246 lines
6.1 KiB
C++
246 lines
6.1 KiB
C++
/* Copyright (c) 2014, 2015, Oracle and/or its affiliates. All rights reserved.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
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#include "my_thread.h" /* my_thread_id */
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#include "my_timer.h" /* my_timer_t */
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#include "sql_class.h" /* THD */
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#include "sql_timer.h" /* thd_timer_set, etc. */
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#include "sql_parse.h" /* Global_THD_manager, Find_thd_with_id */
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#include "mysqld.h"
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struct st_thd_timer_info
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{
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my_thread_id thread_id;
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my_timer_t timer;
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mysql_mutex_t mutex;
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bool destroy;
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};
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C_MODE_START
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static void timer_callback(my_timer_t *);
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C_MODE_END
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/**
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Allocate and initialize a thread timer object.
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@return NULL on failure.
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*/
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static THD_timer_info *
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thd_timer_create(void)
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{
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THD_timer_info *thd_timer;
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DBUG_ENTER("thd_timer_create");
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thd_timer= (THD_timer_info *) my_malloc(key_memory_thd_timer,
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sizeof(THD_timer_info),
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MYF(MY_WME));
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if (thd_timer == NULL)
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DBUG_RETURN(NULL);
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thd_timer->thread_id= 0;
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mysql_mutex_init(key_thd_timer_mutex, &thd_timer->mutex, MY_MUTEX_INIT_FAST);
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thd_timer->destroy= 0;
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thd_timer->timer.notify_function= timer_callback;
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if (DBUG_EVALUATE_IF("thd_timer_create_failure", 0, 1) &&
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! my_timer_create(&thd_timer->timer))
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DBUG_RETURN(thd_timer);
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mysql_mutex_destroy(&thd_timer->mutex);
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my_free(thd_timer);
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DBUG_RETURN(NULL);
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}
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/**
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Notify a thread (session) that its timer has expired.
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@param thd_timer Thread timer object.
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@return true if the object should be destroyed.
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*/
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static bool
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timer_notify(THD_timer_info *thd_timer)
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{
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Find_thd_with_id find_thd_with_id(thd_timer->thread_id);
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THD *thd= Global_THD_manager::get_instance()->find_thd(&find_thd_with_id);
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DBUG_ASSERT(!thd_timer->destroy || !thd_timer->thread_id);
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/*
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Statement might have finished while the timer notification
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was being delivered. If this is the case, the timer object
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was detached (orphaned) and has no associated session (thd).
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*/
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if (thd)
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{
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/* process only if thread is not already undergoing any kill connection. */
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if (thd->killed != THD::KILL_CONNECTION)
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{
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thd->awake(THD::KILL_TIMEOUT);
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}
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mysql_mutex_unlock(&thd->LOCK_thd_data);
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}
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/* Mark the object as unreachable. */
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thd_timer->thread_id= 0;
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return thd_timer->destroy;
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}
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/**
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Timer expiration notification callback.
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@param timer Timer (mysys) object.
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@note Invoked in a separate thread of control.
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*/
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static void
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timer_callback(my_timer_t *timer)
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{
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bool destroy;
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THD_timer_info *thd_timer;
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thd_timer= my_container_of(timer, THD_timer_info, timer);
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mysql_mutex_lock(&thd_timer->mutex);
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destroy= timer_notify(thd_timer);
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mysql_mutex_unlock(&thd_timer->mutex);
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if (destroy)
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thd_timer_destroy(thd_timer);
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}
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/**
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Set the time until the currently running statement is aborted.
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@param thd Thread (session) context.
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@param thd_timer Thread timer object.
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@param time Length of time, in milliseconds, until the currently
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running statement is aborted.
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@return NULL on failure.
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*/
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THD_timer_info *
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thd_timer_set(THD *thd, THD_timer_info *thd_timer, unsigned long time)
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{
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DBUG_ENTER("thd_timer_set");
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/* Create a new thread timer object if one was not provided. */
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if (thd_timer == NULL && (thd_timer= thd_timer_create()) == NULL)
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DBUG_RETURN(NULL);
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DBUG_ASSERT(!thd_timer->destroy && !thd_timer->thread_id);
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/* Mark the notification as pending. */
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thd_timer->thread_id= thd->thread_id();
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/* Arm the timer. */
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if (DBUG_EVALUATE_IF("thd_timer_set_failure", 0, 1) &&
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!my_timer_set(&thd_timer->timer, time))
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DBUG_RETURN(thd_timer);
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/* Dispose of the (cached) timer object. */
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thd_timer_destroy(thd_timer);
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DBUG_RETURN(NULL);
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}
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/**
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Reap a (possibly) pending timer object.
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@param thd_timer Thread timer object.
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@return true if the timer object is unreachable.
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*/
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static bool
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reap_timer(THD_timer_info *thd_timer, bool pending)
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{
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/* Cannot be tagged for destruction. */
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DBUG_ASSERT(!thd_timer->destroy);
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/* If not pending, timer hasn't fired. */
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DBUG_ASSERT(pending || thd_timer->thread_id);
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/*
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The timer object can be reused if the timer was stopped before
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expiring. Otherwise, the timer notification function might be
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executing asynchronously in the context of a separate thread.
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*/
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bool unreachable= pending ? thd_timer->thread_id == 0 : true;
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thd_timer->thread_id= 0;
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return unreachable;
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}
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/**
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Deactivate the given timer.
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@param thd_timer Thread timer object.
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@return NULL if the timer object was orphaned.
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Otherwise, the given timer object is returned.
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*/
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THD_timer_info *
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thd_timer_reset(THD_timer_info *thd_timer)
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{
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bool unreachable;
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int status, state;
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DBUG_ENTER("thd_timer_cancel");
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status= my_timer_cancel(&thd_timer->timer, &state);
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/*
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If the notification function cannot possibly run anymore, cache
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the timer object as there are no outstanding references to it.
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*/
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mysql_mutex_lock(&thd_timer->mutex);
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unreachable= reap_timer(thd_timer, status ? true : !state);
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thd_timer->destroy= !unreachable;
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mysql_mutex_unlock(&thd_timer->mutex);
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DBUG_RETURN(unreachable ? thd_timer : NULL);
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}
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/**
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Release resources allocated for a thread timer.
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@param thd_timer Thread timer object.
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*/
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void
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thd_timer_destroy(THD_timer_info *thd_timer)
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{
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DBUG_ENTER("thd_timer_destroy");
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my_timer_delete(&thd_timer->timer);
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mysql_mutex_destroy(&thd_timer->mutex);
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my_free(thd_timer);
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DBUG_VOID_RETURN;
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}
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