IABSD.fr/xenocara/lib/libxshmfence/src/xshmfence_pthread.c

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• Author : matthieu
  Date : 2018-06-07 21:57:28
  Hash : b1a440ca
  Message : Import libxshmfence 1.4

• lib/libxshmfence/src/xshmfence_pthread.c

• /*
   * Copyright © 2013 Keith Packard
   *
   * Permission to use, copy, modify, distribute, and sell this software and its
   * documentation for any purpose is hereby granted without fee, provided that
   * the above copyright notice appear in all copies and that both that copyright
   * notice and this permission notice appear in supporting documentation, and
   * that the name of the copyright holders not be used in advertising or
   * publicity pertaining to distribution of the software without specific,
   * written prior permission.  The copyright holders make no representations
   * about the suitability of this software for any purpose.  It is provided "as
   * is" without express or implied warranty.
   *
   * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
   * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
   * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
   * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
   * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
   * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
   * OF THIS SOFTWARE.
   */
  
  #if HAVE_CONFIG_H
  #include "config.h"
  #endif
  
  #include "xshmfenceint.h"
  
  /**
   * xshmfence_trigger:
   * @f: An X fence
   *
   * Set @f to triggered, waking all waiters.
   *
   * Return value: 0 on success and -1 on error (in which case, errno
   * will be set as appropriate).
   **/
  int
  xshmfence_trigger(struct xshmfence *f) {
      pthread_mutex_lock(&f->lock);
      if (f->value == 0) {
          f->value = 1;
          if (f->waiting) {
              f->waiting = 0;
              pthread_cond_broadcast(&f->wakeup);
          }
      }
      pthread_mutex_unlock(&f->lock);
      return 0;
  }
  
  /**
   * xshmfence_await:
   * @f: An X fence
   *
   * Wait for @f to be triggered. If @f is already triggered, this
   * function returns immediately.
   *
   * Return value: 0 on success and -1 on error (in which case, errno
   * will be set as appropriate).
   **/
  int
  xshmfence_await(struct xshmfence *f) {
      pthread_mutex_lock(&f->lock);
      while (f->value == 0) {
          f->waiting = 1;
          pthread_cond_wait(&f->wakeup, &f->lock);
      }
      pthread_mutex_unlock(&f->lock);
      return 0;
  }
  
  /**
   * xshmfence_query:
   * @f: An X fence
   *
   * Return value: 1 if @f is triggered, else returns 0.
   **/
  int
  xshmfence_query(struct xshmfence *f) {
      int value;
  
      pthread_mutex_lock(&f->lock);
      value = f->value;
      pthread_mutex_unlock(&f->lock);
      return value;
  }
  
  /**
   * xshmfence_reset:
   * @f: An X fence
   *
   * Reset @f to untriggered. If @f is already untriggered,
   * this function has no effect.
   **/
  void
  xshmfence_reset(struct xshmfence *f) {
  
      pthread_mutex_lock(&f->lock);
      f->value = 0;
      pthread_mutex_unlock(&f->lock);
  }
  
  /**
   * xshmfence_init:
   * @fd: An fd for an X fence
   *
   * Initialize the fence when first allocated
   **/
  
  void
  xshmfence_init(int fd)
  {
      struct xshmfence *f = xshmfence_map_shm(fd);
      pthread_mutexattr_t mutex_attr;
      pthread_condattr_t cond_attr;
  
      if (!f)
          return;
  
      pthread_mutexattr_init(&mutex_attr);
      pthread_mutexattr_setpshared(&mutex_attr, PTHREAD_PROCESS_SHARED);
      pthread_mutex_init(&f->lock, &mutex_attr);
  
      pthread_condattr_init(&cond_attr);
      pthread_condattr_setpshared(&cond_attr, PTHREAD_PROCESS_SHARED);
      pthread_cond_init(&f->wakeup, &cond_attr);
      f->value = 0;
      f->waiting = 0;
      xshmfence_unmap_shm(f);
  }