base/threading/worker_pool.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "base/threading/worker_pool.h"
   6
   7 #include "base/bind.h"
   8 #include "base/compiler_specific.h"
   9 #include "base/debug/leak_annotations.h"
  10 #include "base/lazy_instance.h"
  11 #include "base/task_runner.h"
  12 #include "base/threading/post_task_and_reply_impl.h"
  13 #include "base/tracked_objects.h"
  14
  15 namespace base {
  16
  17 namespace {
  18
  19 class PostTaskAndReplyWorkerPool : public internal::PostTaskAndReplyImpl {
  20  public:
  21   explicit PostTaskAndReplyWorkerPool(bool task_is_slow)
  22       : task_is_slow_(task_is_slow) {
  23   }
  24
  25  private:
  26   virtual bool PostTask(const tracked_objects::Location& from_here,
  27                         const Closure& task) OVERRIDE {
  28     return WorkerPool::PostTask(from_here, task, task_is_slow_);
  29   }
  30
  31   bool task_is_slow_;
  32 };
  33
  34 // WorkerPoolTaskRunner ---------------------------------------------
  35 // A TaskRunner which posts tasks to a WorkerPool with a
  36 // fixed ShutdownBehavior.
  37 //
  38 // Note that this class is RefCountedThreadSafe (inherited from TaskRunner).
  39 class WorkerPoolTaskRunner : public TaskRunner {
  40  public:
  41   explicit WorkerPoolTaskRunner(bool tasks_are_slow);
  42
  43   // TaskRunner implementation
  44   virtual bool PostDelayedTask(const tracked_objects::Location& from_here,
  45                                const Closure& task,
  46                                TimeDelta delay) OVERRIDE;
  47   virtual bool RunsTasksOnCurrentThread() const OVERRIDE;
  48
  49  private:
  50   virtual ~WorkerPoolTaskRunner();
  51
  52   // Helper function for posting a delayed task. Asserts that the delay is
  53   // zero because non-zero delays are not supported.
  54   bool PostDelayedTaskAssertZeroDelay(
  55       const tracked_objects::Location& from_here,
  56       const Closure& task,
  57       base::TimeDelta delay);
  58
  59   const bool tasks_are_slow_;
  60
  61   DISALLOW_COPY_AND_ASSIGN(WorkerPoolTaskRunner);
  62 };
  63
  64 WorkerPoolTaskRunner::WorkerPoolTaskRunner(bool tasks_are_slow)
  65     : tasks_are_slow_(tasks_are_slow) {
  66 }
  67
  68 WorkerPoolTaskRunner::~WorkerPoolTaskRunner() {
  69 }
  70
  71 bool WorkerPoolTaskRunner::PostDelayedTask(
  72     const tracked_objects::Location& from_here,
  73     const Closure& task,
  74     TimeDelta delay) {
  75   return PostDelayedTaskAssertZeroDelay(from_here, task, delay);
  76 }
  77
  78 bool WorkerPoolTaskRunner::RunsTasksOnCurrentThread() const {
  79   return WorkerPool::RunsTasksOnCurrentThread();
  80 }
  81
  82 bool WorkerPoolTaskRunner::PostDelayedTaskAssertZeroDelay(
  83     const tracked_objects::Location& from_here,
  84     const Closure& task,
  85     base::TimeDelta delay) {
  86   DCHECK_EQ(delay.InMillisecondsRoundedUp(), 0)
  87       << "WorkerPoolTaskRunner does not support non-zero delays";
  88   return WorkerPool::PostTask(from_here, task, tasks_are_slow_);
  89 }
  90
  91 struct TaskRunnerHolder {
  92   TaskRunnerHolder() {
  93     taskrunners_[0] = new WorkerPoolTaskRunner(false);
  94     taskrunners_[1] = new WorkerPoolTaskRunner(true);
  95   }
  96   scoped_refptr<TaskRunner> taskrunners_[2];
  97 };
  98
  99 base::LazyInstance<TaskRunnerHolder>::Leaky
 100     g_taskrunners = LAZY_INSTANCE_INITIALIZER;
 101
 102 }  // namespace
 103
 104 bool WorkerPool::PostTaskAndReply(const tracked_objects::Location& from_here,
 105                                   const Closure& task,
 106                                   const Closure& reply,
 107                                   bool task_is_slow) {
 108   // Do not report PostTaskAndReplyRelay leaks in tests. There's nothing we can
 109   // do about them because WorkerPool doesn't have a flushing API.
 110   // http://crbug.com/248513
 111   // http://crbug.com/290897
 112   // Note: this annotation does not cover tasks posted through a TaskRunner.
 113   ANNOTATE_SCOPED_MEMORY_LEAK;
 114   return PostTaskAndReplyWorkerPool(task_is_slow).PostTaskAndReply(
 115       from_here, task, reply);
 116 }
 117
 118 // static
 119 const scoped_refptr<TaskRunner>&
 120 WorkerPool::GetTaskRunner(bool tasks_are_slow) {
 121   return g_taskrunners.Get().taskrunners_[tasks_are_slow];
 122 }
 123
 124 }  // namespace base