google-breakpad/src/common/android/testing/pthread_fixes.h

// Copyright (c) 2012, Google Inc.
// All rights reserved.
//
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// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
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// This contains Pthread-related functions not provided by the Android NDK
// but required by the Breakpad unit test. The functions are inlined here
// in a C++ anonymous namespace in order to keep the build files simples.

#ifndef GOOGLE_BREAKPAD_COMMON_ANDROID_TESTING_PTHREAD_FIXES_H
#define GOOGLE_BREAKPAD_COMMON_ANDROID_TESTING_PTHREAD_FIXES_H

#include <pthread.h>

namespace {

// Android doesn't provide pthread_barrier_t for now.
#ifndef PTHREAD_BARRIER_SERIAL_THREAD

// Anything except 0 will do here.
#define PTHREAD_BARRIER_SERIAL_THREAD  0x12345

typedef struct {
  pthread_mutex_t  mutex;
  pthread_cond_t   cond;
  unsigned         count;
} pthread_barrier_t;

int pthread_barrier_init(pthread_barrier_t* barrier,
                         const void* /* barrier_attr */,
                         unsigned count) {
  barrier->count = count;
  pthread_mutex_init(&barrier->mutex, NULL);
  pthread_cond_init(&barrier->cond, NULL);
  return 0;
}

int pthread_barrier_wait(pthread_barrier_t* barrier) {
  // Lock the mutex
  pthread_mutex_lock(&barrier->mutex);
  // Decrement the count. If this is the first thread to reach 0, wake up
  // waiters, unlock the mutex, then return PTHREAD_BARRIER_SERIAL_THREAD.
  if (--barrier->count == 0) {
    // First thread to reach the barrier
    pthread_cond_broadcast(&barrier->cond);
    pthread_mutex_unlock(&barrier->mutex);
    return PTHREAD_BARRIER_SERIAL_THREAD;
  }
  // Otherwise, wait for other threads until the count reaches 0, then
  // return 0 to indicate this is not the first thread.
  do {
    pthread_cond_wait(&barrier->cond, &barrier->mutex);
  } while (barrier->count > 0);

  pthread_mutex_unlock(&barrier->mutex);
  return 0;
}

int pthread_barrier_destroy(pthread_barrier_t *barrier) {
  barrier->count = 0;
  pthread_cond_destroy(&barrier->cond);
  pthread_mutex_destroy(&barrier->mutex);
  return 0;
}

#endif  // defined(PTHREAD_BARRIER_SERIAL_THREAD)

int pthread_yield(void) {
  sched_yield();
  return 0;
}

}  // namespace

#endif  // GOOGLE_BREAKPAD_COMMON_ANDROID_TESTING_PTHREAD_FIXES_H