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mariadb/sql/sql_handler.cc
Dmitry Lenev 378cdc58c1 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.
2010-11-11 20:11:05 +03:00

994 lines
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/* Copyright (C) 2000-2004 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
/* HANDLER ... commands - direct access to ISAM */
/* TODO:
HANDLER blabla OPEN [ AS foobar ] [ (column-list) ]
the most natural (easiest, fastest) way to do it is to
compute List<Item> field_list not in mysql_ha_read
but in mysql_ha_open, and then store it in TABLE structure.
The problem here is that mysql_parse calls free_item to free all the
items allocated at the end of every query. The workaround would to
keep two item lists per THD - normal free_list and handler_items.
The second is to be freeed only on thread end. mysql_ha_open should
then do { handler_items=concat(handler_items, free_list); free_list=0; }
But !!! do_command calls free_root at the end of every query and frees up
all the sql_alloc'ed memory. It's harder to work around...
*/
/*
The information about open HANDLER objects is stored in a HASH.
It holds objects of type TABLE_LIST, which are indexed by table
name/alias, and allows us to quickly find a HANDLER table for any
operation at hand - be it HANDLER READ or HANDLER CLOSE.
It also allows us to maintain an "open" HANDLER even in cases
when there is no physically open cursor. E.g. a FLUSH TABLE
statement in this or some other connection demands that all open
HANDLERs against the flushed table are closed. In order to
preserve the information about an open HANDLER, we don't perform
a complete HANDLER CLOSE, but only close the TABLE object. The
corresponding TABLE_LIST is kept in the cache with 'table'
pointer set to NULL. The table will be reopened on next access
(this, however, leads to loss of cursor position, unless the
cursor points at the first record).
*/
#include "sql_priv.h"
#include "sql_handler.h"
#include "unireg.h" // REQUIRED: for other includes
#include "sql_base.h" // close_thread_tables
#include "lock.h" // mysql_unlock_tables
#include "key.h" // key_copy
#include "sql_base.h" // insert_fields
#include "sql_select.h"
#include "transaction.h"
#define HANDLER_TABLES_HASH_SIZE 120
static enum enum_ha_read_modes rkey_to_rnext[]=
{ RNEXT_SAME, RNEXT, RPREV, RNEXT, RPREV, RNEXT, RPREV, RPREV };
/*
Get hash key and hash key length.
SYNOPSIS
mysql_ha_hash_get_key()
tables Pointer to the hash object.
key_len_p (out) Pointer to the result for key length.
first Unused.
DESCRIPTION
The hash object is an TABLE_LIST struct.
The hash key is the alias name.
The hash key length is the alias name length plus one for the
terminateing NUL character.
RETURN
Pointer to the TABLE_LIST struct.
*/
static char *mysql_ha_hash_get_key(TABLE_LIST *tables, size_t *key_len_p,
my_bool first __attribute__((unused)))
{
*key_len_p= strlen(tables->alias) + 1 ; /* include '\0' in comparisons */
return tables->alias;
}
/*
Free an hash object.
SYNOPSIS
mysql_ha_hash_free()
tables Pointer to the hash object.
DESCRIPTION
The hash object is an TABLE_LIST struct.
RETURN
Nothing
*/
static void mysql_ha_hash_free(TABLE_LIST *tables)
{
my_free(tables);
}
/**
Close a HANDLER table.
@param thd Thread identifier.
@param tables A list of tables with the first entry to close.
@note Though this function takes a list of tables, only the first list entry
will be closed.
@note Broadcasts refresh if it closed a table with old version.
*/
static void mysql_ha_close_table(THD *thd, TABLE_LIST *tables)
{
if (tables->table && !tables->table->s->tmp_table)
{
/* Non temporary table. */
tables->table->file->ha_index_or_rnd_end();
tables->table->open_by_handler= 0;
(void) close_thread_table(thd, &tables->table);
thd->mdl_context.release_lock(tables->mdl_request.ticket);
}
else if (tables->table)
{
/* Must be a temporary table */
TABLE *table= tables->table;
table->file->ha_index_or_rnd_end();
table->query_id= thd->query_id;
table->open_by_handler= 0;
mark_tmp_table_for_reuse(table);
}
/* Mark table as closed, ready for re-open if necessary. */
tables->table= NULL;
/* Safety, cleanup the pointer to satisfy MDL assertions. */
tables->mdl_request.ticket= NULL;
}
/*
Open a HANDLER table.
SYNOPSIS
mysql_ha_open()
thd Thread identifier.
tables A list of tables with the first entry to open.
reopen Re-open a previously opened handler table.
DESCRIPTION
Though this function takes a list of tables, only the first list entry
will be opened.
'reopen' is set when a handler table is to be re-opened. In this case,
'tables' is the pointer to the hashed TABLE_LIST object which has been
saved on the original open.
'reopen' is also used to suppress the sending of an 'ok' message.
RETURN
FALSE OK
TRUE Error
*/
bool mysql_ha_open(THD *thd, TABLE_LIST *tables, bool reopen)
{
TABLE_LIST *hash_tables = NULL;
char *db, *name, *alias;
uint dblen, namelen, aliaslen, counter;
bool error;
TABLE *backup_open_tables;
MDL_savepoint mdl_savepoint;
DBUG_ENTER("mysql_ha_open");
DBUG_PRINT("enter",("'%s'.'%s' as '%s' reopen: %d",
tables->db, tables->table_name, tables->alias,
(int) reopen));
if (thd->locked_tables_mode)
{
my_error(ER_LOCK_OR_ACTIVE_TRANSACTION, MYF(0));
DBUG_RETURN(TRUE);
}
if (tables->schema_table)
{
my_error(ER_WRONG_USAGE, MYF(0), "HANDLER OPEN",
INFORMATION_SCHEMA_NAME.str);
DBUG_PRINT("exit",("ERROR"));
DBUG_RETURN(TRUE);
}
if (! my_hash_inited(&thd->handler_tables_hash))
{
/*
HASH entries are of type TABLE_LIST.
*/
if (my_hash_init(&thd->handler_tables_hash, &my_charset_latin1,
HANDLER_TABLES_HASH_SIZE, 0, 0,
(my_hash_get_key) mysql_ha_hash_get_key,
(my_hash_free_key) mysql_ha_hash_free, 0))
{
DBUG_PRINT("exit",("ERROR"));
DBUG_RETURN(TRUE);
}
}
else if (! reopen) /* Otherwise we have 'tables' already. */
{
if (my_hash_search(&thd->handler_tables_hash, (uchar*) tables->alias,
strlen(tables->alias) + 1))
{
DBUG_PRINT("info",("duplicate '%s'", tables->alias));
DBUG_PRINT("exit",("ERROR"));
my_error(ER_NONUNIQ_TABLE, MYF(0), tables->alias);
DBUG_RETURN(TRUE);
}
}
if (! reopen)
{
/* copy the TABLE_LIST struct */
dblen= strlen(tables->db) + 1;
namelen= strlen(tables->table_name) + 1;
aliaslen= strlen(tables->alias) + 1;
if (!(my_multi_malloc(MYF(MY_WME),
&hash_tables, (uint) sizeof(*hash_tables),
&db, (uint) dblen,
&name, (uint) namelen,
&alias, (uint) aliaslen,
NullS)))
{
DBUG_PRINT("exit",("ERROR"));
DBUG_RETURN(TRUE);
}
/* structure copy */
*hash_tables= *tables;
hash_tables->db= db;
hash_tables->table_name= name;
hash_tables->alias= alias;
memcpy(hash_tables->db, tables->db, dblen);
memcpy(hash_tables->table_name, tables->table_name, namelen);
memcpy(hash_tables->alias, tables->alias, aliaslen);
/*
We can't request lock with explicit duration for this table
right from the start as open_tables() can't handle properly
back-off for such locks.
*/
hash_tables->mdl_request.init(MDL_key::TABLE, db, name, MDL_SHARED,
MDL_TRANSACTION);
/* for now HANDLER can be used only for real TABLES */
hash_tables->required_type= FRMTYPE_TABLE;
/* add to hash */
if (my_hash_insert(&thd->handler_tables_hash, (uchar*) hash_tables))
{
my_free(hash_tables);
DBUG_PRINT("exit",("ERROR"));
DBUG_RETURN(TRUE);
}
}
else
hash_tables= tables;
/*
Save and reset the open_tables list so that open_tables() won't
be able to access (or know about) the previous list. And on return
from open_tables(), thd->open_tables will contain only the opened
table.
See open_table() back-off comments for more details.
*/
backup_open_tables= thd->open_tables;
thd->set_open_tables(NULL);
mdl_savepoint= thd->mdl_context.mdl_savepoint();
/*
open_tables() will set 'hash_tables->table' if successful.
It must be NULL for a real open when calling open_tables().
*/
DBUG_ASSERT(! hash_tables->table);
/*
We use open_tables() here, rather than, say,
open_ltable() or open_table() because we would like to be able
to open a temporary table.
*/
error= open_tables(thd, &hash_tables, &counter, 0);
if (! error &&
! (hash_tables->table->file->ha_table_flags() & HA_CAN_SQL_HANDLER))
{
my_error(ER_ILLEGAL_HA, MYF(0), tables->alias);
error= TRUE;
}
if (!error &&
hash_tables->mdl_request.ticket &&
thd->mdl_context.has_lock(mdl_savepoint,
hash_tables->mdl_request.ticket))
{
/* The ticket returned is within a savepoint. Make a copy. */
error= thd->mdl_context.clone_ticket(&hash_tables->mdl_request);
hash_tables->table->mdl_ticket= hash_tables->mdl_request.ticket;
}
if (error)
{
/*
No need to rollback statement transaction, it's not started.
If called with reopen flag, no need to rollback either,
it will be done at statement end.
*/
DBUG_ASSERT(thd->transaction.stmt.is_empty());
close_thread_tables(thd);
thd->mdl_context.rollback_to_savepoint(mdl_savepoint);
thd->set_open_tables(backup_open_tables);
if (!reopen)
my_hash_delete(&thd->handler_tables_hash, (uchar*) hash_tables);
else
{
hash_tables->table= NULL;
/* Safety, cleanup the pointer to satisfy MDL assertions. */
hash_tables->mdl_request.ticket= NULL;
}
DBUG_PRINT("exit",("ERROR"));
DBUG_RETURN(TRUE);
}
thd->set_open_tables(backup_open_tables);
if (hash_tables->mdl_request.ticket)
{
thd->mdl_context.set_lock_duration(hash_tables->mdl_request.ticket,
MDL_EXPLICIT);
thd->mdl_context.set_needs_thr_lock_abort(TRUE);
}
/*
Assert that the above check prevents opening of views and merge tables.
For temporary tables, TABLE::next can be set even if only one table
was opened for HANDLER as it is used to link them together
(see thd->temporary_tables).
*/
DBUG_ASSERT(hash_tables->table->next == NULL ||
hash_tables->table->s->tmp_table);
/*
If it's a temp table, don't reset table->query_id as the table is
being used by this handler. For non-temp tables we use this flag
in asserts.
*/
hash_tables->table->open_by_handler= 1;
if (! reopen)
my_ok(thd);
DBUG_PRINT("exit",("OK"));
DBUG_RETURN(FALSE);
}
/*
Close a HANDLER table by alias or table name
SYNOPSIS
mysql_ha_close()
thd Thread identifier.
tables A list of tables with the first entry to close.
DESCRIPTION
Closes the table that is associated (on the handler tables hash) with the
name (table->alias) of the specified table.
RETURN
FALSE ok
TRUE error
*/
bool mysql_ha_close(THD *thd, TABLE_LIST *tables)
{
TABLE_LIST *hash_tables;
DBUG_ENTER("mysql_ha_close");
DBUG_PRINT("enter",("'%s'.'%s' as '%s'",
tables->db, tables->table_name, tables->alias));
if (thd->locked_tables_mode)
{
my_error(ER_LOCK_OR_ACTIVE_TRANSACTION, MYF(0));
DBUG_RETURN(TRUE);
}
if ((hash_tables= (TABLE_LIST*) my_hash_search(&thd->handler_tables_hash,
(uchar*) tables->alias,
strlen(tables->alias) + 1)))
{
mysql_ha_close_table(thd, hash_tables);
my_hash_delete(&thd->handler_tables_hash, (uchar*) hash_tables);
}
else
{
my_error(ER_UNKNOWN_TABLE, MYF(0), tables->alias, "HANDLER");
DBUG_PRINT("exit",("ERROR"));
DBUG_RETURN(TRUE);
}
/*
Mark MDL_context as no longer breaking protocol if we have
closed last HANDLER.
*/
if (! thd->handler_tables_hash.records)
thd->mdl_context.set_needs_thr_lock_abort(FALSE);
my_ok(thd);
DBUG_PRINT("exit", ("OK"));
DBUG_RETURN(FALSE);
}
/**
A helper class to process an error from mysql_lock_tables().
HANDLER READ statement's attempt to lock the subject table
may get aborted if there is a pending DDL. In that case
we close the table, reopen it, and try to read again.
This is implicit and obscure, since HANDLER position
is lost in the process, but it's the legacy server
behaviour we should preserve.
*/
class Sql_handler_lock_error_handler: public Internal_error_handler
{
public:
virtual
bool handle_condition(THD *thd,
uint sql_errno,
const char *sqlstate,
MYSQL_ERROR::enum_warning_level level,
const char* msg,
MYSQL_ERROR **cond_hdl);
bool need_reopen() const { return m_need_reopen; };
void init() { m_need_reopen= FALSE; };
private:
bool m_need_reopen;
};
/**
Handle an error from mysql_lock_tables().
Ignore ER_LOCK_ABORTED errors.
*/
bool
Sql_handler_lock_error_handler::
handle_condition(THD *thd,
uint sql_errno,
const char *sqlstate,
MYSQL_ERROR::enum_warning_level level,
const char* msg,
MYSQL_ERROR **cond_hdl)
{
*cond_hdl= NULL;
if (sql_errno == ER_LOCK_ABORTED)
m_need_reopen= TRUE;
return m_need_reopen;
}
/*
Read from a HANDLER table.
SYNOPSIS
mysql_ha_read()
thd Thread identifier.
tables A list of tables with the first entry to read.
mode
keyname
key_expr
ha_rkey_mode
cond
select_limit_cnt
offset_limit_cnt
RETURN
FALSE ok
TRUE error
*/
bool mysql_ha_read(THD *thd, TABLE_LIST *tables,
enum enum_ha_read_modes mode, char *keyname,
List<Item> *key_expr,
enum ha_rkey_function ha_rkey_mode, Item *cond,
ha_rows select_limit_cnt, ha_rows offset_limit_cnt)
{
TABLE_LIST *hash_tables;
TABLE *table, *backup_open_tables;
MYSQL_LOCK *lock;
List<Item> list;
Protocol *protocol= thd->protocol;
char buff[MAX_FIELD_WIDTH];
String buffer(buff, sizeof(buff), system_charset_info);
int error, keyno= -1;
uint num_rows;
uchar *UNINIT_VAR(key);
uint UNINIT_VAR(key_len);
Sql_handler_lock_error_handler sql_handler_lock_error;
DBUG_ENTER("mysql_ha_read");
DBUG_PRINT("enter",("'%s'.'%s' as '%s'",
tables->db, tables->table_name, tables->alias));
if (thd->locked_tables_mode)
{
my_error(ER_LOCK_OR_ACTIVE_TRANSACTION, MYF(0));
DBUG_RETURN(TRUE);
}
thd->lex->select_lex.context.resolve_in_table_list_only(tables);
list.push_front(new Item_field(&thd->lex->select_lex.context,
NULL, NULL, "*"));
List_iterator<Item> it(list);
it++;
retry:
if ((hash_tables= (TABLE_LIST*) my_hash_search(&thd->handler_tables_hash,
(uchar*) tables->alias,
strlen(tables->alias) + 1)))
{
table= hash_tables->table;
DBUG_PRINT("info-in-hash",("'%s'.'%s' as '%s' table: 0x%lx",
hash_tables->db, hash_tables->table_name,
hash_tables->alias, (long) table));
if (!table)
{
/*
The handler table has been closed. Re-open it.
*/
if (mysql_ha_open(thd, hash_tables, 1))
{
DBUG_PRINT("exit",("reopen failed"));
goto err0;
}
table= hash_tables->table;
DBUG_PRINT("info",("re-opened '%s'.'%s' as '%s' tab %p",
hash_tables->db, hash_tables->table_name,
hash_tables->alias, table));
}
}
else
table= NULL;
if (!table)
{
my_error(ER_UNKNOWN_TABLE, MYF(0), tables->alias, "HANDLER");
goto err0;
}
/* save open_tables state */
backup_open_tables= thd->open_tables;
/* Always a one-element list, see mysql_ha_open(). */
DBUG_ASSERT(hash_tables->table->next == NULL ||
hash_tables->table->s->tmp_table);
/*
mysql_lock_tables() needs thd->open_tables to be set correctly to
be able to handle aborts properly.
*/
thd->set_open_tables(hash_tables->table);
sql_handler_lock_error.init();
thd->push_internal_handler(&sql_handler_lock_error);
lock= mysql_lock_tables(thd, &thd->open_tables, 1, 0);
thd->pop_internal_handler();
/*
In 5.1 and earlier, mysql_lock_tables() could replace the TABLE
object with another one (reopen it). This is no longer the case
with new MDL.
*/
DBUG_ASSERT(hash_tables->table == thd->open_tables);
/* Restore previous context. */
thd->set_open_tables(backup_open_tables);
if (sql_handler_lock_error.need_reopen())
{
DBUG_ASSERT(!lock && !thd->is_error());
/*
Always close statement transaction explicitly,
so that the engine doesn't have to count locks.
*/
trans_rollback_stmt(thd);
mysql_ha_close_table(thd, hash_tables);
goto retry;
}
if (!lock)
goto err0; // mysql_lock_tables() printed error message already
// Always read all columns
hash_tables->table->read_set= &hash_tables->table->s->all_set;
tables->table= hash_tables->table;
if (cond)
{
if (table->query_id != thd->query_id)
cond->cleanup(); // File was reopened
if ((!cond->fixed &&
cond->fix_fields(thd, &cond)) || cond->check_cols(1))
goto err;
}
if (keyname)
{
if ((keyno=find_type(keyname, &table->s->keynames, 1+2)-1)<0)
{
my_error(ER_KEY_DOES_NOT_EXITS, MYF(0), keyname, tables->alias);
goto err;
}
/* Check if the same index involved. */
if ((uint) keyno != table->file->get_index())
{
if (mode == RNEXT)
mode= RFIRST;
else if (mode == RPREV)
mode= RLAST;
}
}
if (insert_fields(thd, &thd->lex->select_lex.context,
tables->db, tables->alias, &it, 0))
goto err;
protocol->send_result_set_metadata(&list, Protocol::SEND_NUM_ROWS | Protocol::SEND_EOF);
/*
In ::external_lock InnoDB resets the fields which tell it that
the handle is used in the HANDLER interface. Tell it again that
we are using it for HANDLER.
*/
table->file->init_table_handle_for_HANDLER();
for (num_rows=0; num_rows < select_limit_cnt; )
{
switch (mode) {
case RNEXT:
if (table->file->inited != handler::NONE)
{
if (keyname)
{
/* Check if we read from the same index. */
DBUG_ASSERT((uint) keyno == table->file->get_index());
error= table->file->index_next(table->record[0]);
}
else
{
error= table->file->rnd_next(table->record[0]);
}
break;
}
/* else fall through */
case RFIRST:
if (keyname)
{
table->file->ha_index_or_rnd_end();
table->file->ha_index_init(keyno, 1);
error= table->file->index_first(table->record[0]);
}
else
{
table->file->ha_index_or_rnd_end();
if (!(error= table->file->ha_rnd_init(1)))
error= table->file->rnd_next(table->record[0]);
}
mode=RNEXT;
break;
case RPREV:
DBUG_ASSERT(keyname != 0);
/* Check if we read from the same index. */
DBUG_ASSERT((uint) keyno == table->file->get_index());
if (table->file->inited != handler::NONE)
{
error=table->file->index_prev(table->record[0]);
break;
}
/* else fall through */
case RLAST:
DBUG_ASSERT(keyname != 0);
table->file->ha_index_or_rnd_end();
table->file->ha_index_init(keyno, 1);
error= table->file->index_last(table->record[0]);
mode=RPREV;
break;
case RNEXT_SAME:
/* Continue scan on "(keypart1,keypart2,...)=(c1, c2, ...) */
DBUG_ASSERT(keyname != 0);
error= table->file->index_next_same(table->record[0], key, key_len);
break;
case RKEY:
{
DBUG_ASSERT(keyname != 0);
KEY *keyinfo=table->key_info+keyno;
KEY_PART_INFO *key_part=keyinfo->key_part;
if (key_expr->elements > keyinfo->key_parts)
{
my_error(ER_TOO_MANY_KEY_PARTS, MYF(0), keyinfo->key_parts);
goto err;
}
List_iterator<Item> it_ke(*key_expr);
Item *item;
key_part_map keypart_map;
for (keypart_map= key_len=0 ; (item=it_ke++) ; key_part++)
{
my_bitmap_map *old_map;
// 'item' can be changed by fix_fields() call
if ((!item->fixed &&
item->fix_fields(thd, it_ke.ref())) ||
(item= *it_ke.ref())->check_cols(1))
goto err;
if (item->used_tables() & ~RAND_TABLE_BIT)
{
my_error(ER_WRONG_ARGUMENTS,MYF(0),"HANDLER ... READ");
goto err;
}
old_map= dbug_tmp_use_all_columns(table, table->write_set);
(void) item->save_in_field(key_part->field, 1);
dbug_tmp_restore_column_map(table->write_set, old_map);
key_len+=key_part->store_length;
keypart_map= (keypart_map << 1) | 1;
}
if (!(key= (uchar*) thd->calloc(ALIGN_SIZE(key_len))))
goto err;
table->file->ha_index_or_rnd_end();
table->file->ha_index_init(keyno, 1);
key_copy(key, table->record[0], table->key_info + keyno, key_len);
error= table->file->index_read_map(table->record[0],
key, keypart_map, ha_rkey_mode);
mode=rkey_to_rnext[(int)ha_rkey_mode];
break;
}
default:
my_message(ER_ILLEGAL_HA, ER(ER_ILLEGAL_HA), MYF(0));
goto err;
}
if (error)
{
if (error == HA_ERR_RECORD_DELETED)
continue;
if (error != HA_ERR_KEY_NOT_FOUND && error != HA_ERR_END_OF_FILE)
{
sql_print_error("mysql_ha_read: Got error %d when reading table '%s'",
error, tables->table_name);
table->file->print_error(error,MYF(0));
goto err;
}
goto ok;
}
if (cond && !cond->val_int())
{
if (thd->is_error())
goto err;
continue;
}
if (num_rows >= offset_limit_cnt)
{
protocol->prepare_for_resend();
if (protocol->send_result_set_row(&list))
goto err;
protocol->write();
}
num_rows++;
}
ok:
/*
Always close statement transaction explicitly,
so that the engine doesn't have to count locks.
*/
trans_commit_stmt(thd);
mysql_unlock_tables(thd,lock);
my_eof(thd);
DBUG_PRINT("exit",("OK"));
DBUG_RETURN(FALSE);
err:
trans_rollback_stmt(thd);
mysql_unlock_tables(thd,lock);
err0:
DBUG_PRINT("exit",("ERROR"));
DBUG_RETURN(TRUE);
}
/**
Scan the handler tables hash for matching tables.
@param thd Thread identifier.
@param tables The list of tables to remove.
@return Pointer to head of linked list (TABLE_LIST::next_local) of matching
TABLE_LIST elements from handler_tables_hash. Otherwise, NULL if no
table was matched.
*/
static TABLE_LIST *mysql_ha_find(THD *thd, TABLE_LIST *tables)
{
TABLE_LIST *hash_tables, *head= NULL, *first= tables;
DBUG_ENTER("mysql_ha_find");
/* search for all handlers with matching table names */
for (uint i= 0; i < thd->handler_tables_hash.records; i++)
{
hash_tables= (TABLE_LIST*) my_hash_element(&thd->handler_tables_hash, i);
for (tables= first; tables; tables= tables->next_local)
{
if ((! *tables->db ||
! my_strcasecmp(&my_charset_latin1, hash_tables->db, tables->db)) &&
! my_strcasecmp(&my_charset_latin1, hash_tables->table_name,
tables->table_name))
break;
}
if (tables)
{
hash_tables->next_local= head;
head= hash_tables;
}
}
DBUG_RETURN(head);
}
/**
Remove matching tables from the HANDLER's hash table.
@param thd Thread identifier.
@param tables The list of tables to remove.
@note Broadcasts refresh if it closed a table with old version.
*/
void mysql_ha_rm_tables(THD *thd, TABLE_LIST *tables)
{
TABLE_LIST *hash_tables, *next;
DBUG_ENTER("mysql_ha_rm_tables");
DBUG_ASSERT(tables);
hash_tables= mysql_ha_find(thd, tables);
while (hash_tables)
{
next= hash_tables->next_local;
if (hash_tables->table)
mysql_ha_close_table(thd, hash_tables);
my_hash_delete(&thd->handler_tables_hash, (uchar*) hash_tables);
hash_tables= next;
}
/*
Mark MDL_context as no longer breaking protocol if we have
closed last HANDLER.
*/
if (! thd->handler_tables_hash.records)
thd->mdl_context.set_needs_thr_lock_abort(FALSE);
DBUG_VOID_RETURN;
}
/**
Close cursors of matching tables from the HANDLER's hash table.
@param thd Thread identifier.
@param tables The list of tables to flush.
*/
void mysql_ha_flush_tables(THD *thd, TABLE_LIST *all_tables)
{
DBUG_ENTER("mysql_ha_flush_tables");
for (TABLE_LIST *table_list= all_tables; table_list;
table_list= table_list->next_global)
{
TABLE_LIST *hash_tables= mysql_ha_find(thd, table_list);
/* Close all aliases of the same table. */
while (hash_tables)
{
TABLE_LIST *next_local= hash_tables->next_local;
if (hash_tables->table)
mysql_ha_close_table(thd, hash_tables);
hash_tables= next_local;
}
}
DBUG_VOID_RETURN;
}
/**
Flush (close and mark for re-open) all tables that should be should
be reopen.
@param thd Thread identifier.
@note Broadcasts refresh if it closed a table with old version.
*/
void mysql_ha_flush(THD *thd)
{
TABLE_LIST *hash_tables;
DBUG_ENTER("mysql_ha_flush");
mysql_mutex_assert_not_owner(&LOCK_open);
/*
Don't try to flush open HANDLERs when we're working with
system tables. The main MDL context is backed up and we can't
properly release HANDLER locks stored there.
*/
if (thd->state_flags & Open_tables_state::BACKUPS_AVAIL)
DBUG_VOID_RETURN;
for (uint i= 0; i < thd->handler_tables_hash.records; i++)
{
hash_tables= (TABLE_LIST*) my_hash_element(&thd->handler_tables_hash, i);
/*
TABLE::mdl_ticket is 0 for temporary tables so we need extra check.
*/
if (hash_tables->table &&
((hash_tables->table->mdl_ticket &&
hash_tables->table->mdl_ticket->has_pending_conflicting_lock()) ||
(!hash_tables->table->s->tmp_table &&
hash_tables->table->s->has_old_version())))
mysql_ha_close_table(thd, hash_tables);
}
DBUG_VOID_RETURN;
}
/**
Close all HANDLER's tables.
@param thd Thread identifier.
@note Broadcasts refresh if it closed a table with old version.
*/
void mysql_ha_cleanup(THD *thd)
{
TABLE_LIST *hash_tables;
DBUG_ENTER("mysql_ha_cleanup");
for (uint i= 0; i < thd->handler_tables_hash.records; i++)
{
hash_tables= (TABLE_LIST*) my_hash_element(&thd->handler_tables_hash, i);
if (hash_tables->table)
mysql_ha_close_table(thd, hash_tables);
}
my_hash_free(&thd->handler_tables_hash);
DBUG_VOID_RETURN;
}
/**
Set explicit duration for metadata locks corresponding to open HANDLERs
to protect them from being released at the end of transaction.
@param thd Thread identifier.
*/
void mysql_ha_set_explicit_lock_duration(THD *thd)
{
TABLE_LIST *hash_tables;
DBUG_ENTER("mysql_ha_set_explicit_lock_duration");
for (uint i= 0; i < thd->handler_tables_hash.records; i++)
{
hash_tables= (TABLE_LIST*) my_hash_element(&thd->handler_tables_hash, i);
if (hash_tables->table && hash_tables->table->mdl_ticket)
thd->mdl_context.set_lock_duration(hash_tables->table->mdl_ticket,
MDL_EXPLICIT);
}
DBUG_VOID_RETURN;
}
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