cc: Rasterize cheap tiles immediately

cc/worker_pool.h

 // Copyright 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 CC_WORKER_POOL_H_
 #define CC_WORKER_POOL_H_
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/threading/thread.h"
 #include "cc/rendering_stats.h"
 #include "cc/scoped_ptr_deque.h"
 
 namespace cc {
 namespace internal {
 
 class WorkerPoolTask {
  public:
   virtual ~WorkerPoolTask();
 
   virtual void Run(RenderingStats* rendering_stats) = 0;
 
+  virtual void DeferToThread(base::Thread* thread) = 0;
+
   void Completed();
 
  protected:
   WorkerPoolTask(const base::Closure& reply);
 
   base::Closure reply_;
 };
 
 }  // namespace internal
 
@@ skipping 20 matching lines @@
   // Returns true when worker pool has reached its internal limit for number
   // of pending tasks.
   bool IsBusy();
 
   // Toggle rendering stats collection.
   void SetRecordRenderingStats(bool record_rendering_stats);
 
   // Collect rendering stats all completed tasks.
   void GetRenderingStats(RenderingStats* stats);
 
+  // Run cheap, low latency tasks on the main thread. If the pending cheap tasks
+  // take too long to run, the remaining ones are deferred to the worker
+  // threads. Returns true if any cheap tasks were run.
+  bool RunCheapTasks();
+
+  // Control whether cheap (main thread) tasks are allowed to be queued for
+  // execution.
+  void SetCheapTasksAllowed(bool allowed);

[reveman, 2013/02/13 22:17:36]

would it be possible to leave this in the tile manager and just not post tasks
with is_cheap=true if they are not allowed?

+
  protected:
   class Worker : public base::Thread {
    public:
     Worker(WorkerPool* worker_pool, const std::string name);
     virtual ~Worker();
 
     // This must be called before the destructor.
     void StopAfterCompletingAllPendingTasks();
 
     // Posts a task to the worker thread.
@@ skipping 19 matching lines @@
     WorkerPool* worker_pool_;
     base::WeakPtrFactory<Worker> weak_ptr_factory_;
     ScopedPtrDeque<internal::WorkerPoolTask> pending_tasks_;
     scoped_ptr<RenderingStats> rendering_stats_;
     bool record_rendering_stats_;
   };
 
   explicit WorkerPool(size_t num_threads);
 
   WorkerPool::Worker* GetWorkerForNextTask();
+  bool CanPostCheapTask() const;
+  void PostCheapTask(scoped_ptr<internal::WorkerPoolTask> task);
 
  private:
   class NumPendingTasksComparator {
    public:
     bool operator() (const Worker* a, const Worker* b) const {
       return a->num_pending_tasks() < b->num_pending_tasks();
     }
   };
 
   void DidNumPendingTasksChange();
   void SortWorkersIfNeeded();
 
   typedef std::vector<Worker*> WorkerVector;
   WorkerVector workers_;
   bool workers_need_sorting_;
   bool shutdown_;
 
+  bool cheap_tasks_allowed_;
+  bool running_cheap_tasks_;
+  ScopedPtrDeque<internal::WorkerPoolTask> pending_cheap_tasks_;
+  scoped_ptr<RenderingStats> cheap_rendering_stats_;
+
   DISALLOW_COPY_AND_ASSIGN(WorkerPool);
 };
 
 }  // namespace cc
 
 #endif  // CC_WORKER_POOL_H_