Implementation of SequencedTaskRunner based on SequencedWorkerPool.

base/threading/sequenced_task_runner_impl.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_TASK_RUNNER_IMPL_H_

[akalin, 2012/03/20 22:16:08]

After thinking about it, I think the best name for this class would be:

SequencedWorkerPoolTaskRunner

The only danger is that a user may think this implements just TaskRunner when he
needs a SequencedTaskRunner.  But if the user knows that SequencedWorkerPool
already implements TaskRunner or that SWPTaskRunner takes a SequenceToken, he
should be ok.

What do you think?

[Francois, 2012/03/26 09:33:21]

Done. I haven't managed to think of anything better. I agree that users of this
class should be familiar with SWP, so it should be OK.

+#define BASE_THREADING_SEQUENCED_TASK_RUNNER_IMPL_H_
+#pragma once
+
+#include "base/compiler_specific.h"
+#include "base/memory/scoped_ptr.h"

[akalin, 2012/03/20 22:16:08]

remove scoped_ptr include, add ref_counted.h include

[Francois, 2012/03/26 09:33:21]

Done.

+#include "base/sequenced_task_runner.h"
+#include "base/threading/sequenced_worker_pool.h"
+
+namespace base {
+
+// Note that this class is RefCountedThreadSafe (inherited from TaskRunner).
+class BASE_EXPORT SequencedTaskRunnerImpl : public base::SequencedTaskRunner {

[akalin, 2012/03/20 22:16:08]

remove base::

[Francois, 2012/03/26 09:33:21]

Done.

+public:

[akalin, 2012/03/20 22:16:08]

indent one space

[Francois, 2012/03/26 09:33:21]

Done. Looks like the presence of BASE_EXPORT causes Emacs (using
google-c-style.el) to not indent labels.

+  SequencedTaskRunnerImpl(scoped_refptr<SequencedWorkerPool> pool,

[akalin, 2012/03/20 22:16:08]

use const scoped_refptr<...>&

[Francois, 2012/03/26 09:33:21]

Done. Is the goal to eliminate the extra ref++ and ref-- of the temporary?

+                          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,
+      base::TimeDelta delay) OVERRIDE;

[akalin, 2012/03/20 22:16:08]

remove base::

[Francois, 2012/03/26 09:33:21]

Done.

+
+private:

[akalin, 2012/03/20 22:16:08]

indent one space

[Francois, 2012/03/26 09:33:21]

Done.

+  ~SequencedTaskRunnerImpl();

[akalin, 2012/03/20 22:16:08]

destructor needs to be virtual

[Francois, 2012/03/26 09:33:21]

Done.

+
+  scoped_refptr<SequencedWorkerPool> pool_;

[akalin, 2012/03/20 22:16:08]

make this const

[Francois, 2012/03/26 09:33:21]

Done.

+
+  SequencedWorkerPool::SequenceToken token_;

[akalin, 2012/03/20 22:16:08]

this, too

[Francois, 2012/03/26 09:33:21]

Done.

+
+  DISALLOW_COPY_AND_ASSIGN(SequencedTaskRunnerImpl);

[akalin, 2012/03/20 22:16:08]

need #include "base/basictypes.h" for this

[Francois, 2012/03/26 09:33:21]

Done.

+};
+
+}  // namespace base
+
+#endif  // BASE_THREADING_SEQUENCED_TASK_RUNNER_IMPL_H_