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mariadb/sql/lock.cc
unknown f631b361b6 Table definition cache, part 2 
The table opening process now works the following way:
- Create common TABLE_SHARE object
- Read the .frm file and unpack it into the TABLE_SHARE object
- Create a TABLE object based on the information in the TABLE_SHARE
  object and open a handler to the table object

Other noteworthy changes:
- In TABLE_SHARE the most common strings are now LEX_STRING's
- Better error message when table is not found
- Variable table_cache is now renamed 'table_open_cache'
- New variable 'table_definition_cache' that is the number of table defintions that will be cached
- strxnmov() calls are now fixed to avoid overflows
- strxnmov() will now always add one end \0 to result
- engine objects are now created with a TABLE_SHARE object instead of a TABLE object.
- After creating a field object one must call field->init(table) before using it

- For a busy system this change will give you:
 - Less memory usage for table object
 - Faster opening of tables (if it's has been in use or is in table definition cache)
 - Allow you to cache many table definitions objects
 - Faster drop of table


mysql-test/mysql-test-run.sh:
  Fixed some problems with --gdb option
  Test both with socket and tcp/ip port that all old servers are killed
mysql-test/r/flush_table.result:
  More tests with lock table with 2 threads + flush table
mysql-test/r/information_schema.result:
  Removed old (now wrong) result
mysql-test/r/innodb.result:
  Better error messages (thanks to TDC patch)
mysql-test/r/merge.result:
  Extra flush table test
mysql-test/r/ndb_bitfield.result:
  Better error messages (thanks to TDC patch)
mysql-test/r/ndb_partition_error.result:
  Better error messages (thanks to TDC patch)
mysql-test/r/query_cache.result:
  Remove tables left from old tests
mysql-test/r/temp_table.result:
  Test truncate with temporary tables
mysql-test/r/variables.result:
  Table_cache -> Table_open_cache
mysql-test/t/flush_table.test:
  More tests with lock table with 2 threads + flush table
mysql-test/t/merge.test:
  Extra flush table test
mysql-test/t/multi_update.test:
  Added 'sleep' to make test predictable
mysql-test/t/query_cache.test:
  Remove tables left from old tests
mysql-test/t/temp_table.test:
  Test truncate with temporary tables
mysql-test/t/variables.test:
  Table_cache -> Table_open_cache
mysql-test/valgrind.supp:
  Remove warning that may happens becasue threads dies in different order
mysys/hash.c:
  Fixed wrong DBUG_PRINT
mysys/mf_dirname.c:
  More DBUG
mysys/mf_pack.c:
  Better comment
mysys/mf_tempdir.c:
  More DBUG
  Ensure that we call cleanup_dirname() on all temporary directory paths.
  
  If we don't do this, we will get a failure when comparing temporary table
  names as in some cases the temporary table name is run through convert_dirname())
mysys/my_alloc.c:
  Indentation fix
sql/examples/ha_example.cc:
  We new use TABLE_SHARE instead of TABLE when creating engine handlers
sql/examples/ha_example.h:
  We new use TABLE_SHARE instead of TABLE when creating engine handlers
sql/examples/ha_tina.cc:
  We new use TABLE_SHARE instead of TABLE when creating engine handlers
sql/examples/ha_tina.h:
  We new use TABLE_SHARE instead of TABLE when creating engine handlers
sql/field.cc:
  Update for table definition cache:
  - Field creation now takes TABLE_SHARE instead of TABLE as argument
    (This is becasue field definitions are now cached in TABLE_SHARE)
    When a field is created, one now must call field->init(TABLE) before using it
  - Use s->db instead of s->table_cache_key
  - Added Field::clone() to create a field in TABLE from a field in TABLE_SHARE
  - make_field() takes TABLE_SHARE as argument instead of TABLE
  - move_field() -> move_field_offset()
sql/field.h:
  Update for table definition cache:
  - Field creation now takes TABLE_SHARE instead of TABLE as argument
    (This is becasue field definitions are now cached in TABLE_SHARE)
    When a field is created, one now must call field->init(TABLE) before using it
  - Added Field::clone() to create a field in TABLE from a field in TABLE_SHARE
  - make_field() takes TABLE_SHARE as argument instead of TABLE
  - move_field() -> move_field_offset()
sql/ha_archive.cc:
  We new use TABLE_SHARE instead of TABLE when creating engine handlers
sql/ha_archive.h:
  We new use TABLE_SHARE instead of TABLE when creating engine handlers
sql/ha_berkeley.cc:
  We new use TABLE_SHARE instead of TABLE when creating engine handlers
  Changed name of argument create() to not hide internal 'table' variable.
  table->s  -> table_share
sql/ha_berkeley.h:
  We new use TABLE_SHARE instead of TABLE when creating engine handlers
sql/ha_blackhole.cc:
  We new use TABLE_SHARE instead of TABLE when creating engine handlers
sql/ha_blackhole.h:
  We new use TABLE_SHARE instead of TABLE when creating engine handlers
sql/ha_federated.cc:
  We new use TABLE_SHARE instead of TABLE when creating engine handlers
  Fixed comments
  Remove index variable and replace with pointers (simple optimization)
  move_field() -> move_field_offset()
  Removed some strlen() calls
sql/ha_federated.h:
  We new use TABLE_SHARE instead of TABLE when creating engine handlers
sql/ha_heap.cc:
  We new use TABLE_SHARE instead of TABLE when creating engine handlers
  Simplify delete_table() and create() as the given file names are now without extension
sql/ha_heap.h:
  We new use TABLE_SHARE instead of TABLE when creating engine handlers
sql/ha_innodb.cc:
  We new use TABLE_SHARE instead of TABLE when creating engine handlers
sql/ha_innodb.h:
  We new use TABLE_SHARE instead of TABLE when creating engine handlers
sql/ha_myisam.cc:
  We new use TABLE_SHARE instead of TABLE when creating engine handlers
  Remove not needed fn_format()
  Fixed for new table->s structure
sql/ha_myisam.h:
  We new use TABLE_SHARE instead of TABLE when creating engine handlers
sql/ha_myisammrg.cc:
  We new use TABLE_SHARE instead of TABLE when creating engine handlers
  Don't set 'is_view' for MERGE tables
  Use new interface to find_temporary_table()
sql/ha_myisammrg.h:
  We new use TABLE_SHARE instead of TABLE when creating engine handlers
  Added flag HA_NO_COPY_ON_ALTER
sql/ha_ndbcluster.cc:
  We new use TABLE_SHARE instead of TABLE when creating engine handlers
  Fixed wrong calls to strxnmov()
  Give error HA_ERR_TABLE_DEF_CHANGED if table definition has changed
  drop_table -> intern_drop_table()
  table->s -> table_share
  Move part_info to TABLE
  Fixed comments & DBUG print's
  New arguments to print_error()
sql/ha_ndbcluster.h:
  We new use TABLE_SHARE instead of TABLE when creating engine handlers
sql/ha_partition.cc:
  We new use TABLE_SHARE instead of TABLE when creating engine handlers
  We can't set up or use part_info when creating handler as there is not yet any table object
  New ha_intialise() to work with TDC (Done by Mikael)
sql/ha_partition.h:
  We new use TABLE_SHARE instead of TABLE when creating engine handlers
  Got set_part_info() from Mikael
sql/handler.cc:
  We new use TABLE_SHARE instead of TABLE when creating engine handlers
  ha_delete_table() now also takes database as an argument
  handler::ha_open() now takes TABLE as argument
  ha_open() now calls ha_allocate_read_write_set()
  Simplify ha_allocate_read_write_set()
  Remove ha_deallocate_read_write_set()
  Use table_share (Cached by table definition cache)
sql/handler.h:
  New table flag: HA_NO_COPY_ON_ALTER (used by merge tables)
  Remove ha_deallocate_read_write_set()
  get_new_handler() now takes TABLE_SHARE as argument
  ha_delete_table() now gets database as argument
sql/item.cc:
  table_name and db are now LEX_STRING objects
  When creating fields, we have now have to call field->init(table)
  move_field -> move_field_offset()
sql/item.h:
  tmp_table_field_from_field_type() now takes an extra paramenter 'fixed_length' to allow one to force usage of CHAR
   instead of BLOB
sql/item_cmpfunc.cc:
  Fixed call to tmp_table_field_from_field_type()
sql/item_create.cc:
  Assert if new not handled cast type
sql/item_func.cc:
  When creating fields, we have now have to call field->init(table)
  dummy_table used by 'sp' now needs a TABLE_SHARE object
sql/item_subselect.cc:
  Trivial code cleanups
sql/item_sum.cc:
  When creating fields, we have now have to call field->init(table)
sql/item_timefunc.cc:
  Item_func_str_to_date::tmp_table_field() now replaced by call to
   tmp_table_field_from_field_type() (see item_timefunc.h)
sql/item_timefunc.h:
  Simply tmp_table_field()
sql/item_uniq.cc:
  When creating fields, we have now have to call field->init(table)
sql/key.cc:
  Added 'KEY' argument to 'find_ref_key' to simplify code
sql/lock.cc:
  More debugging
  Use create_table_def_key() to create key for table cache
  Allocate TABLE_SHARE properly when creating name lock
  Fix that locked_table_name doesn't test same table twice
sql/mysql_priv.h:
  New functions for table definition cache
  New interfaces to a lot of functions.
  New faster interface to find_temporary_table() and close_temporary_table()
sql/mysqld.cc:
  Added support for table definition cache of size 'table_def_size'
  Fixed som calls to strnmov()
  Changed name of 'table_cache' to 'table_open_cache'
sql/opt_range.cc:
  Use new interfaces
  Fixed warnings from valgrind
sql/parse_file.cc:
  Safer calls to strxnmov()
  Fixed typo
sql/set_var.cc:
  Added variable 'table_definition_cache'
  Variable table_cache renamed to 'table_open_cache'
sql/slave.cc:
  Use new interface
sql/sp.cc:
  Proper use of TABLE_SHARE
sql/sp_head.cc:
  Remove compiler warnings
  We have now to call field->init(table)
sql/sp_head.h:
  Pointers to parsed strings are now const
sql/sql_acl.cc:
  table_name is now a LEX_STRING
sql/sql_base.cc:
  Main implementation of table definition cache
  (The #ifdef's are there for the future when table definition cache will replace open table cache)
  Now table definitions are cached indepndent of open tables, which will speed up things when a table is in use at once from several places
  Views are not yet cached; For the moment we only cache if a table is a view or not.
  
  Faster implementation of find_temorary_table()
  Replace 'wait_for_refresh()' with the more general function 'wait_for_condition()'
  Drop table is slightly faster as we can use the table definition cache to know the type of the table
sql/sql_cache.cc:
  table_cache_key and table_name are now LEX_STRING
  'sDBUG print fixes
sql/sql_class.cc:
  table_cache_key is now a LEX_STRING
  safer strxnmov()
sql/sql_class.h:
  Added number of open table shares (table definitions)
sql/sql_db.cc:
  safer strxnmov()
sql/sql_delete.cc:
  Use new interface to find_temporary_table()
sql/sql_derived.cc:
  table_name is now a LEX_STRING
sql/sql_handler.cc:
  TABLE_SHARE->db and TABLE_SHARE->table_name are now LEX_STRING's
sql/sql_insert.cc:
  TABLE_SHARE->db and TABLE_SHARE->table_name are now LEX_STRING's
sql/sql_lex.cc:
  Make parsed string a const (to quickly find out if anything is trying to change the query string)
sql/sql_lex.h:
  Make parsed string a const (to quickly find out if anything is trying to change the query string)
sql/sql_load.cc:
  Safer strxnmov()
sql/sql_parse.cc:
  Better error if wrong DB name
sql/sql_partition.cc:
  part_info moved to TABLE from TABLE_SHARE
  Indentation changes
sql/sql_select.cc:
  Indentation fixes
  Call field->init(TABLE) for new created fields
  Update create_tmp_table() to use TABLE_SHARE properly
sql/sql_select.h:
  Call field->init(TABLE) for new created fields
sql/sql_show.cc:
  table_name is now a LEX_STRING
  part_info moved to TABLE
sql/sql_table.cc:
  Use table definition cache to speed up delete of tables
  Fixed calls to functions with new interfaces
  Don't use 'share_not_to_be_used'
  Instead of doing openfrm() when doing repair, we now have to call
  get_table_share() followed by open_table_from_share().
  Replace some fn_format() with faster unpack_filename().
  Safer strxnmov()
  part_info is now in TABLE
  Added Mikaels patch for partition and ALTER TABLE
  Instead of using 'TABLE_SHARE->is_view' use 'table_flags() & HA_NO_COPY_ON_ALTER
sql/sql_test.cc:
  table_name and table_cache_key are now LEX_STRING's
sql/sql_trigger.cc:
  TABLE_SHARE->db and TABLE_SHARE->table_name are now LEX_STRING's
  safer strxnmov()
  Removed compiler warnings
sql/sql_update.cc:
  Call field->init(TABLE) after field is created
sql/sql_view.cc:
  safer strxnmov()
  Create common TABLE_SHARE object for views to allow us to cache if table is a view
sql/structs.h:
  Added SHOW_TABLE_DEFINITIONS
sql/table.cc:
  Creation and destruct of TABLE_SHARE objects that are common for many TABLE objects
  
  The table opening process now works the following way:
  - Create common TABLE_SHARE object
  - Read the .frm file and unpack it into the TABLE_SHARE object
  - Create a TABLE object based on the information in the TABLE_SHARE
    object and open a handler to the table object
  
  open_table_def() is written in such a way that it should be trival to add parsing of the .frm files in new formats
sql/table.h:
  TABLE objects for the same database table now share a common TABLE_SHARE object
  In TABLE_SHARE the most common strings are now LEX_STRING's
sql/unireg.cc:
  Changed arguments to rea_create_table() to have same order as other functions
  Call field->init(table) for new created fields
sql/unireg.h:
  Added OPEN_VIEW
strings/strxnmov.c:
  Change strxnmov() to always add end \0
  This makes usage of strxnmov() safer as most of MySQL code assumes that strxnmov() will create a null terminated string
2005-11-23 22:45:02 +02:00

1055 lines
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/* Copyright (C) 2000 MySQL AB & MySQL Finland AB & TCX DataKonsult AB
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; either version 2 of the License, or
(at your option) any later version.
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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
/* locking functions for mysql */
/*
Because of the new concurrent inserts, we must first get external locks
before getting internal locks. If we do it in the other order, the status
information is not up to date when called from the lock handler.
GENERAL DESCRIPTION OF LOCKING
When not using LOCK TABLES:
- For each SQL statement mysql_lock_tables() is called for all involved
tables.
- mysql_lock_tables() will call
table_handler->external_lock(thd,locktype) for each table.
This is followed by a call to thr_multi_lock() for all tables.
- When statement is done, we call mysql_unlock_tables().
This will call thr_multi_unlock() followed by
table_handler->external_lock(thd, F_UNLCK) for each table.
- Note that mysql_unlock_tables() may be called several times as
MySQL in some cases can free some tables earlier than others.
- The above is true both for normal and temporary tables.
- Temporary non transactional tables are never passed to thr_multi_lock()
and we never call external_lock(thd, F_UNLOCK) on these.
When using LOCK TABLES:
- LOCK TABLE will call mysql_lock_tables() for all tables.
mysql_lock_tables() will call
table_handler->external_lock(thd,locktype) for each table.
This is followed by a call to thr_multi_lock() for all tables.
- For each statement, we will call table_handler->start_stmt(THD)
to inform the table handler that we are using the table.
The tables used can only be tables used in LOCK TABLES or a
temporary table.
- When statement is done, we will call ha_commit_stmt(thd);
- When calling UNLOCK TABLES we call mysql_unlock_tables() for all
tables used in LOCK TABLES
TODO:
Change to use my_malloc() ONLY when using LOCK TABLES command or when
we are forced to use mysql_lock_merge.
*/
#include "mysql_priv.h"
#include <hash.h>
#include "ha_myisammrg.h"
#ifndef MASTER
#include "../srclib/myisammrg/myrg_def.h"
#else
#include "../storage/myisammrg/myrg_def.h"
#endif
static MYSQL_LOCK *get_lock_data(THD *thd, TABLE **table,uint count,
bool unlock, TABLE **write_locked);
static int lock_external(THD *thd, TABLE **table,uint count);
static int unlock_external(THD *thd, TABLE **table,uint count);
static void print_lock_error(int error, const char *);
/*
Lock tables.
SYNOPSIS
mysql_lock_tables()
thd The current thread.
tables An array of pointers to the tables to lock.
count The number of tables to lock.
flags Options:
MYSQL_LOCK_IGNORE_GLOBAL_READ_LOCK Ignore a global read lock
MYSQL_LOCK_IGNORE_FLUSH Ignore a flush tables.
MYSQL_LOCK_NOTIFY_IF_NEED_REOPEN Instead of reopening altered
or dropped tables by itself,
mysql_lock_tables() should
notify upper level and rely
on caller doing this.
need_reopen Out parameter, TRUE if some tables were altered
or deleted and should be reopened by caller.
RETURN
A lock structure pointer on success.
NULL on error or if some tables should be reopen.
*/
/* Map the return value of thr_lock to an error from errmsg.txt */
static int thr_lock_errno_to_mysql[]=
{ 0, 1, ER_LOCK_WAIT_TIMEOUT, ER_LOCK_DEADLOCK };
MYSQL_LOCK *mysql_lock_tables(THD *thd, TABLE **tables, uint count,
uint flags, bool *need_reopen)
{
MYSQL_LOCK *sql_lock;
TABLE *write_lock_used;
int rc;
DBUG_ENTER("mysql_lock_tables");
*need_reopen= FALSE;
for (;;)
{
if (!(sql_lock = get_lock_data(thd,tables,count, 0,&write_lock_used)))
break;
if (global_read_lock && write_lock_used &&
! (flags & MYSQL_LOCK_IGNORE_GLOBAL_READ_LOCK))
{
/*
Someone has issued LOCK ALL TABLES FOR READ and we want a write lock
Wait until the lock is gone
*/
if (wait_if_global_read_lock(thd, 1, 1))
{
my_free((gptr) sql_lock,MYF(0));
sql_lock=0;
break;
}
if (thd->version != refresh_version)
{
my_free((gptr) sql_lock,MYF(0));
goto retry;
}
}
thd->proc_info="System lock";
DBUG_PRINT("info", ("thd->proc_info %s", thd->proc_info));
if (lock_external(thd, tables, count))
{
my_free((gptr) sql_lock,MYF(0));
sql_lock=0;
break;
}
thd->proc_info="Table lock";
DBUG_PRINT("info", ("thd->proc_info %s", thd->proc_info));
thd->locked=1;
rc= thr_lock_errno_to_mysql[(int) thr_multi_lock(sql_lock->locks,
sql_lock->lock_count,
thd->lock_id)];
if (rc > 1) /* a timeout or a deadlock */
{
my_error(rc, MYF(0));
my_free((gptr) sql_lock,MYF(0));
sql_lock= 0;
break;
}
else if (rc == 1) /* aborted */
{
thd->some_tables_deleted=1; // Try again
sql_lock->lock_count= 0; // Locks are already freed
}
else if (!thd->some_tables_deleted || (flags & MYSQL_LOCK_IGNORE_FLUSH))
{
thd->locked=0;
break;
}
else if (!thd->open_tables)
{
// Only using temporary tables, no need to unlock
thd->some_tables_deleted=0;
thd->locked=0;
break;
}
thd->proc_info=0;
/* some table was altered or deleted. reopen tables marked deleted */
mysql_unlock_tables(thd,sql_lock);
thd->locked=0;
retry:
sql_lock=0;
if (flags & MYSQL_LOCK_NOTIFY_IF_NEED_REOPEN)
{
*need_reopen= TRUE;
break;
}
if (wait_for_tables(thd))
break; // Couldn't open tables
}
thd->proc_info=0;
if (thd->killed)
{
thd->send_kill_message();
if (sql_lock)
{
mysql_unlock_tables(thd,sql_lock);
sql_lock=0;
}
}
thd->lock_time();
DBUG_RETURN (sql_lock);
}
static int lock_external(THD *thd, TABLE **tables, uint count)
{
reg1 uint i;
int lock_type,error;
DBUG_ENTER("lock_external");
DBUG_PRINT("info", ("count %d", count));
for (i=1 ; i <= count ; i++, tables++)
{
DBUG_ASSERT((*tables)->reginfo.lock_type >= TL_READ);
lock_type=F_WRLCK; /* Lock exclusive */
if ((*tables)->db_stat & HA_READ_ONLY ||
((*tables)->reginfo.lock_type >= TL_READ &&
(*tables)->reginfo.lock_type <= TL_READ_NO_INSERT))
lock_type=F_RDLCK;
if ((error=(*tables)->file->external_lock(thd,lock_type)))
{
print_lock_error(error, (*tables)->file->table_type());
for (; i-- ; tables--)
{
(*tables)->file->external_lock(thd, F_UNLCK);
(*tables)->current_lock=F_UNLCK;
}
DBUG_RETURN(error);
}
else
{
(*tables)->db_stat &= ~ HA_BLOCK_LOCK;
(*tables)->current_lock= lock_type;
}
}
DBUG_RETURN(0);
}
void mysql_unlock_tables(THD *thd, MYSQL_LOCK *sql_lock)
{
DBUG_ENTER("mysql_unlock_tables");
if (sql_lock->lock_count)
thr_multi_unlock(sql_lock->locks,sql_lock->lock_count);
if (sql_lock->table_count)
VOID(unlock_external(thd,sql_lock->table,sql_lock->table_count));
my_free((gptr) sql_lock,MYF(0));
DBUG_VOID_RETURN;
}
/*
Unlock some of the tables locked by mysql_lock_tables
This will work even if get_lock_data fails (next unlock will free all)
*/
void mysql_unlock_some_tables(THD *thd, TABLE **table,uint count)
{
MYSQL_LOCK *sql_lock;
TABLE *write_lock_used;
if ((sql_lock = get_lock_data(thd, table, count, 1, &write_lock_used)))
mysql_unlock_tables(thd, sql_lock);
}
/*
** unlock all tables locked for read.
*/
void mysql_unlock_read_tables(THD *thd, MYSQL_LOCK *sql_lock)
{
uint i,found;
DBUG_ENTER("mysql_unlock_read_tables");
/* Move all write locks first */
THR_LOCK_DATA **lock=sql_lock->locks;
for (i=found=0 ; i < sql_lock->lock_count ; i++)
{
if (sql_lock->locks[i]->type >= TL_WRITE_ALLOW_READ)
{
swap_variables(THR_LOCK_DATA *, *lock, sql_lock->locks[i]);
lock++;
found++;
}
}
/* unlock the read locked tables */
if (i != found)
{
thr_multi_unlock(lock,i-found);
sql_lock->lock_count= found;
}
/* Then do the same for the external locks */
/* Move all write locked tables first */
TABLE **table=sql_lock->table;
for (i=found=0 ; i < sql_lock->table_count ; i++)
{
if ((uint) sql_lock->table[i]->reginfo.lock_type >= TL_WRITE_ALLOW_READ)
{
swap_variables(TABLE *, *table, sql_lock->table[i]);
table++;
found++;
}
}
/* Unlock all read locked tables */
if (i != found)
{
VOID(unlock_external(thd,table,i-found));
sql_lock->table_count=found;
}
DBUG_VOID_RETURN;
}
void mysql_lock_remove(THD *thd, MYSQL_LOCK *locked,TABLE *table)
{
mysql_unlock_some_tables(thd, &table,1);
if (locked)
{
reg1 uint i;
for (i=0; i < locked->table_count; i++)
{
if (locked->table[i] == table)
{
locked->table_count--;
bmove((char*) (locked->table+i),
(char*) (locked->table+i+1),
(locked->table_count-i)* sizeof(TABLE*));
break;
}
}
THR_LOCK_DATA **prev=locked->locks;
for (i=0 ; i < locked->lock_count ; i++)
{
if (locked->locks[i]->type != TL_UNLOCK)
*prev++ = locked->locks[i];
}
locked->lock_count=(uint) (prev - locked->locks);
}
}
/* abort all other threads waiting to get lock in table */
void mysql_lock_abort(THD *thd, TABLE *table)
{
MYSQL_LOCK *locked;
TABLE *write_lock_used;
DBUG_ENTER("mysql_lock_abort");
if ((locked = get_lock_data(thd,&table,1,1,&write_lock_used)))
{
for (uint i=0; i < locked->lock_count; i++)
thr_abort_locks(locked->locks[i]->lock);
my_free((gptr) locked,MYF(0));
}
DBUG_VOID_RETURN;
}
/*
Abort one thread / table combination
SYNOPSIS
mysql_lock_abort_for_thread()
thd Thread handler
table Table that should be removed from lock queue
RETURN
0 Table was not locked by another thread
1 Table was locked by at least one other thread
*/
bool mysql_lock_abort_for_thread(THD *thd, TABLE *table)
{
MYSQL_LOCK *locked;
TABLE *write_lock_used;
bool result= FALSE;
DBUG_ENTER("mysql_lock_abort_for_thread");
if ((locked = get_lock_data(thd,&table,1,1,&write_lock_used)))
{
for (uint i=0; i < locked->lock_count; i++)
{
if (thr_abort_locks_for_thread(locked->locks[i]->lock,
table->in_use->real_id))
result= TRUE;
}
my_free((gptr) locked,MYF(0));
}
DBUG_RETURN(result);
}
MYSQL_LOCK *mysql_lock_merge(MYSQL_LOCK *a,MYSQL_LOCK *b)
{
MYSQL_LOCK *sql_lock;
DBUG_ENTER("mysql_lock_merge");
if (!(sql_lock= (MYSQL_LOCK*)
my_malloc(sizeof(*sql_lock)+
sizeof(THR_LOCK_DATA*)*(a->lock_count+b->lock_count)+
sizeof(TABLE*)*(a->table_count+b->table_count),MYF(MY_WME))))
DBUG_RETURN(0); // Fatal error
sql_lock->lock_count=a->lock_count+b->lock_count;
sql_lock->table_count=a->table_count+b->table_count;
sql_lock->locks=(THR_LOCK_DATA**) (sql_lock+1);
sql_lock->table=(TABLE**) (sql_lock->locks+sql_lock->lock_count);
memcpy(sql_lock->locks,a->locks,a->lock_count*sizeof(*a->locks));
memcpy(sql_lock->locks+a->lock_count,b->locks,
b->lock_count*sizeof(*b->locks));
memcpy(sql_lock->table,a->table,a->table_count*sizeof(*a->table));
memcpy(sql_lock->table+a->table_count,b->table,
b->table_count*sizeof(*b->table));
my_free((gptr) a,MYF(0));
my_free((gptr) b,MYF(0));
DBUG_RETURN(sql_lock);
}
/* unlock a set of external */
static int unlock_external(THD *thd, TABLE **table,uint count)
{
int error,error_code;
DBUG_ENTER("unlock_external");
error_code=0;
do
{
if ((*table)->current_lock != F_UNLCK)
{
(*table)->current_lock = F_UNLCK;
if ((error=(*table)->file->external_lock(thd, F_UNLCK)))
{
error_code=error;
print_lock_error(error_code, (*table)->file->table_type());
}
}
table++;
} while (--count);
DBUG_RETURN(error_code);
}
/*
** Get lock structures from table structs and initialize locks
*/
static MYSQL_LOCK *get_lock_data(THD *thd, TABLE **table_ptr, uint count,
bool get_old_locks, TABLE **write_lock_used)
{
uint i,tables,lock_count;
MYSQL_LOCK *sql_lock;
THR_LOCK_DATA **locks;
TABLE **to;
DBUG_ENTER("get_lock_data");
DBUG_PRINT("info", ("count %d", count));
*write_lock_used=0;
for (i=tables=lock_count=0 ; i < count ; i++)
{
if (table_ptr[i]->s->tmp_table != TMP_TABLE)
{
tables+=table_ptr[i]->file->lock_count();
lock_count++;
}
/*
To be able to open and lock for reading system tables like 'mysql.proc',
when we already have some tables opened and locked, and avoid deadlocks
we have to disallow write-locking of these tables with any other tables.
*/
if (table_ptr[i]->s->system_table &&
table_ptr[i]->reginfo.lock_type >= TL_WRITE_ALLOW_WRITE &&
count != 1)
{
my_error(ER_WRONG_LOCK_OF_SYSTEM_TABLE, MYF(0), table_ptr[i]->s->db.str,
table_ptr[i]->s->table_name.str);
DBUG_RETURN(0);
}
}
if (!(sql_lock= (MYSQL_LOCK*)
my_malloc(sizeof(*sql_lock)+
sizeof(THR_LOCK_DATA*)*tables+sizeof(table_ptr)*lock_count,
MYF(0))))
DBUG_RETURN(0);
locks=sql_lock->locks=(THR_LOCK_DATA**) (sql_lock+1);
to=sql_lock->table=(TABLE**) (locks+tables);
sql_lock->table_count=lock_count;
sql_lock->lock_count=tables;
DBUG_PRINT("info", ("sql_lock->table_count %d sql_lock->lock_count %d",
sql_lock->table_count, sql_lock->lock_count));
for (i=0 ; i < count ; i++)
{
TABLE *table;
if ((table=table_ptr[i])->s->tmp_table == TMP_TABLE)
continue;
*to++=table;
enum thr_lock_type lock_type= table->reginfo.lock_type;
if (lock_type >= TL_WRITE_ALLOW_WRITE)
{
*write_lock_used=table;
if (table->db_stat & HA_READ_ONLY)
{
my_error(ER_OPEN_AS_READONLY, MYF(0), table->alias);
my_free((gptr) sql_lock,MYF(0));
DBUG_RETURN(0);
}
}
THR_LOCK_DATA **org_locks = locks;
locks=table->file->store_lock(thd, locks, get_old_locks ? TL_IGNORE :
lock_type);
if (locks)
for ( ; org_locks != locks ; org_locks++)
(*org_locks)->debug_print_param= (void *) table;
}
DBUG_RETURN(sql_lock);
}
/*****************************************************************************
Lock table based on the name.
This is used when we need total access to a closed, not open table
*****************************************************************************/
/*
Lock and wait for the named lock.
SYNOPSIS
lock_and_wait_for_table_name()
thd Thread handler
table_list Lock first table in this list
NOTES
Works together with global read lock.
RETURN
0 ok
1 error
*/
int lock_and_wait_for_table_name(THD *thd, TABLE_LIST *table_list)
{
int lock_retcode;
int error= -1;
DBUG_ENTER("lock_and_wait_for_table_name");
if (wait_if_global_read_lock(thd, 0, 1))
DBUG_RETURN(1);
VOID(pthread_mutex_lock(&LOCK_open));
if ((lock_retcode = lock_table_name(thd, table_list)) < 0)
goto end;
if (lock_retcode && wait_for_locked_table_names(thd, table_list))
{
unlock_table_name(thd, table_list);
goto end;
}
error=0;
end:
pthread_mutex_unlock(&LOCK_open);
start_waiting_global_read_lock(thd);
DBUG_RETURN(error);
}
/*
Put a not open table with an old refresh version in the table cache.
SYNPOSIS
lock_table_name()
thd Thread handler
table_list Lock first table in this list
WARNING
If you are going to update the table, you should use
lock_and_wait_for_table_name instead of this function as this works
together with 'FLUSH TABLES WITH READ LOCK'
NOTES
This will force any other threads that uses the table to release it
as soon as possible.
REQUIREMENTS
One must have a lock on LOCK_open !
RETURN:
< 0 error
== 0 table locked
> 0 table locked, but someone is using it
*/
int lock_table_name(THD *thd, TABLE_LIST *table_list)
{
TABLE *table;
char key[MAX_DBKEY_LENGTH];
char *db= table_list->db;
uint key_length;
DBUG_ENTER("lock_table_name");
DBUG_PRINT("enter",("db: %s name: %s", db, table_list->table_name));
key_length= create_table_def_key(thd, key, table_list, 0);
/* Only insert the table if we haven't insert it already */
for (table=(TABLE*) hash_search(&open_cache,(byte*) key,key_length) ;
table ;
table = (TABLE*) hash_next(&open_cache,(byte*) key,key_length))
{
if (table->in_use == thd)
{
DBUG_PRINT("info", ("Table is in use"));
table->s->version= 0; // Ensure no one can use this
table->locked_by_name= 1;
DBUG_RETURN(0);
}
}
/*
Create a table entry with the right key and with an old refresh version
Note that we must use my_malloc() here as this is freed by the table
cache
*/
if (!(table= (TABLE*) my_malloc(sizeof(*table)+ sizeof(TABLE_SHARE)+
key_length, MYF(MY_WME | MY_ZEROFILL))))
DBUG_RETURN(-1);
table->s= (TABLE_SHARE*) (table+1);
memcpy((table->s->table_cache_key.str= (char*) (table->s+1)), key,
key_length);
table->s->table_cache_key.length= key_length;
table->s->tmp_table= INTERNAL_TMP_TABLE; // for intern_close_table
table->in_use= thd;
table->locked_by_name=1;
table_list->table=table;
if (my_hash_insert(&open_cache, (byte*) table))
{
my_free((gptr) table,MYF(0));
DBUG_RETURN(-1);
}
/* Return 1 if table is in use */
DBUG_RETURN(test(remove_table_from_cache(thd, db, table_list->table_name,
RTFC_NO_FLAG)));
}
void unlock_table_name(THD *thd, TABLE_LIST *table_list)
{
if (table_list->table)
{
hash_delete(&open_cache, (byte*) table_list->table);
(void) pthread_cond_broadcast(&COND_refresh);
}
}
static bool locked_named_table(THD *thd, TABLE_LIST *table_list)
{
for (; table_list ; table_list=table_list->next_local)
{
TABLE *table= table_list->table;
if (table)
{
TABLE *save_next= table->next;
bool result;
table->next= 0;
result= table_is_used(table_list->table, 0);
table->next= save_next;
if (result)
return 1;
}
}
return 0; // All tables are locked
}
bool wait_for_locked_table_names(THD *thd, TABLE_LIST *table_list)
{
bool result=0;
DBUG_ENTER("wait_for_locked_table_names");
safe_mutex_assert_owner(&LOCK_open);
while (locked_named_table(thd,table_list))
{
if (thd->killed)
{
result=1;
break;
}
wait_for_condition(thd, &LOCK_open, &COND_refresh);
pthread_mutex_lock(&LOCK_open);
}
DBUG_RETURN(result);
}
/*
Lock all tables in list with a name lock
SYNOPSIS
lock_table_names()
thd Thread handle
table_list Names of tables to lock
NOTES
If you are just locking one table, you should use
lock_and_wait_for_table_name().
REQUIREMENTS
One must have a lock on LOCK_open when calling this
RETURN
0 ok
1 Fatal error (end of memory ?)
*/
bool lock_table_names(THD *thd, TABLE_LIST *table_list)
{
bool got_all_locks=1;
TABLE_LIST *lock_table;
for (lock_table= table_list; lock_table; lock_table= lock_table->next_local)
{
int got_lock;
if ((got_lock=lock_table_name(thd,lock_table)) < 0)
goto end; // Fatal error
if (got_lock)
got_all_locks=0; // Someone is using table
}
/* If some table was in use, wait until we got the lock */
if (!got_all_locks && wait_for_locked_table_names(thd, table_list))
goto end;
return 0;
end:
unlock_table_names(thd, table_list, lock_table);
return 1;
}
/*
Unlock all tables in list with a name lock
SYNOPSIS
unlock_table_names()
thd Thread handle
table_list Names of tables to unlock
last_table Don't unlock any tables after this one.
(default 0, which will unlock all tables)
NOTES
One must have a lock on LOCK_open when calling this
This function will send a COND_refresh signal to inform other threads
that the name locks are removed
RETURN
0 ok
1 Fatal error (end of memory ?)
*/
void unlock_table_names(THD *thd, TABLE_LIST *table_list,
TABLE_LIST *last_table)
{
for (TABLE_LIST *table= table_list;
table != last_table;
table= table->next_local)
unlock_table_name(thd,table);
pthread_cond_broadcast(&COND_refresh);
}
static void print_lock_error(int error, const char *table)
{
int textno;
DBUG_ENTER("print_lock_error");
switch (error) {
case HA_ERR_LOCK_WAIT_TIMEOUT:
textno=ER_LOCK_WAIT_TIMEOUT;
break;
case HA_ERR_READ_ONLY_TRANSACTION:
textno=ER_READ_ONLY_TRANSACTION;
break;
case HA_ERR_LOCK_DEADLOCK:
textno=ER_LOCK_DEADLOCK;
break;
case HA_ERR_WRONG_COMMAND:
textno=ER_ILLEGAL_HA;
break;
default:
textno=ER_CANT_LOCK;
break;
}
if ( textno == ER_ILLEGAL_HA )
my_error(textno, MYF(ME_BELL+ME_OLDWIN+ME_WAITTANG), table);
else
my_error(textno, MYF(ME_BELL+ME_OLDWIN+ME_WAITTANG), error);
DBUG_VOID_RETURN;
}
/****************************************************************************
Handling of global read locks
Taking the global read lock is TWO steps (2nd step is optional; without
it, COMMIT of existing transactions will be allowed):
lock_global_read_lock() THEN make_global_read_lock_block_commit().
The global locks are handled through the global variables:
global_read_lock
count of threads which have the global read lock (i.e. have completed at
least the first step above)
global_read_lock_blocks_commit
count of threads which have the global read lock and block
commits (i.e. are in or have completed the second step above)
waiting_for_read_lock
count of threads which want to take a global read lock but cannot
protect_against_global_read_lock
count of threads which have set protection against global read lock.
access to them is protected with a mutex LOCK_global_read_lock
(XXX: one should never take LOCK_open if LOCK_global_read_lock is
taken, otherwise a deadlock may occur. Other mutexes could be a
problem too - grep the code for global_read_lock if you want to use
any other mutex here) Also one must not hold LOCK_open when calling
wait_if_global_read_lock(). When the thread with the global read lock
tries to close its tables, it needs to take LOCK_open in
close_thread_table().
How blocking of threads by global read lock is achieved: that's
advisory. Any piece of code which should be blocked by global read lock must
be designed like this:
- call to wait_if_global_read_lock(). When this returns 0, no global read
lock is owned; if argument abort_on_refresh was 0, none can be obtained.
- job
- if abort_on_refresh was 0, call to start_waiting_global_read_lock() to
allow other threads to get the global read lock. I.e. removal of the
protection.
(Note: it's a bit like an implementation of rwlock).
[ I am sorry to mention some SQL syntaxes below I know I shouldn't but found
no better descriptive way ]
Why does FLUSH TABLES WITH READ LOCK need to block COMMIT: because it's used
to read a non-moving SHOW MASTER STATUS, and a COMMIT writes to the binary
log.
Why getting the global read lock is two steps and not one. Because FLUSH
TABLES WITH READ LOCK needs to insert one other step between the two:
flushing tables. So the order is
1) lock_global_read_lock() (prevents any new table write locks, i.e. stalls
all new updates)
2) close_cached_tables() (the FLUSH TABLES), which will wait for tables
currently opened and being updated to close (so it's possible that there is
a moment where all new updates of server are stalled *and* FLUSH TABLES WITH
READ LOCK is, too).
3) make_global_read_lock_block_commit().
If we have merged 1) and 3) into 1), we would have had this deadlock:
imagine thread 1 and 2, in non-autocommit mode, thread 3, and an InnoDB
table t.
thd1: SELECT * FROM t FOR UPDATE;
thd2: UPDATE t SET a=1; # blocked by row-level locks of thd1
thd3: FLUSH TABLES WITH READ LOCK; # blocked in close_cached_tables() by the
table instance of thd2
thd1: COMMIT; # blocked by thd3.
thd1 blocks thd2 which blocks thd3 which blocks thd1: deadlock.
Note that we need to support that one thread does
FLUSH TABLES WITH READ LOCK; and then COMMIT;
(that's what innobackup does, for some good reason).
So in this exceptional case the COMMIT should not be blocked by the FLUSH
TABLES WITH READ LOCK.
****************************************************************************/
volatile uint global_read_lock=0;
volatile uint global_read_lock_blocks_commit=0;
static volatile uint protect_against_global_read_lock=0;
static volatile uint waiting_for_read_lock=0;
#define GOT_GLOBAL_READ_LOCK 1
#define MADE_GLOBAL_READ_LOCK_BLOCK_COMMIT 2
bool lock_global_read_lock(THD *thd)
{
DBUG_ENTER("lock_global_read_lock");
if (!thd->global_read_lock)
{
(void) pthread_mutex_lock(&LOCK_global_read_lock);
const char *old_message=thd->enter_cond(&COND_refresh, &LOCK_global_read_lock,
"Waiting to get readlock");
DBUG_PRINT("info",
("waiting_for: %d protect_against: %d",
waiting_for_read_lock, protect_against_global_read_lock));
waiting_for_read_lock++;
while (protect_against_global_read_lock && !thd->killed)
pthread_cond_wait(&COND_refresh, &LOCK_global_read_lock);
waiting_for_read_lock--;
if (thd->killed)
{
thd->exit_cond(old_message);
DBUG_RETURN(1);
}
thd->global_read_lock= GOT_GLOBAL_READ_LOCK;
global_read_lock++;
thd->exit_cond(old_message); // this unlocks LOCK_global_read_lock
}
/*
We DON'T set global_read_lock_blocks_commit now, it will be set after
tables are flushed (as the present function serves for FLUSH TABLES WITH
READ LOCK only). Doing things in this order is necessary to avoid
deadlocks (we must allow COMMIT until all tables are closed; we should not
forbid it before, or we can have a 3-thread deadlock if 2 do SELECT FOR
UPDATE and one does FLUSH TABLES WITH READ LOCK).
*/
DBUG_RETURN(0);
}
void unlock_global_read_lock(THD *thd)
{
uint tmp;
pthread_mutex_lock(&LOCK_global_read_lock);
tmp= --global_read_lock;
if (thd->global_read_lock == MADE_GLOBAL_READ_LOCK_BLOCK_COMMIT)
--global_read_lock_blocks_commit;
pthread_mutex_unlock(&LOCK_global_read_lock);
/* Send the signal outside the mutex to avoid a context switch */
if (!tmp)
pthread_cond_broadcast(&COND_refresh);
thd->global_read_lock= 0;
}
#define must_wait (global_read_lock && \
(is_not_commit || \
global_read_lock_blocks_commit))
bool wait_if_global_read_lock(THD *thd, bool abort_on_refresh,
bool is_not_commit)
{
const char *old_message;
bool result= 0, need_exit_cond;
DBUG_ENTER("wait_if_global_read_lock");
LINT_INIT(old_message);
/*
Assert that we do not own LOCK_open. If we would own it, other
threads could not close their tables. This would make a pretty
deadlock.
*/
safe_mutex_assert_not_owner(&LOCK_open);
(void) pthread_mutex_lock(&LOCK_global_read_lock);
if ((need_exit_cond= must_wait))
{
if (thd->global_read_lock) // This thread had the read locks
{
if (is_not_commit)
my_message(ER_CANT_UPDATE_WITH_READLOCK,
ER(ER_CANT_UPDATE_WITH_READLOCK), MYF(0));
(void) pthread_mutex_unlock(&LOCK_global_read_lock);
/*
We allow FLUSHer to COMMIT; we assume FLUSHer knows what it does.
This allowance is needed to not break existing versions of innobackup
which do a BEGIN; INSERT; FLUSH TABLES WITH READ LOCK; COMMIT.
*/
DBUG_RETURN(is_not_commit);
}
old_message=thd->enter_cond(&COND_refresh, &LOCK_global_read_lock,
"Waiting for release of readlock");
while (must_wait && ! thd->killed &&
(!abort_on_refresh || thd->version == refresh_version))
(void) pthread_cond_wait(&COND_refresh,&LOCK_global_read_lock);
if (thd->killed)
result=1;
}
if (!abort_on_refresh && !result)
protect_against_global_read_lock++;
/*
The following is only true in case of a global read locks (which is rare)
and if old_message is set
*/
if (unlikely(need_exit_cond))
thd->exit_cond(old_message); // this unlocks LOCK_global_read_lock
else
pthread_mutex_unlock(&LOCK_global_read_lock);
DBUG_RETURN(result);
}
void start_waiting_global_read_lock(THD *thd)
{
bool tmp;
DBUG_ENTER("start_waiting_global_read_lock");
if (unlikely(thd->global_read_lock))
DBUG_VOID_RETURN;
(void) pthread_mutex_lock(&LOCK_global_read_lock);
tmp= (!--protect_against_global_read_lock &&
(waiting_for_read_lock || global_read_lock_blocks_commit));
(void) pthread_mutex_unlock(&LOCK_global_read_lock);
if (tmp)
pthread_cond_broadcast(&COND_refresh);
DBUG_VOID_RETURN;
}
bool make_global_read_lock_block_commit(THD *thd)
{
bool error;
const char *old_message;
DBUG_ENTER("make_global_read_lock_block_commit");
/*
If we didn't succeed lock_global_read_lock(), or if we already suceeded
make_global_read_lock_block_commit(), do nothing.
*/
if (thd->global_read_lock != GOT_GLOBAL_READ_LOCK)
DBUG_RETURN(0);
pthread_mutex_lock(&LOCK_global_read_lock);
/* increment this BEFORE waiting on cond (otherwise race cond) */
global_read_lock_blocks_commit++;
/* For testing we set up some blocking, to see if we can be killed */
DBUG_EXECUTE_IF("make_global_read_lock_block_commit_loop",
protect_against_global_read_lock++;);
old_message= thd->enter_cond(&COND_refresh, &LOCK_global_read_lock,
"Waiting for all running commits to finish");
while (protect_against_global_read_lock && !thd->killed)
pthread_cond_wait(&COND_refresh, &LOCK_global_read_lock);
DBUG_EXECUTE_IF("make_global_read_lock_block_commit_loop",
protect_against_global_read_lock--;);
if ((error= test(thd->killed)))
global_read_lock_blocks_commit--; // undo what we did
else
thd->global_read_lock= MADE_GLOBAL_READ_LOCK_BLOCK_COMMIT;
thd->exit_cond(old_message); // this unlocks LOCK_global_read_lock
DBUG_RETURN(error);
}
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