TaskGraphRunner refactor

content/renderer/raster_worker_pool.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 CONTENT_RENDERER_RASTER_WORKER_POOL_H_
 #define CONTENT_RENDERER_RASTER_WORKER_POOL_H_
 
 #include "base/callback.h"
 #include "base/containers/hash_tables.h"
 #include "base/memory/scoped_vector.h"
 #include "base/sequenced_task_runner.h"
+#include "base/synchronization/condition_variable.h"
 #include "base/task_runner.h"
 #include "base/threading/simple_thread.h"
 #include "cc/raster/task_graph_runner.h"
+#include "cc/raster/task_graph_work_queue.h"
 #include "content/common/content_export.h"
 
 namespace content {
 
 // A pool of threads used to run raster work.
 // Work can be scheduled on the threads using different interfaces.
 // The pool itself implements TaskRunner interface and tasks posted via that
 // interface might run in parallel.
 // CreateSequencedTaskRunner creates a sequenced task runner that might run in
 // parallel with other instances of sequenced task runners.
 // It's also possible to get the underlying TaskGraphRunner to schedule a graph
 // of tasks with their dependencies.
-// TODO(reveman): make TaskGraphRunner an abstract interface and have this
-// WorkerPool class implement it.
 class CONTENT_EXPORT RasterWorkerPool
     : public base::TaskRunner,
+      public cc::TaskGraphRunner,
       public base::DelegateSimpleThread::Delegate {
  public:
   RasterWorkerPool();
 
   // Overridden from base::TaskRunner:
   bool PostDelayedTask(const tracked_objects::Location& from_here,
                        const base::Closure& task,
                        base::TimeDelta delay) override;
   bool RunsTasksOnCurrentThread() const override;
 
+  // Overridden from cc::TaskGraphRunner:
+  cc::NamespaceToken GetNamespaceToken() override;
+  void ScheduleTasks(cc::NamespaceToken token, cc::TaskGraph* graph) override;
+  void WaitForTasksToFinishRunning(cc::NamespaceToken token) override;
+  void CollectCompletedTasks(cc::NamespaceToken token,
+                             cc::Task::Vector* completed_tasks) override;
+
   // Overridden from base::DelegateSimpleThread::Delegate:
   void Run() override;
 
+  void FlushForTesting();
+
   // Spawn |num_threads| number of threads and start running work on the
   // worker threads.
   void Start(int num_threads,
              const base::SimpleThread::Options& thread_options);
 
   // Finish running all the posted tasks (and nested task posted by those tasks)
   // of all the associated task runners.
   // Once all the tasks are executed the method blocks until the threads are
   // terminated.
   void Shutdown();
 
-  cc::TaskGraphRunner* GetTaskGraphRunner() { return &task_graph_runner_; }
+  cc::TaskGraphRunner* GetTaskGraphRunner() { return this; }
 
   // Create a new sequenced task graph runner.
   scoped_refptr<base::SequencedTaskRunner> CreateSequencedTaskRunner();
 
  protected:
   ~RasterWorkerPool() override;
 
  private:
   class RasterWorkerPoolSequencedTaskRunner;
   friend class RasterWorkerPoolSequencedTaskRunner;
 
+  // Run next task. Caller must acquire |lock_| prior to calling this function
+  // and make sure at least one task is ready to run.
+  void RunTaskWithLockAcquired();
+
   // Simple Task for the TaskGraphRunner that wraps a closure.
   // This class is used to schedule TaskRunner tasks on the
   // |task_graph_runner_|.
   class ClosureTask : public cc::Task {
    public:
     explicit ClosureTask(const base::Closure& closure);
 
     // Overridden from cc::Task:
     void RunOnWorkerThread() override;
 
    protected:
     ~ClosureTask() override;
 
    private:
     base::Closure closure_;
 
     DISALLOW_COPY_AND_ASSIGN(ClosureTask);
   };
 
+  void ScheduleTasksWithLockAcquired(cc::NamespaceToken token,
+                                     cc::TaskGraph* graph);
+  void CollectCompletedTasksWithLockAcquired(cc::NamespaceToken token,
+                                             cc::Task::Vector* completed_tasks);
+
   // The actual threads where work is done.
   ScopedVector<base::DelegateSimpleThread> threads_;
-  cc::TaskGraphRunner task_graph_runner_;
 
   // Lock to exclusively access all the following members that are used to
-  // implement the TaskRunner interfaces.
+  // implement the TaskRunner and TaskGraphRunner interfaces.
   base::Lock lock_;
+  // Stores the tasks to be run, sorted by priority.
+  cc::TaskGraphWorkQueue work_queue_;
   // Namespace used to schedule tasks in the task graph runner.
   cc::NamespaceToken namespace_token_;
   // List of tasks currently queued up for execution.
   cc::Task::Vector tasks_;
   // Graph object used for scheduling tasks.
   cc::TaskGraph graph_;
   // Cached vector to avoid allocation when getting the list of complete
   // tasks.
   cc::Task::Vector completed_tasks_;
+  // Condition variable that is waited on by Run() until new tasks are ready to
+  // run or shutdown starts.
+  base::ConditionVariable has_ready_to_run_tasks_cv_;
+  // Condition variable that is waited on by origin threads until a namespace
+  // has finished running all associated tasks.
+  base::ConditionVariable has_namespaces_with_finished_running_tasks_cv_;
+  // Set during shutdown. Tells Run() to return when no more tasks are pending.
+  bool shutdown_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_RASTER_WORKER_POOL_H_