[NaCl SDK] Upate atomic ops in nacl_io

native_client_sdk/src/libraries/sdk_util/thread_pool.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "sdk_util/thread_pool.h"
 
 #include <pthread.h>
 #include <semaphore.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ skipping 42 matching lines @@
 // when all worker threads are sleeping.
 void ThreadPool::Setup(int counter, WorkFunction work, void *data) {
   counter_ = counter;
   user_work_function_ = work;
   user_data_ = data;
 }
 
 // Return decremented task counter.  This function
 // can be called from multiple threads at any given time.
 int ThreadPool::DecCounter() {
-#if defined(__native_client__)
-  // Use fast atomic sub & fetch.
-  return __sync_sub_and_fetch(&counter_, 1);
-#else
-  // Fallback to a more platform independent pthread mutex via AutoLock.
-  static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
-  AutoLock lock(&mutex);
-  return --counter_;
-#endif
+  return AtomicAddFetch(&counter_, 1);

[nfullagar1, 2013/07/18 00:18:06]

This should return the decremented task counter, but is incrementing it instead.
 This change is breaking all examples that are using threadpool.

 }
 
 // Set exit flag, post and join all the threads in the pool.  This function is
 // called only from the dispatch thread, and only when all worker threads are
 // sleeping.
 void ThreadPool::PostExitAndJoinAll() {
   exiting_ = true;
   // Wake up all the sleeping worker threads.
   for (int i = 0; i < num_threads_; ++i)
     sem_post(&work_sem_);
@@ skipping 53 matching lines @@
 // Dispatch() will invoke the user supplied work function across
 // one or more threads for each task.
 // Note: This function will block until all work has completed.
 void ThreadPool::Dispatch(int num_tasks, WorkFunction work, void* data) {
   if (num_threads_ > 0)
     DispatchMany(num_tasks, work, data);
   else
     DispatchHere(num_tasks, work, data);
 }