[Try # 3] Scheduler refactoring to virtually eliminate redundant DoWorks

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 13 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);
+  enum class QueueType { DELAYED, IMMEDIATE };
+
+  WorkQueue(TaskQueueImpl* task_queue, const char* name, QueueType queue_type);
   ~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;
@@ skipping 11 matching lines @@
   const TaskQueueImpl::Task* GetFrontTask() const;
 
   // 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);
 
-  // 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(WTF::Deque<TaskQueueImpl::Task>& incoming_queue);
+  // Reloads the empty |work_queue_| with
+  // |task_queue_->TakeImmediateIncomingQueue| and if a fence hasn't been
+  // reached it informs the WorkQueueSets if the head changed.
+  void ReloadEmptyImmediateQueue();
 
   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 27 matching lines @@
   // 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:
   WTF::Deque<TaskQueueImpl::Task> work_queue_;
-  WorkQueueSets* work_queue_sets_;  // NOT OWNED.
-  TaskQueueImpl* task_queue_;       // NOT OWNED.
+  WorkQueueSets* work_queue_sets_;   // NOT OWNED.
+  TaskQueueImpl* const task_queue_;  // NOT OWNED.
   size_t work_queue_set_index_;
   HeapHandle heap_handle_;
-  const char* name_;
+  const char* const name_;
   EnqueueOrder fence_;
+  const QueueType queue_type_;
 
   DISALLOW_COPY_AND_ASSIGN(WorkQueue);
 };
 
 }  // namespace internal
 }  // namespace scheduler
 }  // namespace blink
 
 #endif  // THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_BASE_WORK_QUEUE_H_