cc: Implement deadine scheduling disabled by default

cc/scheduler/scheduler_state_machine.h

 // Copyright 2011 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_SCHEDULER_SCHEDULER_STATE_MACHINE_H_
 #define CC_SCHEDULER_SCHEDULER_STATE_MACHINE_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 27 matching lines @@
 
   enum OutputSurfaceState {
     OUTPUT_SURFACE_ACTIVE,
     OUTPUT_SURFACE_LOST,
     OUTPUT_SURFACE_CREATING,
     OUTPUT_SURFACE_WAITING_FOR_FIRST_COMMIT,
     OUTPUT_SURFACE_WAITING_FOR_FIRST_ACTIVATION,
   };
   static const char* OutputSurfaceStateToString(OutputSurfaceState state);
 
+  // Note: BeginFrameState will always cycle through all the states in order.
+  // Whether or not it actually waits or draws, it will at least try to wait in
+  // BEGIN_FRAME_STATE_DEADLINE_PENDING and try to draw in
+  // BEGIN_FRAME_STATE_INSIDE_DEADLINE
+  enum BeginFrameState {
+    BEGIN_FRAME_STATE_IDLE,
+    BEGIN_FRAME_STATE_INSIDE_BEGIN_FRAME,
+    BEGIN_FRAME_STATE_DEADLINE_PENDING,

[danakj, 2013/09/17 20:26:19]

I am anti-"pending" in these names as they are not clear to me if we're waiting
on something to start, or something that was already started.

Can INSIDE_BEGIN_FRAME be STARTING_BEGIN_FRAME, and the pending one be
INSIDE_BEGIN_FRAME?

Or can we merge into just INSIDE_BEGIN_FRAME?

[brianderson, 2013/09/17 21:08:24]

Done.

+    BEGIN_FRAME_STATE_INSIDE_DEADLINE,
+  };
+  static const char* BeginFrameStateToString(BeginFrameState state);
+
   enum CommitState {
     COMMIT_STATE_IDLE,
     COMMIT_STATE_FRAME_IN_PROGRESS,
     COMMIT_STATE_READY_TO_COMMIT,
     COMMIT_STATE_WAITING_FOR_FIRST_DRAW,
   };
   static const char* CommitStateToString(CommitState state);
 
   enum TextureState {
     LAYER_TEXTURE_STATE_UNLOCKED,
@@ skipping 17 matching lines @@
   enum ForcedRedrawOnTimeoutState {
     FORCED_REDRAW_STATE_IDLE,
     FORCED_REDRAW_STATE_WAITING_FOR_COMMIT,
     FORCED_REDRAW_STATE_WAITING_FOR_ACTIVATION,
     FORCED_REDRAW_STATE_WAITING_FOR_DRAW,
   };
   static const char* ForcedRedrawOnTimeoutStateToString(
       ForcedRedrawOnTimeoutState state);
 
   bool CommitPending() const {
-    return commit_state_ == COMMIT_STATE_FRAME_IN_PROGRESS ||
-           commit_state_ == COMMIT_STATE_READY_TO_COMMIT;

[danakj, 2013/09/17 20:26:19]

This is going to affect the unit tests that do not want to exit until there's no
commit pending:
https://code.google.com/p/chromium/codesearch#chromium/src/cc/test/layer_tree...

I'm worried this will add flakiness.

[brianderson, 2013/09/17 21:08:24]

Ok. To recap offline discussions: I thought I needed this change a while ago to
ensure that there was actually a begin frame behind a readback, but the main
thread will be blocked in both cases and getting a readback in either state will
not be an issue.

+    return commit_state_ == COMMIT_STATE_FRAME_IN_PROGRESS;
   }
 
   bool RedrawPending() const { return needs_redraw_; }
   bool ManageTilesPending() const { return needs_manage_tiles_; }
 
   enum Action {
     ACTION_NONE,
     ACTION_SEND_BEGIN_FRAME_TO_MAIN_THREAD,
     ACTION_COMMIT,
     ACTION_UPDATE_VISIBLE_TILES,
     ACTION_ACTIVATE_PENDING_TREE,
     ACTION_DRAW_AND_SWAP_IF_POSSIBLE,
     ACTION_DRAW_AND_SWAP_FORCED,
     ACTION_DRAW_AND_SWAP_ABORT,
     ACTION_DRAW_AND_READBACK,
     ACTION_BEGIN_OUTPUT_SURFACE_CREATION,
     ACTION_ACQUIRE_LAYER_TEXTURES_FOR_MAIN_THREAD,
     ACTION_MANAGE_TILES,
   };
   static const char* ActionToString(Action action);
 
   scoped_ptr<base::Value> AsValue() const;
 
   Action NextAction() const;
   void UpdateState(Action action);
+
   void CheckInvariants();
 
   // Indicates whether the main thread needs a begin frame callback in order to
   // make progress.
-  bool BeginFrameNeededToDrawByImplThread() const;
-  bool ProactiveBeginFrameWantedByImplThread() const;
+  bool BeginFrameNeededByImplThread() const;
+
+  // Idicates that we need to independently poll for new state and actions
+  // because we can't expect a BeginFrame. This is mostly used to avoid
+  // drawing repeat frames with the synchronous compositor without dropping
+  // necessary actions on the floor.
+  bool ShouldPollForAnticipatedDrawTriggers() const;
 
   // Indicates that the system has entered and left a BeginFrame callback.
   // The scheduler will not draw more than once in a given BeginFrame
   // callback nor send more than one BeginFrame message.
-  void DidEnterBeginFrame(const BeginFrameArgs& args);
-  void DidLeaveBeginFrame();
-  bool inside_begin_frame() const { return inside_begin_frame_; }
+  void OnBeginFrame(const BeginFrameArgs& args);
+  void OnBeginFrameDeadlinePending();
+  void OnBeginFrameDeadline();
+  void OnBeginFrameIdle();
+  bool ShouldTriggerBeginFrameDeadlineEarly() const;
+  BeginFrameState begin_frame_state() const {
+    return begin_frame_state_;
+  }
 
   // PollForAnticipatedDrawTriggers is used by the synchronous compositor to
   // avoid requesting BeginImplFrames when we won't actually draw but still
   // need to advance our state at vsync intervals.
   void DidEnterPollForAnticipatedDrawTriggers();
   void DidLeavePollForAnticipatedDrawTriggers();
   bool inside_poll_for_anticipated_draw_triggers() const {
     return inside_poll_for_anticipated_draw_triggers_;
   }
 
   // Indicates whether the LayerTreeHostImpl is visible.
   void SetVisible(bool visible);
 
   // Indicates that a redraw is required, either due to the impl tree changing
   // or the screen being damaged and simply needing redisplay.
   void SetNeedsRedraw();
+  bool needs_redraw() const { return needs_redraw_; }
 
   // Indicates that manage-tiles is required. This guarantees another
   // ManageTiles will occur shortly (even if no redraw is required).
   void SetNeedsManageTiles();
 
   // Indicates whether a redraw is required because we are currently rendering
   // with a low resolution or checkerboarded tile.
   void SetSwapUsedIncompleteTile(bool used_incomplete_tile);
 
-  // Indicates whether ACTION_DRAW_AND_SWAP_IF_POSSIBLE drew to the screen or
-  // not.
+  // Indicates whether ACTION_DRAW_AND_SWAP_IF_POSSIBLE drew to the screen.
   void DidDrawIfPossibleCompleted(bool success);
 
   // Indicates that a new commit flow needs to be performed, either to pull
   // updates from the main thread to the impl, or to push deltas from the impl
   // thread to main.
   void SetNeedsCommit();
 
   // As SetNeedsCommit(), but ensures the begin frame will be sent to the main
   // thread even if we are not visible.  After this call we expect to go through
   // the forced commit flow and then return to waiting for a non-forced
@@ skipping 32 matching lines @@
   bool has_pending_tree() const { return has_pending_tree_; }
 
   void DidLoseOutputSurface();
   void DidCreateAndInitializeOutputSurface();
   bool HasInitializedOutputSurface() const;
 
   // True if we need to abort draws to make forward progress.
   bool PendingDrawsShouldBeAborted() const;
 
  protected:
+  bool BeginFrameNeededToDrawByImplThread() const;
+  bool ProactiveBeginFrameWantedByImplThread() const;
+
   // True if we need to force activations to make forward progress.
   bool PendingActivationsShouldBeForced() const;
 
   bool ShouldBeginOutputSurfaceCreation() const;
   bool ShouldDrawForced() const;
   bool ShouldDraw() const;
   bool ShouldActivatePendingTree() const;
   bool ShouldAcquireLayerTexturesForMainThread() const;
   bool ShouldUpdateVisibleTiles() const;
   bool ShouldSendBeginFrameToMainThread() const;
   bool ShouldCommit() const;
   bool ShouldManageTiles() const;
 
-  bool HasDrawnAndSwappedThisFrame() const;
-  bool HasActivatedPendingTreeThisFrame() const;
-  bool HasUpdatedVisibleTilesThisFrame() const;
   bool HasSentBeginFrameToMainThreadThisFrame() const;
   bool HasScheduledManageTilesThisFrame() const;
+  bool HasUpdatedVisibleTilesThisFrame() const;
+  bool HasSwappedThisFrame() const;
 
   void UpdateStateOnCommit(bool commit_was_aborted);
   void UpdateStateOnActivation();
   void UpdateStateOnDraw(bool did_swap);
   void UpdateStateOnManageTiles();
 
   const SchedulerSettings settings_;
 
   OutputSurfaceState output_surface_state_;
+  BeginFrameState begin_frame_state_;
   CommitState commit_state_;
   TextureState texture_state_;
   ForcedRedrawOnTimeoutState forced_redraw_state_;
   SynchronousReadbackState readback_state_;
 
+  BeginFrameArgs last_begin_frame_args_;
+
   int commit_count_;
   int current_frame_number_;
-  int last_frame_number_where_begin_frame_sent_to_main_thread_;
   int last_frame_number_swap_performed_;
-  int last_frame_number_where_update_visible_tiles_was_called_;
+  int last_frame_number_begin_frame_sent_to_main_thread_;
+  int last_frame_number_update_visible_tiles_was_called_;
+
   int consecutive_failed_draws_;
   bool needs_redraw_;
   bool needs_manage_tiles_;
   bool swap_used_incomplete_tile_;
   bool needs_commit_;
   bool main_thread_needs_layer_textures_;
-  bool inside_begin_frame_;
   bool inside_poll_for_anticipated_draw_triggers_;
-
-  BeginFrameArgs last_begin_frame_args_;
   bool visible_;
   bool can_start_;
   bool can_draw_;
   bool has_pending_tree_;
   bool pending_tree_is_ready_for_activation_;
   bool active_tree_needs_first_draw_;
   bool draw_if_possible_failed_;
   bool did_create_and_initialize_first_output_surface_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(SchedulerStateMachine);
 };
 
 }  // namespace cc
 
 #endif  // CC_SCHEDULER_SCHEDULER_STATE_MACHINE_H_