[Reland] Make canceling Timers fast.

third_party/WebKit/Source/platform/scheduler/base/work_queue.h

 // Copyright 2015 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 THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_BASE_WORK_QUEUE_H_
 #define THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_BASE_WORK_QUEUE_H_
 
 #include <stddef.h>
 
 #include <set>
@@ skipping 12 matching lines @@
 // now. It interfaces deeply with WorkQueueSets which keeps track of which queue
 // (with a given priority) contains the oldest task.
 //
 // If a fence is inserted, WorkQueue behaves normally up until
 // TakeTaskFromWorkQueue reaches or exceeds the fence.  At that point it the
 // API subset used by WorkQueueSets pretends the WorkQueue is empty until the
 // fence is removed.  This functionality is a primitive intended for use by
 // throttling mechanisms.
 class BLINK_PLATFORM_EXPORT WorkQueue {
  public:
-  WorkQueue(TaskQueueImpl* task_queue,
-            const char* name,
-            TaskQueueImpl::Task::ComparatorFn queue_comparator);
+  WorkQueue(TaskQueueImpl* task_queue, const char* name);
   ~WorkQueue();
 
   // Associates this work queue with the given work queue sets. This must be
   // called before any tasks can be inserted into this work queue.
   void AssignToWorkQueueSets(WorkQueueSets* work_queue_sets);
 
   // Assigns the current set index.
   void AssignSetIndex(size_t work_queue_set_index);
 
   void AsValueInto(base::trace_event::TracedValue* state) const;
 
   // Returns true if the |work_queue_| is empty. This method ignores any fences.
   bool Empty() const { return work_queue_.empty(); }
 
   // If the |work_queue_| isn't empty and a fence hasn't been reached,
   // |enqueue_order| gets set to the enqueue order of the front task and the
   // function returns true.  Otherwise the function returns false.
   bool GetFrontTaskEnqueueOrder(EnqueueOrder* enqueue_order) const;
 
   // Returns the first task in this queue or null if the queue is empty. This
   // method ignores any fences.
   const TaskQueueImpl::Task* GetFrontTask() const;
 
-  // Returns the first task in this queue or null if the queue is empty. This
+  // Returns the last task in this queue or null if the queue is empty. This
   // method ignores any fences.
   const TaskQueueImpl::Task* GetBackTask() const;
 
   // Pushes the task onto the |work_queue_| and a fence hasn't been reached it
   // informs the WorkQueueSets if the head changed.
   void Push(TaskQueueImpl::Task task);
 
-  // Removes a cancelled task from the |work_queue_|. Note |key| isn't required
-  // to be the original task posted, it can be a fake key constructed by
-  // TaskQueueImpl::Task::CreateFakeTaskFromHandle.
-  bool CancelTask(const TaskQueueImpl::Task& key);
-
-  // Returns true if |work_queue_| contains a task matching |key|. Note |key|
-  // isn't required to be the original task posted, it can be a fake key
-  // constructed by TaskQueueImpl::Task::CreateFakeTaskFromHandle.
-  bool IsTaskPending(const TaskQueueImpl::Task& key) const;
-
   // Swap the |work_queue_| with |incoming_queue| and if a fence hasn't been
   // reached it informs the WorkQueueSets if the head changed. Assumes
   // |task_queue_->any_thread_lock_| is locked.
-  void SwapLocked(TaskQueueImpl::ComparatorQueue& incoming_queue);
+  void SwapLocked(std::queue<TaskQueueImpl::Task>& incoming_queue);
 
   size_t Size() const { return work_queue_.size(); }
 
   // Pulls a task off the |work_queue_| and informs the WorkQueueSets.  If the
   // task removed had an enqueue order >= the current fence then WorkQueue
   // pretends to be empty as far as the WorkQueueSets is concrned.
   TaskQueueImpl::Task TakeTaskFromWorkQueue();
 
   const char* name() const { return name_; }
 
@@ skipping 22 matching lines @@
   // empty, then the real value is reported to WorkQueueSets. Returns true if
   // any tasks where unblocked.
   bool RemoveFence();
 
   // Returns true if any tasks are blocked by the fence. Returns true if the
   // queue is empty and fence has been set (i.e. future tasks would be blocked).
   // Otherwise returns false.
   bool BlockedByFence() const;
 
  private:
-  TaskQueueImpl::ComparatorQueue work_queue_;
+  std::queue<TaskQueueImpl::Task> work_queue_;
   WorkQueueSets* work_queue_sets_;  // NOT OWNED.
   TaskQueueImpl* task_queue_;       // NOT OWNED.
   size_t work_queue_set_index_;
   const char* name_;
   EnqueueOrder fence_;
 
   DISALLOW_COPY_AND_ASSIGN(WorkQueue);
 };
 
 }  // namespace internal
 }  // namespace scheduler
 }  // namespace blink
 
 #endif  // THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_BASE_WORK_QUEUE_H_