kc3-lang/SDL/src/thread/pthread/SDL_sysmutex.c

Branch : - branch - v2.28 - tag -

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  Commit

• Author : Sam Lantinga
  Date : 2014-02-02 00:53:27
  Hash : 58edac3e
  Message : Fixed bug 2374 - Update copyright for 2014... Is it that time already??

• src/thread/pthread/SDL_sysmutex.c

• /*
    Simple DirectMedia Layer
    Copyright (C) 1997-2014 Sam Lantinga <slouken@libsdl.org>
  
    This software is provided 'as-is', without any express or implied
    warranty.  In no event will the authors be held liable for any damages
    arising from the use of this software.
  
    Permission is granted to anyone to use this software for any purpose,
    including commercial applications, and to alter it and redistribute it
    freely, subject to the following restrictions:
  
    1. The origin of this software must not be misrepresented; you must not
       claim that you wrote the original software. If you use this software
       in a product, an acknowledgment in the product documentation would be
       appreciated but is not required.
    2. Altered source versions must be plainly marked as such, and must not be
       misrepresented as being the original software.
    3. This notice may not be removed or altered from any source distribution.
  */
  #include "../../SDL_internal.h"
  
  #define _GNU_SOURCE
  #include <pthread.h>
  #include <errno.h>
  
  #include "SDL_thread.h"
  
  #if !SDL_THREAD_PTHREAD_RECURSIVE_MUTEX && \
      !SDL_THREAD_PTHREAD_RECURSIVE_MUTEX_NP
  #define FAKE_RECURSIVE_MUTEX 1
  #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_LockMutex(SDL_mutex * mutex)
  {
  #if FAKE_RECURSIVE_MUTEX
      pthread_t this_thread;
  #endif
  
      if (mutex == NULL) {
          return SDL_SetError("Passed a NULL mutex");
      }
  
  #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 {
              return SDL_SetError("pthread_mutex_lock() failed");
          }
      }
  #else
      if (pthread_mutex_lock(&mutex->id) < 0) {
          return SDL_SetError("pthread_mutex_lock() failed");
      }
  #endif
      return 0;
  }
  
  int
  SDL_TryLockMutex(SDL_mutex * mutex)
  {
      int retval;
  #if FAKE_RECURSIVE_MUTEX
      pthread_t this_thread;
  #endif
  
      if (mutex == NULL) {
          return SDL_SetError("Passed a NULL mutex");
      }
  
      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 if (errno == EBUSY) {
              retval = SDL_MUTEX_TIMEDOUT;
          } else {
              retval = SDL_SetError("pthread_mutex_trylock() failed");
          }
      }
  #else
      if (pthread_mutex_trylock(&mutex->id) != 0) {
          if (errno == EBUSY) {
              retval = SDL_MUTEX_TIMEDOUT;
          } else {
              retval = SDL_SetError("pthread_mutex_trylock() failed");
          }
      }
  #endif
      return retval;
  }
  
  int
  SDL_UnlockMutex(SDL_mutex * mutex)
  {
      if (mutex == NULL) {
          return SDL_SetError("Passed a NULL mutex");
      }
  
  #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 {
          return SDL_SetError("mutex not owned by this thread");
      }
  
  #else
      if (pthread_mutex_unlock(&mutex->id) < 0) {
          return SDL_SetError("pthread_mutex_unlock() failed");
      }
  #endif /* FAKE_RECURSIVE_MUTEX */
  
      return 0;
  }
  
  /* vi: set ts=4 sw=4 expandtab: */