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   ~PostTaskAndReplyWorkerPool() override = default;
  25
  26  private:
  27   bool PostTask(const tracked_objects::Location& from_here,
  28                 const Closure& task) override {
  29     return WorkerPool::PostTask(from_here, task, task_is_slow_);
  30   }
  31
  32   bool task_is_slow_;
  33 };
  34
  35 // WorkerPoolTaskRunner ---------------------------------------------
  36 // A TaskRunner which posts tasks to a WorkerPool with a
  37 // fixed ShutdownBehavior.
  38 //
  39 // Note that this class is RefCountedThreadSafe (inherited from TaskRunner).
  40 class WorkerPoolTaskRunner : public TaskRunner {
  41  public:
  42   explicit WorkerPoolTaskRunner(bool tasks_are_slow);
  43
  44   // TaskRunner implementation
  45   bool PostDelayedTask(const tracked_objects::Location& from_here,
  46                        const Closure& task,
  47                        TimeDelta delay) override;
  48   bool RunsTasksOnCurrentThread() const override;
  49
  50  private:
  51   ~WorkerPoolTaskRunner() override;
  52
  53   // Helper function for posting a delayed task. Asserts that the delay is
  54   // zero because non-zero delays are not supported.
  55   bool PostDelayedTaskAssertZeroDelay(
  56       const tracked_objects::Location& from_here,
  57       const Closure& task,
  58       base::TimeDelta delay);
  59
  60   const bool tasks_are_slow_;
  61
  62   DISALLOW_COPY_AND_ASSIGN(WorkerPoolTaskRunner);
  63 };
  64
  65 WorkerPoolTaskRunner::WorkerPoolTaskRunner(bool tasks_are_slow)
  66     : tasks_are_slow_(tasks_are_slow) {
  67 }
  68
  69 WorkerPoolTaskRunner::~WorkerPoolTaskRunner() {
  70 }
  71
  72 bool WorkerPoolTaskRunner::PostDelayedTask(
  73     const tracked_objects::Location& from_here,
  74     const Closure& task,
  75     TimeDelta delay) {
  76   return PostDelayedTaskAssertZeroDelay(from_here, task, delay);
  77 }
  78
  79 bool WorkerPoolTaskRunner::RunsTasksOnCurrentThread() const {
  80   return WorkerPool::RunsTasksOnCurrentThread();
  81 }
  82
  83 bool WorkerPoolTaskRunner::PostDelayedTaskAssertZeroDelay(
  84     const tracked_objects::Location& from_here,
  85     const Closure& task,
  86     base::TimeDelta delay) {
  87   DCHECK_EQ(delay.InMillisecondsRoundedUp(), 0)
  88       << "WorkerPoolTaskRunner does not support non-zero delays";
  89   return WorkerPool::PostTask(from_here, task, tasks_are_slow_);
  90 }
  91
  92 struct TaskRunnerHolder {
  93   TaskRunnerHolder() {
  94     taskrunners_[0] = new WorkerPoolTaskRunner(false);
  95     taskrunners_[1] = new WorkerPoolTaskRunner(true);
  96   }
  97   scoped_refptr<TaskRunner> taskrunners_[2];
  98 };
  99
 100 base::LazyInstance<TaskRunnerHolder>::Leaky
 101     g_taskrunners = LAZY_INSTANCE_INITIALIZER;
 102
 103 }  // namespace
 104
 105 bool WorkerPool::PostTaskAndReply(const tracked_objects::Location& from_here,
 106                                   const Closure& task,
 107                                   const Closure& reply,
 108                                   bool task_is_slow) {
 109   // Do not report PostTaskAndReplyRelay leaks in tests. There's nothing we can
 110   // do about them because WorkerPool doesn't have a flushing API.
 111   // http://crbug.com/248513
 112   // http://crbug.com/290897
 113   // Note: this annotation does not cover tasks posted through a TaskRunner.
 114   ANNOTATE_SCOPED_MEMORY_LEAK;
 115   return PostTaskAndReplyWorkerPool(task_is_slow).PostTaskAndReply(
 116       from_here, task, reply);
 117 }
 118
 119 // static
 120 const scoped_refptr<TaskRunner>&
 121 WorkerPool::GetTaskRunner(bool tasks_are_slow) {
 122   return g_taskrunners.Get().taskrunners_[tasks_are_slow];
 123 }
 124
 125 }  // namespace base