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e6090f10bb
htttp://lists.mysql.com/commits/50957?f=plain
Always use TLS functions instead of __declspec(thread) to access
thread local storage variables.
The change removes the necessity to recomplile the same source
files twice - with USE_TLS for DLLs and without USE_TLS for EXEs.
Real benefit of this change is better readability and maintainability
of TLS functions within MySQL.
There is a performance loss using TlsXXX functions compared to __declspec
but the difference is negligible in practice. In a sysbench-like benchmark
I ran with with TlsGetValue, pthread_[get|set]_specific was called 600000000
times and took 0.17sec of total 35min CPU time, or 0.008%.
134 lines
3.7 KiB
C
134 lines
3.7 KiB
C
/* Copyright (C) 2000 MySQL AB
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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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
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/*****************************************************************************
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** Simulation of posix threads calls for WIN95 and NT
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*****************************************************************************/
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/* SAFE_MUTEX will not work until the thread structure is up to date */
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#undef SAFE_MUTEX
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#include "mysys_priv.h"
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#if defined(THREAD) && defined(__WIN__)
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#include <m_string.h>
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#undef getpid
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#include <process.h>
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static pthread_mutex_t THR_LOCK_thread;
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struct pthread_map
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{
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HANDLE pthreadself;
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pthread_handler func;
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void *param;
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};
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void win_pthread_init(void)
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{
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pthread_mutex_init(&THR_LOCK_thread,MY_MUTEX_INIT_FAST);
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}
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/**
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Adapter to @c pthread_mutex_trylock()
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@retval 0 Mutex was acquired
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@retval EBUSY Mutex was already locked by a thread
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*/
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int
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win_pthread_mutex_trylock(pthread_mutex_t *mutex)
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{
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if (TryEnterCriticalSection(mutex))
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{
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/* Don't allow recursive lock */
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if (mutex->RecursionCount > 1){
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LeaveCriticalSection(mutex);
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return EBUSY;
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}
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return 0;
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}
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return EBUSY;
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}
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/*
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** We have tried to use '_beginthreadex' instead of '_beginthread' here
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** but in this case the program leaks about 512 characters for each
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** created thread !
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** As we want to save the created thread handler for other threads to
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** use and to be returned by pthread_self() (instead of the Win32 pseudo
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** handler), we have to go trough pthread_start() to catch the returned handler
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** in the new thread.
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*/
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pthread_handler_t pthread_start(void *param)
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{
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pthread_handler func=((struct pthread_map *) param)->func;
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void *func_param=((struct pthread_map *) param)->param;
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my_thread_init(); /* Will always succeed in windows */
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pthread_mutex_lock(&THR_LOCK_thread); /* Wait for beginthread to return */
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win_pthread_self=((struct pthread_map *) param)->pthreadself;
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pthread_mutex_unlock(&THR_LOCK_thread);
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free((char*) param); /* Free param from create */
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pthread_exit((void*) (*func)(func_param));
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return 0; /* Safety */
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}
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int pthread_create(pthread_t *thread_id, pthread_attr_t *attr,
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pthread_handler func, void *param)
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{
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HANDLE hThread;
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struct pthread_map *map;
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DBUG_ENTER("pthread_create");
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if (!(map=malloc(sizeof(*map))))
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DBUG_RETURN(-1);
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map->func=func;
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map->param=param;
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pthread_mutex_lock(&THR_LOCK_thread);
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#ifdef __BORLANDC__
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hThread=(HANDLE)_beginthread((void(_USERENTRY *)(void *)) pthread_start,
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attr->dwStackSize ? attr->dwStackSize :
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65535, (void*) map);
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#else
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hThread=(HANDLE)_beginthread((void( __cdecl *)(void *)) pthread_start,
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attr->dwStackSize ? attr->dwStackSize :
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65535, (void*) map);
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#endif
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DBUG_PRINT("info", ("hThread=%lu",(long) hThread));
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*thread_id=map->pthreadself=hThread;
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pthread_mutex_unlock(&THR_LOCK_thread);
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if (hThread == (HANDLE) -1)
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{
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int error=errno;
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DBUG_PRINT("error",
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("Can't create thread to handle request (error %d)",error));
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DBUG_RETURN(error ? error : -1);
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}
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VOID(SetThreadPriority(hThread, attr->priority)) ;
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DBUG_RETURN(0);
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}
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void pthread_exit(void *a)
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{
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_endthread();
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}
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#endif
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