Prioritizing input and compositor tasks in the blink scheduler.

Source/platform/scheduler/Scheduler.h

Index: Source/platform/scheduler/Scheduler.h
diff --git a/Source/platform/scheduler/Scheduler.h b/Source/platform/scheduler/Scheduler.h
index c492e580aa17268afe30b6c439a9c08acd08638f..21ba5a6797193b3c8f0d69ee5f37f1ee44315f07 100644
--- a/Source/platform/scheduler/Scheduler.h
+++ b/Source/platform/scheduler/Scheduler.h
@@ -6,8 +6,12 @@
 #define Scheduler_h
 
 #include "platform/PlatformExport.h"
+#include "platform/TraceLocation.h"
+#include "public/platform/WebThread.h"
+#include "wtf/Deque.h"
 #include "wtf/Functional.h"
 #include "wtf/Noncopyable.h"
+#include "wtf/ThreadingPrimitives.h"
 
 namespace blink {
 class WebThread;
@@ -53,16 +57,54 @@ private:
     Scheduler();
     ~Scheduler();
 
-    void scheduleTask(const TraceLocation&, const Task&);
     void scheduleIdleTask(const IdleTask&);
 
     static void sharedTimerAdapter();
     void tickSharedTimer();
 
     static Scheduler* s_sharedScheduler;
-    blink::WebThread* m_mainThread;
 
+    class TracedTask {
+    public:
+        TracedTask(const Task& task, const TraceLocation& location)
+            : m_task(task)
+            , m_location(location) { }
+
+        void run();
+
+    private:
+        Task m_task;
+        TraceLocation m_location;
+    };
+
+    class LockingTracedTaskDeque {
+    public:
+        void append(const TracedTask& value);
+        bool isEmpty();
+
+        // Returns true if a task was executed, false otherwise.
+        bool runFirstTaskIfNotEmpty();
+
+    private:
+        WTF::Deque<TracedTask> m_queue;
+        Mutex m_mutex;
+    };
+
+    class MainThreadPendingTaskRunner;

[Sami, 2014/08/07 15:51:26]

It doesn't look like this declaration is needed?

+
+    // These members can be accessed from any thread.
+    blink::WebThread* m_mainThread;
+    LockingTracedTaskDeque m_pendingInputTasks;
+    LockingTracedTaskDeque m_pendingCompositorTasks;
+    LockingTracedTaskDeque m_pendingLowPriorityTasks;
     void (*m_sharedTimerFunction)();

[Sami, 2014/08/07 15:51:26]

This should be separated from the cross-thread fields.

+    volatile int m_mainThreadInFlight;
+
+    void maybePostTaskLoopOnMainThread();

[Sami, 2014/08/07 15:51:26]

Looks like these got moved after the data members again.

+    void runHighPriorityTasks();
+    void runPendingTasks();
+
+    friend class MainThreadPendingTaskRunner;

[Sami, 2014/08/07 15:51:27]

Could you move this right after the private: line?

 };
 
 } // namespace blink