led to a deadlock with a new GRL implementation. This deadlock didn't occur with old implementation due to fact that code acquiring protection against GRL ignored pending GRL requests (which lead to GRL starvation). One of goals of new implementation is to disallow GRL starvation and so we have to solve problem with this deadlock in a different way. sql/events.cc: Changed methods of Events class to acquire protection against GRL while perfoming DDL statement and keep it until statement is written to the binary log. Unfortunately this step together with new GRL implementation exposed deadlock involving Events::LOCK_event_metadata and GRL. To solve it Events::LOCK_event_metadata mutex was replaced with a metadata lock on event. As a side-effect events DDL has to be prohibited under LOCK TABLES even in cases when mysql.events table was explicitly locked for write. sql/events.h: Replaced Events::LOCK_event_metadata mutex with a metadata lock on event. sql/ha_ndbcluster.cc: Updated code after replacing custom global read lock implementation with one based on MDL. Since MDL subsystem should now be able to detect deadlocks involving metadata locks and GRL there is no need for special handling of active GRL. sql/handler.cc: Replaced custom implementation of global read lock with one based on metadata locks. Consequently when doing commit instead of calling method of Global_read_lock class to acquire protection against GRL we simply acquire IX in COMMIT namespace. sql/lock.cc: Replaced custom implementation of global read lock with one based on metadata locks. This step allows to expose wait for GRL to deadlock detector of MDL subsystem and thus succesfully resolve deadlocks similar to one behind bug #57006 "Deadlock between HANDLER and FLUSH TABLES WITH READ LOCK". It also solves problem with GRL starvation described in bug #54673 "It takes too long to get readlock for 'FLUSH TABLES WITH READ LOCK'" since metadata locks used by GRL give preference to FTWRL statement instead of DML statements (if needed in future this can be changed to fair scheduling). Similar to old implementation of acquisition of GRL is two-step. During the first step we block all concurrent DML and DDL statements by acquiring global S metadata lock (each DML and DDL statement acquires global IX lock for its duration). During the second step we block commits by acquiring global S lock in COMMIT namespace (commit code acquires global IX lock in this namespace). Note that unlike in old implementation acquisition of protection against GRL in DML and DDL is semi-automatic. We assume that any statement which should be blocked by GRL will either open and acquires write-lock on tables or acquires metadata locks on objects it is going to modify. For any such statement global IX metadata lock is automatically acquired for its duration. To support this change: - Global_read_lock::lock/unlock_global_read_lock and make_global_read_lock_block_commit methods were changed accordingly. - Global_read_lock::wait_if_global_read_lock() and start_waiting_global_read_lock() methods were dropped. It is now responsibility of code acquiring metadata locks opening tables to acquire protection against GRL by explicitly taking global IX lock with statement duration. - Global variables, mutex and condition variable used by old implementation was removed. - lock_routine_name() was changed to use statement duration for its global IX lock. It was also renamed to lock_object_name() as it now also used to take metadata locks on events. - Global_read_lock::set_explicit_lock_duration() was added which allows not to release locks used for GRL when leaving prelocked mode. sql/lock.h: - Renamed lock_routine_name() to lock_object_name() and changed its signature to allow its usage for events. - Removed broadcast_refresh() function. It is no longer needed with new GRL implementation. sql/log_event.cc: Release metadata locks with statement duration at the end of processing legacy event for LOAD DATA. This ensures that replication thread processing such event properly releases its protection against global read lock. sql/mdl.cc: Changed MDL subsystem to support new MDL-based implementation of global read lock. Added COMMIT and EVENTS namespaces for metadata locks. Changed thread state name for GLOBAL namespace to "Waiting for global read lock". Optimized MDL_map::find_or_insert() method to avoid taking m_mutex mutex when looking up MDL_lock objects for GLOBAL or COMMIT namespaces. We keep pre-created MDL_lock objects for these namespaces around and simply return pointers to these global objects when needed. Changed MDL_lock/MDL_scoped_lock to properly handle notification of insert delayed handler threads when FTWRL takes global S lock. Introduced concept of lock duration. In addition to locks with transaction duration which work in the way which is similar to how locks worked before (i.e. they are released at the end of transaction), locks with statement and explicit duration were introduced. Locks with statement duration are automatically released at the end of statement. Locks with explicit duration require explicit release and obsolete concept of transactional sentinel. * Changed MDL_request and MDL_ticket classes to support notion of duration. * Changed MDL_context to keep locks with different duration in different lists. Changed code handling ticket list to take this into account. * Changed methods responsible for releasing locks to take into account duration of tickets. Particularly public MDL_context::release_lock() method now only can release tickets with explicit duration (there is still internal method which allows to specify duration). To release locks with statement or transaction duration one have to use release_statement/transactional_locks() methods. * Concept of savepoint for MDL subsystem now has to take into account locks with statement duration. Consequently MDL_savepoint class was introduced and methods working with savepoints were updated accordingly. * Added methods which allow to set duration for one or all locks in the context. sql/mdl.h: Changed MDL subsystem to support new MDL-based implementation of global read lock. Added COMMIT and EVENTS namespaces for metadata locks. Introduced concept of lock duration. In addition to locks with transaction duration which work in the way which is similar to how locks worked before (i.e. they are released at the end of transaction), locks with statement and explicit duration were introduced. Locks with statement duration are automatically released at the end of statement. Locks with explicit duration require explicit release and obsolete concept of transactional sentinel. * Changed MDL_request and MDL_ticket classes to support notion of duration. * Changed MDL_context to keep locks with different duration in different lists. Changed code handling ticket list to take this into account. * Changed methods responsible for releasing locks to take into account duration of tickets. Particularly public MDL_context::release_lock() method now only can release tickets with explicit duration (there is still internal method which allows to specify duration). To release locks with statement or transaction duration one have to use release_statement/transactional_locks() methods. * Concept of savepoint for MDL subsystem now has to take into account locks with statement duration. Consequently MDL_savepoint class was introduced and methods working with savepoints were updated accordingly. * Added methods which allow to set duration for one or all locks in the context. sql/mysqld.cc: Removed global mutex and condition variables which were used by old implementation of GRL. Also we no longer need to initialize Events::LOCK_event_metadata mutex as it was replaced with metadata locks on events. sql/mysqld.h: Removed global variable, mutex and condition variables which were used by old implementation of GRL. sql/rpl_rli.cc: When slave thread closes tables which were open for handling of RBR events ensure that it releases global IX lock which was acquired as protection against GRL. sql/sp.cc: Adjusted code to the new signature of lock_object/routine_name(), to the fact that one now needs specify duration of lock when initializing MDL_request and to the fact that savepoints for MDL subsystem are now represented by MDL_savepoint class. sql/sp_head.cc: Ensure that statements in stored procedures release statement metadata locks and thus release their protectiong against GRL in proper moment in time. Adjusted code to the fact that one now needs specify duration of lock when initializing MDL_request. sql/sql_admin.cc: Adjusted code to the fact that one now needs specify duration of lock when initializing MDL_request. sql/sql_base.cc: - Implemented support for new approach to acquiring protection against global read lock. We no longer acquire such protection explicitly on the basis of statement flags. Instead we always rely on code which is responsible for acquiring metadata locks on object to be changed acquiring this protection. This is achieved by acquiring global IX metadata lock with statement duration. Code doing this also responsible for checking that current connection has no active GRL by calling an Global_read_lock::can_acquire_protection() method. Changed code in open_table() and lock_table_names() accordingly. Note that as result of this change DDL and DML on temporary tables is always compatible with GRL (before it was incompatible in some cases and compatible in other cases). - To speed-up code acquiring protection against GRL introduced m_has_protection_against_grl member in Open_table_context class. It indicates that protection was already acquired sometime during open_tables() execution and new attempts can be skipped. - Thanks to new GRL implementation calls to broadcast_refresh() became unnecessary and were removed. - Adjusted code to the fact that one now needs specify duration of lock when initializing MDL_request and to the fact that savepoints for MDL subsystem are now represented by MDL_savepoint class. sql/sql_base.h: Adjusted code to the fact that savepoints for MDL subsystem are now represented by MDL_savepoint class. Also introduced Open_table_context::m_has_protection_against_grl member which allows to avoid acquiring protection against GRL while opening tables if such protection was already acquired. sql/sql_class.cc: Changed THD::leave_locked_tables_mode() after transactional sentinel for metadata locks was obsoleted by introduction of locks with explicit duration. sql/sql_class.h: - Adjusted code to the fact that savepoints for MDL subsystem are now represented by MDL_savepoint class. - Changed Global_read_lock class according to changes in global read lock implementation: * wait_if_global_read_lock and start_waiting_global_read_lock are now gone. Instead code needing protection against GRL has to acquire global IX metadata lock with statement duration itself. To help it new can_acquire_protection() was introduced. Also as result of the above change m_protection_count member is gone too. * Added m_mdl_blocks_commits_lock member to store metadata lock blocking commits. * Adjusted code to the fact that concept of transactional sentinel was obsoleted by concept of lock duration. - Removed CF_PROTECT_AGAINST_GRL flag as it is no longer necessary. New GRL implementation acquires protection against global read lock automagically when statement acquires metadata locks on tables or other objects it is going to change. sql/sql_db.cc: Adjusted code to the fact that one now needs specify duration of lock when initializing MDL_request. sql/sql_handler.cc: Removed call to broadcast_refresh() function. It is no longer needed with new GRL implementation. Adjusted code after introducing duration concept for metadata locks. Particularly to the fact transactional sentinel was replaced with explicit duration. sql/sql_handler.h: Renamed mysql_ha_move_tickets_after_trans_sentinel() to mysql_ha_set_explicit_lock_duration() after transactional sentinel was obsoleted by locks with explicit duration. sql/sql_insert.cc: Adjusted code handling delaying inserts after switching to new GRL implementation. Now connection thread initiating delayed insert has to acquire global IX lock in addition to metadata lock on table being inserted into. This IX lock protects against GRL and similarly to SW lock on table being inserted into has to be passed to handler thread in order to avoid deadlocks. sql/sql_lex.cc: LEX::protect_against_global_read_lock member is no longer necessary since protection against GRL is automatically taken by code acquiring metadata locks/opening tables. sql/sql_lex.h: LEX::protect_against_global_read_lock member is no longer necessary since protection against GRL is automatically taken by code acquiring metadata locks/opening tables. sql/sql_parse.cc: - Implemented support for new approach to acquiring protection against global read lock. We no longer acquire such protection explicitly on the basis of statement flags. Instead we always rely on code which is responsible for acquiring metadata locks on object to be changed acquiring this protection. This is achieved by acquiring global IX metadata lock with statement duration. This lock is automatically released at the end of statement execution. - Changed implementation of CREATE/DROP PROCEDURE/FUNCTION not to release metadata locks and thus protection against of GRL in the middle of statement execution. - Adjusted code to the fact that one now needs specify duration of lock when initializing MDL_request and to the fact that savepoints for MDL subsystem are now represented by MDL_savepoint class. sql/sql_prepare.cc: Adjusted code to the to the fact that savepoints for MDL subsystem are now represented by MDL_savepoint class. sql/sql_rename.cc: With new GRL implementation there is no need to explicitly acquire protection against GRL before renaming tables. This happens automatically in code which acquires metadata locks on tables being renamed. sql/sql_show.cc: Adjusted code to the fact that one now needs specify duration of lock when initializing MDL_request and to the fact that savepoints for MDL subsystem are now represented by MDL_savepoint class. sql/sql_table.cc: - With new GRL implementation there is no need to explicitly acquire protection against GRL before dropping tables. This happens automatically in code which acquires metadata locks on tables being dropped. - Changed mysql_alter_table() not to release lock on new table name explicitly and to rely on automatic release of locks at the end of statement instead. This was necessary since now MDL_context::release_lock() is supported only for locks for explicit duration. sql/sql_trigger.cc: With new GRL implementation there is no need to explicitly acquire protection against GRL before changing table triggers. This happens automatically in code which acquires metadata locks on tables which triggers are to be changed. sql/sql_update.cc: Fix bug exposed by GRL testing. During prepare phase acquire only S metadata locks instead of SW locks to keep prepare of multi-UPDATE compatible with concurrent LOCK TABLES WRITE and global read lock. sql/sql_view.cc: With new GRL implementation there is no need to explicitly acquire protection against GRL before creating view. This happens automatically in code which acquires metadata lock on view to be created. sql/sql_yacc.yy: LEX::protect_against_global_read_lock member is no longer necessary since protection against GRL is automatically taken by code acquiring metadata locks/opening tables. sql/table.cc: Adjusted code to the fact that one now needs specify duration of lock when initializing MDL_request. sql/table.h: Adjusted code to the fact that one now needs specify duration of lock when initializing MDL_request. sql/transaction.cc: Replaced custom implementation of global read lock with one based on metadata locks. Consequently when doing commit instead of calling method of Global_read_lock class to acquire protection against GRL we simply acquire IX in COMMIT namespace. Also adjusted code to the fact that MDL savepoint is now represented by MDL_savepoint class.
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extern uint volatile thread_count;
extern uint connection_count;
extern my_bool opt_safe_user_create;
extern my_bool opt_safe_show_db, opt_local_infile, opt_myisam_use_mmap;
extern my_bool opt_slave_compressed_protocol, use_temp_pool;
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extern ulong slave_exec_mode_options;
extern ulonglong slave_type_conversions_options;
extern my_bool read_only, opt_readonly;
extern my_bool lower_case_file_system;
extern my_bool opt_enable_named_pipe, opt_sync_frm, opt_allow_suspicious_udfs;
extern my_bool opt_secure_auth;
extern char* opt_secure_file_priv;
extern char* opt_secure_backup_file_priv;
extern size_t opt_secure_backup_file_priv_len;
extern my_bool opt_log_slow_admin_statements, opt_log_slow_slave_statements;
extern my_bool sp_automatic_privileges, opt_noacl;
extern my_bool opt_old_style_user_limits, trust_function_creators;
extern uint opt_crash_binlog_innodb;
extern char *shared_memory_base_name, *mysqld_unix_port;
extern my_bool opt_enable_shared_memory;
extern char *default_tz_name;
extern Time_zone *default_tz;
extern char *default_storage_engine;
extern bool opt_endinfo, using_udf_functions;
extern my_bool locked_in_memory;
extern bool opt_using_transactions;
extern ulong current_pid;
extern ulong expire_logs_days;
extern my_bool relay_log_recovery;
extern uint sync_binlog_period, sync_relaylog_period,
sync_relayloginfo_period, sync_masterinfo_period;
extern ulong opt_tc_log_size, tc_log_max_pages_used, tc_log_page_size;
extern ulong tc_log_page_waits;
extern my_bool relay_log_purge, opt_innodb_safe_binlog, opt_innodb;
extern my_bool relay_log_recovery;
extern uint test_flags,select_errors,ha_open_options;
extern uint protocol_version, mysqld_port, dropping_tables;
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extern ulong delay_key_write_options;
extern char *opt_logname, *opt_slow_logname;
extern char *opt_backup_history_logname, *opt_backup_progress_logname,
*opt_backup_settings_name;
extern const char *log_output_str;
extern const char *log_backup_output_str;
extern char *mysql_home_ptr, *pidfile_name_ptr;
extern char glob_hostname[FN_REFLEN], mysql_home[FN_REFLEN];
extern char pidfile_name[FN_REFLEN], system_time_zone[30], *opt_init_file;
extern char default_logfile_name[FN_REFLEN];
extern char log_error_file[FN_REFLEN], *opt_tc_log_file;
extern const double log_10[309];
extern ulonglong keybuff_size;
extern ulonglong thd_startup_options;
extern ulong thread_id;
extern ulong binlog_cache_use, binlog_cache_disk_use;
BUG#57275 binlog_cache_size affects trx- and stmt-cache and gets twice the expected memory After the WL#2687, the binlog_cache_size and max_binlog_cache_size affect both the stmt-cache and the trx-cache. This means that the resource used is twice the amount expected/defined by the user. The binlog_cache_use is incremented when the stmt-cache or the trx-cache is used and binlog_cache_disk_use is incremented when the disk space from the stmt-cache or the trx-cache is used. This behavior does not allow to distinguish which cache may be harming performance due to the extra disk accesses and needs to have its in-memory cache increased. To fix the problem, we introduced two new options and status variables related to the stmt-cache: Options: . binlog_stmt_cache_size . max_binlog_stmt_cache_size Status Variables: . binlog_stmt_cache_use . binlog_stmt_cache_disk_use So there are . binlog_cache_size that defines the size of the transactional cache for updates to transactional engines for the binary log. . binlog_stmt_cache_size that defines the size of the statement cache for updates to non-transactional engines for the binary log. . max_binlog_cache_size that sets the total size of the transactional cache. . max_binlog_stmt_cache_size that sets the total size of the statement cache. . binlog_cache_use that identifies the number of transactions that used the temporary transactional binary log cache. . binlog_cache_disk_use that identifies the number of transactions that used the temporary transactional binary log cache but that exceeded the value of binlog_cache_size. . binlog_stmt_cache_use that identifies the number of statements that used the temporary non-transactional binary log cache. . binlog_stmt_cache_disk_use that identifies the number of statements that used the temporary non-transactional binary log cache but that exceeded the value of binlog_stmt_cache_size. include/my_sys.h: Updated message on disk_writes' usage. mysql-test/extra/binlog_tests/binlog_cache_stat.test: Updated the test case and added code to check the new status variables binlog_stmt_cache_use and binlog_stmt_cache_disk_use. mysql-test/extra/rpl_tests/rpl_binlog_max_cache_size.test: Updated the test case to use the new system variables max_binlog_stmt_cache_size and binlog_stmt_cache_size. mysql-test/r/mysqld--help-notwin.result: Updated the result file. mysql-test/suite/binlog/r/binlog_mixed_cache_stat.result: Updated the result file. mysql-test/suite/binlog/r/binlog_row_cache_stat.result: Updated the result file. mysql-test/suite/binlog/r/binlog_stm_cache_stat.result: Updated the result file. mysql-test/suite/rpl/r/rpl_mixed_binlog_max_cache_size.result: Update the result file. mysql-test/suite/rpl/r/rpl_row_binlog_max_cache_size.result: Update the result file. mysql-test/suite/rpl/r/rpl_stm_binlog_max_cache_size.result: Updated the result file. mysql-test/suite/sys_vars/inc/binlog_stmt_cache_size_basic.inc: Added a test case to check the binlog_stmt_cache_size. mysql-test/suite/sys_vars/r/binlog_stmt_cache_size_basic_32.result: Updated the result file. mysql-test/suite/sys_vars/r/binlog_stmt_cache_size_basic_64.result: Updated the result file. mysql-test/suite/sys_vars/r/max_binlog_stmt_cache_size_basic.result: Updated the result file. mysql-test/suite/sys_vars/t/binlog_stmt_cache_size_basic_32.test: Added a test case to check the binlog_stmt_cache_size. mysql-test/suite/sys_vars/t/binlog_stmt_cache_size_basic_64.test: Added a test case to check the binlog_stmt_cache_size. mysql-test/suite/sys_vars/t/max_binlog_cache_size_func-master.opt: Removed because there is no test case max_binlog_cache_size_func. mysql-test/suite/sys_vars/t/max_binlog_stmt_cache_size_basic.test: Added a test case to check the system variable max_binlog_stmt_cache_size. sql/log.cc: There two main changes in here: . Changed the set_write_error() as an error message is set according to the type of the cache. . Created the function set_binlog_cache_info where references to the appropriate status and system variables are set and the server can smoothly compute statistics and set the maximum size for each cache. sql/log.h: Changed the signature of the function in order to identify the error message to be printed out as there is a different error code for each type of cache. sql/mysqld.cc: Added new status variables binlog_stmt_cache_use and binlog_stmt_cache_disk_use. sql/mysqld.h: Added new system variables max_binlog_stmt_cache_size and binlog_stmt_cache_size. sql/share/errmsg-utf8.txt: Added new error message related to the statement cache. sql/sys_vars.cc: Added new system variables max_binlog_stmt_cache_size and binlog_stmt_cache_size.
2010-11-05 18:42:37 +01:00
extern ulong binlog_stmt_cache_use, binlog_stmt_cache_disk_use;
extern ulong aborted_threads,aborted_connects;
extern ulong delayed_insert_timeout;
extern ulong delayed_insert_limit, delayed_queue_size;
extern ulong delayed_insert_threads, delayed_insert_writes;
extern ulong delayed_rows_in_use,delayed_insert_errors;
extern ulong slave_open_temp_tables;
extern ulong query_cache_size, query_cache_min_res_unit;
extern ulong slow_launch_threads, slow_launch_time;
extern ulong table_cache_size, table_def_size;
extern MYSQL_PLUGIN_IMPORT ulong max_connections;
extern ulong max_connect_errors, connect_timeout;
extern my_bool slave_allow_batching;
extern my_bool allow_slave_start;
extern LEX_CSTRING reason_slave_blocked;
extern ulong slave_trans_retries;
extern uint slave_net_timeout;
extern uint max_user_connections;
extern ulong what_to_log,flush_time;
extern ulong max_prepared_stmt_count, prepared_stmt_count;
BUG#57275 binlog_cache_size affects trx- and stmt-cache and gets twice the expected memory After the WL#2687, the binlog_cache_size and max_binlog_cache_size affect both the stmt-cache and the trx-cache. This means that the resource used is twice the amount expected/defined by the user. The binlog_cache_use is incremented when the stmt-cache or the trx-cache is used and binlog_cache_disk_use is incremented when the disk space from the stmt-cache or the trx-cache is used. This behavior does not allow to distinguish which cache may be harming performance due to the extra disk accesses and needs to have its in-memory cache increased. To fix the problem, we introduced two new options and status variables related to the stmt-cache: Options: . binlog_stmt_cache_size . max_binlog_stmt_cache_size Status Variables: . binlog_stmt_cache_use . binlog_stmt_cache_disk_use So there are . binlog_cache_size that defines the size of the transactional cache for updates to transactional engines for the binary log. . binlog_stmt_cache_size that defines the size of the statement cache for updates to non-transactional engines for the binary log. . max_binlog_cache_size that sets the total size of the transactional cache. . max_binlog_stmt_cache_size that sets the total size of the statement cache. . binlog_cache_use that identifies the number of transactions that used the temporary transactional binary log cache. . binlog_cache_disk_use that identifies the number of transactions that used the temporary transactional binary log cache but that exceeded the value of binlog_cache_size. . binlog_stmt_cache_use that identifies the number of statements that used the temporary non-transactional binary log cache. . binlog_stmt_cache_disk_use that identifies the number of statements that used the temporary non-transactional binary log cache but that exceeded the value of binlog_stmt_cache_size. include/my_sys.h: Updated message on disk_writes' usage. mysql-test/extra/binlog_tests/binlog_cache_stat.test: Updated the test case and added code to check the new status variables binlog_stmt_cache_use and binlog_stmt_cache_disk_use. mysql-test/extra/rpl_tests/rpl_binlog_max_cache_size.test: Updated the test case to use the new system variables max_binlog_stmt_cache_size and binlog_stmt_cache_size. mysql-test/r/mysqld--help-notwin.result: Updated the result file. mysql-test/suite/binlog/r/binlog_mixed_cache_stat.result: Updated the result file. mysql-test/suite/binlog/r/binlog_row_cache_stat.result: Updated the result file. mysql-test/suite/binlog/r/binlog_stm_cache_stat.result: Updated the result file. mysql-test/suite/rpl/r/rpl_mixed_binlog_max_cache_size.result: Update the result file. mysql-test/suite/rpl/r/rpl_row_binlog_max_cache_size.result: Update the result file. mysql-test/suite/rpl/r/rpl_stm_binlog_max_cache_size.result: Updated the result file. mysql-test/suite/sys_vars/inc/binlog_stmt_cache_size_basic.inc: Added a test case to check the binlog_stmt_cache_size. mysql-test/suite/sys_vars/r/binlog_stmt_cache_size_basic_32.result: Updated the result file. mysql-test/suite/sys_vars/r/binlog_stmt_cache_size_basic_64.result: Updated the result file. mysql-test/suite/sys_vars/r/max_binlog_stmt_cache_size_basic.result: Updated the result file. mysql-test/suite/sys_vars/t/binlog_stmt_cache_size_basic_32.test: Added a test case to check the binlog_stmt_cache_size. mysql-test/suite/sys_vars/t/binlog_stmt_cache_size_basic_64.test: Added a test case to check the binlog_stmt_cache_size. mysql-test/suite/sys_vars/t/max_binlog_cache_size_func-master.opt: Removed because there is no test case max_binlog_cache_size_func. mysql-test/suite/sys_vars/t/max_binlog_stmt_cache_size_basic.test: Added a test case to check the system variable max_binlog_stmt_cache_size. sql/log.cc: There two main changes in here: . Changed the set_write_error() as an error message is set according to the type of the cache. . Created the function set_binlog_cache_info where references to the appropriate status and system variables are set and the server can smoothly compute statistics and set the maximum size for each cache. sql/log.h: Changed the signature of the function in order to identify the error message to be printed out as there is a different error code for each type of cache. sql/mysqld.cc: Added new status variables binlog_stmt_cache_use and binlog_stmt_cache_disk_use. sql/mysqld.h: Added new system variables max_binlog_stmt_cache_size and binlog_stmt_cache_size. sql/share/errmsg-utf8.txt: Added new error message related to the statement cache. sql/sys_vars.cc: Added new system variables max_binlog_stmt_cache_size and binlog_stmt_cache_size.
2010-11-05 18:42:37 +01:00
extern ulong open_files_limit;
extern ulong binlog_cache_size, binlog_stmt_cache_size;
extern ulonglong max_binlog_cache_size, max_binlog_stmt_cache_size;
extern ulong max_binlog_size, max_relay_log_size;
extern ulong opt_binlog_rows_event_max_size;
extern ulong rpl_recovery_rank, thread_cache_size;
extern ulong back_log;
extern char language[FN_REFLEN];
extern ulong server_id, concurrency;
extern time_t server_start_time, flush_status_time;
extern char *opt_mysql_tmpdir, mysql_charsets_dir[];
extern int mysql_unpacked_real_data_home_len;
extern MYSQL_PLUGIN_IMPORT MY_TMPDIR mysql_tmpdir_list;
extern const char *first_keyword, *delayed_user, *binary_keyword;
extern MYSQL_PLUGIN_IMPORT const char *my_localhost;
extern MYSQL_PLUGIN_IMPORT const char **errmesg; /* Error messages */
extern const char *myisam_recover_options_str;
extern const char *in_left_expr_name, *in_additional_cond, *in_having_cond;
extern SHOW_VAR status_vars[];
extern struct system_variables max_system_variables;
extern struct system_status_var global_status_var;
extern struct rand_struct sql_rand;
extern const char *opt_date_time_formats[];
extern handlerton *partition_hton;
extern handlerton *myisam_hton;
extern handlerton *heap_hton;
extern const char *load_default_groups[];
extern struct my_option my_long_options[];
extern int mysqld_server_started;
extern int orig_argc;
extern char **orig_argv;
extern pthread_attr_t connection_attrib;
extern MYSQL_FILE *bootstrap_file;
extern my_bool old_mode;
extern LEX_STRING opt_init_connect, opt_init_slave;
extern int bootstrap_error;
extern I_List<THD> threads;
extern char err_shared_dir[];
extern TYPELIB thread_handling_typelib;
extern my_decimal decimal_zero;
extern pthread_key(MEM_ROOT**,THR_MALLOC);
#ifdef HAVE_PSI_INTERFACE
#ifdef HAVE_MMAP
extern PSI_mutex_key key_PAGE_lock, key_LOCK_sync, key_LOCK_active,
key_LOCK_pool;
#endif /* HAVE_MMAP */
#ifdef HAVE_OPENSSL
extern PSI_mutex_key key_LOCK_des_key_file;
#endif
extern PSI_mutex_key key_BINLOG_LOCK_index, key_BINLOG_LOCK_prep_xids,
key_delayed_insert_mutex, key_hash_filo_lock, key_LOCK_active_mi,
key_LOCK_connection_count, key_LOCK_crypt, key_LOCK_delayed_create,
key_LOCK_delayed_insert, key_LOCK_delayed_status, key_LOCK_error_log,
Patch that refactors global read lock implementation and fixes bug #57006 "Deadlock between HANDLER and FLUSH TABLES WITH READ LOCK" and bug #54673 "It takes too long to get readlock for 'FLUSH TABLES WITH READ LOCK'". The first bug manifested itself as a deadlock which occurred when a connection, which had some table open through HANDLER statement, tried to update some data through DML statement while another connection tried to execute FLUSH TABLES WITH READ LOCK concurrently. What happened was that FTWRL in the second connection managed to perform first step of GRL acquisition and thus blocked all upcoming DML. After that it started to wait for table open through HANDLER statement to be flushed. When the first connection tried to execute DML it has started to wait for GRL/the second connection creating deadlock. The second bug manifested itself as starvation of FLUSH TABLES WITH READ LOCK statements in cases when there was a constant stream of concurrent DML statements (in two or more connections). This has happened because requests for protection against GRL which were acquired by DML statements were ignoring presence of pending GRL and thus the latter was starved. This patch solves both these problems by re-implementing GRL using metadata locks. Similar to the old implementation acquisition of GRL in new implementation is two-step. During the first step we block all concurrent DML and DDL statements by acquiring global S metadata lock (each DML and DDL statement acquires global IX lock for its duration). During the second step we block commits by acquiring global S lock in COMMIT namespace (commit code acquires global IX lock in this namespace). Note that unlike in old implementation acquisition of protection against GRL in DML and DDL is semi-automatic. We assume that any statement which should be blocked by GRL will either open and acquires write-lock on tables or acquires metadata locks on objects it is going to modify. For any such statement global IX metadata lock is automatically acquired for its duration. The first problem is solved because waits for GRL become visible to deadlock detector in metadata locking subsystem and thus deadlocks like one in the first bug become impossible. The second problem is solved because global S locks which are used for GRL implementation are given preference over IX locks which are acquired by concurrent DML (and we can switch to fair scheduling in future if needed). Important change: FTWRL/GRL no longer blocks DML and DDL on temporary tables. Before this patch behavior was not consistent in this respect: in some cases DML/DDL statements on temporary tables were blocked while in others they were not. Since the main use cases for FTWRL are various forms of backups and temporary tables are not preserved during backups we have opted for consistently allowing DML/DDL on temporary tables during FTWRL/GRL. Important change: This patch changes thread state names which are used when DML/DDL of FTWRL is waiting for global read lock. It is now either "Waiting for global read lock" or "Waiting for commit lock" depending on the stage on which FTWRL is. Incompatible change: To solve deadlock in events code which was exposed by this patch we have to replace LOCK_event_metadata mutex with metadata locks on events. As result we have to prohibit DDL on events under LOCK TABLES. This patch also adds extensive test coverage for interaction of DML/DDL and FTWRL. Performance of new and old global read lock implementations in sysbench tests were compared. There were no significant difference between new and old implementations. mysql-test/include/check_ftwrl_compatible.inc: Added helper script which allows to check that a statement is compatible with FLUSH TABLES WITH READ LOCK. mysql-test/include/check_ftwrl_incompatible.inc: Added helper script which allows to check that a statement is incompatible with FLUSH TABLES WITH READ LOCK. mysql-test/include/handler.inc: Adjusted test case to the fact that now DROP TABLE closes open HANDLERs for the table to be dropped before checking if there active FTWRL in this connection. mysql-test/include/wait_show_condition.inc: Fixed small error in the timeout message. The correct name of variable used as parameter for this script is "$condition" and not "$wait_condition". mysql-test/r/delayed.result: Added test coverage for scenario which triggered assert in metadata locking subsystem. mysql-test/r/events_2.result: Updated test results after prohibiting event DDL operations under LOCK TABLES. mysql-test/r/flush.result: Added test coverage for bug #57006 "Deadlock between HANDLER and FLUSH TABLES WITH READ LOCK". mysql-test/r/flush_read_lock.result: Added test coverage for various aspects of FLUSH TABLES WITH READ LOCK functionality. mysql-test/r/flush_read_lock_kill.result: Adjusted test case after replacing custom global read lock implementation with one based on metadata locks. Use new debug_sync point. Do not disable concurrent inserts as now InnoDB we always use InnoDB table. mysql-test/r/handler_innodb.result: Adjusted test case to the fact that now DROP TABLE closes open HANDLERs for the table to be dropped before checking if there active FTWRL in this connection. mysql-test/r/handler_myisam.result: Adjusted test case to the fact that now DROP TABLE closes open HANDLERs for the table to be dropped before checking if there active FTWRL in this connection. mysql-test/r/mdl_sync.result: Adjusted test case after replacing custom global read lock implementation with one based on metadata locks. Replaced usage of GRL-specific debug_sync's with appropriate sync points in MDL subsystem. mysql-test/suite/perfschema/r/dml_setup_instruments.result: Updated test results after removing global COND_global_read_lock condition variable. mysql-test/suite/perfschema/r/func_file_io.result: Ensure that this test doesn't affect subsequent tests. At the end of its execution enable back P_S instrumentation which this test disables at some point. mysql-test/suite/perfschema/r/func_mutex.result: Ensure that this test doesn't affect subsequent tests. At the end of its execution enable back P_S instrumentation which this test disables at some point. mysql-test/suite/perfschema/r/global_read_lock.result: Adjusted test case to take into account that new GRL implementation is based on MDL. mysql-test/suite/perfschema/r/server_init.result: Adjusted test case after replacing custom global read lock implementation with one based on MDL and replacing LOCK_event_metadata mutex with metadata lock. mysql-test/suite/perfschema/t/func_file_io.test: Ensure that this test doesn't affect subsequent tests. At the end of its execution enable back P_S instrumentation which this test disables at some point. mysql-test/suite/perfschema/t/func_mutex.test: Ensure that this test doesn't affect subsequent tests. At the end of its execution enable back P_S instrumentation which this test disables at some point. mysql-test/suite/perfschema/t/global_read_lock.test: Adjusted test case to take into account that new GRL implementation is based on MDL. mysql-test/suite/perfschema/t/server_init.test: Adjusted test case after replacing custom global read lock implementation with one based on MDL and replacing LOCK_event_metadata mutex with metadata lock. mysql-test/suite/rpl/r/rpl_tmp_table_and_DDL.result: Updated test results after prohibiting event DDL under LOCK TABLES. mysql-test/t/delayed.test: Added test coverage for scenario which triggered assert in metadata locking subsystem. mysql-test/t/events_2.test: Updated test case after prohibiting event DDL operations under LOCK TABLES. mysql-test/t/flush.test: Added test coverage for bug #57006 "Deadlock between HANDLER and FLUSH TABLES WITH READ LOCK". mysql-test/t/flush_block_commit.test: Adjusted test case after changing thread state name which is used when COMMIT waits for FLUSH TABLES WITH READ LOCK from "Waiting for release of readlock" to "Waiting for commit lock". mysql-test/t/flush_block_commit_notembedded.test: Adjusted test case after changing thread state name which is used when DML waits for FLUSH TABLES WITH READ LOCK. Now we use "Waiting for global read lock" in this case. mysql-test/t/flush_read_lock.test: Added test coverage for various aspects of FLUSH TABLES WITH READ LOCK functionality. mysql-test/t/flush_read_lock_kill-master.opt: We no longer need to use make_global_read_lock_block_commit_loop debug tag in this test. Instead we rely on an appropriate debug_sync point in MDL code. mysql-test/t/flush_read_lock_kill.test: Adjusted test case after replacing custom global read lock implementation with one based on metadata locks. Use new debug_sync point. Do not disable concurrent inserts as now InnoDB we always use InnoDB table. mysql-test/t/lock_multi.test: Adjusted test case after changing thread state names which are used when DML or DDL waits for FLUSH TABLES WITH READ LOCK to "Waiting for global read lock". mysql-test/t/mdl_sync.test: Adjusted test case after replacing custom global read lock implementation with one based on metadata locks. Replaced usage of GRL-specific debug_sync's with appropriate sync points in MDL subsystem. Updated thread state names which are used when DDL waits for FTWRL. mysql-test/t/trigger_notembedded.test: Adjusted test case after changing thread state names which are used when DML or DDL waits for FLUSH TABLES WITH READ LOCK to "Waiting for global read lock". sql/event_data_objects.cc: Removed Event_queue_element::status/last_executed_changed members and Event_queue_element::update_timing_fields() method. We no longer use this class for updating mysql.events once event is chosen for execution. Accesses to instances of this class in scheduler thread require protection by Event_queue::LOCK_event_queue mutex and we try to avoid updating table while holding this lock. sql/event_data_objects.h: Removed Event_queue_element::status/last_executed_changed members and Event_queue_element::update_timing_fields() method. We no longer use this class for updating mysql.events once event is chosen for execution. Accesses to instances of this class in scheduler thread require protection by Event_queue::LOCK_event_queue mutex and we try to avoid updating table while holding this lock. sql/event_db_repository.cc: - Changed Event_db_repository methods to not release all metadata locks once they are done updating mysql.events table. This allows to keep metadata lock protecting against GRL and lock protecting particular event around until corresponding DDL statement is written to the binary log. - Removed logic for conditional update of "status" and "last_executed" fields from update_timing_fields_for_event() method. In the only case when this method is called now "last_executed" is always modified and tracking change of "status" is too much hassle. sql/event_db_repository.h: Removed logic for conditional update of "status" and "last_executed" fields from Event_db_repository:: update_timing_fields_for_event() method. In the only case when this method is called now "last_executed" is always modified and tracking change of "status" field is too much hassle. sql/event_queue.cc: Changed event scheduler code not to update mysql.events table while holding Event_queue::LOCK_event_queue mutex. Doing so led to a deadlock with a new GRL implementation. This deadlock didn't occur with old implementation due to fact that code acquiring protection against GRL ignored pending GRL requests (which lead to GRL starvation). One of goals of new implementation is to disallow GRL starvation and so we have to solve problem with this deadlock in a different way. sql/events.cc: Changed methods of Events class to acquire protection against GRL while perfoming DDL statement and keep it until statement is written to the binary log. Unfortunately this step together with new GRL implementation exposed deadlock involving Events::LOCK_event_metadata and GRL. To solve it Events::LOCK_event_metadata mutex was replaced with a metadata lock on event. As a side-effect events DDL has to be prohibited under LOCK TABLES even in cases when mysql.events table was explicitly locked for write. sql/events.h: Replaced Events::LOCK_event_metadata mutex with a metadata lock on event. sql/ha_ndbcluster.cc: Updated code after replacing custom global read lock implementation with one based on MDL. Since MDL subsystem should now be able to detect deadlocks involving metadata locks and GRL there is no need for special handling of active GRL. sql/handler.cc: Replaced custom implementation of global read lock with one based on metadata locks. Consequently when doing commit instead of calling method of Global_read_lock class to acquire protection against GRL we simply acquire IX in COMMIT namespace. sql/lock.cc: Replaced custom implementation of global read lock with one based on metadata locks. This step allows to expose wait for GRL to deadlock detector of MDL subsystem and thus succesfully resolve deadlocks similar to one behind bug #57006 "Deadlock between HANDLER and FLUSH TABLES WITH READ LOCK". It also solves problem with GRL starvation described in bug #54673 "It takes too long to get readlock for 'FLUSH TABLES WITH READ LOCK'" since metadata locks used by GRL give preference to FTWRL statement instead of DML statements (if needed in future this can be changed to fair scheduling). Similar to old implementation of acquisition of GRL is two-step. During the first step we block all concurrent DML and DDL statements by acquiring global S metadata lock (each DML and DDL statement acquires global IX lock for its duration). During the second step we block commits by acquiring global S lock in COMMIT namespace (commit code acquires global IX lock in this namespace). Note that unlike in old implementation acquisition of protection against GRL in DML and DDL is semi-automatic. We assume that any statement which should be blocked by GRL will either open and acquires write-lock on tables or acquires metadata locks on objects it is going to modify. For any such statement global IX metadata lock is automatically acquired for its duration. To support this change: - Global_read_lock::lock/unlock_global_read_lock and make_global_read_lock_block_commit methods were changed accordingly. - Global_read_lock::wait_if_global_read_lock() and start_waiting_global_read_lock() methods were dropped. It is now responsibility of code acquiring metadata locks opening tables to acquire protection against GRL by explicitly taking global IX lock with statement duration. - Global variables, mutex and condition variable used by old implementation was removed. - lock_routine_name() was changed to use statement duration for its global IX lock. It was also renamed to lock_object_name() as it now also used to take metadata locks on events. - Global_read_lock::set_explicit_lock_duration() was added which allows not to release locks used for GRL when leaving prelocked mode. sql/lock.h: - Renamed lock_routine_name() to lock_object_name() and changed its signature to allow its usage for events. - Removed broadcast_refresh() function. It is no longer needed with new GRL implementation. sql/log_event.cc: Release metadata locks with statement duration at the end of processing legacy event for LOAD DATA. This ensures that replication thread processing such event properly releases its protection against global read lock. sql/mdl.cc: Changed MDL subsystem to support new MDL-based implementation of global read lock. Added COMMIT and EVENTS namespaces for metadata locks. Changed thread state name for GLOBAL namespace to "Waiting for global read lock". Optimized MDL_map::find_or_insert() method to avoid taking m_mutex mutex when looking up MDL_lock objects for GLOBAL or COMMIT namespaces. We keep pre-created MDL_lock objects for these namespaces around and simply return pointers to these global objects when needed. Changed MDL_lock/MDL_scoped_lock to properly handle notification of insert delayed handler threads when FTWRL takes global S lock. Introduced concept of lock duration. In addition to locks with transaction duration which work in the way which is similar to how locks worked before (i.e. they are released at the end of transaction), locks with statement and explicit duration were introduced. Locks with statement duration are automatically released at the end of statement. Locks with explicit duration require explicit release and obsolete concept of transactional sentinel. * Changed MDL_request and MDL_ticket classes to support notion of duration. * Changed MDL_context to keep locks with different duration in different lists. Changed code handling ticket list to take this into account. * Changed methods responsible for releasing locks to take into account duration of tickets. Particularly public MDL_context::release_lock() method now only can release tickets with explicit duration (there is still internal method which allows to specify duration). To release locks with statement or transaction duration one have to use release_statement/transactional_locks() methods. * Concept of savepoint for MDL subsystem now has to take into account locks with statement duration. Consequently MDL_savepoint class was introduced and methods working with savepoints were updated accordingly. * Added methods which allow to set duration for one or all locks in the context. sql/mdl.h: Changed MDL subsystem to support new MDL-based implementation of global read lock. Added COMMIT and EVENTS namespaces for metadata locks. Introduced concept of lock duration. In addition to locks with transaction duration which work in the way which is similar to how locks worked before (i.e. they are released at the end of transaction), locks with statement and explicit duration were introduced. Locks with statement duration are automatically released at the end of statement. Locks with explicit duration require explicit release and obsolete concept of transactional sentinel. * Changed MDL_request and MDL_ticket classes to support notion of duration. * Changed MDL_context to keep locks with different duration in different lists. Changed code handling ticket list to take this into account. * Changed methods responsible for releasing locks to take into account duration of tickets. Particularly public MDL_context::release_lock() method now only can release tickets with explicit duration (there is still internal method which allows to specify duration). To release locks with statement or transaction duration one have to use release_statement/transactional_locks() methods. * Concept of savepoint for MDL subsystem now has to take into account locks with statement duration. Consequently MDL_savepoint class was introduced and methods working with savepoints were updated accordingly. * Added methods which allow to set duration for one or all locks in the context. sql/mysqld.cc: Removed global mutex and condition variables which were used by old implementation of GRL. Also we no longer need to initialize Events::LOCK_event_metadata mutex as it was replaced with metadata locks on events. sql/mysqld.h: Removed global variable, mutex and condition variables which were used by old implementation of GRL. sql/rpl_rli.cc: When slave thread closes tables which were open for handling of RBR events ensure that it releases global IX lock which was acquired as protection against GRL. sql/sp.cc: Adjusted code to the new signature of lock_object/routine_name(), to the fact that one now needs specify duration of lock when initializing MDL_request and to the fact that savepoints for MDL subsystem are now represented by MDL_savepoint class. sql/sp_head.cc: Ensure that statements in stored procedures release statement metadata locks and thus release their protectiong against GRL in proper moment in time. Adjusted code to the fact that one now needs specify duration of lock when initializing MDL_request. sql/sql_admin.cc: Adjusted code to the fact that one now needs specify duration of lock when initializing MDL_request. sql/sql_base.cc: - Implemented support for new approach to acquiring protection against global read lock. We no longer acquire such protection explicitly on the basis of statement flags. Instead we always rely on code which is responsible for acquiring metadata locks on object to be changed acquiring this protection. This is achieved by acquiring global IX metadata lock with statement duration. Code doing this also responsible for checking that current connection has no active GRL by calling an Global_read_lock::can_acquire_protection() method. Changed code in open_table() and lock_table_names() accordingly. Note that as result of this change DDL and DML on temporary tables is always compatible with GRL (before it was incompatible in some cases and compatible in other cases). - To speed-up code acquiring protection against GRL introduced m_has_protection_against_grl member in Open_table_context class. It indicates that protection was already acquired sometime during open_tables() execution and new attempts can be skipped. - Thanks to new GRL implementation calls to broadcast_refresh() became unnecessary and were removed. - Adjusted code to the fact that one now needs specify duration of lock when initializing MDL_request and to the fact that savepoints for MDL subsystem are now represented by MDL_savepoint class. sql/sql_base.h: Adjusted code to the fact that savepoints for MDL subsystem are now represented by MDL_savepoint class. Also introduced Open_table_context::m_has_protection_against_grl member which allows to avoid acquiring protection against GRL while opening tables if such protection was already acquired. sql/sql_class.cc: Changed THD::leave_locked_tables_mode() after transactional sentinel for metadata locks was obsoleted by introduction of locks with explicit duration. sql/sql_class.h: - Adjusted code to the fact that savepoints for MDL subsystem are now represented by MDL_savepoint class. - Changed Global_read_lock class according to changes in global read lock implementation: * wait_if_global_read_lock and start_waiting_global_read_lock are now gone. Instead code needing protection against GRL has to acquire global IX metadata lock with statement duration itself. To help it new can_acquire_protection() was introduced. Also as result of the above change m_protection_count member is gone too. * Added m_mdl_blocks_commits_lock member to store metadata lock blocking commits. * Adjusted code to the fact that concept of transactional sentinel was obsoleted by concept of lock duration. - Removed CF_PROTECT_AGAINST_GRL flag as it is no longer necessary. New GRL implementation acquires protection against global read lock automagically when statement acquires metadata locks on tables or other objects it is going to change. sql/sql_db.cc: Adjusted code to the fact that one now needs specify duration of lock when initializing MDL_request. sql/sql_handler.cc: Removed call to broadcast_refresh() function. It is no longer needed with new GRL implementation. Adjusted code after introducing duration concept for metadata locks. Particularly to the fact transactional sentinel was replaced with explicit duration. sql/sql_handler.h: Renamed mysql_ha_move_tickets_after_trans_sentinel() to mysql_ha_set_explicit_lock_duration() after transactional sentinel was obsoleted by locks with explicit duration. sql/sql_insert.cc: Adjusted code handling delaying inserts after switching to new GRL implementation. Now connection thread initiating delayed insert has to acquire global IX lock in addition to metadata lock on table being inserted into. This IX lock protects against GRL and similarly to SW lock on table being inserted into has to be passed to handler thread in order to avoid deadlocks. sql/sql_lex.cc: LEX::protect_against_global_read_lock member is no longer necessary since protection against GRL is automatically taken by code acquiring metadata locks/opening tables. sql/sql_lex.h: LEX::protect_against_global_read_lock member is no longer necessary since protection against GRL is automatically taken by code acquiring metadata locks/opening tables. sql/sql_parse.cc: - Implemented support for new approach to acquiring protection against global read lock. We no longer acquire such protection explicitly on the basis of statement flags. Instead we always rely on code which is responsible for acquiring metadata locks on object to be changed acquiring this protection. This is achieved by acquiring global IX metadata lock with statement duration. This lock is automatically released at the end of statement execution. - Changed implementation of CREATE/DROP PROCEDURE/FUNCTION not to release metadata locks and thus protection against of GRL in the middle of statement execution. - Adjusted code to the fact that one now needs specify duration of lock when initializing MDL_request and to the fact that savepoints for MDL subsystem are now represented by MDL_savepoint class. sql/sql_prepare.cc: Adjusted code to the to the fact that savepoints for MDL subsystem are now represented by MDL_savepoint class. sql/sql_rename.cc: With new GRL implementation there is no need to explicitly acquire protection against GRL before renaming tables. This happens automatically in code which acquires metadata locks on tables being renamed. sql/sql_show.cc: Adjusted code to the fact that one now needs specify duration of lock when initializing MDL_request and to the fact that savepoints for MDL subsystem are now represented by MDL_savepoint class. sql/sql_table.cc: - With new GRL implementation there is no need to explicitly acquire protection against GRL before dropping tables. This happens automatically in code which acquires metadata locks on tables being dropped. - Changed mysql_alter_table() not to release lock on new table name explicitly and to rely on automatic release of locks at the end of statement instead. This was necessary since now MDL_context::release_lock() is supported only for locks for explicit duration. sql/sql_trigger.cc: With new GRL implementation there is no need to explicitly acquire protection against GRL before changing table triggers. This happens automatically in code which acquires metadata locks on tables which triggers are to be changed. sql/sql_update.cc: Fix bug exposed by GRL testing. During prepare phase acquire only S metadata locks instead of SW locks to keep prepare of multi-UPDATE compatible with concurrent LOCK TABLES WRITE and global read lock. sql/sql_view.cc: With new GRL implementation there is no need to explicitly acquire protection against GRL before creating view. This happens automatically in code which acquires metadata lock on view to be created. sql/sql_yacc.yy: LEX::protect_against_global_read_lock member is no longer necessary since protection against GRL is automatically taken by code acquiring metadata locks/opening tables. sql/table.cc: Adjusted code to the fact that one now needs specify duration of lock when initializing MDL_request. sql/table.h: Adjusted code to the fact that one now needs specify duration of lock when initializing MDL_request. sql/transaction.cc: Replaced custom implementation of global read lock with one based on metadata locks. Consequently when doing commit instead of calling method of Global_read_lock class to acquire protection against GRL we simply acquire IX in COMMIT namespace. Also adjusted code to the fact that MDL savepoint is now represented by MDL_savepoint class.
2010-11-11 18:11:05 +01:00
key_LOCK_gdl, key_LOCK_global_system_variables,
key_LOCK_logger, key_LOCK_manager,
key_LOCK_prepared_stmt_count,
key_LOCK_rpl_status, key_LOCK_server_started, key_LOCK_status,
key_LOCK_table_share, key_LOCK_thd_data,
key_LOCK_user_conn, key_LOCK_uuid_generator, key_LOG_LOCK_log,
key_master_info_data_lock, key_master_info_run_lock,
key_mutex_slave_reporting_capability_err_lock, key_relay_log_info_data_lock,
key_relay_log_info_log_space_lock, key_relay_log_info_run_lock,
key_structure_guard_mutex, key_TABLE_SHARE_LOCK_ha_data,
key_LOCK_error_messages, key_LOCK_thread_count, key_PARTITION_LOCK_auto_inc;
extern PSI_rwlock_key key_rwlock_LOCK_grant, key_rwlock_LOCK_logger,
key_rwlock_LOCK_sys_init_connect, key_rwlock_LOCK_sys_init_slave,
key_rwlock_LOCK_system_variables_hash, key_rwlock_query_cache_query_lock;
#ifdef HAVE_MMAP
extern PSI_cond_key key_PAGE_cond, key_COND_active, key_COND_pool;
#endif /* HAVE_MMAP */
extern PSI_cond_key key_BINLOG_COND_prep_xids, key_BINLOG_update_cond,
Patch that refactors global read lock implementation and fixes bug #57006 "Deadlock between HANDLER and FLUSH TABLES WITH READ LOCK" and bug #54673 "It takes too long to get readlock for 'FLUSH TABLES WITH READ LOCK'". The first bug manifested itself as a deadlock which occurred when a connection, which had some table open through HANDLER statement, tried to update some data through DML statement while another connection tried to execute FLUSH TABLES WITH READ LOCK concurrently. What happened was that FTWRL in the second connection managed to perform first step of GRL acquisition and thus blocked all upcoming DML. After that it started to wait for table open through HANDLER statement to be flushed. When the first connection tried to execute DML it has started to wait for GRL/the second connection creating deadlock. The second bug manifested itself as starvation of FLUSH TABLES WITH READ LOCK statements in cases when there was a constant stream of concurrent DML statements (in two or more connections). This has happened because requests for protection against GRL which were acquired by DML statements were ignoring presence of pending GRL and thus the latter was starved. This patch solves both these problems by re-implementing GRL using metadata locks. Similar to the old implementation acquisition of GRL in new implementation is two-step. During the first step we block all concurrent DML and DDL statements by acquiring global S metadata lock (each DML and DDL statement acquires global IX lock for its duration). During the second step we block commits by acquiring global S lock in COMMIT namespace (commit code acquires global IX lock in this namespace). Note that unlike in old implementation acquisition of protection against GRL in DML and DDL is semi-automatic. We assume that any statement which should be blocked by GRL will either open and acquires write-lock on tables or acquires metadata locks on objects it is going to modify. For any such statement global IX metadata lock is automatically acquired for its duration. The first problem is solved because waits for GRL become visible to deadlock detector in metadata locking subsystem and thus deadlocks like one in the first bug become impossible. The second problem is solved because global S locks which are used for GRL implementation are given preference over IX locks which are acquired by concurrent DML (and we can switch to fair scheduling in future if needed). Important change: FTWRL/GRL no longer blocks DML and DDL on temporary tables. Before this patch behavior was not consistent in this respect: in some cases DML/DDL statements on temporary tables were blocked while in others they were not. Since the main use cases for FTWRL are various forms of backups and temporary tables are not preserved during backups we have opted for consistently allowing DML/DDL on temporary tables during FTWRL/GRL. Important change: This patch changes thread state names which are used when DML/DDL of FTWRL is waiting for global read lock. It is now either "Waiting for global read lock" or "Waiting for commit lock" depending on the stage on which FTWRL is. Incompatible change: To solve deadlock in events code which was exposed by this patch we have to replace LOCK_event_metadata mutex with metadata locks on events. As result we have to prohibit DDL on events under LOCK TABLES. This patch also adds extensive test coverage for interaction of DML/DDL and FTWRL. Performance of new and old global read lock implementations in sysbench tests were compared. There were no significant difference between new and old implementations. mysql-test/include/check_ftwrl_compatible.inc: Added helper script which allows to check that a statement is compatible with FLUSH TABLES WITH READ LOCK. mysql-test/include/check_ftwrl_incompatible.inc: Added helper script which allows to check that a statement is incompatible with FLUSH TABLES WITH READ LOCK. mysql-test/include/handler.inc: Adjusted test case to the fact that now DROP TABLE closes open HANDLERs for the table to be dropped before checking if there active FTWRL in this connection. mysql-test/include/wait_show_condition.inc: Fixed small error in the timeout message. The correct name of variable used as parameter for this script is "$condition" and not "$wait_condition". mysql-test/r/delayed.result: Added test coverage for scenario which triggered assert in metadata locking subsystem. mysql-test/r/events_2.result: Updated test results after prohibiting event DDL operations under LOCK TABLES. mysql-test/r/flush.result: Added test coverage for bug #57006 "Deadlock between HANDLER and FLUSH TABLES WITH READ LOCK". mysql-test/r/flush_read_lock.result: Added test coverage for various aspects of FLUSH TABLES WITH READ LOCK functionality. mysql-test/r/flush_read_lock_kill.result: Adjusted test case after replacing custom global read lock implementation with one based on metadata locks. Use new debug_sync point. Do not disable concurrent inserts as now InnoDB we always use InnoDB table. mysql-test/r/handler_innodb.result: Adjusted test case to the fact that now DROP TABLE closes open HANDLERs for the table to be dropped before checking if there active FTWRL in this connection. mysql-test/r/handler_myisam.result: Adjusted test case to the fact that now DROP TABLE closes open HANDLERs for the table to be dropped before checking if there active FTWRL in this connection. mysql-test/r/mdl_sync.result: Adjusted test case after replacing custom global read lock implementation with one based on metadata locks. Replaced usage of GRL-specific debug_sync's with appropriate sync points in MDL subsystem. mysql-test/suite/perfschema/r/dml_setup_instruments.result: Updated test results after removing global COND_global_read_lock condition variable. mysql-test/suite/perfschema/r/func_file_io.result: Ensure that this test doesn't affect subsequent tests. At the end of its execution enable back P_S instrumentation which this test disables at some point. mysql-test/suite/perfschema/r/func_mutex.result: Ensure that this test doesn't affect subsequent tests. At the end of its execution enable back P_S instrumentation which this test disables at some point. mysql-test/suite/perfschema/r/global_read_lock.result: Adjusted test case to take into account that new GRL implementation is based on MDL. mysql-test/suite/perfschema/r/server_init.result: Adjusted test case after replacing custom global read lock implementation with one based on MDL and replacing LOCK_event_metadata mutex with metadata lock. mysql-test/suite/perfschema/t/func_file_io.test: Ensure that this test doesn't affect subsequent tests. At the end of its execution enable back P_S instrumentation which this test disables at some point. mysql-test/suite/perfschema/t/func_mutex.test: Ensure that this test doesn't affect subsequent tests. At the end of its execution enable back P_S instrumentation which this test disables at some point. mysql-test/suite/perfschema/t/global_read_lock.test: Adjusted test case to take into account that new GRL implementation is based on MDL. mysql-test/suite/perfschema/t/server_init.test: Adjusted test case after replacing custom global read lock implementation with one based on MDL and replacing LOCK_event_metadata mutex with metadata lock. mysql-test/suite/rpl/r/rpl_tmp_table_and_DDL.result: Updated test results after prohibiting event DDL under LOCK TABLES. mysql-test/t/delayed.test: Added test coverage for scenario which triggered assert in metadata locking subsystem. mysql-test/t/events_2.test: Updated test case after prohibiting event DDL operations under LOCK TABLES. mysql-test/t/flush.test: Added test coverage for bug #57006 "Deadlock between HANDLER and FLUSH TABLES WITH READ LOCK". mysql-test/t/flush_block_commit.test: Adjusted test case after changing thread state name which is used when COMMIT waits for FLUSH TABLES WITH READ LOCK from "Waiting for release of readlock" to "Waiting for commit lock". mysql-test/t/flush_block_commit_notembedded.test: Adjusted test case after changing thread state name which is used when DML waits for FLUSH TABLES WITH READ LOCK. Now we use "Waiting for global read lock" in this case. mysql-test/t/flush_read_lock.test: Added test coverage for various aspects of FLUSH TABLES WITH READ LOCK functionality. mysql-test/t/flush_read_lock_kill-master.opt: We no longer need to use make_global_read_lock_block_commit_loop debug tag in this test. Instead we rely on an appropriate debug_sync point in MDL code. mysql-test/t/flush_read_lock_kill.test: Adjusted test case after replacing custom global read lock implementation with one based on metadata locks. Use new debug_sync point. Do not disable concurrent inserts as now InnoDB we always use InnoDB table. mysql-test/t/lock_multi.test: Adjusted test case after changing thread state names which are used when DML or DDL waits for FLUSH TABLES WITH READ LOCK to "Waiting for global read lock". mysql-test/t/mdl_sync.test: Adjusted test case after replacing custom global read lock implementation with one based on metadata locks. Replaced usage of GRL-specific debug_sync's with appropriate sync points in MDL subsystem. Updated thread state names which are used when DDL waits for FTWRL. mysql-test/t/trigger_notembedded.test: Adjusted test case after changing thread state names which are used when DML or DDL waits for FLUSH TABLES WITH READ LOCK to "Waiting for global read lock". sql/event_data_objects.cc: Removed Event_queue_element::status/last_executed_changed members and Event_queue_element::update_timing_fields() method. We no longer use this class for updating mysql.events once event is chosen for execution. Accesses to instances of this class in scheduler thread require protection by Event_queue::LOCK_event_queue mutex and we try to avoid updating table while holding this lock. sql/event_data_objects.h: Removed Event_queue_element::status/last_executed_changed members and Event_queue_element::update_timing_fields() method. We no longer use this class for updating mysql.events once event is chosen for execution. Accesses to instances of this class in scheduler thread require protection by Event_queue::LOCK_event_queue mutex and we try to avoid updating table while holding this lock. sql/event_db_repository.cc: - Changed Event_db_repository methods to not release all metadata locks once they are done updating mysql.events table. This allows to keep metadata lock protecting against GRL and lock protecting particular event around until corresponding DDL statement is written to the binary log. - Removed logic for conditional update of "status" and "last_executed" fields from update_timing_fields_for_event() method. In the only case when this method is called now "last_executed" is always modified and tracking change of "status" is too much hassle. sql/event_db_repository.h: Removed logic for conditional update of "status" and "last_executed" fields from Event_db_repository:: update_timing_fields_for_event() method. In the only case when this method is called now "last_executed" is always modified and tracking change of "status" field is too much hassle. sql/event_queue.cc: Changed event scheduler code not to update mysql.events table while holding Event_queue::LOCK_event_queue mutex. Doing so led to a deadlock with a new GRL implementation. This deadlock didn't occur with old implementation due to fact that code acquiring protection against GRL ignored pending GRL requests (which lead to GRL starvation). One of goals of new implementation is to disallow GRL starvation and so we have to solve problem with this deadlock in a different way. sql/events.cc: Changed methods of Events class to acquire protection against GRL while perfoming DDL statement and keep it until statement is written to the binary log. Unfortunately this step together with new GRL implementation exposed deadlock involving Events::LOCK_event_metadata and GRL. To solve it Events::LOCK_event_metadata mutex was replaced with a metadata lock on event. As a side-effect events DDL has to be prohibited under LOCK TABLES even in cases when mysql.events table was explicitly locked for write. sql/events.h: Replaced Events::LOCK_event_metadata mutex with a metadata lock on event. sql/ha_ndbcluster.cc: Updated code after replacing custom global read lock implementation with one based on MDL. Since MDL subsystem should now be able to detect deadlocks involving metadata locks and GRL there is no need for special handling of active GRL. sql/handler.cc: Replaced custom implementation of global read lock with one based on metadata locks. Consequently when doing commit instead of calling method of Global_read_lock class to acquire protection against GRL we simply acquire IX in COMMIT namespace. sql/lock.cc: Replaced custom implementation of global read lock with one based on metadata locks. This step allows to expose wait for GRL to deadlock detector of MDL subsystem and thus succesfully resolve deadlocks similar to one behind bug #57006 "Deadlock between HANDLER and FLUSH TABLES WITH READ LOCK". It also solves problem with GRL starvation described in bug #54673 "It takes too long to get readlock for 'FLUSH TABLES WITH READ LOCK'" since metadata locks used by GRL give preference to FTWRL statement instead of DML statements (if needed in future this can be changed to fair scheduling). Similar to old implementation of acquisition of GRL is two-step. During the first step we block all concurrent DML and DDL statements by acquiring global S metadata lock (each DML and DDL statement acquires global IX lock for its duration). During the second step we block commits by acquiring global S lock in COMMIT namespace (commit code acquires global IX lock in this namespace). Note that unlike in old implementation acquisition of protection against GRL in DML and DDL is semi-automatic. We assume that any statement which should be blocked by GRL will either open and acquires write-lock on tables or acquires metadata locks on objects it is going to modify. For any such statement global IX metadata lock is automatically acquired for its duration. To support this change: - Global_read_lock::lock/unlock_global_read_lock and make_global_read_lock_block_commit methods were changed accordingly. - Global_read_lock::wait_if_global_read_lock() and start_waiting_global_read_lock() methods were dropped. It is now responsibility of code acquiring metadata locks opening tables to acquire protection against GRL by explicitly taking global IX lock with statement duration. - Global variables, mutex and condition variable used by old implementation was removed. - lock_routine_name() was changed to use statement duration for its global IX lock. It was also renamed to lock_object_name() as it now also used to take metadata locks on events. - Global_read_lock::set_explicit_lock_duration() was added which allows not to release locks used for GRL when leaving prelocked mode. sql/lock.h: - Renamed lock_routine_name() to lock_object_name() and changed its signature to allow its usage for events. - Removed broadcast_refresh() function. It is no longer needed with new GRL implementation. sql/log_event.cc: Release metadata locks with statement duration at the end of processing legacy event for LOAD DATA. This ensures that replication thread processing such event properly releases its protection against global read lock. sql/mdl.cc: Changed MDL subsystem to support new MDL-based implementation of global read lock. Added COMMIT and EVENTS namespaces for metadata locks. Changed thread state name for GLOBAL namespace to "Waiting for global read lock". Optimized MDL_map::find_or_insert() method to avoid taking m_mutex mutex when looking up MDL_lock objects for GLOBAL or COMMIT namespaces. We keep pre-created MDL_lock objects for these namespaces around and simply return pointers to these global objects when needed. Changed MDL_lock/MDL_scoped_lock to properly handle notification of insert delayed handler threads when FTWRL takes global S lock. Introduced concept of lock duration. In addition to locks with transaction duration which work in the way which is similar to how locks worked before (i.e. they are released at the end of transaction), locks with statement and explicit duration were introduced. Locks with statement duration are automatically released at the end of statement. Locks with explicit duration require explicit release and obsolete concept of transactional sentinel. * Changed MDL_request and MDL_ticket classes to support notion of duration. * Changed MDL_context to keep locks with different duration in different lists. Changed code handling ticket list to take this into account. * Changed methods responsible for releasing locks to take into account duration of tickets. Particularly public MDL_context::release_lock() method now only can release tickets with explicit duration (there is still internal method which allows to specify duration). To release locks with statement or transaction duration one have to use release_statement/transactional_locks() methods. * Concept of savepoint for MDL subsystem now has to take into account locks with statement duration. Consequently MDL_savepoint class was introduced and methods working with savepoints were updated accordingly. * Added methods which allow to set duration for one or all locks in the context. sql/mdl.h: Changed MDL subsystem to support new MDL-based implementation of global read lock. Added COMMIT and EVENTS namespaces for metadata locks. Introduced concept of lock duration. In addition to locks with transaction duration which work in the way which is similar to how locks worked before (i.e. they are released at the end of transaction), locks with statement and explicit duration were introduced. Locks with statement duration are automatically released at the end of statement. Locks with explicit duration require explicit release and obsolete concept of transactional sentinel. * Changed MDL_request and MDL_ticket classes to support notion of duration. * Changed MDL_context to keep locks with different duration in different lists. Changed code handling ticket list to take this into account. * Changed methods responsible for releasing locks to take into account duration of tickets. Particularly public MDL_context::release_lock() method now only can release tickets with explicit duration (there is still internal method which allows to specify duration). To release locks with statement or transaction duration one have to use release_statement/transactional_locks() methods. * Concept of savepoint for MDL subsystem now has to take into account locks with statement duration. Consequently MDL_savepoint class was introduced and methods working with savepoints were updated accordingly. * Added methods which allow to set duration for one or all locks in the context. sql/mysqld.cc: Removed global mutex and condition variables which were used by old implementation of GRL. Also we no longer need to initialize Events::LOCK_event_metadata mutex as it was replaced with metadata locks on events. sql/mysqld.h: Removed global variable, mutex and condition variables which were used by old implementation of GRL. sql/rpl_rli.cc: When slave thread closes tables which were open for handling of RBR events ensure that it releases global IX lock which was acquired as protection against GRL. sql/sp.cc: Adjusted code to the new signature of lock_object/routine_name(), to the fact that one now needs specify duration of lock when initializing MDL_request and to the fact that savepoints for MDL subsystem are now represented by MDL_savepoint class. sql/sp_head.cc: Ensure that statements in stored procedures release statement metadata locks and thus release their protectiong against GRL in proper moment in time. Adjusted code to the fact that one now needs specify duration of lock when initializing MDL_request. sql/sql_admin.cc: Adjusted code to the fact that one now needs specify duration of lock when initializing MDL_request. sql/sql_base.cc: - Implemented support for new approach to acquiring protection against global read lock. We no longer acquire such protection explicitly on the basis of statement flags. Instead we always rely on code which is responsible for acquiring metadata locks on object to be changed acquiring this protection. This is achieved by acquiring global IX metadata lock with statement duration. Code doing this also responsible for checking that current connection has no active GRL by calling an Global_read_lock::can_acquire_protection() method. Changed code in open_table() and lock_table_names() accordingly. Note that as result of this change DDL and DML on temporary tables is always compatible with GRL (before it was incompatible in some cases and compatible in other cases). - To speed-up code acquiring protection against GRL introduced m_has_protection_against_grl member in Open_table_context class. It indicates that protection was already acquired sometime during open_tables() execution and new attempts can be skipped. - Thanks to new GRL implementation calls to broadcast_refresh() became unnecessary and were removed. - Adjusted code to the fact that one now needs specify duration of lock when initializing MDL_request and to the fact that savepoints for MDL subsystem are now represented by MDL_savepoint class. sql/sql_base.h: Adjusted code to the fact that savepoints for MDL subsystem are now represented by MDL_savepoint class. Also introduced Open_table_context::m_has_protection_against_grl member which allows to avoid acquiring protection against GRL while opening tables if such protection was already acquired. sql/sql_class.cc: Changed THD::leave_locked_tables_mode() after transactional sentinel for metadata locks was obsoleted by introduction of locks with explicit duration. sql/sql_class.h: - Adjusted code to the fact that savepoints for MDL subsystem are now represented by MDL_savepoint class. - Changed Global_read_lock class according to changes in global read lock implementation: * wait_if_global_read_lock and start_waiting_global_read_lock are now gone. Instead code needing protection against GRL has to acquire global IX metadata lock with statement duration itself. To help it new can_acquire_protection() was introduced. Also as result of the above change m_protection_count member is gone too. * Added m_mdl_blocks_commits_lock member to store metadata lock blocking commits. * Adjusted code to the fact that concept of transactional sentinel was obsoleted by concept of lock duration. - Removed CF_PROTECT_AGAINST_GRL flag as it is no longer necessary. New GRL implementation acquires protection against global read lock automagically when statement acquires metadata locks on tables or other objects it is going to change. sql/sql_db.cc: Adjusted code to the fact that one now needs specify duration of lock when initializing MDL_request. sql/sql_handler.cc: Removed call to broadcast_refresh() function. It is no longer needed with new GRL implementation. Adjusted code after introducing duration concept for metadata locks. Particularly to the fact transactional sentinel was replaced with explicit duration. sql/sql_handler.h: Renamed mysql_ha_move_tickets_after_trans_sentinel() to mysql_ha_set_explicit_lock_duration() after transactional sentinel was obsoleted by locks with explicit duration. sql/sql_insert.cc: Adjusted code handling delaying inserts after switching to new GRL implementation. Now connection thread initiating delayed insert has to acquire global IX lock in addition to metadata lock on table being inserted into. This IX lock protects against GRL and similarly to SW lock on table being inserted into has to be passed to handler thread in order to avoid deadlocks. sql/sql_lex.cc: LEX::protect_against_global_read_lock member is no longer necessary since protection against GRL is automatically taken by code acquiring metadata locks/opening tables. sql/sql_lex.h: LEX::protect_against_global_read_lock member is no longer necessary since protection against GRL is automatically taken by code acquiring metadata locks/opening tables. sql/sql_parse.cc: - Implemented support for new approach to acquiring protection against global read lock. We no longer acquire such protection explicitly on the basis of statement flags. Instead we always rely on code which is responsible for acquiring metadata locks on object to be changed acquiring this protection. This is achieved by acquiring global IX metadata lock with statement duration. This lock is automatically released at the end of statement execution. - Changed implementation of CREATE/DROP PROCEDURE/FUNCTION not to release metadata locks and thus protection against of GRL in the middle of statement execution. - Adjusted code to the fact that one now needs specify duration of lock when initializing MDL_request and to the fact that savepoints for MDL subsystem are now represented by MDL_savepoint class. sql/sql_prepare.cc: Adjusted code to the to the fact that savepoints for MDL subsystem are now represented by MDL_savepoint class. sql/sql_rename.cc: With new GRL implementation there is no need to explicitly acquire protection against GRL before renaming tables. This happens automatically in code which acquires metadata locks on tables being renamed. sql/sql_show.cc: Adjusted code to the fact that one now needs specify duration of lock when initializing MDL_request and to the fact that savepoints for MDL subsystem are now represented by MDL_savepoint class. sql/sql_table.cc: - With new GRL implementation there is no need to explicitly acquire protection against GRL before dropping tables. This happens automatically in code which acquires metadata locks on tables being dropped. - Changed mysql_alter_table() not to release lock on new table name explicitly and to rely on automatic release of locks at the end of statement instead. This was necessary since now MDL_context::release_lock() is supported only for locks for explicit duration. sql/sql_trigger.cc: With new GRL implementation there is no need to explicitly acquire protection against GRL before changing table triggers. This happens automatically in code which acquires metadata locks on tables which triggers are to be changed. sql/sql_update.cc: Fix bug exposed by GRL testing. During prepare phase acquire only S metadata locks instead of SW locks to keep prepare of multi-UPDATE compatible with concurrent LOCK TABLES WRITE and global read lock. sql/sql_view.cc: With new GRL implementation there is no need to explicitly acquire protection against GRL before creating view. This happens automatically in code which acquires metadata lock on view to be created. sql/sql_yacc.yy: LEX::protect_against_global_read_lock member is no longer necessary since protection against GRL is automatically taken by code acquiring metadata locks/opening tables. sql/table.cc: Adjusted code to the fact that one now needs specify duration of lock when initializing MDL_request. sql/table.h: Adjusted code to the fact that one now needs specify duration of lock when initializing MDL_request. sql/transaction.cc: Replaced custom implementation of global read lock with one based on metadata locks. Consequently when doing commit instead of calling method of Global_read_lock class to acquire protection against GRL we simply acquire IX in COMMIT namespace. Also adjusted code to the fact that MDL savepoint is now represented by MDL_savepoint class.
2010-11-11 18:11:05 +01:00
key_COND_cache_status_changed, key_COND_manager,
Fix for bug #52044 "FLUSH TABLES WITH READ LOCK and FLUSH TABLES <list> WITH READ LOCK are incompatible". The problem was that FLUSH TABLES <list> WITH READ LOCK which was issued when other connection has acquired global read lock using FLUSH TABLES WITH READ LOCK was blocked and has to wait until global read lock is released. This issue stemmed from the fact that FLUSH TABLES <list> WITH READ LOCK implementation has acquired X metadata locks on tables to be flushed. Since these locks required acquiring of global IX lock this statement was incompatible with global read lock. This patch addresses problem by using SNW metadata type of lock for tables to be flushed by FLUSH TABLES <list> WITH READ LOCK. It is OK to acquire them without global IX lock as long as we won't try to upgrade those locks. Since SNW locks allow concurrent statements using same table FLUSH TABLE <list> WITH READ LOCK now has to wait until old versions of tables to be flushed go away after acquiring metadata locks. Since such waiting can lead to deadlock MDL deadlock detector was extended to take into account waits for flush and resolve such deadlocks. As a bonus code in open_tables() which was responsible for waiting old versions of tables to go away was refactored. Now when we encounter old version of table in open_table() we don't back-off and wait for all old version to go away, but instead wait for this particular table to be flushed. Such approach supported by deadlock detection should reduce number of scenarios in which FLUSH TABLES aborts concurrent multi-statement transactions. Note that active FLUSH TABLES <list> WITH READ LOCK still blocks concurrent FLUSH TABLES WITH READ LOCK statement as the former keeps tables open and thus prevents the latter statement from doing flush. mysql-test/include/handler.inc: Adjusted test case after changing status which is set when FLUSH TABLES waits for tables to be flushed from "Flushing tables" to "Waiting for table". mysql-test/r/flush.result: Added test which checks that "flush tables <list> with read lock" is compatible with active "flush tables with read lock" but not vice-versa. This test also covers bug #52044 "FLUSH TABLES WITH READ LOCK and FLUSH TABLES <list> WITH READ LOCK are incompatible". mysql-test/r/mdl_sync.result: Added scenarios in which wait for table to be flushed causes deadlocks to the coverage of MDL deadlock detector. mysql-test/suite/perfschema/r/dml_setup_instruments.result: Adjusted test results after removal of COND_refresh condition variable. mysql-test/suite/perfschema/r/server_init.result: Adjusted test and its results after removal of COND_refresh condition variable. mysql-test/suite/perfschema/t/server_init.test: Adjusted test and its results after removal of COND_refresh condition variable. mysql-test/t/flush.test: Added test which checks that "flush tables <list> with read lock" is compatible with active "flush tables with read lock" but not vice-versa. This test also covers bug #52044 "FLUSH TABLES WITH READ LOCK and FLUSH TABLES <list> WITH READ LOCK are incompatible". mysql-test/t/kill.test: Adjusted test case after changing status which is set when FLUSH TABLES waits for tables to be flushed from "Flushing tables" to "Waiting for table". mysql-test/t/lock_multi.test: Adjusted test case after changing status which is set when FLUSH TABLES waits for tables to be flushed from "Flushing tables" to "Waiting for table". mysql-test/t/mdl_sync.test: Added scenarios in which wait for table to be flushed causes deadlocks to the coverage of MDL deadlock detector. sql/ha_ndbcluster.cc: Adjusted code after adding one more parameter for close_cached_tables() call - timeout for waiting for table to be flushed. sql/ha_ndbcluster_binlog.cc: Adjusted code after adding one more parameter for close_cached_tables() call - timeout for waiting for table to be flushed. sql/lock.cc: Removed COND_refresh condition variable. See comment for sql_base.cc for details. sql/mdl.cc: Now MDL deadlock detector takes into account information about waits for table flushes when searching for deadlock. To implement this change: - Declaration of enum_deadlock_weight and Deadlock_detection_visitor were moved to mdl.h header to make them available to the code in table.cc which implements deadlock detector traversal through edges of waiters graph representing waiting for flush. - Since now MDL_context may wait not only for metadata lock but also for table to be flushed an abstract Wait_for_edge class was introduced. Its descendants MDL_ticket and Flush_ticket incapsulate specifics of inspecting waiters graph when following through edge representing wait of particular type. We no longer require global IX metadata lock when acquiring SNW or SNRW locks. Such locks are needed only when metadata locks of these types are upgraded to X locks. This allows to use SNW locks in FLUSH TABLES <list> WITH READ LOCK implementation and keep the latter compatible with global read lock. sql/mdl.h: Now MDL deadlock detector takes into account information about waits for table flushes when searching for deadlock. To implement this change: - Declaration of enum_deadlock_weight and Deadlock_detection_visitor were moved to mdl.h header to make them available to the code in table.cc which implements deadlock detector traversal through edges of waiters graph representing waiting for flush. - Since now MDL_context may wait not only for metadata lock but also for table to be flushed an abstract Wait_for_edge class was introduced. Its descendants MDL_ticket and Flush_ticket incapsulate specifics of inspecting waiters graph when following through edge representing wait of particular type. - Deadlock_detection_visitor now has m_table_shares_visited member which allows to support recursive locking for LOCK_open. This is required when deadlock detector inspects waiters graph which contains several edges representing waits for flushes or needs to come through the such edge more than once. sql/mysqld.cc: Removed COND_refresh condition variable. See comment for sql_base.cc for details. sql/mysqld.h: Removed COND_refresh condition variable. See comment for sql_base.cc for details. sql/sql_base.cc: Changed approach to how threads are waiting for table to be flushed. Now thread that wants to wait for old table to go away subscribes for notification by adding Flush_ticket to table's share and waits using MDL_context::m_wait object. Once table gets flushed (i.e. all tables are closed and table share is ready to be destroyed) all such waiters are notified individually. Thanks to this change MDL deadlock detector can take such waits into account. To implement this/as result of this change: - tdc_wait_for_old_versions() was replaced with tdc_wait_for_old_version() which waits for individual old share to go away and which is called by open_table() after finding out that share is outdated. We don't need to perform back-off before such waiting thanks to the fact that deadlock detector now sees such waits. - As result Open_table_ctx::m_mdl_requests became unnecessary and was removed. We no longer allocate copies of MDL_request objects on MEM_ROOT when MYSQL_OPEN_FORCE_SHARED/SHARED_HIGH_PRIO flags are in effect. - close_cached_tables() and tdc_wait_for_old_version() share code which implements waiting for share to be flushed - the both use TABLE_SHARE::wait_until_flush() method. Thanks to this close_cached_tables() supports timeouts and has extra parameter for this. - Open_table_context::OT_MDL_CONFLICT enum element was renamed to OT_CONFLICT as it is now also used in cases when back-off is required to resolve deadlock caused by waiting for flush and not metadata lock. - In cases when we discover that current connection tries to open tables from different generation we now simply back-off and restart process of opening tables. To support this Open_table_context::OT_REOPEN_TABLES enum element was added. - COND_refresh condition variable became unnecessary and was removed. - mysql_notify_thread_having_shared_lock() no longer wakes up connections waiting for flush as all such connections can be waken up by deadlock detector if necessary. sql/sql_base.h: - close_cached_tables() now has one more parameter - timeout for waiting for table to be flushed. - Open_table_context::OT_MDL_CONFLICT enum element was renamed to OT_CONFLICT as it is now also used in cases when back-off is required to resolve deadlock caused by waiting for flush and not metadata lock. Added new OT_REOPEN_TABLES enum element to be used in cases when we need to restart open tables process even in the middle of transaction. - Open_table_ctx::m_mdl_requests became unnecessary and was removed. sql/sql_class.h: Added assert ensuring that we won't use LOCK_open mutex with THD::enter_cond(). Otherwise deadlocks can arise in MDL deadlock detector. sql/sql_parse.cc: Changed FLUSH TABLES <list> WITH READ LOCK to take SNW metadata locks instead of X locks on tables to be flushed. Since we no longer require global IX lock to be taken when SNW locks are taken this makes this statement compatible with FLUSH TABLES WITH READ LOCK statement. Since SNW locks allow other connections to have table opened FLUSH TABLES <list> WITH READ LOCK now has to wait during open_tables() for old version to go away. Such waits can lead to deadlocks which will be detected by MDL deadlock detector which now takes waits for table to be flushed into account. Also adjusted code after adding one more parameter for close_cached_tables() call - timeout for waiting for table to be flushed. sql/sql_yacc.yy: FLUSH TABLES <list> WITH READ LOCK now needs only SNW metadata locks on tables. sql/sys_vars.cc: Adjusted code after adding one more parameter for close_cached_tables() call - timeout for waiting for table to be flushed. sql/table.cc: Implemented new approach to how threads are waiting for table to be flushed. Now thread that wants to wait for old table to go away subscribes for notification by adding Flush_ticket to table's share and waits using MDL_context::m_wait object. Once table gets flushed (i.e. all tables are closed and table share is ready to be destroyed) all such waiters are notified individually. This change allows to make such waits visible inside of MDL deadlock detector. To do it: - Added list of waiters/Flush_tickets to TABLE_SHARE class. - Changed free_table_share() to postpone freeing of share memory until last waiter goes away and to wake up subscribed waiters. - Added TABLE_SHARE::wait_until_flushed() method which implements subscription to the list of waiters for table to be flushed and waiting for this event. Implemented interface which allows to expose waits for flushes to MDL deadlock detector: - Introduced Flush_ticket class a descendant of Wait_for_edge class. - Added TABLE_SHARE::find_deadlock() method which allows deadlock detector to find out what contexts are still using old version of table in question (i.e. to find out what contexts are waited for by owner of Flush_ticket). sql/table.h: In order to support new strategy of waiting for table flush (see comment for table.cc for details) added list of waiters/Flush_tickets to TABLE_SHARE class. Implemented interface which allows to expose waits for flushes to MDL deadlock detector: - Introduced Flush_ticket class a descendant of Wait_for_edge class. - Added TABLE_SHARE::find_deadlock() method which allows deadlock detector to find out what contexts are still using old version of table in question (i.e. to find out what contexts are waited for by owner of Flush_ticket).
2010-07-27 15:34:58 +02:00
key_COND_rpl_status, key_COND_server_started,
key_delayed_insert_cond, key_delayed_insert_cond_client,
key_item_func_sleep_cond, key_master_info_data_cond,
key_master_info_start_cond, key_master_info_stop_cond,
key_relay_log_info_data_cond, key_relay_log_info_log_space_cond,
key_relay_log_info_start_cond, key_relay_log_info_stop_cond,
key_TABLE_SHARE_cond, key_user_level_lock_cond,
key_COND_thread_count, key_COND_thread_cache, key_COND_flush_thread_cache;
extern PSI_thread_key key_thread_bootstrap, key_thread_delayed_insert,
key_thread_handle_manager, key_thread_kill_server, key_thread_main,
key_thread_one_connection, key_thread_signal_hand;
#ifdef HAVE_MMAP
extern PSI_file_key key_file_map;
#endif /* HAVE_MMAP */
extern PSI_file_key key_file_binlog, key_file_binlog_index, key_file_casetest,
key_file_dbopt, key_file_des_key_file, key_file_ERRMSG, key_select_to_file,
key_file_fileparser, key_file_frm, key_file_global_ddl_log, key_file_load,
key_file_loadfile, key_file_log_event_data, key_file_log_event_info,
key_file_master_info, key_file_misc, key_file_partition,
key_file_pid, key_file_relay_log_info, key_file_send_file, key_file_tclog,
key_file_trg, key_file_trn, key_file_init;
extern PSI_file_key key_file_query_log, key_file_slow_log;
void init_server_psi_keys();
#endif /* HAVE_PSI_INTERFACE */
#ifndef __WIN__
extern pthread_t signal_thread;
#endif
#ifdef HAVE_OPENSSL
extern struct st_VioSSLFd * ssl_acceptor_fd;
#endif /* HAVE_OPENSSL */
/*
The following variables were under INNODB_COMPABILITY_HOOKS
*/
extern my_bool opt_large_pages;
extern uint opt_large_page_size;
extern char lc_messages_dir[FN_REFLEN];
extern char *lc_messages_dir_ptr, *log_error_file_ptr;
extern MYSQL_PLUGIN_IMPORT char reg_ext[FN_EXTLEN];
extern MYSQL_PLUGIN_IMPORT uint reg_ext_length;
extern MYSQL_PLUGIN_IMPORT uint lower_case_table_names;
extern MYSQL_PLUGIN_IMPORT bool mysqld_embedded;
extern ulong specialflag;
extern uint mysql_data_home_len;
extern uint mysql_real_data_home_len;
extern const char *mysql_real_data_home_ptr;
2010-08-05 14:34:19 +02:00
extern ulong thread_handling;
extern MYSQL_PLUGIN_IMPORT char *mysql_data_home;
extern char server_version[SERVER_VERSION_LENGTH];
extern MYSQL_PLUGIN_IMPORT char mysql_real_data_home[];
extern char mysql_unpacked_real_data_home[];
extern MYSQL_PLUGIN_IMPORT struct system_variables global_system_variables;
extern char default_logfile_name[FN_REFLEN];
#define mysql_tmpdir (my_tmpdir(&mysql_tmpdir_list))
extern MYSQL_PLUGIN_IMPORT const key_map key_map_empty;
extern MYSQL_PLUGIN_IMPORT key_map key_map_full; /* Should be threaded as const */
/*
Server mutex locks and condition variables.
*/
extern mysql_mutex_t
LOCK_user_locks, LOCK_status,
LOCK_error_log, LOCK_delayed_insert, LOCK_uuid_generator,
LOCK_delayed_status, LOCK_delayed_create, LOCK_crypt, LOCK_timezone,
Patch that refactors global read lock implementation and fixes bug #57006 "Deadlock between HANDLER and FLUSH TABLES WITH READ LOCK" and bug #54673 "It takes too long to get readlock for 'FLUSH TABLES WITH READ LOCK'". The first bug manifested itself as a deadlock which occurred when a connection, which had some table open through HANDLER statement, tried to update some data through DML statement while another connection tried to execute FLUSH TABLES WITH READ LOCK concurrently. What happened was that FTWRL in the second connection managed to perform first step of GRL acquisition and thus blocked all upcoming DML. After that it started to wait for table open through HANDLER statement to be flushed. When the first connection tried to execute DML it has started to wait for GRL/the second connection creating deadlock. The second bug manifested itself as starvation of FLUSH TABLES WITH READ LOCK statements in cases when there was a constant stream of concurrent DML statements (in two or more connections). This has happened because requests for protection against GRL which were acquired by DML statements were ignoring presence of pending GRL and thus the latter was starved. This patch solves both these problems by re-implementing GRL using metadata locks. Similar to the old implementation acquisition of GRL in new implementation is two-step. During the first step we block all concurrent DML and DDL statements by acquiring global S metadata lock (each DML and DDL statement acquires global IX lock for its duration). During the second step we block commits by acquiring global S lock in COMMIT namespace (commit code acquires global IX lock in this namespace). Note that unlike in old implementation acquisition of protection against GRL in DML and DDL is semi-automatic. We assume that any statement which should be blocked by GRL will either open and acquires write-lock on tables or acquires metadata locks on objects it is going to modify. For any such statement global IX metadata lock is automatically acquired for its duration. The first problem is solved because waits for GRL become visible to deadlock detector in metadata locking subsystem and thus deadlocks like one in the first bug become impossible. The second problem is solved because global S locks which are used for GRL implementation are given preference over IX locks which are acquired by concurrent DML (and we can switch to fair scheduling in future if needed). Important change: FTWRL/GRL no longer blocks DML and DDL on temporary tables. Before this patch behavior was not consistent in this respect: in some cases DML/DDL statements on temporary tables were blocked while in others they were not. Since the main use cases for FTWRL are various forms of backups and temporary tables are not preserved during backups we have opted for consistently allowing DML/DDL on temporary tables during FTWRL/GRL. Important change: This patch changes thread state names which are used when DML/DDL of FTWRL is waiting for global read lock. It is now either "Waiting for global read lock" or "Waiting for commit lock" depending on the stage on which FTWRL is. Incompatible change: To solve deadlock in events code which was exposed by this patch we have to replace LOCK_event_metadata mutex with metadata locks on events. As result we have to prohibit DDL on events under LOCK TABLES. This patch also adds extensive test coverage for interaction of DML/DDL and FTWRL. Performance of new and old global read lock implementations in sysbench tests were compared. There were no significant difference between new and old implementations. mysql-test/include/check_ftwrl_compatible.inc: Added helper script which allows to check that a statement is compatible with FLUSH TABLES WITH READ LOCK. mysql-test/include/check_ftwrl_incompatible.inc: Added helper script which allows to check that a statement is incompatible with FLUSH TABLES WITH READ LOCK. mysql-test/include/handler.inc: Adjusted test case to the fact that now DROP TABLE closes open HANDLERs for the table to be dropped before checking if there active FTWRL in this connection. mysql-test/include/wait_show_condition.inc: Fixed small error in the timeout message. The correct name of variable used as parameter for this script is "$condition" and not "$wait_condition". mysql-test/r/delayed.result: Added test coverage for scenario which triggered assert in metadata locking subsystem. mysql-test/r/events_2.result: Updated test results after prohibiting event DDL operations under LOCK TABLES. mysql-test/r/flush.result: Added test coverage for bug #57006 "Deadlock between HANDLER and FLUSH TABLES WITH READ LOCK". mysql-test/r/flush_read_lock.result: Added test coverage for various aspects of FLUSH TABLES WITH READ LOCK functionality. mysql-test/r/flush_read_lock_kill.result: Adjusted test case after replacing custom global read lock implementation with one based on metadata locks. Use new debug_sync point. Do not disable concurrent inserts as now InnoDB we always use InnoDB table. mysql-test/r/handler_innodb.result: Adjusted test case to the fact that now DROP TABLE closes open HANDLERs for the table to be dropped before checking if there active FTWRL in this connection. mysql-test/r/handler_myisam.result: Adjusted test case to the fact that now DROP TABLE closes open HANDLERs for the table to be dropped before checking if there active FTWRL in this connection. mysql-test/r/mdl_sync.result: Adjusted test case after replacing custom global read lock implementation with one based on metadata locks. Replaced usage of GRL-specific debug_sync's with appropriate sync points in MDL subsystem. mysql-test/suite/perfschema/r/dml_setup_instruments.result: Updated test results after removing global COND_global_read_lock condition variable. mysql-test/suite/perfschema/r/func_file_io.result: Ensure that this test doesn't affect subsequent tests. At the end of its execution enable back P_S instrumentation which this test disables at some point. mysql-test/suite/perfschema/r/func_mutex.result: Ensure that this test doesn't affect subsequent tests. At the end of its execution enable back P_S instrumentation which this test disables at some point. mysql-test/suite/perfschema/r/global_read_lock.result: Adjusted test case to take into account that new GRL implementation is based on MDL. mysql-test/suite/perfschema/r/server_init.result: Adjusted test case after replacing custom global read lock implementation with one based on MDL and replacing LOCK_event_metadata mutex with metadata lock. mysql-test/suite/perfschema/t/func_file_io.test: Ensure that this test doesn't affect subsequent tests. At the end of its execution enable back P_S instrumentation which this test disables at some point. mysql-test/suite/perfschema/t/func_mutex.test: Ensure that this test doesn't affect subsequent tests. At the end of its execution enable back P_S instrumentation which this test disables at some point. mysql-test/suite/perfschema/t/global_read_lock.test: Adjusted test case to take into account that new GRL implementation is based on MDL. mysql-test/suite/perfschema/t/server_init.test: Adjusted test case after replacing custom global read lock implementation with one based on MDL and replacing LOCK_event_metadata mutex with metadata lock. mysql-test/suite/rpl/r/rpl_tmp_table_and_DDL.result: Updated test results after prohibiting event DDL under LOCK TABLES. mysql-test/t/delayed.test: Added test coverage for scenario which triggered assert in metadata locking subsystem. mysql-test/t/events_2.test: Updated test case after prohibiting event DDL operations under LOCK TABLES. mysql-test/t/flush.test: Added test coverage for bug #57006 "Deadlock between HANDLER and FLUSH TABLES WITH READ LOCK". mysql-test/t/flush_block_commit.test: Adjusted test case after changing thread state name which is used when COMMIT waits for FLUSH TABLES WITH READ LOCK from "Waiting for release of readlock" to "Waiting for commit lock". mysql-test/t/flush_block_commit_notembedded.test: Adjusted test case after changing thread state name which is used when DML waits for FLUSH TABLES WITH READ LOCK. Now we use "Waiting for global read lock" in this case. mysql-test/t/flush_read_lock.test: Added test coverage for various aspects of FLUSH TABLES WITH READ LOCK functionality. mysql-test/t/flush_read_lock_kill-master.opt: We no longer need to use make_global_read_lock_block_commit_loop debug tag in this test. Instead we rely on an appropriate debug_sync point in MDL code. mysql-test/t/flush_read_lock_kill.test: Adjusted test case after replacing custom global read lock implementation with one based on metadata locks. Use new debug_sync point. Do not disable concurrent inserts as now InnoDB we always use InnoDB table. mysql-test/t/lock_multi.test: Adjusted test case after changing thread state names which are used when DML or DDL waits for FLUSH TABLES WITH READ LOCK to "Waiting for global read lock". mysql-test/t/mdl_sync.test: Adjusted test case after replacing custom global read lock implementation with one based on metadata locks. Replaced usage of GRL-specific debug_sync's with appropriate sync points in MDL subsystem. Updated thread state names which are used when DDL waits for FTWRL. mysql-test/t/trigger_notembedded.test: Adjusted test case after changing thread state names which are used when DML or DDL waits for FLUSH TABLES WITH READ LOCK to "Waiting for global read lock". sql/event_data_objects.cc: Removed Event_queue_element::status/last_executed_changed members and Event_queue_element::update_timing_fields() method. We no longer use this class for updating mysql.events once event is chosen for execution. Accesses to instances of this class in scheduler thread require protection by Event_queue::LOCK_event_queue mutex and we try to avoid updating table while holding this lock. sql/event_data_objects.h: Removed Event_queue_element::status/last_executed_changed members and Event_queue_element::update_timing_fields() method. We no longer use this class for updating mysql.events once event is chosen for execution. Accesses to instances of this class in scheduler thread require protection by Event_queue::LOCK_event_queue mutex and we try to avoid updating table while holding this lock. sql/event_db_repository.cc: - Changed Event_db_repository methods to not release all metadata locks once they are done updating mysql.events table. This allows to keep metadata lock protecting against GRL and lock protecting particular event around until corresponding DDL statement is written to the binary log. - Removed logic for conditional update of "status" and "last_executed" fields from update_timing_fields_for_event() method. In the only case when this method is called now "last_executed" is always modified and tracking change of "status" is too much hassle. sql/event_db_repository.h: Removed logic for conditional update of "status" and "last_executed" fields from Event_db_repository:: update_timing_fields_for_event() method. In the only case when this method is called now "last_executed" is always modified and tracking change of "status" field is too much hassle. sql/event_queue.cc: Changed event scheduler code not to update mysql.events table while holding Event_queue::LOCK_event_queue mutex. Doing so led to a deadlock with a new GRL implementation. This deadlock didn't occur with old implementation due to fact that code acquiring protection against GRL ignored pending GRL requests (which lead to GRL starvation). One of goals of new implementation is to disallow GRL starvation and so we have to solve problem with this deadlock in a different way. sql/events.cc: Changed methods of Events class to acquire protection against GRL while perfoming DDL statement and keep it until statement is written to the binary log. Unfortunately this step together with new GRL implementation exposed deadlock involving Events::LOCK_event_metadata and GRL. To solve it Events::LOCK_event_metadata mutex was replaced with a metadata lock on event. As a side-effect events DDL has to be prohibited under LOCK TABLES even in cases when mysql.events table was explicitly locked for write. sql/events.h: Replaced Events::LOCK_event_metadata mutex with a metadata lock on event. sql/ha_ndbcluster.cc: Updated code after replacing custom global read lock implementation with one based on MDL. Since MDL subsystem should now be able to detect deadlocks involving metadata locks and GRL there is no need for special handling of active GRL. sql/handler.cc: Replaced custom implementation of global read lock with one based on metadata locks. Consequently when doing commit instead of calling method of Global_read_lock class to acquire protection against GRL we simply acquire IX in COMMIT namespace. sql/lock.cc: Replaced custom implementation of global read lock with one based on metadata locks. This step allows to expose wait for GRL to deadlock detector of MDL subsystem and thus succesfully resolve deadlocks similar to one behind bug #57006 "Deadlock between HANDLER and FLUSH TABLES WITH READ LOCK". It also solves problem with GRL starvation described in bug #54673 "It takes too long to get readlock for 'FLUSH TABLES WITH READ LOCK'" since metadata locks used by GRL give preference to FTWRL statement instead of DML statements (if needed in future this can be changed to fair scheduling). Similar to old implementation of acquisition of GRL is two-step. During the first step we block all concurrent DML and DDL statements by acquiring global S metadata lock (each DML and DDL statement acquires global IX lock for its duration). During the second step we block commits by acquiring global S lock in COMMIT namespace (commit code acquires global IX lock in this namespace). Note that unlike in old implementation acquisition of protection against GRL in DML and DDL is semi-automatic. We assume that any statement which should be blocked by GRL will either open and acquires write-lock on tables or acquires metadata locks on objects it is going to modify. For any such statement global IX metadata lock is automatically acquired for its duration. To support this change: - Global_read_lock::lock/unlock_global_read_lock and make_global_read_lock_block_commit methods were changed accordingly. - Global_read_lock::wait_if_global_read_lock() and start_waiting_global_read_lock() methods were dropped. It is now responsibility of code acquiring metadata locks opening tables to acquire protection against GRL by explicitly taking global IX lock with statement duration. - Global variables, mutex and condition variable used by old implementation was removed. - lock_routine_name() was changed to use statement duration for its global IX lock. It was also renamed to lock_object_name() as it now also used to take metadata locks on events. - Global_read_lock::set_explicit_lock_duration() was added which allows not to release locks used for GRL when leaving prelocked mode. sql/lock.h: - Renamed lock_routine_name() to lock_object_name() and changed its signature to allow its usage for events. - Removed broadcast_refresh() function. It is no longer needed with new GRL implementation. sql/log_event.cc: Release metadata locks with statement duration at the end of processing legacy event for LOAD DATA. This ensures that replication thread processing such event properly releases its protection against global read lock. sql/mdl.cc: Changed MDL subsystem to support new MDL-based implementation of global read lock. Added COMMIT and EVENTS namespaces for metadata locks. Changed thread state name for GLOBAL namespace to "Waiting for global read lock". Optimized MDL_map::find_or_insert() method to avoid taking m_mutex mutex when looking up MDL_lock objects for GLOBAL or COMMIT namespaces. We keep pre-created MDL_lock objects for these namespaces around and simply return pointers to these global objects when needed. Changed MDL_lock/MDL_scoped_lock to properly handle notification of insert delayed handler threads when FTWRL takes global S lock. Introduced concept of lock duration. In addition to locks with transaction duration which work in the way which is similar to how locks worked before (i.e. they are released at the end of transaction), locks with statement and explicit duration were introduced. Locks with statement duration are automatically released at the end of statement. Locks with explicit duration require explicit release and obsolete concept of transactional sentinel. * Changed MDL_request and MDL_ticket classes to support notion of duration. * Changed MDL_context to keep locks with different duration in different lists. Changed code handling ticket list to take this into account. * Changed methods responsible for releasing locks to take into account duration of tickets. Particularly public MDL_context::release_lock() method now only can release tickets with explicit duration (there is still internal method which allows to specify duration). To release locks with statement or transaction duration one have to use release_statement/transactional_locks() methods. * Concept of savepoint for MDL subsystem now has to take into account locks with statement duration. Consequently MDL_savepoint class was introduced and methods working with savepoints were updated accordingly. * Added methods which allow to set duration for one or all locks in the context. sql/mdl.h: Changed MDL subsystem to support new MDL-based implementation of global read lock. Added COMMIT and EVENTS namespaces for metadata locks. Introduced concept of lock duration. In addition to locks with transaction duration which work in the way which is similar to how locks worked before (i.e. they are released at the end of transaction), locks with statement and explicit duration were introduced. Locks with statement duration are automatically released at the end of statement. Locks with explicit duration require explicit release and obsolete concept of transactional sentinel. * Changed MDL_request and MDL_ticket classes to support notion of duration. * Changed MDL_context to keep locks with different duration in different lists. Changed code handling ticket list to take this into account. * Changed methods responsible for releasing locks to take into account duration of tickets. Particularly public MDL_context::release_lock() method now only can release tickets with explicit duration (there is still internal method which allows to specify duration). To release locks with statement or transaction duration one have to use release_statement/transactional_locks() methods. * Concept of savepoint for MDL subsystem now has to take into account locks with statement duration. Consequently MDL_savepoint class was introduced and methods working with savepoints were updated accordingly. * Added methods which allow to set duration for one or all locks in the context. sql/mysqld.cc: Removed global mutex and condition variables which were used by old implementation of GRL. Also we no longer need to initialize Events::LOCK_event_metadata mutex as it was replaced with metadata locks on events. sql/mysqld.h: Removed global variable, mutex and condition variables which were used by old implementation of GRL. sql/rpl_rli.cc: When slave thread closes tables which were open for handling of RBR events ensure that it releases global IX lock which was acquired as protection against GRL. sql/sp.cc: Adjusted code to the new signature of lock_object/routine_name(), to the fact that one now needs specify duration of lock when initializing MDL_request and to the fact that savepoints for MDL subsystem are now represented by MDL_savepoint class. sql/sp_head.cc: Ensure that statements in stored procedures release statement metadata locks and thus release their protectiong against GRL in proper moment in time. Adjusted code to the fact that one now needs specify duration of lock when initializing MDL_request. sql/sql_admin.cc: Adjusted code to the fact that one now needs specify duration of lock when initializing MDL_request. sql/sql_base.cc: - Implemented support for new approach to acquiring protection against global read lock. We no longer acquire such protection explicitly on the basis of statement flags. Instead we always rely on code which is responsible for acquiring metadata locks on object to be changed acquiring this protection. This is achieved by acquiring global IX metadata lock with statement duration. Code doing this also responsible for checking that current connection has no active GRL by calling an Global_read_lock::can_acquire_protection() method. Changed code in open_table() and lock_table_names() accordingly. Note that as result of this change DDL and DML on temporary tables is always compatible with GRL (before it was incompatible in some cases and compatible in other cases). - To speed-up code acquiring protection against GRL introduced m_has_protection_against_grl member in Open_table_context class. It indicates that protection was already acquired sometime during open_tables() execution and new attempts can be skipped. - Thanks to new GRL implementation calls to broadcast_refresh() became unnecessary and were removed. - Adjusted code to the fact that one now needs specify duration of lock when initializing MDL_request and to the fact that savepoints for MDL subsystem are now represented by MDL_savepoint class. sql/sql_base.h: Adjusted code to the fact that savepoints for MDL subsystem are now represented by MDL_savepoint class. Also introduced Open_table_context::m_has_protection_against_grl member which allows to avoid acquiring protection against GRL while opening tables if such protection was already acquired. sql/sql_class.cc: Changed THD::leave_locked_tables_mode() after transactional sentinel for metadata locks was obsoleted by introduction of locks with explicit duration. sql/sql_class.h: - Adjusted code to the fact that savepoints for MDL subsystem are now represented by MDL_savepoint class. - Changed Global_read_lock class according to changes in global read lock implementation: * wait_if_global_read_lock and start_waiting_global_read_lock are now gone. Instead code needing protection against GRL has to acquire global IX metadata lock with statement duration itself. To help it new can_acquire_protection() was introduced. Also as result of the above change m_protection_count member is gone too. * Added m_mdl_blocks_commits_lock member to store metadata lock blocking commits. * Adjusted code to the fact that concept of transactional sentinel was obsoleted by concept of lock duration. - Removed CF_PROTECT_AGAINST_GRL flag as it is no longer necessary. New GRL implementation acquires protection against global read lock automagically when statement acquires metadata locks on tables or other objects it is going to change. sql/sql_db.cc: Adjusted code to the fact that one now needs specify duration of lock when initializing MDL_request. sql/sql_handler.cc: Removed call to broadcast_refresh() function. It is no longer needed with new GRL implementation. Adjusted code after introducing duration concept for metadata locks. Particularly to the fact transactional sentinel was replaced with explicit duration. sql/sql_handler.h: Renamed mysql_ha_move_tickets_after_trans_sentinel() to mysql_ha_set_explicit_lock_duration() after transactional sentinel was obsoleted by locks with explicit duration. sql/sql_insert.cc: Adjusted code handling delaying inserts after switching to new GRL implementation. Now connection thread initiating delayed insert has to acquire global IX lock in addition to metadata lock on table being inserted into. This IX lock protects against GRL and similarly to SW lock on table being inserted into has to be passed to handler thread in order to avoid deadlocks. sql/sql_lex.cc: LEX::protect_against_global_read_lock member is no longer necessary since protection against GRL is automatically taken by code acquiring metadata locks/opening tables. sql/sql_lex.h: LEX::protect_against_global_read_lock member is no longer necessary since protection against GRL is automatically taken by code acquiring metadata locks/opening tables. sql/sql_parse.cc: - Implemented support for new approach to acquiring protection against global read lock. We no longer acquire such protection explicitly on the basis of statement flags. Instead we always rely on code which is responsible for acquiring metadata locks on object to be changed acquiring this protection. This is achieved by acquiring global IX metadata lock with statement duration. This lock is automatically released at the end of statement execution. - Changed implementation of CREATE/DROP PROCEDURE/FUNCTION not to release metadata locks and thus protection against of GRL in the middle of statement execution. - Adjusted code to the fact that one now needs specify duration of lock when initializing MDL_request and to the fact that savepoints for MDL subsystem are now represented by MDL_savepoint class. sql/sql_prepare.cc: Adjusted code to the to the fact that savepoints for MDL subsystem are now represented by MDL_savepoint class. sql/sql_rename.cc: With new GRL implementation there is no need to explicitly acquire protection against GRL before renaming tables. This happens automatically in code which acquires metadata locks on tables being renamed. sql/sql_show.cc: Adjusted code to the fact that one now needs specify duration of lock when initializing MDL_request and to the fact that savepoints for MDL subsystem are now represented by MDL_savepoint class. sql/sql_table.cc: - With new GRL implementation there is no need to explicitly acquire protection against GRL before dropping tables. This happens automatically in code which acquires metadata locks on tables being dropped. - Changed mysql_alter_table() not to release lock on new table name explicitly and to rely on automatic release of locks at the end of statement instead. This was necessary since now MDL_context::release_lock() is supported only for locks for explicit duration. sql/sql_trigger.cc: With new GRL implementation there is no need to explicitly acquire protection against GRL before changing table triggers. This happens automatically in code which acquires metadata locks on tables which triggers are to be changed. sql/sql_update.cc: Fix bug exposed by GRL testing. During prepare phase acquire only S metadata locks instead of SW locks to keep prepare of multi-UPDATE compatible with concurrent LOCK TABLES WRITE and global read lock. sql/sql_view.cc: With new GRL implementation there is no need to explicitly acquire protection against GRL before creating view. This happens automatically in code which acquires metadata lock on view to be created. sql/sql_yacc.yy: LEX::protect_against_global_read_lock member is no longer necessary since protection against GRL is automatically taken by code acquiring metadata locks/opening tables. sql/table.cc: Adjusted code to the fact that one now needs specify duration of lock when initializing MDL_request. sql/table.h: Adjusted code to the fact that one now needs specify duration of lock when initializing MDL_request. sql/transaction.cc: Replaced custom implementation of global read lock with one based on metadata locks. Consequently when doing commit instead of calling method of Global_read_lock class to acquire protection against GRL we simply acquire IX in COMMIT namespace. Also adjusted code to the fact that MDL savepoint is now represented by MDL_savepoint class.
2010-11-11 18:11:05 +01:00
LOCK_slave_list, LOCK_active_mi, LOCK_manager,
LOCK_global_system_variables, LOCK_user_conn,
LOCK_prepared_stmt_count, LOCK_error_messages, LOCK_connection_count;
extern MYSQL_PLUGIN_IMPORT mysql_mutex_t LOCK_thread_count;
#ifdef HAVE_OPENSSL
extern mysql_mutex_t LOCK_des_key_file;
#endif
extern mysql_mutex_t LOCK_server_started;
extern mysql_cond_t COND_server_started;
extern mysql_rwlock_t LOCK_grant, LOCK_sys_init_connect, LOCK_sys_init_slave;
extern mysql_rwlock_t LOCK_system_variables_hash;
extern mysql_cond_t COND_thread_count;
Fix for bug #52044 "FLUSH TABLES WITH READ LOCK and FLUSH TABLES <list> WITH READ LOCK are incompatible". The problem was that FLUSH TABLES <list> WITH READ LOCK which was issued when other connection has acquired global read lock using FLUSH TABLES WITH READ LOCK was blocked and has to wait until global read lock is released. This issue stemmed from the fact that FLUSH TABLES <list> WITH READ LOCK implementation has acquired X metadata locks on tables to be flushed. Since these locks required acquiring of global IX lock this statement was incompatible with global read lock. This patch addresses problem by using SNW metadata type of lock for tables to be flushed by FLUSH TABLES <list> WITH READ LOCK. It is OK to acquire them without global IX lock as long as we won't try to upgrade those locks. Since SNW locks allow concurrent statements using same table FLUSH TABLE <list> WITH READ LOCK now has to wait until old versions of tables to be flushed go away after acquiring metadata locks. Since such waiting can lead to deadlock MDL deadlock detector was extended to take into account waits for flush and resolve such deadlocks. As a bonus code in open_tables() which was responsible for waiting old versions of tables to go away was refactored. Now when we encounter old version of table in open_table() we don't back-off and wait for all old version to go away, but instead wait for this particular table to be flushed. Such approach supported by deadlock detection should reduce number of scenarios in which FLUSH TABLES aborts concurrent multi-statement transactions. Note that active FLUSH TABLES <list> WITH READ LOCK still blocks concurrent FLUSH TABLES WITH READ LOCK statement as the former keeps tables open and thus prevents the latter statement from doing flush. mysql-test/include/handler.inc: Adjusted test case after changing status which is set when FLUSH TABLES waits for tables to be flushed from "Flushing tables" to "Waiting for table". mysql-test/r/flush.result: Added test which checks that "flush tables <list> with read lock" is compatible with active "flush tables with read lock" but not vice-versa. This test also covers bug #52044 "FLUSH TABLES WITH READ LOCK and FLUSH TABLES <list> WITH READ LOCK are incompatible". mysql-test/r/mdl_sync.result: Added scenarios in which wait for table to be flushed causes deadlocks to the coverage of MDL deadlock detector. mysql-test/suite/perfschema/r/dml_setup_instruments.result: Adjusted test results after removal of COND_refresh condition variable. mysql-test/suite/perfschema/r/server_init.result: Adjusted test and its results after removal of COND_refresh condition variable. mysql-test/suite/perfschema/t/server_init.test: Adjusted test and its results after removal of COND_refresh condition variable. mysql-test/t/flush.test: Added test which checks that "flush tables <list> with read lock" is compatible with active "flush tables with read lock" but not vice-versa. This test also covers bug #52044 "FLUSH TABLES WITH READ LOCK and FLUSH TABLES <list> WITH READ LOCK are incompatible". mysql-test/t/kill.test: Adjusted test case after changing status which is set when FLUSH TABLES waits for tables to be flushed from "Flushing tables" to "Waiting for table". mysql-test/t/lock_multi.test: Adjusted test case after changing status which is set when FLUSH TABLES waits for tables to be flushed from "Flushing tables" to "Waiting for table". mysql-test/t/mdl_sync.test: Added scenarios in which wait for table to be flushed causes deadlocks to the coverage of MDL deadlock detector. sql/ha_ndbcluster.cc: Adjusted code after adding one more parameter for close_cached_tables() call - timeout for waiting for table to be flushed. sql/ha_ndbcluster_binlog.cc: Adjusted code after adding one more parameter for close_cached_tables() call - timeout for waiting for table to be flushed. sql/lock.cc: Removed COND_refresh condition variable. See comment for sql_base.cc for details. sql/mdl.cc: Now MDL deadlock detector takes into account information about waits for table flushes when searching for deadlock. To implement this change: - Declaration of enum_deadlock_weight and Deadlock_detection_visitor were moved to mdl.h header to make them available to the code in table.cc which implements deadlock detector traversal through edges of waiters graph representing waiting for flush. - Since now MDL_context may wait not only for metadata lock but also for table to be flushed an abstract Wait_for_edge class was introduced. Its descendants MDL_ticket and Flush_ticket incapsulate specifics of inspecting waiters graph when following through edge representing wait of particular type. We no longer require global IX metadata lock when acquiring SNW or SNRW locks. Such locks are needed only when metadata locks of these types are upgraded to X locks. This allows to use SNW locks in FLUSH TABLES <list> WITH READ LOCK implementation and keep the latter compatible with global read lock. sql/mdl.h: Now MDL deadlock detector takes into account information about waits for table flushes when searching for deadlock. To implement this change: - Declaration of enum_deadlock_weight and Deadlock_detection_visitor were moved to mdl.h header to make them available to the code in table.cc which implements deadlock detector traversal through edges of waiters graph representing waiting for flush. - Since now MDL_context may wait not only for metadata lock but also for table to be flushed an abstract Wait_for_edge class was introduced. Its descendants MDL_ticket and Flush_ticket incapsulate specifics of inspecting waiters graph when following through edge representing wait of particular type. - Deadlock_detection_visitor now has m_table_shares_visited member which allows to support recursive locking for LOCK_open. This is required when deadlock detector inspects waiters graph which contains several edges representing waits for flushes or needs to come through the such edge more than once. sql/mysqld.cc: Removed COND_refresh condition variable. See comment for sql_base.cc for details. sql/mysqld.h: Removed COND_refresh condition variable. See comment for sql_base.cc for details. sql/sql_base.cc: Changed approach to how threads are waiting for table to be flushed. Now thread that wants to wait for old table to go away subscribes for notification by adding Flush_ticket to table's share and waits using MDL_context::m_wait object. Once table gets flushed (i.e. all tables are closed and table share is ready to be destroyed) all such waiters are notified individually. Thanks to this change MDL deadlock detector can take such waits into account. To implement this/as result of this change: - tdc_wait_for_old_versions() was replaced with tdc_wait_for_old_version() which waits for individual old share to go away and which is called by open_table() after finding out that share is outdated. We don't need to perform back-off before such waiting thanks to the fact that deadlock detector now sees such waits. - As result Open_table_ctx::m_mdl_requests became unnecessary and was removed. We no longer allocate copies of MDL_request objects on MEM_ROOT when MYSQL_OPEN_FORCE_SHARED/SHARED_HIGH_PRIO flags are in effect. - close_cached_tables() and tdc_wait_for_old_version() share code which implements waiting for share to be flushed - the both use TABLE_SHARE::wait_until_flush() method. Thanks to this close_cached_tables() supports timeouts and has extra parameter for this. - Open_table_context::OT_MDL_CONFLICT enum element was renamed to OT_CONFLICT as it is now also used in cases when back-off is required to resolve deadlock caused by waiting for flush and not metadata lock. - In cases when we discover that current connection tries to open tables from different generation we now simply back-off and restart process of opening tables. To support this Open_table_context::OT_REOPEN_TABLES enum element was added. - COND_refresh condition variable became unnecessary and was removed. - mysql_notify_thread_having_shared_lock() no longer wakes up connections waiting for flush as all such connections can be waken up by deadlock detector if necessary. sql/sql_base.h: - close_cached_tables() now has one more parameter - timeout for waiting for table to be flushed. - Open_table_context::OT_MDL_CONFLICT enum element was renamed to OT_CONFLICT as it is now also used in cases when back-off is required to resolve deadlock caused by waiting for flush and not metadata lock. Added new OT_REOPEN_TABLES enum element to be used in cases when we need to restart open tables process even in the middle of transaction. - Open_table_ctx::m_mdl_requests became unnecessary and was removed. sql/sql_class.h: Added assert ensuring that we won't use LOCK_open mutex with THD::enter_cond(). Otherwise deadlocks can arise in MDL deadlock detector. sql/sql_parse.cc: Changed FLUSH TABLES <list> WITH READ LOCK to take SNW metadata locks instead of X locks on tables to be flushed. Since we no longer require global IX lock to be taken when SNW locks are taken this makes this statement compatible with FLUSH TABLES WITH READ LOCK statement. Since SNW locks allow other connections to have table opened FLUSH TABLES <list> WITH READ LOCK now has to wait during open_tables() for old version to go away. Such waits can lead to deadlocks which will be detected by MDL deadlock detector which now takes waits for table to be flushed into account. Also adjusted code after adding one more parameter for close_cached_tables() call - timeout for waiting for table to be flushed. sql/sql_yacc.yy: FLUSH TABLES <list> WITH READ LOCK now needs only SNW metadata locks on tables. sql/sys_vars.cc: Adjusted code after adding one more parameter for close_cached_tables() call - timeout for waiting for table to be flushed. sql/table.cc: Implemented new approach to how threads are waiting for table to be flushed. Now thread that wants to wait for old table to go away subscribes for notification by adding Flush_ticket to table's share and waits using MDL_context::m_wait object. Once table gets flushed (i.e. all tables are closed and table share is ready to be destroyed) all such waiters are notified individually. This change allows to make such waits visible inside of MDL deadlock detector. To do it: - Added list of waiters/Flush_tickets to TABLE_SHARE class. - Changed free_table_share() to postpone freeing of share memory until last waiter goes away and to wake up subscribed waiters. - Added TABLE_SHARE::wait_until_flushed() method which implements subscription to the list of waiters for table to be flushed and waiting for this event. Implemented interface which allows to expose waits for flushes to MDL deadlock detector: - Introduced Flush_ticket class a descendant of Wait_for_edge class. - Added TABLE_SHARE::find_deadlock() method which allows deadlock detector to find out what contexts are still using old version of table in question (i.e. to find out what contexts are waited for by owner of Flush_ticket). sql/table.h: In order to support new strategy of waiting for table flush (see comment for table.cc for details) added list of waiters/Flush_tickets to TABLE_SHARE class. Implemented interface which allows to expose waits for flushes to MDL deadlock detector: - Introduced Flush_ticket class a descendant of Wait_for_edge class. - Added TABLE_SHARE::find_deadlock() method which allows deadlock detector to find out what contexts are still using old version of table in question (i.e. to find out what contexts are waited for by owner of Flush_ticket).
2010-07-27 15:34:58 +02:00
extern mysql_cond_t COND_manager;
extern int32 thread_running;
extern my_atomic_rwlock_t thread_running_lock;
extern char *opt_ssl_ca, *opt_ssl_capath, *opt_ssl_cert, *opt_ssl_cipher,
*opt_ssl_key;
extern MYSQL_PLUGIN_IMPORT pthread_key(THD*, THR_THD);
/**
only options that need special treatment in get_one_option() deserve
to be listed below
*/
enum options_mysqld
{
OPT_to_set_the_start_number=256,
OPT_BIND_ADDRESS,
OPT_BINLOG_DO_DB,
OPT_BINLOG_FORMAT,
OPT_BINLOG_IGNORE_DB,
OPT_BIN_LOG,
OPT_BOOTSTRAP,
OPT_CONSOLE,
OPT_DEBUG_SYNC_TIMEOUT,
OPT_DELAY_KEY_WRITE_ALL,
OPT_ISAM_LOG,
OPT_KEY_BUFFER_SIZE,
OPT_KEY_CACHE_AGE_THRESHOLD,
OPT_KEY_CACHE_BLOCK_SIZE,
OPT_KEY_CACHE_DIVISION_LIMIT,
OPT_LOWER_CASE_TABLE_NAMES,
OPT_ONE_THREAD,
OPT_POOL_OF_THREADS,
OPT_REPLICATE_DO_DB,
OPT_REPLICATE_DO_TABLE,
OPT_REPLICATE_IGNORE_DB,
OPT_REPLICATE_IGNORE_TABLE,
OPT_REPLICATE_REWRITE_DB,
OPT_REPLICATE_WILD_DO_TABLE,
OPT_REPLICATE_WILD_IGNORE_TABLE,
OPT_SAFE,
OPT_SERVER_ID,
OPT_SKIP_HOST_CACHE,
OPT_SKIP_LOCK,
OPT_SKIP_NEW,
OPT_SKIP_PRIOR,
OPT_SKIP_RESOLVE,
OPT_SKIP_STACK_TRACE,
OPT_SKIP_SYMLINKS,
OPT_SLOW_QUERY_LOG,
OPT_SSL_CA,
OPT_SSL_CAPATH,
OPT_SSL_CERT,
OPT_SSL_CIPHER,
OPT_SSL_KEY,
OPT_UPDATE_LOG,
OPT_WANT_CORE,
OPT_ENGINE_CONDITION_PUSHDOWN,
OPT_LOG_ERROR
};
/**
Query type constants.
QT_ORDINARY -- ordinary SQL query.
QT_IS -- SQL query to be shown in INFORMATION_SCHEMA (in utf8 and without
character set introducers).
*/
enum enum_query_type
{
QT_ORDINARY,
QT_IS
};
/* query_id */
typedef int64 query_id_t;
extern query_id_t global_query_id;
extern my_atomic_rwlock_t global_query_id_lock;
void unireg_end(void) __attribute__((noreturn));
/* increment query_id and return it. */
inline query_id_t next_query_id()
{
query_id_t id;
my_atomic_rwlock_wrlock(&global_query_id_lock);
id= my_atomic_add64(&global_query_id, 1);
my_atomic_rwlock_wrunlock(&global_query_id_lock);
return (id+1);
}
inline query_id_t get_query_id()
{
query_id_t id;
my_atomic_rwlock_wrlock(&global_query_id_lock);
id= my_atomic_load64(&global_query_id);
my_atomic_rwlock_wrunlock(&global_query_id_lock);
return id;
}
/*
TODO: Replace this with an inline function.
*/
#ifndef EMBEDDED_LIBRARY
extern "C" void unireg_abort(int exit_code) __attribute__((noreturn));
#else
extern "C" void unireg_clear(int exit_code);
#define unireg_abort(exit_code) do { unireg_clear(exit_code); DBUG_RETURN(exit_code); } while(0)
#endif
inline void table_case_convert(char * name, uint length)
{
if (lower_case_table_names)
files_charset_info->cset->casedn(files_charset_info,
name, length, name, length);
}
inline ulong sql_rnd_with_mutex()
{
mysql_mutex_lock(&LOCK_thread_count);
ulong tmp=(ulong) (my_rnd(&sql_rand) * 0xffffffff); /* make all bits random */
mysql_mutex_unlock(&LOCK_thread_count);
return tmp;
}
inline int32
inc_thread_running()
{
int32 num_thread_running;
my_atomic_rwlock_wrlock(&thread_running_lock);
num_thread_running= my_atomic_add32(&thread_running, 1);
my_atomic_rwlock_wrunlock(&thread_running_lock);
return (num_thread_running+1);
}
inline int32
dec_thread_running()
{
int32 num_thread_running;
my_atomic_rwlock_wrlock(&thread_running_lock);
num_thread_running= my_atomic_add32(&thread_running, -1);
my_atomic_rwlock_wrunlock(&thread_running_lock);
return (num_thread_running-1);
}
inline int32
get_thread_running()
{
int32 num_thread_running;
my_atomic_rwlock_wrlock(&thread_running_lock);
num_thread_running= my_atomic_load32(&thread_running);
my_atomic_rwlock_wrunlock(&thread_running_lock);
return num_thread_running;
}
#if defined(MYSQL_DYNAMIC_PLUGIN) && defined(_WIN32)
extern "C" THD *_current_thd_noinline();
#define _current_thd() _current_thd_noinline()
#else
extern pthread_key(THD*, THR_THD);
inline THD *_current_thd(void)
{
return my_pthread_getspecific_ptr(THD*,THR_THD);
}
#endif
#define current_thd _current_thd()
#endif /* MYSQLD_INCLUDED */