mariadb/sql/sql_manager.cc

/* Copyright (c) 2000, 2013, 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 02110-1335  USA */

/* 
 * sql_manager.cc
 * This thread manages various maintenance tasks.
 *
 *   o Flushing the tables every flush_time seconds.
 *   o Berkeley DB: removing unneeded log files.
 */

#include "mariadb.h"
#include "sql_priv.h"
#include "sql_manager.h"
#include "sql_base.h"                           // flush_tables

/*
  Values for manager_thread_in_use: 0 means "not started". 1 means "started
  and active". 2 means "stopped".
*/
static int volatile manager_thread_in_use = 0;
static bool abort_manager = false;

pthread_t manager_thread;
mysql_mutex_t LOCK_manager;
mysql_cond_t COND_manager;

struct handler_cb {
   struct handler_cb *next;
   void (*action)(void *);
   void *data;
};

static struct handler_cb *cb_list; // protected by LOCK_manager

bool mysql_manager_submit(void (*action)(void *), void *data)
{
  bool result= FALSE;
  DBUG_ASSERT(manager_thread_in_use == 1);
  struct handler_cb **cb;
  mysql_mutex_lock(&LOCK_manager);
  cb= &cb_list;
  while (*cb)
    cb= &(*cb)->next;
  *cb= (struct handler_cb *)my_malloc(PSI_INSTRUMENT_ME,
                                      sizeof(struct handler_cb), MYF(MY_WME));
  if (!*cb)
    result= TRUE;
  else
  {
    (*cb)->next= NULL;
    (*cb)->action= action;
    (*cb)->data= data;
  }
  mysql_cond_signal(&COND_manager);
  mysql_mutex_unlock(&LOCK_manager);
  return result;
}

pthread_handler_t handle_manager(void *arg __attribute__((unused)))
{
  int error = 0;
  struct timespec abstime;
  bool reset_flush_time = TRUE;
  my_thread_init();
  my_thread_set_name("manager");
  DBUG_ENTER("handle_manager");

  pthread_detach_this_thread();
  manager_thread = pthread_self();
  mysql_mutex_lock(&LOCK_manager);
  manager_thread_in_use = 1;
  mysql_cond_signal(&COND_manager);
  while (!abort_manager || cb_list)
  {
    /* XXX: This will need to be made more general to handle different
     * polling needs. */
    if (flush_time)
    {
      if (reset_flush_time)
      {
	set_timespec(abstime, flush_time);
        reset_flush_time = FALSE;
      }
      while ((!error || error == EINTR) && !abort_manager && !cb_list)
        error= mysql_cond_timedwait(&COND_manager, &LOCK_manager, &abstime);

      if (error == ETIMEDOUT || error == ETIME)
      {
        tc_purge();
        error = 0;
        reset_flush_time = TRUE;
      }
    }
    else
    {
      while ((!error || error == EINTR) && !abort_manager && !cb_list)
        error= mysql_cond_wait(&COND_manager, &LOCK_manager);
    }

    struct handler_cb *cb= cb_list;
    cb_list= NULL;
    mysql_mutex_unlock(&LOCK_manager);

    while (cb)
    {
      struct handler_cb *next= cb->next;
      cb->action(cb->data);
      my_free(cb);
      cb= next;
    }
    mysql_mutex_lock(&LOCK_manager);
  }
  DBUG_ASSERT(cb_list == NULL);
  manager_thread_in_use = 2;
  mysql_mutex_unlock(&LOCK_manager);
  mysql_mutex_destroy(&LOCK_manager);
  mysql_cond_destroy(&COND_manager);
  DBUG_LEAVE; // Can't use DBUG_RETURN after my_thread_end
  my_thread_end();
  return (NULL);
}


/* Start handle manager thread */
void start_handle_manager()
{
  DBUG_ENTER("start_handle_manager");
  abort_manager = false;
  {
    pthread_t hThread;
    int err;
    DBUG_EXECUTE_IF("delay_start_handle_manager", my_sleep(1000););
    mysql_cond_init(key_COND_manager, &COND_manager,NULL);
    mysql_mutex_init(key_LOCK_manager, &LOCK_manager, NULL);
    if ((err= mysql_thread_create(key_thread_handle_manager, &hThread,
                                  &connection_attrib, handle_manager, 0)))
    {
      sql_print_warning("Can't create handle_manager thread (errno: %M)", err);
      DBUG_VOID_RETURN;
    }

    mysql_mutex_lock(&LOCK_manager);
    /*
      Wait for manager thread to have started, otherwise in extreme cases the
      server may start up and have initiated shutdown at the time the manager
      thread even starts to run.

      Allow both values 1 and 2 for manager_thread_in_use, so that we will not
      get stuck here if the manager thread somehow manages to start up and
      abort again before we have time to test it here.
    */
    while (!manager_thread_in_use)
      mysql_cond_wait(&COND_manager, &LOCK_manager);
    mysql_mutex_unlock(&LOCK_manager);
  }
  DBUG_VOID_RETURN;
}


/* Initiate shutdown of handle manager thread */
void stop_handle_manager()
{
  DBUG_ENTER("stop_handle_manager");
  if (manager_thread_in_use)
  {
    mysql_mutex_lock(&LOCK_manager);
    abort_manager = true;
    DBUG_PRINT("quit", ("initiate shutdown of handle manager thread: %lu",
                        (ulong)manager_thread));
    mysql_cond_signal(&COND_manager);
    mysql_mutex_unlock(&LOCK_manager);
  }
  DBUG_VOID_RETURN;
}