Re-land: cc: Remove WorkerPool class and instead use TaskGraphRunner directly.

cc/resources/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_RESOURCES_WORKER_POOL_H_
-#define CC_RESOURCES_WORKER_POOL_H_
-
-#include <deque>
-#include <string>
-#include <vector>
-
-#include "base/cancelable_callback.h"
-#include "base/containers/scoped_ptr_hash_map.h"
-#include "base/memory/ref_counted.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/memory/weak_ptr.h"
-#include "base/message_loop/message_loop.h"
-#include "cc/base/cc_export.h"
-
-namespace cc {
-namespace internal {
-
-class CC_EXPORT WorkerPoolTask
-    : public base::RefCountedThreadSafe<WorkerPoolTask> {
- public:
-  virtual void RunOnWorkerThread(unsigned thread_index) = 0;
-  virtual void CompleteOnOriginThread() = 0;
-
-  void DidSchedule();
-  void WillRun();
-  void DidRun();
-  void WillComplete();
-  void DidComplete();
-
-  bool HasFinishedRunning() const;
-  bool HasCompleted() const;
-
- protected:
-  friend class base::RefCountedThreadSafe<WorkerPoolTask>;
-
-  WorkerPoolTask();
-  virtual ~WorkerPoolTask();
-
- private:
-  bool did_schedule_;
-  bool did_run_;
-  bool did_complete_;
-};
-
-class CC_EXPORT GraphNode {
- public:
-  typedef std::vector<GraphNode*> Vector;
-
-  GraphNode(internal::WorkerPoolTask* task, unsigned priority);
-  ~GraphNode();
-
-  WorkerPoolTask* task() { return task_; }
-
-  void add_dependent(GraphNode* dependent) {
-    DCHECK(dependent);
-    dependents_.push_back(dependent);
-  }
-  const Vector& dependents() const { return dependents_; }
-
-  unsigned priority() const { return priority_; }
-
-  unsigned num_dependencies() const { return num_dependencies_; }
-  void add_dependency() { ++num_dependencies_; }
-  void remove_dependency() {
-    DCHECK(num_dependencies_);
-    --num_dependencies_;
-  }
-
- private:
-  WorkerPoolTask* task_;
-  Vector dependents_;
-  unsigned priority_;
-  unsigned num_dependencies_;
-
-  DISALLOW_COPY_AND_ASSIGN(GraphNode);
-};
-
-}  // namespace internal
-}  // namespace cc
-
-#if defined(COMPILER_GCC)
-namespace BASE_HASH_NAMESPACE {
-template <> struct hash<cc::internal::WorkerPoolTask*> {
-  size_t operator()(cc::internal::WorkerPoolTask* ptr) const {
-    return hash<size_t>()(reinterpret_cast<size_t>(ptr));
-  }
-};
-}  // namespace BASE_HASH_NAMESPACE
-#endif  // COMPILER
-
-namespace cc {
-
-// A worker thread pool that runs tasks provided by task graph and
-// guarantees completion of all pending tasks at shutdown.
-class CC_EXPORT WorkerPool {
- public:
-  virtual ~WorkerPool();
-
-  // Tells the worker pool to shutdown and returns once all pending tasks have
-  // completed.
-  virtual void Shutdown();
-
-  // Sets the number of threads to use for running raster tasks.
-  // Can only be called once prior to GetNumRasterThreads().
-  // Caller is responsible for correct ordering.
-  // TODO(reveman): Move this to RasterWorkerPool: crbug.com/331844
-  static void SetNumRasterThreads(int num_threads);
-
-  // Gets the number of threads to use for running raster tasks.
-  // TODO(reveman): Move this to RasterWorkerPool: crbug.com/331844
-  static int GetNumRasterThreads();
-
-  // A task graph contains a unique set of tasks with edges between
-  // dependencies pointing in the direction of the dependents. Each task
-  // need to be assigned a unique priority and a run count that matches
-  // the number of dependencies.
-  typedef base::ScopedPtrHashMap<internal::WorkerPoolTask*, internal::GraphNode>
-      GraphNodeMap;
-  typedef GraphNodeMap TaskGraph;
-  typedef std::vector<scoped_refptr<internal::WorkerPoolTask> > TaskVector;
-
- protected:
-  WorkerPool();
-
-  // Schedule running of tasks in |graph|. Any previously scheduled tasks
-  // that are not already running will be canceled. Canceled tasks don't run
-  // but completion of them is still processed.
-  void SetTaskGraph(TaskGraph* graph);
-
-  // Force a check for completed tasks.
-  void CheckForCompletedWorkerTasks();
-
- private:
-  void ProcessCompletedTasks(const TaskVector& completed_tasks);
-
-  bool in_dispatch_completion_callbacks_;
-};
-
-}  // namespace cc
-
-#endif  // CC_RESOURCES_WORKER_POOL_H_