cc: Check for completed raster tasks at interval.

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/cancelable_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;
 
-  void Completed();
+  bool HasCompleted();
+  void DidComplete();
 
  protected:
   WorkerPoolTask(const base::Closure& reply);
 
-  base::Closure reply_;
+  const base::Closure reply_;
+
+  // Accessed from multiple threads. Set to 1 when task has completed.
+  base::subtle::Atomic32 completed_;
 };
 
 }  // namespace internal
 
+class WorkerPoolClient {
+ public:
+  virtual void DidFinishDispatchingCompletionCallbacks() = 0;
+
+ protected:
+  virtual ~WorkerPoolClient() {}
+};
+
 // A worker thread pool that runs rendering tasks and guarantees completion
 // of all pending tasks at shutdown.
 class WorkerPool {
  public:
   typedef base::Callback<void(RenderingStats*)> Callback;
 
   virtual ~WorkerPool();
 
-  static scoped_ptr<WorkerPool> Create(size_t num_threads) {
-    return make_scoped_ptr(new WorkerPool(num_threads));
+  static scoped_ptr<WorkerPool> Create(
+      WorkerPoolClient* client, size_t num_threads) {
+    return make_scoped_ptr(new WorkerPool(client, num_threads));
   }
 
   // Tells the worker pool to shutdown and returns once all pending tasks have
   // completed.
   void Shutdown();
 
   // Posts |task| to worker pool. On completion, |reply|
   // is posted to the thread that called PostTaskAndReply().
   void PostTaskAndReply(const Callback& task, const base::Closure& reply);
 
-  // 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);
 
  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.
     void PostTask(scoped_ptr<internal::WorkerPoolTask> task);
 
+    // Check for completed tasks and run reply callbacks.
+    void CheckForCompletedTasks();
+
     int num_pending_tasks() const { return pending_tasks_.size(); }
     void set_record_rendering_stats(bool record_rendering_stats) {
       record_rendering_stats_ = record_rendering_stats;
     }
     const RenderingStats* rendering_stats() const {
       return rendering_stats_.get();
     }
 
     // Overridden from base::Thread:
     virtual void Init() OVERRIDE;
 
    private:
     static void RunTask(
-        internal::WorkerPoolTask* task, RenderingStats* rendering_stats);
+        internal::WorkerPoolTask* task,
+        WorkerPool* worker_pool,
+        RenderingStats* rendering_stats);
 
     void OnTaskCompleted();
 
     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(WorkerPoolClient* client, size_t num_threads);
 
   WorkerPool::Worker* GetWorkerForNextTask();
 
  private:
   class NumPendingTasksComparator {
    public:
     bool operator() (const Worker* a, const Worker* b) const {
       return a->num_pending_tasks() < b->num_pending_tasks();
     }
   };
 
-  void DidNumPendingTasksChange();
+  // Schedule a completed tasks check if not already pending.
+  void ScheduleCheckForCompletedTasks();
+
+  // Called on origin thread before posting task to worker.
+  void WillPostTask();
+
+  // Called on worker thread after completing work.
+  void OnWorkCompletedOnWorkerThread();
+
+  // Called on origin thread after becoming idle.
+  void OnIdle();
+
+  // Check for completed tasks and run reply callbacks.
+  void CheckForCompletedTasks();
+
+  // Called when processing task completion.
+  void OnTaskCompleted();
+
+  // Returns true when work has completed in worker thread but
+  // task completion has not yet been processed.
+  bool MoreTasksCompleted();
+
+  // Ensure workers are sorted by number of pending tasks.
   void SortWorkersIfNeeded();
 
   typedef std::vector<Worker*> WorkerVector;
   WorkerVector workers_;
+  WorkerPoolClient* client_;
+  scoped_refptr<base::MessageLoopProxy> origin_loop_;
+  base::WeakPtrFactory<WorkerPool> weak_ptr_factory_;
   bool workers_need_sorting_;
   bool shutdown_;
+  base::CancelableClosure check_for_completed_tasks_callback_;
+  bool check_for_completed_tasks_pending_;
+  base::Closure idle_callback_;
+  // Accessed from multiple threads. 0 when worker pool is idle.
+  base::subtle::Atomic32 pending_task_count_;
 
   DISALLOW_COPY_AND_ASSIGN(WorkerPool);
 };
 
 }  // namespace cc
 
 #endif  // CC_WORKER_POOL_H_