Implementation of SequencedTaskRunner based on SequencedWorkerPool.

base/threading/sequenced_worker_pool_task_runner.h

+// 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.
+
+#ifndef BASE_THREADING_SEQUENCED_WORKER_POOL_TASK_RUNNER_H_
+#define BASE_THREADING_SEQUENCED_WORKER_POOL_TASK_RUNNER_H_
+#pragma once
+
+#include "base/basictypes.h"
+#include "base/callback_forward.h"
+#include "base/compiler_specific.h"
+#include "base/memory/ref_counted.h"
+#include "base/sequenced_task_runner.h"
+#include "base/threading/sequenced_worker_pool.h"
+#include "base/time.h"
+
+namespace tracked_objects {
+class Location;
+}  // namespace tracked_objects
+
+namespace base {
+
+// A SequencedTaskRunner which posts tasks to a SequencedWorkerPool with a
+// fixed sequence token.
+//
+// Note that this class is RefCountedThreadSafe (inherited from TaskRunner).
+class BASE_EXPORT SequencedWorkerPoolTaskRunner : public SequencedTaskRunner {
+ public:
+  SequencedWorkerPoolTaskRunner(const scoped_refptr<SequencedWorkerPool>& pool,
+                                SequencedWorkerPool::SequenceToken token);
+
+  // 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;
+
+  // SequencedTaskRunner implementation
+  virtual bool PostNonNestableDelayedTask(
+      const tracked_objects::Location& from_here,
+      const Closure& task,
+      int64 delay_ms) OVERRIDE;
+  virtual bool PostNonNestableDelayedTask(
+      const tracked_objects::Location& from_here,
+      const Closure& task,
+      TimeDelta delay) OVERRIDE;
+
+ private:
+  virtual ~SequencedWorkerPoolTaskRunner();
+
+  // Helper function for posting a delayed task. Asserts that the delay is
+  // zero because non-zero delays are not yet supported.
+  bool PostDelayedTaskAssertZeroDelay(
+      const tracked_objects::Location& from_here,
+      const Closure& task,
+      int64 delay_ms);
+  bool PostDelayedTaskAssertZeroDelay(
+      const tracked_objects::Location& from_here,
+      const Closure& task,
+      TimeDelta delay);
+
+  const scoped_refptr<SequencedWorkerPool> pool_;
+
+  const SequencedWorkerPool::SequenceToken token_;
+
+  DISALLOW_COPY_AND_ASSIGN(SequencedWorkerPoolTaskRunner);
+};
+
+}  // namespace base
+
+#endif  // BASE_THREADING_SEQUENCED_TASK_RUNNER_IMPL_H_