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8969530cff
As documented in the bug report, the double checked locking pattern has inherent issues, and cannot guarantee correct initialization. This patch replaces the logic in init_available_charsets() with the use of pthread_once(3). A wrapper function, my_pthread_once(), is introduced and is used in lieu of direct calls to init_available_charsets(). Related defines MY_PTHREAD_ONCE_* are also introduced. For the Windows platform, the implementation in lp:sysbench is ported. For single-thread use, a simple define calls the function and sets the pthread_once control variable. Charset initialization is modified to use my_pthread_once(). include/my_no_pthread.h: Dummy my_pthread_once() for single thread use. include/my_pthread.h: Declaration for new function my_pthread_once(). mysys/charset.c: Logic in init_available_charsets() is simplified. Using my_pthread_once() for all calls to this func. mysys/my_winthread.c: Windows implementation of my_pthread_once().
58 lines
1.7 KiB
C
58 lines
1.7 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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#if !defined(_my_no_pthread_h) && !defined(THREAD)
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#define _my_no_pthread_h
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/*
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This block is to access some thread-related type definitions
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even in builds which do not need thread functions,
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as some variables (based on these types) are declared
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even in non-threaded builds.
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Case in point: 'mf_keycache.c'
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*/
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#if defined(__WIN__)
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#else /* Normal threads */
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#include <pthread.h>
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#endif /* defined(__WIN__) */
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/*
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This undefs some pthread mutex locks when one isn't using threads
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to make thread safe code, that should also work in single thread
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environment, easier to use.
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*/
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#define pthread_mutex_init(A,B)
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#define pthread_mutex_lock(A)
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#define pthread_mutex_unlock(A)
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#define pthread_mutex_destroy(A)
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#define my_rwlock_init(A,B)
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#define rw_rdlock(A)
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#define rw_wrlock(A)
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#define rw_unlock(A)
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#define rwlock_destroy(A)
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typedef int my_pthread_once_t;
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#define MY_PTHREAD_ONCE_INIT 0
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#define MY_PTHREAD_ONCE_DONE 1
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#define my_pthread_once(C,F) do { \
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if (*(C) != MY_PTHREAD_ONCE_DONE) { F(); *(C)= MY_PTHREAD_ONCE_DONE; } \
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} while(0)
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#endif
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