Mercurial > sdl-ios-xcode
view src/thread/pthread/SDL_sysmutex.c @ 4235:88aa213ffc7b SDL-1.2
Possibly fixed bug #601, definitely fixed a potential issue with threads
stopping and starting in rapid succession.
author | Sam Lantinga <slouken@libsdl.org> |
---|---|
date | Wed, 23 Sep 2009 06:35:28 +0000 |
parents | a1b03ba2fcd0 |
children |
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/* SDL - Simple DirectMedia Layer Copyright (C) 1997-2009 Sam Lantinga This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. This library 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 Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA Sam Lantinga slouken@libsdl.org */ #include "SDL_config.h" #include <pthread.h> #include "SDL_thread.h" #if !SDL_THREAD_PTHREAD_RECURSIVE_MUTEX && \ !SDL_THREAD_PTHREAD_RECURSIVE_MUTEX_NP #define FAKE_RECURSIVE_MUTEX #endif struct SDL_mutex { pthread_mutex_t id; #if FAKE_RECURSIVE_MUTEX int recursive; pthread_t owner; #endif }; SDL_mutex *SDL_CreateMutex (void) { SDL_mutex *mutex; pthread_mutexattr_t attr; /* Allocate the structure */ mutex = (SDL_mutex *)SDL_calloc(1, sizeof(*mutex)); if ( mutex ) { pthread_mutexattr_init(&attr); #if SDL_THREAD_PTHREAD_RECURSIVE_MUTEX pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE); #elif SDL_THREAD_PTHREAD_RECURSIVE_MUTEX_NP pthread_mutexattr_setkind_np(&attr, PTHREAD_MUTEX_RECURSIVE_NP); #else /* No extra attributes necessary */ #endif if ( pthread_mutex_init(&mutex->id, &attr) != 0 ) { SDL_SetError("pthread_mutex_init() failed"); SDL_free(mutex); mutex = NULL; } } else { SDL_OutOfMemory(); } return(mutex); } void SDL_DestroyMutex(SDL_mutex *mutex) { if ( mutex ) { pthread_mutex_destroy(&mutex->id); SDL_free(mutex); } } /* Lock the mutex */ int SDL_mutexP(SDL_mutex *mutex) { int retval; #if FAKE_RECURSIVE_MUTEX pthread_t this_thread; #endif if ( mutex == NULL ) { SDL_SetError("Passed a NULL mutex"); return -1; } retval = 0; #if FAKE_RECURSIVE_MUTEX this_thread = pthread_self(); if ( mutex->owner == this_thread ) { ++mutex->recursive; } else { /* The order of operations is important. We set the locking thread id after we obtain the lock so unlocks from other threads will fail. */ if ( pthread_mutex_lock(&mutex->id) == 0 ) { mutex->owner = this_thread; mutex->recursive = 0; } else { SDL_SetError("pthread_mutex_lock() failed"); retval = -1; } } #else if ( pthread_mutex_lock(&mutex->id) < 0 ) { SDL_SetError("pthread_mutex_lock() failed"); retval = -1; } #endif return retval; } int SDL_mutexV(SDL_mutex *mutex) { int retval; if ( mutex == NULL ) { SDL_SetError("Passed a NULL mutex"); return -1; } retval = 0; #if FAKE_RECURSIVE_MUTEX /* We can only unlock the mutex if we own it */ if ( pthread_self() == mutex->owner ) { if ( mutex->recursive ) { --mutex->recursive; } else { /* The order of operations is important. First reset the owner so another thread doesn't lock the mutex and set the ownership before we reset it, then release the lock semaphore. */ mutex->owner = 0; pthread_mutex_unlock(&mutex->id); } } else { SDL_SetError("mutex not owned by this thread"); retval = -1; } #else if ( pthread_mutex_unlock(&mutex->id) < 0 ) { SDL_SetError("pthread_mutex_unlock() failed"); retval = -1; } #endif /* FAKE_RECURSIVE_MUTEX */ return retval; }