Add m-esr52 at 52.6.0

1 files changed, 257 insertions, 0 deletions

diff --git a/gfx/2d/JobScheduler.h b/gfx/2d/JobScheduler.h
new file mode 100644
index 000000000..483842904
--- /dev/null
+++ b/gfx/2d/JobScheduler.h
@@ -0,0 +1,257 @@
+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZILLA_GFX_TASKSCHEDULER_H_
+#define MOZILLA_GFX_TASKSCHEDULER_H_
+
+#include "mozilla/RefPtr.h"
+#include "mozilla/gfx/Types.h"
+#include "mozilla/RefCounted.h"
+
+#ifdef WIN32
+#include "mozilla/gfx/JobScheduler_win32.h"
+#else
+#include "mozilla/gfx/JobScheduler_posix.h"
+#endif
+
+#include <vector>
+
+namespace mozilla {
+namespace gfx {
+
+class MultiThreadedJobQueue;
+class SyncObject;
+class WorkerThread;
+
+class JobScheduler {
+public:
+  /// Return one of the queues that the drawing worker threads pull from, chosen
+  /// pseudo-randomly.
+  static MultiThreadedJobQueue* GetDrawingQueue()
+  {
+    return sSingleton->mDrawingQueues[
+      sSingleton->mNextQueue++ % sSingleton->mDrawingQueues.size()
+    ];
+  }
+
+  /// Return one of the queues that the drawing worker threads pull from with a
+  /// hash to choose the queue.
+  ///
+  /// Calling this function several times with the same hash will yield the same queue.
+  static MultiThreadedJobQueue* GetDrawingQueue(uint32_t aHash)
+  {
+    return sSingleton->mDrawingQueues[
+      aHash % sSingleton->mDrawingQueues.size()
+    ];
+  }
+
+  /// Return the task queue associated to the worker the task is pinned to if
+  /// the task is pinned to a worker, or a random queue.
+  static MultiThreadedJobQueue* GetQueueForJob(Job* aJob);
+
+  /// Initialize the task scheduler with aNumThreads worker threads for drawing
+  /// and aNumQueues task queues.
+  ///
+  /// The number of threads must be superior or equal to the number of queues
+  /// (since for now a worker thread only pulls from one queue).
+  static bool Init(uint32_t aNumThreads, uint32_t aNumQueues);
+
+  /// Shut the scheduler down.
+  ///
+  /// This will block until worker threads are joined and deleted.
+  static void ShutDown();
+
+  /// Returns true if there is a successfully initialized JobScheduler singleton.
+  static bool IsEnabled() { return !!sSingleton; }
+
+  /// Submit a task buffer to its associated queue.
+  ///
+  /// The caller looses ownership of the task buffer.
+  static void SubmitJob(Job* aJobs);
+
+  /// Convenience function to block the current thread until a given SyncObject
+  /// is in the signaled state.
+  ///
+  /// The current thread will first try to steal jobs before blocking.
+  static void Join(SyncObject* aCompletionSync);
+
+  /// Process commands until the command buffer needs to block on a sync object,
+  /// completes, yields, or encounters an error.
+  ///
+  /// Can be used on any thread. Worker threads basically loop over this, but the
+  /// main thread can also dequeue pending task buffers and process them alongside
+  /// the worker threads if it is about to block until completion anyway.
+  ///
+  /// The caller looses ownership of the task buffer.
+  static JobStatus ProcessJob(Job* aJobs);
+
+protected:
+  static JobScheduler* sSingleton;
+
+  // queues of Job that are ready to be processed
+  std::vector<MultiThreadedJobQueue*> mDrawingQueues;
+  std::vector<WorkerThread*> mWorkerThreads;
+  Atomic<uint32_t> mNextQueue;
+};
+
+/// Jobs are not reference-counted because they don't have shared ownership.
+/// The ownership of tasks can change when they are passed to certain methods
+/// of JobScheduler and SyncObject. See the docuumentaion of these classes.
+class Job {
+public:
+  Job(SyncObject* aStart, SyncObject* aCompletion, WorkerThread* aThread = nullptr);
+
+  virtual ~Job();
+
+  virtual JobStatus Run() = 0;
+
+  /// For use in JobScheduler::SubmitJob. Don't use it anywhere else.
+  //already_AddRefed<SyncObject> GetAndResetStartSync();
+  SyncObject* GetStartSync() { return mStartSync; }
+
+  bool IsPinnedToAThread() const { return !!mPinToThread; }
+
+  WorkerThread* GetWorkerThread() { return mPinToThread; }
+
+protected:
+  // An intrusive linked list of tasks waiting for a sync object to enter the
+  // signaled state. When the task is not waiting for a sync object, mNextWaitingJob
+  // should be null. This is only accessed from the thread that owns the task.
+  Job* mNextWaitingJob;
+
+  RefPtr<SyncObject> mStartSync;
+  RefPtr<SyncObject> mCompletionSync;
+  WorkerThread* mPinToThread;
+
+  friend class SyncObject;
+};
+
+class EventObject;
+
+/// This task will set an EventObject.
+///
+/// Typically used as the final task, so that the main thread can block on the
+/// corresponfing EventObject until all of the tasks are processed.
+class SetEventJob : public Job
+{
+public:
+  explicit SetEventJob(EventObject* aEvent,
+                        SyncObject* aStart, SyncObject* aCompletion = nullptr,
+                        WorkerThread* aPinToWorker = nullptr);
+
+  ~SetEventJob();
+
+  JobStatus Run() override;
+
+  EventObject* GetEvent() { return mEvent; }
+
+protected:
+  RefPtr<EventObject> mEvent;
+};
+
+/// A synchronization object that can be used to express dependencies and ordering between
+/// tasks.
+///
+/// Jobs can register to SyncObjects in order to asynchronously wait for a signal.
+/// In practice, Job objects usually start with a sync object (startSyc) and end
+/// with another one (completionSync).
+/// a Job never gets processed before its startSync is in the signaled state, and
+/// signals its completionSync as soon as it finishes. This is how dependencies
+/// between tasks is expressed.
+class SyncObject final : public external::AtomicRefCounted<SyncObject> {
+public:
+  MOZ_DECLARE_REFCOUNTED_TYPENAME(SyncObject)
+
+  /// Create a synchronization object.
+  ///
+  /// aNumPrerequisites represents the number of times the object must be signaled
+  /// before actually entering the signaled state (in other words, it means the
+  /// number of dependencies of this sync object).
+  ///
+  /// Explicitly specifying the number of prerequisites when creating sync objects
+  /// makes it easy to start scheduling some of the prerequisite tasks while
+  /// creating the others, which is how we typically use the task scheduler.
+  /// Automatically determining the number of prerequisites using Job's constructor
+  /// brings the risk that the sync object enters the signaled state while we
+  /// are still adding prerequisites which is hard to fix without using muteces.
+  explicit SyncObject(uint32_t aNumPrerequisites = 1);
+
+  ~SyncObject();
+
+  /// Attempt to register a task.
+  ///
+  /// If the sync object is already in the signaled state, the buffer is *not*
+  /// registered and the sync object does not take ownership of the task.
+  /// If the object is not yet in the signaled state, it takes ownership of
+  /// the task and places it in a list of pending tasks.
+  /// Pending tasks will not be processed by the worker thread.
+  /// When the SyncObject reaches the signaled state, it places the pending
+  /// tasks back in the available buffer queue, so that they can be
+  /// scheduled again.
+  ///
+  /// Returns true if the SyncOject is not already in the signaled state.
+  /// This means that if this method returns true, the SyncObject has taken
+  /// ownership of the Job.
+  bool Register(Job* aJob);
+
+  /// Signal the SyncObject.
+  ///
+  /// This decrements an internal counter. The sync object reaches the signaled
+  /// state when the counter gets to zero.
+  void Signal();
+
+  /// Returns true if mSignals is equal to zero. In other words, returns true
+  /// if all prerequisite tasks have already signaled the sync object.
+  bool IsSignaled();
+
+  /// Asserts that the number of added prerequisites is equal to the number
+  /// specified in the constructor (does nothin in release builds).
+  void FreezePrerequisites();
+
+private:
+  // Called by Job's constructor
+  void AddSubsequent(Job* aJob);
+  void AddPrerequisite(Job* aJob);
+
+  void AddWaitingJob(Job* aJob);
+
+  void SubmitWaitingJobs();
+
+  Atomic<int32_t> mSignals;
+  Atomic<Job*> mFirstWaitingJob;
+
+#ifdef DEBUG
+  uint32_t mNumPrerequisites;
+  Atomic<uint32_t> mAddedPrerequisites;
+#endif
+
+  friend class Job;
+  friend class JobScheduler;
+};
+
+/// Base class for worker threads.
+class WorkerThread
+{
+public:
+  static WorkerThread* Create(MultiThreadedJobQueue* aJobQueue);
+
+  virtual ~WorkerThread() {}
+
+  void Run();
+
+  MultiThreadedJobQueue* GetJobQueue() { return mQueue; }
+
+protected:
+  explicit WorkerThread(MultiThreadedJobQueue* aJobQueue);
+
+  virtual void SetName(const char* aName) {}
+
+  MultiThreadedJobQueue* mQueue;
+};
+
+} // namespace
+} // namespace
+
+#endif