Revert of scheduler: Add a base directory

components/scheduler/child/task_queue_selector.cc

+// Copyright 2014 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 "components/scheduler/child/task_queue_selector.h"
+
+#include "base/logging.h"
+#include "base/trace_event/trace_event_argument.h"
+#include "components/scheduler/child/task_queue_impl.h"
+
+namespace scheduler {
+namespace internal {
+
+TaskQueueSelector::TaskQueueSelector()
+    : task_queue_sets_(TaskQueue::QUEUE_PRIORITY_COUNT),
+      starvation_count_(0),
+      task_queue_selector_observer_(nullptr) {}
+
+TaskQueueSelector::~TaskQueueSelector() {}
+
+void TaskQueueSelector::AddQueue(internal::TaskQueueImpl* queue) {
+  DCHECK(main_thread_checker_.CalledOnValidThread());
+  task_queue_sets_.AssignQueueToSet(queue, TaskQueue::NORMAL_PRIORITY);
+}
+
+void TaskQueueSelector::RemoveQueue(internal::TaskQueueImpl* queue) {
+  DCHECK(main_thread_checker_.CalledOnValidThread());
+  task_queue_sets_.RemoveQueue(queue);
+}
+
+void TaskQueueSelector::SetQueuePriority(internal::TaskQueueImpl* queue,
+                                         TaskQueue::QueuePriority priority) {
+  DCHECK(main_thread_checker_.CalledOnValidThread());
+  DCHECK_LT(priority, TaskQueue::QUEUE_PRIORITY_COUNT);
+  TaskQueue::QueuePriority old_priority =
+      static_cast<TaskQueue::QueuePriority>(queue->get_task_queue_set_index());
+  task_queue_sets_.AssignQueueToSet(queue, priority);
+  if (task_queue_selector_observer_ &&
+      old_priority == TaskQueue::DISABLED_PRIORITY) {
+    task_queue_selector_observer_->OnTaskQueueEnabled(queue);
+  }
+}
+
+bool TaskQueueSelector::IsQueueEnabled(
+    const internal::TaskQueueImpl* queue) const {
+  DCHECK(main_thread_checker_.CalledOnValidThread());
+  return static_cast<TaskQueue::QueuePriority>(
+             queue->get_task_queue_set_index()) != TaskQueue::DISABLED_PRIORITY;
+}
+
+TaskQueue::QueuePriority TaskQueueSelector::NextPriority(
+    TaskQueue::QueuePriority priority) {
+  DCHECK(priority < TaskQueue::QUEUE_PRIORITY_COUNT);
+  return static_cast<TaskQueue::QueuePriority>(static_cast<int>(priority) + 1);
+}
+
+bool TaskQueueSelector::ChooseOldestWithPriority(
+    TaskQueue::QueuePriority priority,
+    internal::TaskQueueImpl** out_queue) const {
+  return task_queue_sets_.GetOldestQueueInSet(priority, out_queue);
+}
+
+bool TaskQueueSelector::SelectQueueToService(
+    internal::TaskQueueImpl** out_queue) {
+  DCHECK(main_thread_checker_.CalledOnValidThread());
+  // Always service the control queue if it has any work.
+  if (ChooseOldestWithPriority(TaskQueue::CONTROL_PRIORITY, out_queue)) {
+    DidSelectQueueWithPriority(TaskQueue::CONTROL_PRIORITY);
+    return true;
+  }
+  // Select from the normal priority queue if we are starving it.
+  if (starvation_count_ >= kMaxStarvationTasks &&
+      ChooseOldestWithPriority(TaskQueue::NORMAL_PRIORITY, out_queue)) {
+    DidSelectQueueWithPriority(TaskQueue::NORMAL_PRIORITY);
+    return true;
+  }
+  // Otherwise choose in priority order.
+  for (TaskQueue::QueuePriority priority = TaskQueue::HIGH_PRIORITY;
+       priority < TaskQueue::DISABLED_PRIORITY;
+       priority = NextPriority(priority)) {
+    if (ChooseOldestWithPriority(priority, out_queue)) {
+      DidSelectQueueWithPriority(priority);
+      return true;
+    }
+  }
+  return false;
+}
+
+void TaskQueueSelector::DidSelectQueueWithPriority(
+    TaskQueue::QueuePriority priority) {
+  switch (priority) {
+    case TaskQueue::CONTROL_PRIORITY:
+      break;
+    case TaskQueue::HIGH_PRIORITY:
+      starvation_count_++;
+      break;
+    case TaskQueue::NORMAL_PRIORITY:
+    case TaskQueue::BEST_EFFORT_PRIORITY:
+      starvation_count_ = 0;
+      break;
+    default:
+      NOTREACHED();
+  }
+}
+
+void TaskQueueSelector::AsValueInto(
+    base::trace_event::TracedValue* state) const {
+  DCHECK(main_thread_checker_.CalledOnValidThread());
+  state->SetInteger("starvation_count", starvation_count_);
+}
+
+void TaskQueueSelector::SetTaskQueueSelectorObserver(Observer* observer) {
+  task_queue_selector_observer_ = observer;
+}
+
+bool TaskQueueSelector::EnabledWorkQueuesEmpty() const {
+  for (TaskQueue::QueuePriority priority = TaskQueue::HIGH_PRIORITY;
+       priority < TaskQueue::DISABLED_PRIORITY;
+       priority = NextPriority(priority)) {
+    if (!task_queue_sets_.IsSetEmpty(priority))
+      return false;
+  }
+  return true;
+}
+
+}  // namespace internal
+}  // namespace scheduler