Reference CL for the new task scheduler.

base/task_scheduler/task_scheduler_impl.cc

+// Copyright 2016 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/task_scheduler/task_scheduler_impl.h"
+
+#include "base/bind.h"
+#include "base/logging.h"
+#include "base/task_scheduler/worker_thread.h"
+
+namespace base {
+namespace internal {
+
+TaskSchedulerImpl::TaskSchedulerImpl() {
+  // Using Unretained() is safe because a TaskSchedulerImpl is never destroyed
+  // before all its ThreadPools have been destroyed.
+  const WorkerThread::ReinsertSequenceCallback reinsert_sequence_callback =
+      Bind(&TaskSchedulerImpl::ReinsertSequenceCallback, Unretained(this));
+
+  background_thread_pool_ = ThreadPool::CreateThreadPool(
+      ThreadPriority::BACKGROUND, 1, reinsert_sequence_callback,
+      &shutdown_manager_);
+  CHECK(background_thread_pool_.get());
+
+  background_file_io_thread_pool_ = ThreadPool::CreateThreadPool(
+      ThreadPriority::BACKGROUND, 1, reinsert_sequence_callback,
+      &shutdown_manager_);
+  CHECK(background_file_io_thread_pool_.get());
+
+  normal_thread_pool_ = ThreadPool::CreateThreadPool(ThreadPriority::NORMAL, 4,
+                                                     reinsert_sequence_callback,
+                                                     &shutdown_manager_);
+  CHECK(normal_thread_pool_.get());
+
+  normal_file_io_thread_pool_ = ThreadPool::CreateThreadPool(
+      ThreadPriority::NORMAL, 12, reinsert_sequence_callback,
+      &shutdown_manager_);
+  CHECK(normal_file_io_thread_pool_.get());
+}
+
+TaskSchedulerImpl::~TaskSchedulerImpl() {
+  // In production code, a TaskSchedulerImpl is never destroyed. In test code,
+  // ShutdownAndJoinAllThreadsForTesting() must be called before the
+  // TaskSchedulerImpl is destroyed.
+  DCHECK(!background_thread_pool_.get());
+  DCHECK(!background_file_io_thread_pool_.get());
+  DCHECK(!normal_thread_pool_.get());
+  DCHECK(!normal_file_io_thread_pool_.get());
+}
+
+void TaskSchedulerImpl::PostTaskWithTraits(
+    const tracked_objects::Location& from_here,
+    TaskTraits traits,
+    const Closure& task) {
+  CreateTaskRunnerWithTraits(traits, ExecutionMode::PARALLEL)
+      ->PostTask(from_here, task);
+}
+
+scoped_refptr<TaskRunner> TaskSchedulerImpl::CreateTaskRunnerWithTraits(
+    TaskTraits traits,
+    ExecutionMode execution_mode) {
+  return GetThreadPoolForTraits(traits)
+      ->CreateTaskRunnerWithTraits(traits, execution_mode);
+}
+
+void TaskSchedulerImpl::Shutdown() {
+  // TODO(fdoray): Increase the priority of BACKGROUND tasks blocking shutdown.
+  shutdown_manager_.Shutdown();
+}
+
+void TaskSchedulerImpl::ShutdownAndJoinAllThreadsForTesting() {
+  background_thread_pool_->ShutdownAndJoinAllThreadsForTesting();
+  background_thread_pool_.reset();
+  background_file_io_thread_pool_->ShutdownAndJoinAllThreadsForTesting();
+  background_file_io_thread_pool_.reset();
+  normal_thread_pool_->ShutdownAndJoinAllThreadsForTesting();
+  normal_thread_pool_.reset();
+  normal_file_io_thread_pool_->ShutdownAndJoinAllThreadsForTesting();
+  normal_file_io_thread_pool_.reset();
+}
+
+ThreadPool* TaskSchedulerImpl::GetThreadPoolForTraits(
+    const TaskTraits& traits) {
+  if (traits.with_file_io()) {
+    if (traits.priority() == TaskPriority::BACKGROUND)
+      return background_file_io_thread_pool_.get();
+    return normal_file_io_thread_pool_.get();
+  }
+
+  if (traits.priority() == TaskPriority::BACKGROUND)
+    return background_thread_pool_.get();
+  return normal_thread_pool_.get();
+}
+
+void TaskSchedulerImpl::ReinsertSequenceCallback(
+    scoped_refptr<Sequence> sequence,
+    const WorkerThread* worker_thread) {
+  const SequenceSortKey sort_key = sequence->GetSortKey();
+  const Task* next_task_in_sequence = sequence->PeekTask();
+  DCHECK(next_task_in_sequence);
+
+  TaskTraits traits = TaskTraits().WithPriority(sort_key.priority());
+  if (next_task_in_sequence->traits.with_file_io())
+    traits = traits.WithFileIO();
+
+  GetThreadPoolForTraits(traits)
+      ->ReinsertSequence(sequence, sort_key, worker_thread);
+}
+
+}  // namespace internal
+}  // namespace base