cc: Handle retroactive BeginFrames in the Scheduler.

cc/scheduler/scheduler.cc

 // 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.
 
 #include "cc/scheduler/scheduler.h"
 
 #include <algorithm>
 #include "base/auto_reset.h"
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
 #include "cc/debug/devtools_instrumentation.h"
 #include "cc/debug/traced_value.h"
 #include "ui/gfx/frame_time.h"
 
 namespace cc {
 
 Scheduler::Scheduler(
     SchedulerClient* client,
     const SchedulerSettings& scheduler_settings,
     int layer_tree_host_id,
     const scoped_refptr<base::SequencedTaskRunner>& impl_task_runner)
     : settings_(scheduler_settings),
       client_(client),
       layer_tree_host_id_(layer_tree_host_id),
       impl_task_runner_(impl_task_runner),
-      last_set_needs_begin_impl_frame_(false),
+      last_set_needs_begin_frame_(false),
+      begin_retro_frame_posted_(false),
       state_machine_(scheduler_settings),
       inside_process_scheduled_actions_(false),
       inside_action_(SchedulerStateMachine::ACTION_NONE),
       weak_factory_(this) {
   DCHECK(client_);
-  DCHECK(!state_machine_.BeginImplFrameNeeded());
+  DCHECK(!state_machine_.BeginFrameNeeded());
   if (settings_.main_frame_before_activation_enabled) {
     DCHECK(settings_.main_frame_before_draw_enabled);
   }
 }
 
 Scheduler::~Scheduler() {}
 
 void Scheduler::SetCanStart() {
   state_machine_.SetCanStart();
   ProcessScheduledActions();
@@ skipping 66 matching lines @@
   ProcessScheduledActions();
 }
 
 void Scheduler::DidManageTiles() {
   state_machine_.DidManageTiles();
 }
 
 void Scheduler::DidLoseOutputSurface() {
   TRACE_EVENT0("cc", "Scheduler::DidLoseOutputSurface");
   state_machine_.DidLoseOutputSurface();
-  last_set_needs_begin_impl_frame_ = false;
+  last_set_needs_begin_frame_ = false;
   ProcessScheduledActions();
 }
 
 void Scheduler::DidCreateAndInitializeOutputSurface() {
   TRACE_EVENT0("cc", "Scheduler::DidCreateAndInitializeOutputSurface");
-  DCHECK(!last_set_needs_begin_impl_frame_);
+  DCHECK(!last_set_needs_begin_frame_);
   DCHECK(begin_impl_frame_deadline_closure_.IsCancelled());
   state_machine_.DidCreateAndInitializeOutputSurface();
   ProcessScheduledActions();
 }
 
 void Scheduler::NotifyBeginMainFrameStarted() {
   TRACE_EVENT0("cc", "Scheduler::NotifyBeginMainFrameStarted");
   state_machine_.NotifyBeginMainFrameStarted();
 }
 
 base::TimeTicks Scheduler::AnticipatedDrawTime() const {
-  if (!last_set_needs_begin_impl_frame_ ||
-      last_begin_impl_frame_args_.interval <= base::TimeDelta())
+  if (!last_set_needs_begin_frame_ ||
+      begin_impl_frame_args_.interval <= base::TimeDelta())
     return base::TimeTicks();
 
   base::TimeTicks now = gfx::FrameTime::Now();
-  base::TimeTicks timebase = std::max(last_begin_impl_frame_args_.frame_time,
-                                      last_begin_impl_frame_args_.deadline);
-  int64 intervals =
-      1 + ((now - timebase) / last_begin_impl_frame_args_.interval);
-  return timebase + (last_begin_impl_frame_args_.interval * intervals);
+  base::TimeTicks timebase = std::max(begin_impl_frame_args_.frame_time,
+                                      begin_impl_frame_args_.deadline);
+  int64 intervals = 1 + ((now - timebase) / begin_impl_frame_args_.interval);
+  return timebase + (begin_impl_frame_args_.interval * intervals);
 }
 
 base::TimeTicks Scheduler::LastBeginImplFrameTime() {
-  return last_begin_impl_frame_args_.frame_time;
+  return begin_impl_frame_args_.frame_time;
 }
 
-void Scheduler::SetupNextBeginImplFrameIfNeeded() {
-  bool needs_begin_impl_frame =
-      state_machine_.BeginImplFrameNeeded();
+void Scheduler::SetupNextBeginFrameIfNeeded() {
+  bool needs_begin_frame = state_machine_.BeginFrameNeeded();
+  if (needs_begin_frame != last_set_needs_begin_frame_) {
+    client_->SetNeedsBeginFrame(needs_begin_frame);
+    last_set_needs_begin_frame_ = needs_begin_frame;
+  }
 
-  bool at_end_of_deadline =
-      state_machine_.begin_impl_frame_state() ==
-          SchedulerStateMachine::BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE;
-
-  bool should_call_set_needs_begin_impl_frame =
-      // Always request the BeginImplFrame immediately if it wasn't needed
-      // before.
-      (needs_begin_impl_frame && !last_set_needs_begin_impl_frame_) ||
-      // We always need to explicitly request our next BeginImplFrame.
-      at_end_of_deadline;
-
-  if (should_call_set_needs_begin_impl_frame) {
-    client_->SetNeedsBeginImplFrame(needs_begin_impl_frame);
-    last_set_needs_begin_impl_frame_ = needs_begin_impl_frame;
+  // Handle Retroactive BeginFrames

[Sami, 2014/04/01 13:09:10]

nit: Add '.'.

+  if (state_machine_.begin_impl_frame_state() ==
+          SchedulerStateMachine::BEGIN_IMPL_FRAME_STATE_IDLE &&
+      begin_retro_frame_args_.IsValid()) {

[Sami, 2014/04/01 13:09:10]

Do we also need to check for needs_begin_frame?

[brianderson, 2014/04/01 19:12:53]

That would be better, yes. I was thinking that we could get the post task out of
the way just in case needs_begin_frame does become true soon, but that would
make us decide the deadline with less information than we'd otherwise have.

[brianderson, 2014/04/02 04:15:57]

Done.

+    begin_retro_frame_posted_ = true;
+    begin_frame_args_ = begin_retro_frame_args_;
+    begin_retro_frame_args_ = BeginFrameArgs();
+    impl_task_runner_->PostTask(
+        FROM_HERE,
+        base::Bind(&Scheduler::BeginRetroFrame, weak_factory_.GetWeakPtr()));
   }
 
   bool needs_advance_commit_state_timer = false;
   // Setup PollForAnticipatedDrawTriggers if we need to monitor state but
-  // aren't expecting any more BeginImplFrames. This should only be needed by
-  // the synchronous compositor when BeginImplFrameNeeded is false.
+  // aren't expecting any more BeginFrames. This should only be needed by
+  // the synchronous compositor when BeginFrameNeeded is false.
   if (state_machine_.ShouldPollForAnticipatedDrawTriggers()) {
-    DCHECK(!state_machine_.SupportsProactiveBeginImplFrame());
-    DCHECK(!needs_begin_impl_frame);
+    DCHECK(!state_machine_.SupportsProactiveBeginFrame());
+    DCHECK(!needs_begin_frame);
     if (poll_for_draw_triggers_closure_.IsCancelled()) {
       poll_for_draw_triggers_closure_.Reset(
           base::Bind(&Scheduler::PollForAnticipatedDrawTriggers,
                      weak_factory_.GetWeakPtr()));
       impl_task_runner_->PostDelayedTask(
           FROM_HERE,
           poll_for_draw_triggers_closure_.callback(),
-          last_begin_impl_frame_args_.interval);
+          begin_impl_frame_args_.interval);
     }
   } else {
     poll_for_draw_triggers_closure_.Cancel();
 
     // At this point we'd prefer to advance through the commit flow by
     // drawing a frame, however it's possible that the frame rate controller
-    // will not give us a BeginImplFrame until the commit completes.  See
+    // will not give us a BeginFrame until the commit completes.  See
     // crbug.com/317430 for an example of a swap ack being held on commit. Thus
     // we set a repeating timer to poll on ProcessScheduledActions until we
-    // successfully reach BeginImplFrame. Synchronous compositor does not use
+    // successfully reach BeginFrame. Synchronous compositor does not use
     // frame rate controller or have the circular wait in the bug.
     if (IsBeginMainFrameSentOrStarted() &&
         !settings_.using_synchronous_renderer_compositor) {
       needs_advance_commit_state_timer = true;
     }
   }
   if (needs_advance_commit_state_timer !=
       advance_commit_state_timer_.IsRunning()) {
-    if (needs_advance_commit_state_timer &&
-        last_begin_impl_frame_args_.IsValid()) {
+    if (needs_advance_commit_state_timer && begin_impl_frame_args_.IsValid()) {
       // Since we'd rather get a BeginImplFrame by the normal mechanism, we
       // set the interval to twice the interval from the previous frame.
       advance_commit_state_timer_.Start(
           FROM_HERE,
-          last_begin_impl_frame_args_.interval * 2,
+          begin_impl_frame_args_.interval * 2,
           base::Bind(&Scheduler::ProcessScheduledActions,
                      base::Unretained(this)));
     } else {
       advance_commit_state_timer_.Stop();
     }
   }
 }
 
-void Scheduler::BeginImplFrame(const BeginFrameArgs& args) {
-  TRACE_EVENT0("cc", "Scheduler::BeginImplFrame");
+void Scheduler::BeginFrame(const BeginFrameArgs& args) {
+  if (!begin_retro_frame_posted_ &&
+      state_machine_.begin_impl_frame_state() ==
+          SchedulerStateMachine::BEGIN_IMPL_FRAME_STATE_IDLE) {
+    TRACE_EVENT0("cc", "Scheduler::BeginImplFrame");
+    begin_frame_args_ = args;
+    BeginImplFrame();
+  } else {
+    TRACE_EVENT0("cc", "Scheduler::BeginFrame deferred");
+    begin_retro_frame_args_ = args;
+  }
+}
+
+void Scheduler::BeginRetroFrame() {
+  TRACE_EVENT0("cc", "Scheduler::BeginRetroFrame");
+  begin_retro_frame_posted_ = false;
+  BeginImplFrame();
+}
+
+void Scheduler::BeginImplFrame() {
   DCHECK(state_machine_.begin_impl_frame_state() ==
          SchedulerStateMachine::BEGIN_IMPL_FRAME_STATE_IDLE);
   DCHECK(state_machine_.HasInitializedOutputSurface());
 
-  last_begin_impl_frame_args_ = args;
-  last_begin_impl_frame_args_.deadline -= client_->DrawDurationEstimate();
+  begin_impl_frame_args_ = begin_frame_args_;
+  begin_impl_frame_args_.deadline -= client_->DrawDurationEstimate();
 
   if (!state_machine_.smoothness_takes_priority() &&
       state_machine_.MainThreadIsInHighLatencyMode() &&
       CanCommitAndActivateBeforeDeadline()) {
     state_machine_.SetSkipNextBeginMainFrameToReduceLatency();
   }
 
-  state_machine_.OnBeginImplFrame(last_begin_impl_frame_args_);
+  client_->OnBeginImplFrame(begin_impl_frame_args_);
+  state_machine_.OnBeginImplFrame(begin_impl_frame_args_);
   devtools_instrumentation::DidBeginFrame(layer_tree_host_id_);
 
   ProcessScheduledActions();
 
   if (!state_machine_.HasInitializedOutputSurface())
     return;
 
   state_machine_.OnBeginImplFrameDeadlinePending();
   base::TimeTicks adjusted_deadline = AdjustedBeginImplFrameDeadline();
   ScheduleBeginImplFrameDeadline(adjusted_deadline);
 }
 
 base::TimeTicks Scheduler::AdjustedBeginImplFrameDeadline() const {
   if (settings_.using_synchronous_renderer_compositor) {
     // The synchronous compositor needs to draw right away.
     return base::TimeTicks();
   } else if (state_machine_.ShouldTriggerBeginImplFrameDeadlineEarly()) {
     // We are ready to draw a new active tree immediately.
     return base::TimeTicks();
   } else if (state_machine_.needs_redraw()) {
     // We have an animation or fast input path on the impl thread that wants
     // to draw, so don't wait too long for a new active tree.
-    return last_begin_impl_frame_args_.deadline;
+    return begin_impl_frame_args_.deadline;
   } else {
     // The impl thread doesn't have anything it wants to draw and we are just
     // waiting for a new active tree, so post the deadline for the next
     // expected BeginImplFrame start. This allows us to draw immediately when
     // there is a new active tree, instead of waiting for the next
     // BeginImplFrame.
     // TODO(brianderson): Handle long deadlines (that are past the next frame's
     // frame time) properly instead of using this hack.
-    return last_begin_impl_frame_args_.frame_time +
-           last_begin_impl_frame_args_.interval;
+    return begin_impl_frame_args_.frame_time + begin_impl_frame_args_.interval;
   }
 }
 
 void Scheduler::ScheduleBeginImplFrameDeadline(base::TimeTicks deadline) {
   if (settings_.using_synchronous_renderer_compositor) {
     // The synchronous renderer compositor has to make its GL calls
     // within this call.
     // TODO(brianderson): Have the OutputSurface initiate the deadline tasks
     // so the sychronous renderer compositor can take advantage of splitting
     // up the BeginImplFrame and deadline as well.
@@ skipping 111 matching lines @@
         break;
       case SchedulerStateMachine::ACTION_ACQUIRE_LAYER_TEXTURES_FOR_MAIN_THREAD:
         client_->ScheduledActionAcquireLayerTexturesForMainThread();
         break;
       case SchedulerStateMachine::ACTION_MANAGE_TILES:
         client_->ScheduledActionManageTiles();
         break;
     }
   } while (action != SchedulerStateMachine::ACTION_NONE);
 
-  SetupNextBeginImplFrameIfNeeded();
+  SetupNextBeginFrameIfNeeded();
   client_->DidAnticipatedDrawTimeChange(AnticipatedDrawTime());
 
   if (state_machine_.ShouldTriggerBeginImplFrameDeadlineEarly()) {
     DCHECK(!settings_.using_synchronous_renderer_compositor);
     ScheduleBeginImplFrameDeadline(base::TimeTicks());
   }
 }
 
 bool Scheduler::WillDrawIfNeeded() const {
   return !state_machine_.PendingDrawsShouldBeAborted();
@@ skipping 16 matching lines @@
       "commit_to_activate_duration_estimate_ms",
       client_->CommitToActivateDurationEstimate().InMillisecondsF());
   state->Set("client_state", client_state.release());
   return state.PassAs<base::Value>();
 }
 
 bool Scheduler::CanCommitAndActivateBeforeDeadline() const {
   // Check if the main thread computation and commit can be finished before the
   // impl thread's deadline.
   base::TimeTicks estimated_draw_time =
-      last_begin_impl_frame_args_.frame_time +
+      begin_impl_frame_args_.frame_time +
       client_->BeginMainFrameToCommitDurationEstimate() +
       client_->CommitToActivateDurationEstimate();
 
-  TRACE_EVENT2(TRACE_DISABLED_BY_DEFAULT("cc.debug.scheduler"),
-               "CanCommitAndActivateBeforeDeadline",
-               "time_left_after_drawing_ms",
-               (last_begin_impl_frame_args_.deadline - estimated_draw_time)
-                   .InMillisecondsF(),
-               "state",
-               TracedValue::FromValue(StateAsValue().release()));
+  TRACE_EVENT2(
+      TRACE_DISABLED_BY_DEFAULT("cc.debug.scheduler"),
+      "CanCommitAndActivateBeforeDeadline",
+      "time_left_after_drawing_ms",
+      (begin_impl_frame_args_.deadline - estimated_draw_time).InMillisecondsF(),
+      "state",
+      TracedValue::FromValue(StateAsValue().release()));
 
-  return estimated_draw_time < last_begin_impl_frame_args_.deadline;
+  return estimated_draw_time < begin_impl_frame_args_.deadline;
 }
 
 bool Scheduler::IsBeginMainFrameSentOrStarted() const {
   return (state_machine_.commit_state() ==
               SchedulerStateMachine::COMMIT_STATE_BEGIN_MAIN_FRAME_SENT ||
           state_machine_.commit_state() ==
               SchedulerStateMachine::COMMIT_STATE_BEGIN_MAIN_FRAME_STARTED);
 }
 
 }  // namespace cc