Add TaskRunner wrapper for WorkerPool.

base/threading/worker_pool.cc

-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Copyright (c) 2012 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 "base/threading/worker_pool.h"
 
 #include "base/bind.h"
 #include "base/compiler_specific.h"
+#include "base/lazy_instance.h"
+#include "base/task_runner.h"
 #include "base/threading/post_task_and_reply_impl.h"
 #include "base/tracked_objects.h"
 
 namespace base {
 
 namespace {
 
 class PostTaskAndReplyWorkerPool : public internal::PostTaskAndReplyImpl {
  public:
   PostTaskAndReplyWorkerPool(bool task_is_slow) : task_is_slow_(task_is_slow) {
   }
 
  private:
   virtual bool PostTask(const tracked_objects::Location& from_here,
                         const Closure& task) OVERRIDE {
     return WorkerPool::PostTask(from_here, task, task_is_slow_);
   }
 
   bool task_is_slow_;
 };
 
+// WorkerPoolTaskRunner ---------------------------------------------
+// A TaskRunner which posts tasks to a WorkerPool with a
+// fixed ShutdownBehavior.
+//
+// Note that this class is RefCountedThreadSafe (inherited from TaskRunner).
+class WorkerPoolTaskRunner : public TaskRunner {
+ public:
+  WorkerPoolTaskRunner(bool tasks_are_slow);
+
+  // TaskRunner implementation
+  virtual bool PostDelayedTask(const tracked_objects::Location& from_here,
+                               const Closure& task,
+                               int64 delay_ms) OVERRIDE;
+  virtual bool PostDelayedTask(const tracked_objects::Location& from_here,
+                               const Closure& task,
+                               TimeDelta delay) OVERRIDE;
+  virtual bool RunsTasksOnCurrentThread() const OVERRIDE;
+
+ private:
+  virtual ~WorkerPoolTaskRunner();
+
+  // Helper function for posting a delayed task. Asserts that the delay is
+  // zero because non-zero delays are not supported.
+  bool PostDelayedTaskAssertZeroDelay(
+      const tracked_objects::Location& from_here,
+      const Closure& task,
+      int64 delay_ms);
+
+  const bool tasks_are_slow_;
+
+  DISALLOW_COPY_AND_ASSIGN(WorkerPoolTaskRunner);
+};
+
+WorkerPoolTaskRunner::WorkerPoolTaskRunner(bool tasks_are_slow)
+    : tasks_are_slow_(tasks_are_slow) {
+}
+
+WorkerPoolTaskRunner::~WorkerPoolTaskRunner() {
+}
+
+bool WorkerPoolTaskRunner::PostDelayedTask(
+    const tracked_objects::Location& from_here,
+    const Closure& task,
+    int64 delay_ms) {
+  return PostDelayedTaskAssertZeroDelay(from_here, task, delay_ms);
+}
+
+bool WorkerPoolTaskRunner::PostDelayedTask(
+    const tracked_objects::Location& from_here,
+    const Closure& task,
+    TimeDelta delay) {
+  return PostDelayedTask(from_here, task, delay.InMillisecondsRoundedUp());
+}
+
+bool WorkerPoolTaskRunner::RunsTasksOnCurrentThread() const {
+  return WorkerPool::RunsTasksOnCurrentThread();
+}
+
+bool WorkerPoolTaskRunner::PostDelayedTaskAssertZeroDelay(
+    const tracked_objects::Location& from_here,
+    const Closure& task,
+    int64 delay_ms) {
+  DCHECK_EQ(delay_ms, 0)
+      << "WorkerPoolTaskRunner does not support non-zero delays";
+  return WorkerPool::PostTask(from_here, task, tasks_are_slow_);
+}
+
+struct TaskRunnerHolder {
+  TaskRunnerHolder() {
+    taskrunners_[0] = new WorkerPoolTaskRunner(false);
+    taskrunners_[1] = new WorkerPoolTaskRunner(true);
+  }
+  scoped_refptr<TaskRunner> taskrunners_[2];
+};
+
+base::LazyInstance<TaskRunnerHolder>::Leaky
+    g_taskrunners = LAZY_INSTANCE_INITIALIZER;
+
 }  // namespace
 
 bool WorkerPool::PostTaskAndReply(const tracked_objects::Location& from_here,
                                   const Closure& task,
                                   const Closure& reply,
                                   bool task_is_slow) {
   return PostTaskAndReplyWorkerPool(task_is_slow).PostTaskAndReply(
       from_here, task, reply);
 }
 
+// static
+const scoped_refptr<TaskRunner>&
+WorkerPool::GetTaskRunner(bool tasks_are_slow) {
+  return g_taskrunners.Get().taskrunners_[tasks_are_slow];
+}
+
 }  // namespace base