Delay bookmarks load while the profile is loading.

This CL adds a new DeferredSequencedtaskRunner that queues up tasks
until a first call to Start is issued. It creates such a task runner for the 
execution of bookmarks I/O operations. At profile creation, the bookmarks
task runner is stopped and its execution is started after the profile has
finished loading.

BUG=NONE

Review URL: https://chromiumcodereview.appspot.com/12952005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@194956 0039d316-1c4b-4281-b951-d872f2087c98

5 files changed, 365 insertions, 0 deletions

diff --git a/base/base.gyp b/base/base.gyp
index 290961e..b026dcb 100644
--- a/base/base.gyp
+++ b/base/base.gyp
@@ -463,6 +463,7 @@
         'debug/trace_event_unittest.cc',
         'debug/trace_event_unittest.h',
         'debug/trace_event_win_unittest.cc',
+        'deferred_sequenced_task_runner_unittest.cc',
         'environment_unittest.cc',
         'file_util_unittest.cc',
         'file_version_info_unittest.cc',
diff --git a/base/base.gypi b/base/base.gypi
index f26c4c7..164aa23 100644
--- a/base/base.gypi
+++ b/base/base.gypi
@@ -137,6 +137,8 @@
           'debug/trace_event_impl.cc',
           'debug/trace_event_impl.h',
           'debug/trace_event_win.cc',
+          'deferred_sequenced_task_runner.cc',
+          'deferred_sequenced_task_runner.h',
           'environment.cc',
           'environment.h',
           'file_descriptor_posix.h',
diff --git a/base/deferred_sequenced_task_runner.cc b/base/deferred_sequenced_task_runner.cc
new file mode 100644
index 0000000..c96704c
--- /dev/null
+++ b/base/deferred_sequenced_task_runner.cc
@@ -0,0 +1,99 @@
+// Copyright (c) 2013 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/deferred_sequenced_task_runner.h"
+
+#include "base/bind.h"
+#include "base/logging.h"
+
+namespace base {
+
+DeferredSequencedTaskRunner::DeferredTask::DeferredTask() {
+}
+
+DeferredSequencedTaskRunner::DeferredTask::~DeferredTask() {
+}
+
+DeferredSequencedTaskRunner::DeferredSequencedTaskRunner(
+    const scoped_refptr<SequencedTaskRunner>& target_task_runner)
+    : started_(false),
+      target_task_runner_(target_task_runner) {
+}
+
+DeferredSequencedTaskRunner::~DeferredSequencedTaskRunner() {
+}
+
+bool DeferredSequencedTaskRunner::PostDelayedTask(
+    const tracked_objects::Location& from_here,
+    const Closure& task,
+    TimeDelta delay) {
+  AutoLock lock(lock_);
+  if (started_) {
+    DCHECK(deferred_tasks_queue_.empty());
+    return target_task_runner_->PostDelayedTask(from_here, task, delay);
+  }
+
+  QueueDeferredTask(from_here, task, delay, false /* is_non_nestable */);
+  return true;
+}
+
+bool DeferredSequencedTaskRunner::RunsTasksOnCurrentThread() const {
+  return target_task_runner_->RunsTasksOnCurrentThread();
+}
+
+bool DeferredSequencedTaskRunner::PostNonNestableDelayedTask(
+    const tracked_objects::Location& from_here,
+    const Closure& task,
+    TimeDelta delay) {
+  AutoLock lock(lock_);
+  if (started_) {
+    DCHECK(deferred_tasks_queue_.empty());
+    return target_task_runner_->PostNonNestableDelayedTask(from_here,
+                                                           task,
+                                                           delay);
+  }
+  QueueDeferredTask(from_here, task, delay, true /* is_non_nestable */);
+  return true;
+}
+
+void DeferredSequencedTaskRunner::QueueDeferredTask(
+    const tracked_objects::Location& from_here,
+    const Closure& task,
+    TimeDelta delay,
+    bool is_non_nestable) {
+  DeferredTask deferred_task;
+  deferred_task.posted_from = from_here;
+  deferred_task.task = task;
+  deferred_task.delay = delay;
+  deferred_task.is_non_nestable = is_non_nestable;
+  deferred_tasks_queue_.push_back(deferred_task);
+}
+
+
+void DeferredSequencedTaskRunner::Start() {
+  AutoLock lock(lock_);
+  DCHECK(!started_);
+  started_ = true;
+  for (std::vector<DeferredTask>::iterator i = deferred_tasks_queue_.begin();
+      i != deferred_tasks_queue_.end();
+      ++i) {
+    const DeferredTask& task = *i;
+    if (task.is_non_nestable) {
+      target_task_runner_->PostNonNestableDelayedTask(task.posted_from,
+                                                      task.task,
+                                                      task.delay);
+    } else {
+      target_task_runner_->PostDelayedTask(task.posted_from,
+                                           task.task,
+                                           task.delay);
+    }
+    // Replace the i-th element in the |deferred_tasks_queue_| with an empty
+    // |DelayedTask| to ensure that |task| is destroyed before the next task
+    // is posted.
+    *i = DeferredTask();
+  }
+  deferred_tasks_queue_.clear();
+}
+
+}  // namespace base
diff --git a/base/deferred_sequenced_task_runner.h b/base/deferred_sequenced_task_runner.h
new file mode 100644
index 0000000..d1cdb43
--- /dev/null
+++ b/base/deferred_sequenced_task_runner.h
@@ -0,0 +1,79 @@
+// Copyright (c) 2013 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_DEFERRED_SEQUENCED_TASKRUNNER_H_
+#define BASE_DEFERRED_SEQUENCED_TASKRUNNER_H_
+
+#include <vector>
+
+#include "base/base_export.h"
+#include "base/basictypes.h"
+#include "base/callback.h"
+#include "base/compiler_specific.h"
+#include "base/memory/ref_counted.h"
+#include "base/sequenced_task_runner.h"
+#include "base/synchronization/lock.h"
+#include "base/time.h"
+#include "base/tracked_objects.h"
+
+namespace base {
+
+// A DeferredSequencedTaskRunner is a subclass of SequencedTaskRunner that
+// queues up all requests until the first call to Start() is issued.
+class BASE_EXPORT DeferredSequencedTaskRunner : public SequencedTaskRunner {
+ public:
+  explicit DeferredSequencedTaskRunner(
+      const scoped_refptr<SequencedTaskRunner>& target_runner);
+
+  // TaskRunner implementation
+  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,
+      TimeDelta delay) OVERRIDE;
+
+  // Start the execution - posts all queued tasks to the target executor. The
+  // deferred tasks are posted with their initial delay, meaning that the task
+  // execution delay is actually measured from Start.
+  // Fails when called a second time.
+  void Start();
+
+ private:
+  struct DeferredTask  {
+    DeferredTask();
+    ~DeferredTask();
+
+    tracked_objects::Location posted_from;
+    Closure task;
+    // The delay this task was initially posted with.
+    TimeDelta delay;
+    bool is_non_nestable;
+  };
+
+  virtual ~DeferredSequencedTaskRunner();
+
+  // Creates a |Task| object and adds it to |deferred_tasks_queue_|.
+  void QueueDeferredTask(const tracked_objects::Location& from_here,
+                         const Closure& task,
+                         TimeDelta delay,
+                         bool is_non_nestable);
+
+  // // Protects |started_| and |deferred_tasks_queue_|.
+  mutable Lock lock_;
+
+  bool started_;
+  const scoped_refptr<SequencedTaskRunner> target_task_runner_;
+  std::vector<DeferredTask> deferred_tasks_queue_;
+
+  DISALLOW_COPY_AND_ASSIGN(DeferredSequencedTaskRunner);
+};
+
+}  // namespace base
+
+#endif  // BASE_DEFERRED_SEQUENCED_TASKRUNNER_H_
diff --git a/base/deferred_sequenced_task_runner_unittest.cc b/base/deferred_sequenced_task_runner_unittest.cc
new file mode 100644
index 0000000..c033ba8
--- /dev/null
+++ b/base/deferred_sequenced_task_runner_unittest.cc
@@ -0,0 +1,184 @@
+// Copyright (c) 2013 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/deferred_sequenced_task_runner.h"
+
+#include "base/basictypes.h"
+#include "base/bind.h"
+#include "base/bind_helpers.h"
+#include "base/memory/ref_counted.h"
+#include "base/message_loop.h"
+#include "base/message_loop_proxy.h"
+#include "base/threading/non_thread_safe.h"
+#include "base/threading/thread.h"
+#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace {
+
+class DeferredSequencedTaskRunnerTest : public testing::Test,
+                                        public base::NonThreadSafe {
+ public:
+  class ExecuteTaskOnDestructor :
+      public base::RefCounted<ExecuteTaskOnDestructor> {
+   public:
+    ExecuteTaskOnDestructor(
+        DeferredSequencedTaskRunnerTest* executor,
+        int task_id)
+        : executor_(executor),
+          task_id_(task_id) {
+    }
+  private:
+    friend class base::RefCounted<ExecuteTaskOnDestructor>;
+    virtual ~ExecuteTaskOnDestructor() {
+      executor_->ExecuteTask(task_id_);
+    }
+    DeferredSequencedTaskRunnerTest* executor_;
+    int task_id_;
+  };
+
+  void ExecuteTask(int task_id) {
+    base::AutoLock lock(lock_);
+    executed_task_ids_.push_back(task_id);
+  }
+
+  void PostExecuteTask(int task_id) {
+    runner_->PostTask(FROM_HERE,
+                      base::Bind(&DeferredSequencedTaskRunnerTest::ExecuteTask,
+                                 base::Unretained(this),
+                                 task_id));
+  }
+
+  void StartRunner() {
+    runner_->Start();
+  }
+
+  void DoNothing(ExecuteTaskOnDestructor* object) {
+  }
+
+ protected:
+  DeferredSequencedTaskRunnerTest() :
+      loop_(),
+      runner_(
+          new base::DeferredSequencedTaskRunner(loop_.message_loop_proxy())) {
+  }
+
+  MessageLoop loop_;
+  scoped_refptr<base::DeferredSequencedTaskRunner> runner_;
+  mutable base::Lock lock_;
+  std::vector<int> executed_task_ids_;
+};
+
+TEST_F(DeferredSequencedTaskRunnerTest, Stopped) {
+  PostExecuteTask(1);
+  loop_.RunUntilIdle();
+  EXPECT_THAT(executed_task_ids_, testing::ElementsAre());
+}
+
+TEST_F(DeferredSequencedTaskRunnerTest, Start) {
+  StartRunner();
+  PostExecuteTask(1);
+  loop_.RunUntilIdle();
+  EXPECT_THAT(executed_task_ids_, testing::ElementsAre(1));
+}
+
+TEST_F(DeferredSequencedTaskRunnerTest, StartWithMultipleElements) {
+  StartRunner();
+  for (int i = 1; i < 5; ++i)
+    PostExecuteTask(i);
+
+  loop_.RunUntilIdle();
+  EXPECT_THAT(executed_task_ids_, testing::ElementsAre(1, 2, 3, 4));
+}
+
+TEST_F(DeferredSequencedTaskRunnerTest, DeferredStart) {
+  PostExecuteTask(1);
+  loop_.RunUntilIdle();
+  EXPECT_THAT(executed_task_ids_, testing::ElementsAre());
+
+  StartRunner();
+  loop_.RunUntilIdle();
+  EXPECT_THAT(executed_task_ids_, testing::ElementsAre(1));
+
+  PostExecuteTask(2);
+  loop_.RunUntilIdle();
+  EXPECT_THAT(executed_task_ids_, testing::ElementsAre(1, 2));
+}
+
+TEST_F(DeferredSequencedTaskRunnerTest, DeferredStartWithMultipleElements) {
+  for (int i = 1; i < 5; ++i)
+    PostExecuteTask(i);
+  loop_.RunUntilIdle();
+  EXPECT_THAT(executed_task_ids_, testing::ElementsAre());
+
+  StartRunner();
+  for (int i = 5; i < 9; ++i)
+    PostExecuteTask(i);
+  loop_.RunUntilIdle();
+  EXPECT_THAT(executed_task_ids_, testing::ElementsAre(1, 2, 3, 4, 5, 6, 7, 8));
+}
+
+TEST_F(DeferredSequencedTaskRunnerTest, DeferredStartWithMultipleThreads) {
+  {
+    base::Thread thread1("DeferredSequencedTaskRunnerTestThread1");
+    base::Thread thread2("DeferredSequencedTaskRunnerTestThread2");
+    thread1.Start();
+    thread2.Start();
+    for (int i = 0; i < 5; ++i) {
+      thread1.message_loop()->PostTask(
+          FROM_HERE,
+          base::Bind(&DeferredSequencedTaskRunnerTest::PostExecuteTask,
+                     base::Unretained(this),
+                     2 * i));
+      thread2.message_loop()->PostTask(
+          FROM_HERE,
+          base::Bind(&DeferredSequencedTaskRunnerTest::PostExecuteTask,
+                     base::Unretained(this),
+                     2 * i + 1));
+      if (i == 2) {
+        thread1.message_loop()->PostTask(
+            FROM_HERE,
+            base::Bind(&DeferredSequencedTaskRunnerTest::StartRunner,
+                       base::Unretained(this)));
+      }
+    }
+  }
+
+  loop_.RunUntilIdle();
+  EXPECT_THAT(executed_task_ids_,
+      testing::WhenSorted(testing::ElementsAre(0, 1, 2, 3, 4, 5, 6, 7, 8, 9)));
+}
+
+TEST_F(DeferredSequencedTaskRunnerTest, ObjectDestructionOrder) {
+  {
+    base::Thread thread("DeferredSequencedTaskRunnerTestThread");
+    thread.Start();
+    runner_ =
+        new base::DeferredSequencedTaskRunner(thread.message_loop_proxy());
+    for (int i = 0; i < 5; ++i) {
+      {
+        // Use a block to ensure that no reference to |short_lived_object|
+        // is kept on the main thread after it is posted to |runner_|.
+        scoped_refptr<ExecuteTaskOnDestructor> short_lived_object =
+            new ExecuteTaskOnDestructor(this, 2 * i);
+        runner_->PostTask(
+            FROM_HERE,
+            base::Bind(&DeferredSequencedTaskRunnerTest::DoNothing,
+                       base::Unretained(this),
+                       short_lived_object));
+      }
+      // |short_lived_object| with id |2 * i| should be destroyed before the
+      // task |2 * i + 1| is executed.
+      PostExecuteTask(2 * i + 1);
+    }
+    StartRunner();
+  }
+
+  // All |short_lived_object| with id |2 * i| are destroyed before the task
+  // |2 * i + 1| is executed.
+  EXPECT_THAT(executed_task_ids_,
+              testing::ElementsAre(0, 1, 2, 3, 4, 5, 6, 7, 8, 9));
+}
+
+}  // namespace