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bb1b61b312088ba9f5f2cb606594b6f33c284402
mariadb/sql/sql_reload.cc
Sergei Golubchik bfe703a458 don't let current_thd to point to a destroyed THD 
* reset current_thd in THD::~THD, otherwise my_malloc_size_cb_func()
  might access THD after it was destroyed.
* remove now redundant set_current_thd(0) calls that follow delete thd.
2015-02-03 18:19:56 +01:00

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/* Copyright (c) 2010, 2011, Oracle and/or its affiliates. All rights reserved.
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 */
#include <my_global.h>
#include "sql_reload.h"
#include "sql_priv.h"
#include "mysqld.h" // select_errors
#include "sql_class.h" // THD
#include "sql_acl.h" // acl_reload
#include "sql_servers.h" // servers_reload
#include "sql_connect.h" // reset_mqh
#include "sql_base.h" // close_cached_tables
#include "sql_db.h" // my_dbopt_cleanup
#include "hostname.h" // hostname_cache_refresh
#include "sql_repl.h" // reset_master, reset_slave
#include "rpl_mi.h" // Master_info::data_lock
#include "sql_show.h"
#include "debug_sync.h"
#include "rpl_mi.h"
static void disable_checkpoints(THD *thd);
/**
Reload/resets privileges and the different caches.
@param thd Thread handler (can be NULL!)
@param options What should be reset/reloaded (tables, privileges, slave...)
@param tables Tables to flush (if any)
@param write_to_binlog < 0 if there was an error while interacting with the binary log inside
reload_acl_and_cache,
0 if we should not write to the binary log,
> 0 if we can write to the binlog.
@note Depending on 'options', it may be very bad to write the
query to the binlog (e.g. FLUSH SLAVE); this is a
pointer where reload_acl_and_cache() will put 0 if
it thinks we really should not write to the binlog.
Otherwise it will put 1.
@return Error status code
@retval 0 Ok
@retval !=0 Error; thd->killed is set or thd->is_error() is true
*/
bool reload_acl_and_cache(THD *thd, unsigned long long options,
TABLE_LIST *tables, int *write_to_binlog)
{
bool result=0;
select_errors=0; /* Write if more errors */
int tmp_write_to_binlog= *write_to_binlog= 1;
DBUG_ASSERT(!thd || !thd->in_sub_stmt);
#ifndef NO_EMBEDDED_ACCESS_CHECKS
if (options & REFRESH_GRANT)
{
THD *tmp_thd= 0;
/*
If reload_acl_and_cache() is called from SIGHUP handler we have to
allocate temporary THD for execution of acl_reload()/grant_reload().
*/
if (!thd && (thd= (tmp_thd= new THD)))
{
thd->thread_stack= (char*) &tmp_thd;
thd->store_globals();
}
if (thd)
{
bool reload_acl_failed= acl_reload(thd);
bool reload_grants_failed= grant_reload(thd);
bool reload_servers_failed= servers_reload(thd);
if (reload_acl_failed || reload_grants_failed || reload_servers_failed)
{
result= 1;
/*
When an error is returned, my_message may have not been called and
the client will hang waiting for a response.
*/
my_error(ER_UNKNOWN_ERROR, MYF(0));
}
}
if (tmp_thd)
{
delete tmp_thd;
thd= 0;
}
reset_mqh((LEX_USER *)NULL, TRUE);
}
#endif
if (options & REFRESH_LOG)
{
/*
Flush the normal query log, the update log, the binary log,
the slow query log, the relay log (if it exists) and the log
tables.
*/
options|= REFRESH_BINARY_LOG;
options|= REFRESH_RELAY_LOG;
options|= REFRESH_SLOW_LOG;
options|= REFRESH_GENERAL_LOG;
options|= REFRESH_ENGINE_LOG;
options|= REFRESH_ERROR_LOG;
}
if (options & REFRESH_ERROR_LOG)
if (flush_error_log())
{
/*
When flush_error_log() failed, my_error() has not been called.
So, we have to do it here to keep the protocol.
*/
my_error(ER_UNKNOWN_ERROR, MYF(0));
result= 1;
}
if ((options & REFRESH_SLOW_LOG) && global_system_variables.sql_log_slow)
logger.flush_slow_log();
if ((options & REFRESH_GENERAL_LOG) && opt_log)
logger.flush_general_log();
if (options & REFRESH_ENGINE_LOG)
if (ha_flush_logs(NULL))
result= 1;
if (options & REFRESH_BINARY_LOG)
{
/*
Writing this command to the binlog may result in infinite loops
when doing mysqlbinlog|mysql, and anyway it does not really make
sense to log it automatically (would cause more trouble to users
than it would help them)
*/
tmp_write_to_binlog= 0;
if (mysql_bin_log.is_open())
{
if (mysql_bin_log.rotate_and_purge(true))
*write_to_binlog= -1;
}
}
if (options & REFRESH_RELAY_LOG)
{
#ifdef HAVE_REPLICATION
LEX_STRING connection_name;
Master_info *mi;
if (thd)
connection_name= thd->lex->relay_log_connection_name;
else
{
connection_name.str= (char*) "";
connection_name.length= 0;
}
/*
Writing this command to the binlog may cause problems as the
slave is not likely to have the same connection names.
*/
tmp_write_to_binlog= 0;
mysql_mutex_lock(&LOCK_active_mi);
if (master_info_index)
{
if (!(mi= (master_info_index->
get_master_info(&connection_name,
Sql_condition::WARN_LEVEL_ERROR))))
{
result= 1;
}
else
{
mysql_mutex_lock(&mi->data_lock);
if (rotate_relay_log(mi))
*write_to_binlog= -1;
mysql_mutex_unlock(&mi->data_lock);
}
}
mysql_mutex_unlock(&LOCK_active_mi);
#endif
}
#ifdef HAVE_QUERY_CACHE
if (options & REFRESH_QUERY_CACHE_FREE)
{
query_cache.pack(thd); // FLUSH QUERY CACHE
options &= ~REFRESH_QUERY_CACHE; // Don't flush cache, just free memory
}
if (options & (REFRESH_TABLES | REFRESH_QUERY_CACHE))
{
query_cache.flush(); // RESET QUERY CACHE
}
#endif /*HAVE_QUERY_CACHE*/
DBUG_ASSERT(!thd || thd->locked_tables_mode ||
!thd->mdl_context.has_locks() ||
thd->handler_tables_hash.records ||
thd->ull_hash.records ||
thd->global_read_lock.is_acquired());
/*
Note that if REFRESH_READ_LOCK bit is set then REFRESH_TABLES is set too
(see sql_yacc.yy)
*/
if (options & (REFRESH_TABLES | REFRESH_READ_LOCK))
{
if ((options & REFRESH_READ_LOCK) && thd)
{
/*
On the first hand we need write lock on the tables to be flushed,
on the other hand we must not try to aspire a global read lock
if we have a write locked table as this would lead to a deadlock
when trying to reopen (and re-lock) the table after the flush.
*/
if (thd->locked_tables_mode)
{
my_error(ER_LOCK_OR_ACTIVE_TRANSACTION, MYF(0));
return 1;
}
/*
Writing to the binlog could cause deadlocks, as we don't log
UNLOCK TABLES
*/
tmp_write_to_binlog= 0;
if (thd->global_read_lock.lock_global_read_lock(thd))
return 1; // Killed
if (close_cached_tables(thd, tables,
((options & REFRESH_FAST) ? FALSE : TRUE),
thd->variables.lock_wait_timeout))
{
/*
NOTE: my_error() has been already called by reopen_tables() within
close_cached_tables().
*/
result= 1;
}
if (thd->global_read_lock.make_global_read_lock_block_commit(thd)) // Killed
{
/* Don't leave things in a half-locked state */
thd->global_read_lock.unlock_global_read_lock(thd);
return 1;
}
if (options & REFRESH_CHECKPOINT)
disable_checkpoints(thd);
/*
We need to do it second time after wsrep appliers were blocked in
make_global_read_lock_block_commit(thd) above since they could have
modified the tables too.
*/
if (WSREP(thd) &&
close_cached_tables(thd, tables, (options & REFRESH_FAST) ?
FALSE : TRUE, TRUE))
result= 1;
}
else
{
if (thd && thd->locked_tables_mode)
{
/*
If we are under LOCK TABLES we should have a write
lock on tables which we are going to flush.
*/
if (tables)
{
for (TABLE_LIST *t= tables; t; t= t->next_local)
if (!find_table_for_mdl_upgrade(thd, t->db, t->table_name, false))
return 1;
}
else
{
/*
It is not safe to upgrade the metadata lock without GLOBAL IX lock.
This can happen with FLUSH TABLES <list> WITH READ LOCK as we in
these cases don't take a GLOBAL IX lock in order to be compatible
with global read lock.
*/
if (thd->open_tables &&
!thd->mdl_context.is_lock_owner(MDL_key::GLOBAL, "", "",
MDL_INTENTION_EXCLUSIVE))
{
my_error(ER_TABLE_NOT_LOCKED_FOR_WRITE, MYF(0),
thd->open_tables->s->table_name.str);
return true;
}
for (TABLE *tab= thd->open_tables; tab; tab= tab->next)
{
if (! tab->mdl_ticket->is_upgradable_or_exclusive())
{
my_error(ER_TABLE_NOT_LOCKED_FOR_WRITE, MYF(0),
tab->s->table_name.str);
return 1;
}
}
}
}
if (close_cached_tables(thd, tables,
((options & REFRESH_FAST) ? FALSE : TRUE),
(thd ? thd->variables.lock_wait_timeout :
LONG_TIMEOUT)))
{
/*
NOTE: my_error() has been already called by reopen_tables() within
close_cached_tables().
*/
result= 1;
}
}
my_dbopt_cleanup();
}
if (options & REFRESH_HOSTS)
hostname_cache_refresh();
if (thd && (options & REFRESH_STATUS))
refresh_status(thd);
if (options & REFRESH_THREADS)
flush_thread_cache();
#ifdef HAVE_REPLICATION
if (options & REFRESH_MASTER)
{
DBUG_ASSERT(thd);
tmp_write_to_binlog= 0;
if (reset_master(thd, NULL, 0))
{
/* NOTE: my_error() has been already called by reset_master(). */
result= 1;
}
}
#endif
#ifdef OPENSSL
if (options & REFRESH_DES_KEY_FILE)
{
if (des_key_file && load_des_key_file(des_key_file))
{
/* NOTE: my_error() has been already called by load_des_key_file(). */
result= 1;
}
}
#endif
#ifdef HAVE_REPLICATION
if (options & REFRESH_SLAVE)
{
LEX_MASTER_INFO* lex_mi= &thd->lex->mi;
Master_info *mi;
tmp_write_to_binlog= 0;
mysql_mutex_lock(&LOCK_active_mi);
if (master_info_index)
{
if (!(mi= (master_info_index->
get_master_info(&lex_mi->connection_name,
Sql_condition::WARN_LEVEL_ERROR))))
{
result= 1;
}
else if (reset_slave(thd, mi))
{
/* NOTE: my_error() has been already called by reset_slave(). */
result= 1;
}
else if (mi->connection_name.length && thd->lex->reset_slave_info.all)
{
/* If not default connection and 'all' is used */
master_info_index->remove_master_info(&mi->connection_name);
}
}
mysql_mutex_unlock(&LOCK_active_mi);
}
#endif
if (options & REFRESH_USER_RESOURCES)
reset_mqh((LEX_USER *) NULL, 0); /* purecov: inspected */
if (options & REFRESH_GENERIC)
{
List_iterator_fast<LEX_STRING> li(thd->lex->view_list);
LEX_STRING *ls;
while ((ls= li++))
{
ST_SCHEMA_TABLE *table= find_schema_table(thd, ls->str);
if (table->reset_table())
result= 1;
}
}
if (*write_to_binlog != -1)
*write_to_binlog= tmp_write_to_binlog;
/*
If the query was killed then this function must fail.
*/
return result || (thd ? thd->killed : 0);
}
/**
Implementation of FLUSH TABLES <table_list> WITH READ LOCK
and FLUSH TABLES <table_list> FOR EXPORT
In brief: take exclusive locks, expel tables from the table
cache, reopen the tables, enter the 'LOCKED TABLES' mode,
downgrade the locks.
Note: the function is written to be called from
mysql_execute_command(), it is not reusable in arbitrary
execution context.
Required privileges
-------------------
Since the statement implicitly enters LOCK TABLES mode,
it requires LOCK TABLES privilege on every table.
But since the rest of FLUSH commands require
the global RELOAD_ACL, it also requires RELOAD_ACL.
Compatibility with the global read lock
---------------------------------------
We don't wait for the GRL, since neither the
5.1 combination that this new statement is intended to
replace (LOCK TABLE <list> WRITE; FLUSH TABLES;),
nor FLUSH TABLES WITH READ LOCK do.
@todo: this is not implemented, Dmitry disagrees.
Currently we wait for GRL in another connection,
but are compatible with a GRL in our own connection.
Behaviour under LOCK TABLES
---------------------------
Bail out: i.e. don't perform an implicit UNLOCK TABLES.
This is not consistent with LOCK TABLES statement, but is
in line with behaviour of FLUSH TABLES WITH READ LOCK, and we
try to not introduce any new statements with implicit
semantics.
Compatibility with parallel updates
-----------------------------------
As a result, we will wait for all open transactions
against the tables to complete. After the lock downgrade,
new transactions will be able to read the tables, but not
write to them.
Differences from FLUSH TABLES <list>
-------------------------------------
- you can't flush WITH READ LOCK a non-existent table
- you can't flush WITH READ LOCK under LOCK TABLES
Effect on views and temporary tables.
------------------------------------
You can only apply this command to existing base tables.
If a view with such name exists, ER_WRONG_OBJECT is returned.
If a temporary table with such name exists, it's ignored:
if there is a base table, it's used, otherwise ER_NO_SUCH_TABLE
is returned.
Handling of MERGE tables
------------------------
For MERGE table this statement will open and lock child tables
for read (it is impossible to lock parent table without it).
Child tables won't be flushed unless they are explicitly present
in the statement's table list.
Implicit commit
---------------
This statement causes an implicit commit before and
after it.
HANDLER SQL
-----------
If this connection has HANDLERs open against
some of the tables being FLUSHed, these handlers
are implicitly flushed (lose their position).
*/
bool flush_tables_with_read_lock(THD *thd, TABLE_LIST *all_tables)
{
Lock_tables_prelocking_strategy lock_tables_prelocking_strategy;
TABLE_LIST *table_list;
/*
This is called from SQLCOM_FLUSH, the transaction has
been committed implicitly.
*/
if (thd->locked_tables_mode)
{
my_error(ER_LOCK_OR_ACTIVE_TRANSACTION, MYF(0));
goto error;
}
if (thd->lex->type & REFRESH_READ_LOCK)
{
/*
Acquire SNW locks on tables to be flushed. Don't acquire global
IX and database-scope IX locks on the tables as this will make
this statement incompatible with FLUSH TABLES WITH READ LOCK.
*/
if (lock_table_names(thd, all_tables, NULL,
thd->variables.lock_wait_timeout,
MYSQL_OPEN_SKIP_SCOPED_MDL_LOCK))
goto error;
DEBUG_SYNC(thd,"flush_tables_with_read_lock_after_acquire_locks");
for (table_list= all_tables; table_list;
table_list= table_list->next_global)
{
/* Request removal of table from cache. */
tdc_remove_table(thd, TDC_RT_REMOVE_UNUSED,
table_list->db,
table_list->table_name, FALSE);
/* Reset ticket to satisfy asserts in open_tables(). */
table_list->mdl_request.ticket= NULL;
}
}
thd->variables.option_bits|= OPTION_TABLE_LOCK;
/*
Before opening and locking tables the below call also waits
for old shares to go away, so the fact that we don't pass
MYSQL_OPEN_IGNORE_FLUSH flag to it is important.
Also we don't pass MYSQL_OPEN_HAS_MDL_LOCK flag as we want
to open underlying tables if merge table is flushed.
For underlying tables of the merge the below call has to
acquire SNW locks to ensure that they can be locked for
read without further waiting.
*/
if (open_and_lock_tables(thd, all_tables, FALSE,
MYSQL_OPEN_SKIP_SCOPED_MDL_LOCK,
&lock_tables_prelocking_strategy))
goto error_reset_bits;
if (thd->lex->type & REFRESH_FOR_EXPORT)
{
// Check if all storage engines support FOR EXPORT.
for (TABLE_LIST *table_list= all_tables; table_list;
table_list= table_list->next_global)
{
if (!(table_list->table->file->ha_table_flags() & HA_CAN_EXPORT))
{
my_error(ER_ILLEGAL_HA, MYF(0),table_list->table->file->table_type(),
table_list->db, table_list->table_name);
goto error_reset_bits;
}
}
}
if (thd->locked_tables_list.init_locked_tables(thd))
goto error_reset_bits;
/*
We don't downgrade MDL_SHARED_NO_WRITE here as the intended
post effect of this call is identical to LOCK TABLES <...> READ,
and we didn't use thd->in_lock_talbes and
thd->sql_command= SQLCOM_LOCK_TABLES hacks to enter the LTM.
*/
return FALSE;
error_reset_bits:
close_thread_tables(thd);
thd->variables.option_bits&= ~OPTION_TABLE_LOCK;
error:
return TRUE;
}
/**
Disable checkpoints for all handlers
This is released in unlock_global_read_lock()
*/
static void disable_checkpoints(THD *thd)
{
if (!thd->global_disable_checkpoint)
{
thd->global_disable_checkpoint= 1;
if (!global_disable_checkpoint++)
ha_checkpoint_state(1); // Disable checkpoints
}
}
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