cc: Move WorkerPool from cc/base to cc/resources.

cc/base/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_BASE_WORKER_POOL_H_
-#define CC_BASE_WORKER_POOL_H_
-
-#include <deque>
-#include <string>
-#include <vector>
-
-#include "base/cancelable_callback.h"
-#include "base/memory/ref_counted.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/memory/weak_ptr.h"
-#include "base/message_loop.h"
-#include "cc/base/cc_export.h"
-#include "cc/base/scoped_ptr_hash_map.h"
-
-namespace cc {
-namespace internal {
-
-class CC_EXPORT WorkerPoolTask
-    : public base::RefCountedThreadSafe<WorkerPoolTask> {
- public:
-  typedef std::vector<scoped_refptr<WorkerPoolTask> > TaskVector;
-
-  virtual void RunOnThread(unsigned thread_index) = 0;
-  virtual void DispatchCompletionCallback() = 0;
-
-  void DidSchedule();
-  void WillRun();
-  void DidRun();
-  void DidComplete();
-
-  bool IsReadyToRun() const;
-  bool HasFinishedRunning() const;
-  bool HasCompleted() const;
-
-  TaskVector& dependencies() { return dependencies_; }
-
- protected:
-  friend class base::RefCountedThreadSafe<WorkerPoolTask>;
-
-  WorkerPoolTask();
-  explicit WorkerPoolTask(TaskVector* dependencies);
-  virtual ~WorkerPoolTask();
-
- private:
-  bool did_schedule_;
-  bool did_run_;
-  bool did_complete_;
-  TaskVector dependencies_;
-};
-
-}  // 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();
-
-  // Force a check for completed tasks.
-  virtual void CheckForCompletedTasks();
-
- protected:
-  class CC_EXPORT GraphNode {
-   public:
-    GraphNode(internal::WorkerPoolTask* dependent, unsigned priority);
-    ~GraphNode();
-
-    void AddDependent(internal::WorkerPoolTask* dependent);
-
-    const internal::WorkerPoolTask::TaskVector& dependents() const {
-      return dependents_;
-    }
-    unsigned priority() const { return priority_; }
-
-   private:
-    internal::WorkerPoolTask::TaskVector dependents_;
-    unsigned priority_;
-
-    DISALLOW_COPY_AND_ASSIGN(GraphNode);
-  };
-  typedef ScopedPtrHashMap<internal::WorkerPoolTask*, GraphNode> GraphNodeMap;
-  typedef GraphNodeMap TaskGraph;
-
-  WorkerPool(size_t num_threads, const std::string& thread_name_prefix);
-
-  // 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);
-
-  // BuildTaskGraph() takes a task tree as input and constructs a
-  // unique set of tasks with edges between dependencies pointing in
-  // the direction of the dependents. Each task is given a unique priority
-  // which is currently the same as the DFS traversal order.
-  //
-  // Input:             Output:
-  //
-  //       root               task4          Task | Priority (lower is better)
-  //     /      \           /       \      -------+---------------------------
-  //  task1    task2      task3    task2     root | 4
-  //    |        |          |        |      task1 | 2
-  //  task3      |        task1      |      task2 | 3
-  //    |        |           \      /       task3 | 1
-  //  task4    task4           root         task4 | 0
-  //
-  // The output can be used to efficiently maintain a queue of
-  // "ready to run" tasks.
-  static unsigned BuildTaskGraphRecursive(
-      internal::WorkerPoolTask* task,
-      internal::WorkerPoolTask* dependent,
-      unsigned priority,
-      TaskGraph* tasks);
-  static void BuildTaskGraph(
-      internal::WorkerPoolTask* root, TaskGraph* tasks);
-
- private:
-  class Inner;
-  friend class Inner;
-
-  typedef std::deque<scoped_refptr<internal::WorkerPoolTask> > TaskDeque;
-
-  void DispatchCompletionCallbacks(TaskDeque* completed_tasks);
-
-  bool in_dispatch_completion_callbacks_;
-
-  // Hide the gory details of the worker pool in |inner_|.
-  const scoped_ptr<Inner> inner_;
-};
-
-}  // namespace cc
-
-#endif  // CC_BASE_WORKER_POOL_H_