sql_reload.cc

/* Copyright (c) 2010, 2012, 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 "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 "rpl_master.h"  // reset_master
#include "rpl_slave.h"   // reset_slave
#include "rpl_rli.h"     // rotate_relay_log
#include "rpl_mi.h"
#include "debug_sync.h"


bool reload_acl_and_cache(THD *thd, unsigned 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;
      /* Remember that we don't have a THD */
      my_pthread_setspecific_ptr(THR_THD,  0);
      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) && opt_slow_log)
    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
    mysql_mutex_lock(&LOCK_active_mi);
    if (active_mi != NULL)
    {
      mysql_mutex_lock(&active_mi->data_lock);
      if (rotate_relay_log(active_mi))
        *write_to_binlog= -1;
      mysql_mutex_unlock(&active_mi->data_lock);
    }
    mysql_mutex_unlock(&LOCK_active_mi);
#endif
  }
#ifdef HAVE_QUERY_CACHE
  if (options & REFRESH_QUERY_CACHE_FREE)
  {
    query_cache.pack();                         // 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->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;
      }
    }
    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)
    kill_blocked_pthreads();
#ifdef HAVE_REPLICATION
  if (options & REFRESH_MASTER)
  {
    DBUG_ASSERT(thd);
    tmp_write_to_binlog= 0;
    if (reset_master(thd))
    {
      /* 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)
 {
   tmp_write_to_binlog= 0;
   mysql_mutex_lock(&LOCK_active_mi);
   if (active_mi != NULL && reset_slave(thd, active_mi))
   {
     /* NOTE: my_error() has been already called by reset_slave(). */
     result= 1;
   }
   else if (active_mi == NULL)
   {
     result= 1;
     my_error(ER_SLAVE_CONFIGURATION, MYF(0));
   }
   mysql_mutex_unlock(&LOCK_active_mi);
 }
#endif
 if (options & REFRESH_USER_RESOURCES)
   reset_mqh((LEX_USER *) NULL, 0);             /* purecov: inspected */
 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);
}


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;
  }

  /*
    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;
  }

  /*
    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) ||
      thd->locked_tables_list.init_locked_tables(thd))
  {
    goto error;
  }
  thd->variables.option_bits|= OPTION_TABLE_LOCK;

  /*
    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:
  return TRUE;
}


bool flush_tables_for_export(THD *thd, TABLE_LIST *all_tables)
{
  Lock_tables_prelocking_strategy lock_tables_prelocking_strategy;

  /*
    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));
    return true;
  }

  /*
    Acquire SNW locks on tables to be exported. Don't acquire
    global IX as this will make this statement incompatible
    with FLUSH TABLES WITH READ LOCK.
  */
  if (open_and_lock_tables(thd, all_tables, false,
                           MYSQL_OPEN_SKIP_SCOPED_MDL_LOCK,
                           &lock_tables_prelocking_strategy))
  {
    return true;
  }

  // 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_name);
      return true;
    }
  }

  // Notify the storage engines that the tables should be made ready for export.
  for (TABLE_LIST *table_list= all_tables; table_list;
       table_list= table_list->next_global)
  {
    handler *handler_file= table_list->table->file;
    int error= handler_file->extra(HA_EXTRA_EXPORT);
    if (error)
    {
      handler_file->print_error(error, MYF(0));
      return true;
    }
  }

  // Enter LOCKED TABLES mode.
  if (thd->locked_tables_list.init_locked_tables(thd))
    return true;
  thd->variables.option_bits|= OPTION_TABLE_LOCK;

  return false;
}