Revert "Delete CC."

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"
+#include "base/memory/scoped_ptr.h"
+#include "cc/output/begin_frame_args.h"
+#include "cc/scheduler/commit_earlyout_reason.h"
+#include "cc/scheduler/draw_result.h"
+#include "cc/scheduler/scheduler_settings.h"
+
+namespace base {
+namespace trace_event {
+class ConvertableToTraceFormat;
+class TracedValue;
+}
+class Value;
+}
+
+namespace cc {
+
+// The SchedulerStateMachine decides how to coordinate main thread activites
+// like painting/running javascript with rendering and input activities on the
+// impl thread.
+//
+// The state machine tracks internal state but is also influenced by external
+// state.  Internal state includes things like whether a frame has been
+// requested, while external state includes things like the current time being
+// near to the vblank time.
+//
+// The scheduler seperates "what to do next" from the updating of its internal
+// state to make testing cleaner.
+class SchedulerStateMachine {
+ public:
+  // settings must be valid for the lifetime of this class.
+  explicit SchedulerStateMachine(const SchedulerSettings& settings);
+
+  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: BeginImplFrameState 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_IMPL_FRAME_STATE_INSIDE_BEGIN_FRAME and try to draw in
+  // BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE
+  enum BeginImplFrameState {
+    BEGIN_IMPL_FRAME_STATE_IDLE,
+    BEGIN_IMPL_FRAME_STATE_BEGIN_FRAME_STARTING,
+    BEGIN_IMPL_FRAME_STATE_INSIDE_BEGIN_FRAME,
+    BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE,
+  };
+  static const char* BeginImplFrameStateToString(BeginImplFrameState state);
+
+  enum BeginImplFrameDeadlineMode {
+    BEGIN_IMPL_FRAME_DEADLINE_MODE_IMMEDIATE,
+    BEGIN_IMPL_FRAME_DEADLINE_MODE_REGULAR,
+    BEGIN_IMPL_FRAME_DEADLINE_MODE_LATE,
+  };
+  static const char* BeginImplFrameDeadlineModeToString(
+      BeginImplFrameDeadlineMode mode);
+
+  enum CommitState {
+    COMMIT_STATE_IDLE,
+    COMMIT_STATE_BEGIN_MAIN_FRAME_SENT,
+    COMMIT_STATE_BEGIN_MAIN_FRAME_STARTED,
+    COMMIT_STATE_READY_TO_COMMIT,
+    COMMIT_STATE_WAITING_FOR_ACTIVATION,
+    COMMIT_STATE_WAITING_FOR_DRAW,
+  };
+  static const char* CommitStateToString(CommitState state);
+
+  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_BEGIN_MAIN_FRAME_SENT ||
+           commit_state_ == COMMIT_STATE_BEGIN_MAIN_FRAME_STARTED ||
+           commit_state_ == COMMIT_STATE_READY_TO_COMMIT;
+  }
+  CommitState commit_state() const { return commit_state_; }
+
+  bool RedrawPending() const { return needs_redraw_; }
+  bool PrepareTilesPending() const { return needs_prepare_tiles_; }
+
+  enum Action {
+    ACTION_NONE,
+    ACTION_ANIMATE,
+    ACTION_SEND_BEGIN_MAIN_FRAME,
+    ACTION_COMMIT,
+    ACTION_ACTIVATE_SYNC_TREE,
+    ACTION_DRAW_AND_SWAP_IF_POSSIBLE,
+    ACTION_DRAW_AND_SWAP_FORCED,
+    ACTION_DRAW_AND_SWAP_ABORT,
+    ACTION_BEGIN_OUTPUT_SURFACE_CREATION,
+    ACTION_PREPARE_TILES,
+  };
+  static const char* ActionToString(Action action);
+
+  scoped_refptr<base::trace_event::ConvertableToTraceFormat> AsValue() const;
+  void AsValueInto(base::trace_event::TracedValue* dict) const;
+
+  Action NextAction() const;
+  void UpdateState(Action action);
+
+  // Indicates whether the impl thread needs a BeginImplFrame callback in order
+  // to make progress.
+  bool BeginFrameNeeded() const;
+
+  // Indicates that we need to independently poll for new state and actions
+  // because we can't expect a BeginImplFrame. 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 BeginImplFrame callback.
+  // The scheduler will not draw more than once in a given BeginImplFrame
+  // callback nor send more than one BeginMainFrame message.
+  void OnBeginImplFrame();
+  void OnBeginImplFrameDeadlinePending();
+  void OnBeginImplFrameDeadline();
+  void OnBeginImplFrameIdle();
+  BeginImplFrameState begin_impl_frame_state() const {
+    return begin_impl_frame_state_;
+  }
+  BeginImplFrameDeadlineMode CurrentBeginImplFrameDeadlineMode() const;
+
+  // If the main thread didn't manage to produce a new frame in time for the
+  // impl thread to draw, it is in a high latency mode.
+  bool MainThreadIsInHighLatencyMode() const;
+
+  // 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);
+  bool visible() const { return 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_; }
+
+  void SetNeedsAnimate();
+  bool needs_animate() const { return needs_animate_; }
+
+  // Indicates that prepare-tiles is required. This guarantees another
+  // PrepareTiles will occur shortly (even if no redraw is required).
+  void SetNeedsPrepareTiles();
+
+  // Sets how many swaps can be pending to the OutputSurface.
+  void SetMaxSwapsPending(int max);
+
+  // If the scheduler attempted to draw and swap, this provides feedback
+  // regarding whether or not the swap actually occured. We might skip the
+  // swap when there is not damage, for example.
+  void DidSwapBuffers();
+
+  // Indicates whether a redraw is required because we are currently rendering
+  // with a low resolution or checkerboarded tile.
+  void SetSwapUsedIncompleteTile(bool used_incomplete_tile);
+
+  // Notification from the OutputSurface that a swap has been consumed.
+  void DidSwapBuffersComplete();
+
+  // Indicates whether to prioritize impl thread latency (i.e., animation
+  // smoothness) over new content activation.
+  void SetImplLatencyTakesPriority(bool impl_latency_takes_priority);
+  bool impl_latency_takes_priority() const {
+    return impl_latency_takes_priority_;
+  }
+
+  // Indicates whether ACTION_DRAW_AND_SWAP_IF_POSSIBLE drew to the screen.
+  void DidDrawIfPossibleCompleted(DrawResult result);
+
+  // 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();
+
+  // Call this only in response to receiving an ACTION_SEND_BEGIN_MAIN_FRAME
+  // from NextAction.
+  // Indicates that all painting is complete.
+  void NotifyReadyToCommit();
+
+  // Call this only in response to receiving an ACTION_SEND_BEGIN_MAIN_FRAME
+  // from NextAction if the client rejects the BeginMainFrame message.
+  void BeginMainFrameAborted(CommitEarlyOutReason reason);
+
+  // Set that we can create the first OutputSurface and start the scheduler.
+  void SetCanStart() { can_start_ = true; }
+  // Allow access of the can_start_ state in tests.
+  bool CanStartForTesting() const { return can_start_; }
+
+  void SetSkipNextBeginMainFrameToReduceLatency();
+
+  // Indicates whether drawing would, at this time, make sense.
+  // CanDraw can be used to suppress flashes or checkerboarding
+  // when such behavior would be undesirable.
+  void SetCanDraw(bool can);
+
+  // Indicates that scheduled BeginMainFrame is started.
+  void NotifyBeginMainFrameStarted();
+
+  // Indicates that the pending tree is ready for activation.
+  void NotifyReadyToActivate();
+
+  bool has_pending_tree() const { return has_pending_tree_; }
+  bool active_tree_needs_first_draw() const {
+    return active_tree_needs_first_draw_;
+  }
+
+  void DidPrepareTiles();
+  void DidLoseOutputSurface();
+  void DidCreateAndInitializeOutputSurface();
+  bool HasInitializedOutputSurface() const;
+
+  // True if we need to abort draws to make forward progress.
+  bool PendingDrawsShouldBeAborted() const;
+
+  bool SupportsProactiveBeginFrame() const;
+
+  void SetContinuousPainting(bool continuous_painting) {
+    continuous_painting_ = continuous_painting;
+  }
+
+  bool CouldSendBeginMainFrame() const;
+
+  void SetDeferCommits(bool defer_commits);
+
+  // TODO(zmo): This is temporary for debugging crbug.com/393331.
+  // We should remove it afterwards.
+  std::string GetStatesForDebugging() const;
+
+  void SetChildrenNeedBeginFrames(bool children_need_begin_frames);
+  bool children_need_begin_frames() const {
+    return children_need_begin_frames_;
+  }
+
+ protected:
+  bool BeginFrameNeededToAnimateOrDraw() const;
+  bool BeginFrameNeededForChildren() const;
+  bool ProactiveBeginFrameWanted() const;
+
+  bool ShouldTriggerBeginImplFrameDeadlineImmediately() const;
+
+  // True if we need to force activations to make forward progress.
+  bool PendingActivationsShouldBeForced() const;
+
+  bool ShouldAnimate() const;
+  bool ShouldBeginOutputSurfaceCreation() const;
+  bool ShouldDraw() const;
+  bool ShouldActivatePendingTree() const;
+  bool ShouldSendBeginMainFrame() const;
+  bool ShouldCommit() const;
+  bool ShouldPrepareTiles() const;
+
+  void AdvanceCurrentFrameNumber();
+
+  void UpdateStateOnCommit(bool commit_had_no_updates);
+  void UpdateStateOnActivation();
+  void UpdateStateOnDraw(bool did_request_swap);
+  void UpdateStateOnPrepareTiles();
+
+  const SchedulerSettings settings_;
+
+  OutputSurfaceState output_surface_state_;
+  BeginImplFrameState begin_impl_frame_state_;
+  CommitState commit_state_;
+  ForcedRedrawOnTimeoutState forced_redraw_state_;
+
+  // These are used for tracing only.
+  int commit_count_;
+  int current_frame_number_;
+  int last_frame_number_animate_performed_;
+  int last_frame_number_swap_performed_;
+  int last_frame_number_swap_requested_;
+  int last_frame_number_begin_main_frame_sent_;
+
+  // These are used to ensure that an action only happens once per frame,
+  // deadline, etc.
+  bool animate_funnel_;
+  bool perform_swap_funnel_;
+  bool request_swap_funnel_;
+  bool send_begin_main_frame_funnel_;
+  // prepare_tiles_funnel_ is "filled" each time PrepareTiles is called
+  // and "drained" on each BeginImplFrame. If the funnel gets too full,
+  // we start throttling ACTION_PREPARE_TILES such that we average one
+  // PrepareTiles per BeginImplFrame.
+  int prepare_tiles_funnel_;
+
+  int consecutive_checkerboard_animations_;
+  int max_pending_swaps_;
+  int pending_swaps_;
+  bool needs_redraw_;
+  bool needs_animate_;
+  bool needs_prepare_tiles_;
+  bool needs_commit_;
+  bool inside_poll_for_anticipated_draw_triggers_;
+  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 did_create_and_initialize_first_output_surface_;
+  bool impl_latency_takes_priority_;
+  bool skip_next_begin_main_frame_to_reduce_latency_;
+  bool skip_begin_main_frame_to_reduce_latency_;
+  bool continuous_painting_;
+  bool children_need_begin_frames_;
+  bool defer_commits_;
+  bool last_commit_had_no_updates_;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(SchedulerStateMachine);
+};
+
+}  // namespace cc
+
+#endif  // CC_SCHEDULER_SCHEDULER_STATE_MACHINE_H_