content: Implement dynamic priorities for raster threads.

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/macros.h"
@@ skipping 11 matching lines @@
 
 // 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.
 class CONTENT_EXPORT RasterWorkerPool : public base::TaskRunner,
-                                        public cc::TaskGraphRunner {
+                                        public cc::TaskGraphRunner,
+                                        public cc::TaskGraphWorkQueueClient {
  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;
 
+  // TODO(prashant.n): Move this to separate class to control workers
+  // efficiently.
+  // Overridden from cc::TaskGraphWorkQueueClient:
+  void AdjustWorkerPriorityForTask(cc::Task* task,
+                                   uint16_t old_category,
+                                   uint16_t new_category) override;
+
   // Runs a task from one of the provided categories. Categories listed first
   // have higher priority.
-  void Run(const std::vector<cc::TaskCategory>& categories,
+  void Run(cc::TaskWorker* worker,
+           const std::vector<cc::TaskCategory>& categories,
            base::ConditionVariable* has_ready_to_run_tasks_cv);
 
   void FlushForTesting();
 
   // Spawn |num_threads| number of threads and start running work on the
   // worker threads.
   void Start(int num_threads);
 
   // Finish running all the posted tasks (and nested task posted by those tasks)
   // of all the associated task runners.
@@ skipping 32 matching lines @@
     DISALLOW_COPY_AND_ASSIGN(ClosureTask);
   };
 
   void ScheduleTasksWithLockAcquired(cc::NamespaceToken token,
                                      cc::TaskGraph* graph);
   void CollectCompletedTasksWithLockAcquired(cc::NamespaceToken token,
                                              cc::Task::Vector* completed_tasks);
 
   // Runs a task from one of the provided categories. Categories listed first
   // have higher priority. Returns false if there were no tasks to run.
-  bool RunTaskWithLockAcquired(const std::vector<cc::TaskCategory>& categories);
+  bool RunTaskWithLockAcquired(cc::TaskWorker* worker,
+                               const std::vector<cc::TaskCategory>& categories);
 
   // Run next task for the given category. Caller must acquire |lock_| prior to
   // calling this function and make sure at least one task is ready to run.
-  void RunTaskInCategoryWithLockAcquired(cc::TaskCategory category);
+  void RunTaskInCategoryWithLockAcquired(cc::TaskWorker* worker,
+                                         cc::TaskCategory category);
 
   // Helper function which signals worker threads if tasks are ready to run.
   void SignalHasReadyToRunTasksWithLockAcquired();
 
   // Determines if we should run a new task for the given category. This factors
   // in whether a task is available and whether the count of running tasks is
   // low enough to start a new one.
   bool ShouldRunTaskForCategoryWithLockAcquired(cc::TaskCategory category);
 
   // The actual threads where work is done.
-  std::vector<scoped_ptr<base::SimpleThread>> threads_;
+  std::vector<scoped_ptr<base::DynamicPriorityThread>> threads_;
 
   // Lock to exclusively access all the following members that are used to
   // 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 variables for foreground and background tasks.
   base::ConditionVariable has_ready_to_run_foreground_tasks_cv_;
   base::ConditionVariable has_ready_to_run_background_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_