cc: Make scheduling be driven by vsync for android webview.

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"
@@ skipping 88 matching lines @@
                "Scheduler::Scheduler",
                "settings",
                settings_.AsValue());
   DCHECK(client_);
   DCHECK(!state_machine_.BeginFrameNeeded());
 
   begin_retro_frame_closure_ =
       base::Bind(&Scheduler::BeginRetroFrame, weak_factory_.GetWeakPtr());
   begin_impl_frame_deadline_closure_ = base::Bind(
       &Scheduler::OnBeginImplFrameDeadline, weak_factory_.GetWeakPtr());
-  poll_for_draw_triggers_closure_ = base::Bind(
-      &Scheduler::PollForAnticipatedDrawTriggers, weak_factory_.GetWeakPtr());
   advance_commit_state_closure_ = base::Bind(
       &Scheduler::PollToAdvanceCommitState, weak_factory_.GetWeakPtr());
 
   frame_source_ = BeginFrameSourceMultiplexer::Create();
   frame_source_->AddObserver(this);
 
   // Primary frame source
   primary_frame_source_ =
       frame_sources_constructor->ConstructPrimaryFrameSource(this);
   frame_source_->AddSource(primary_frame_source_);
@@ skipping 91 matching lines @@
 void Scheduler::SetNeedsCommit() {
   state_machine_.SetNeedsCommit();
   ProcessScheduledActions();
 }
 
 void Scheduler::SetNeedsRedraw() {
   state_machine_.SetNeedsRedraw();
   ProcessScheduledActions();
 }
 
+void Scheduler::OutputSurfaceDidRequestDraw() {
+  state_machine_.OutputSurfaceDidRequestDraw();
+  ProcessScheduledActions();
+}
+
 void Scheduler::SetNeedsAnimate() {
   state_machine_.SetNeedsAnimate();
   ProcessScheduledActions();
 }
 
 void Scheduler::SetNeedsPrepareTiles() {
   DCHECK(!IsInsideAction(SchedulerStateMachine::ACTION_PREPARE_TILES));
   state_machine_.SetNeedsPrepareTiles();
   ProcessScheduledActions();
 }
@@ skipping 101 matching lines @@
     frame_source_->DidFinishFrame(begin_retro_frame_args_.size());
   }
 
   PostBeginRetroFrameIfNeeded();
   SetupPollingMechanisms(needs_begin_frame);
 }
 
 // We may need to poll when we can't rely on BeginFrame to advance certain
 // state or to avoid deadlock.
 void Scheduler::SetupPollingMechanisms(bool needs_begin_frame) {
-  bool needs_advance_commit_state_timer = false;
-  // Setup PollForAnticipatedDrawTriggers if we need to monitor state but
-  // 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_.SupportsProactiveBeginFrame());
-    DCHECK(!needs_begin_frame);
-    if (poll_for_draw_triggers_task_.IsCancelled()) {
-      poll_for_draw_triggers_task_.Reset(poll_for_draw_triggers_closure_);
-      base::TimeDelta delay = begin_impl_frame_args_.IsValid()
-                                  ? begin_impl_frame_args_.interval
-                                  : BeginFrameArgs::DefaultInterval();
-      task_runner_->PostDelayedTask(
-          FROM_HERE, poll_for_draw_triggers_task_.callback(), delay);
-    }
-  } else {
-    poll_for_draw_triggers_task_.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 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 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) {
+  // 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

[brianderson, 2014/12/20 00:34:13]

frame rate controller doesn't exist anymore. Since you are touching this
comment, might as well update it so it refers to the BeginFrameSource instead.

Note: I notice the advance_commit_state_task_ isn't actually needed anywhere at
ToT, because the SytheticBeginFrame source won't get blocked like the frame rate
controller used to. However, once Windows switches to the Browser as the
BeginFrame source, we could have the same deadlock issues - so we sadly can't
get rid of all polling. So close.

[sunnyps, 2014/12/20 00:39:30]

Acknowledged.

+  // 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 BeginFrame. Synchronous compositor does not use
+  // frame rate controller or have the circular wait in the bug.
+  if (IsBeginMainFrameSentOrStarted() && 
+      !settings_.using_synchronous_renderer_compositor) {
     if (advance_commit_state_task_.IsCancelled() &&
         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_task_.Reset(advance_commit_state_closure_);
       task_runner_->PostDelayedTask(FROM_HERE,
                                     advance_commit_state_task_.callback(),
                                     begin_impl_frame_args_.interval * 2);
     }
   } else {
@@ skipping 168 matching lines @@
   }
 
   client_->WillBeginImplFrame(begin_impl_frame_args_);
   state_machine_.OnBeginImplFrame(begin_impl_frame_args_);
   devtools_instrumentation::DidBeginFrame(layer_tree_host_id_);
 
   ProcessScheduledActions();
 
   state_machine_.OnBeginImplFrameDeadlinePending();
 
-  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 synchronous renderer compositor can take advantage of splitting
-    // up the BeginImplFrame and deadline as well.
-    OnBeginImplFrameDeadline();
-  } else {
-    ScheduleBeginImplFrameDeadline();
-  }
+  ProcessScheduledActions();

[brianderson, 2014/12/20 00:34:13]

Nice.

 }
 
 void Scheduler::ScheduleBeginImplFrameDeadline() {
-  // The synchronous compositor does not post a deadline task.
-  DCHECK(!settings_.using_synchronous_renderer_compositor);
-
   begin_impl_frame_deadline_task_.Cancel();
   begin_impl_frame_deadline_task_.Reset(begin_impl_frame_deadline_closure_);
 
   begin_impl_frame_deadline_mode_ =
       state_machine_.CurrentBeginImplFrameDeadlineMode();
 
   base::TimeTicks deadline;
   switch (begin_impl_frame_deadline_mode_) {
-    case SchedulerStateMachine::BEGIN_IMPL_FRAME_DEADLINE_MODE_IMMEDIATE:
+    case SchedulerStateMachine::BEGIN_IMPL_FRAME_DEADLINE_MODE_IMMEDIATE_SYNCHRONOUS:
+      // The synchronous renderer compositor has to make its GL calls
+      // within this call.
+      OnBeginImplFrameDeadline();
+      return;
+    case SchedulerStateMachine::BEGIN_IMPL_FRAME_DEADLINE_MODE_IMMEDIATE_ASYNCHRONOUS:
       // We are ready to draw a new active tree immediately.
       // We don't use Now() here because it's somewhat expensive to call.
       deadline = base::TimeTicks();
       break;
     case SchedulerStateMachine::BEGIN_IMPL_FRAME_DEADLINE_MODE_REGULAR:
       // We are animating on the impl thread but we can wait for some time.
       deadline = begin_impl_frame_args_.deadline;
       break;
     case SchedulerStateMachine::BEGIN_IMPL_FRAME_DEADLINE_MODE_LATE:
       // We are blocked for one reason or another and we should wait.
       // TODO(brianderson): Handle long deadlines (that are past the next
       // frame's frame time) properly instead of using this hack.
       deadline =
           begin_impl_frame_args_.frame_time + begin_impl_frame_args_.interval;
       break;
   }
 
-  TRACE_EVENT1(
-      "cc", "Scheduler::ScheduleBeginImplFrameDeadline", "deadline", deadline);
+  TRACE_EVENT2(
+      "cc", 
+      "Scheduler::ScheduleBeginImplFrameDeadline",
+      "mode", 
+      SchedulerStateMachine::BeginImplFrameDeadlineModeToString(
+        begin_impl_frame_deadline_mode_),
+      "deadline",
+      deadline);
 
-  base::TimeDelta delta = deadline - Now();
-  if (delta <= base::TimeDelta())
-    delta = base::TimeDelta();
+  base::TimeDelta delta = std::max(deadline - Now(), base::TimeDelta());
   task_runner_->PostDelayedTask(
       FROM_HERE, begin_impl_frame_deadline_task_.callback(), delta);
 }
 
-void Scheduler::RescheduleBeginImplFrameDeadlineIfNeeded() {
-  if (settings_.using_synchronous_renderer_compositor)
-    return;
-
+void Scheduler::ScheduleBeginImplFrameDeadlineIfNeeded() {
   if (state_machine_.begin_impl_frame_state() !=
       SchedulerStateMachine::BEGIN_IMPL_FRAME_STATE_INSIDE_BEGIN_FRAME)
     return;
 
-  if (begin_impl_frame_deadline_mode_ !=
-      state_machine_.CurrentBeginImplFrameDeadlineMode())
-    ScheduleBeginImplFrameDeadline();
+  if (begin_impl_frame_deadline_mode_ == state_machine_.CurrentBeginImplFrameDeadlineMode() &&
+      BeginImplFrameDeadlinePending())
+    return;
+
+  ScheduleBeginImplFrameDeadline();
 }
 
 void Scheduler::OnBeginImplFrameDeadline() {
   TRACE_EVENT0("cc", "Scheduler::OnBeginImplFrameDeadline");
   begin_impl_frame_deadline_task_.Cancel();
   // We split the deadline actions up into two phases so the state machine
   // has a chance to trigger actions that should occur durring and after
   // the deadline separately. For example:
   // * Sending the BeginMainFrame will not occur after the deadline in
   //     order to wait for more user-input before starting the next commit.
   // * Creating a new OuputSurface will not occur during the deadline in
   //     order to allow the state machine to "settle" first.
   state_machine_.OnBeginImplFrameDeadline();
   ProcessScheduledActions();
   state_machine_.OnBeginImplFrameIdle();
   ProcessScheduledActions();
 
   client_->DidBeginImplFrameDeadline();
 }
 
-void Scheduler::PollForAnticipatedDrawTriggers() {
-  TRACE_EVENT0("cc", "Scheduler::PollForAnticipatedDrawTriggers");
-  poll_for_draw_triggers_task_.Cancel();
-  state_machine_.DidEnterPollForAnticipatedDrawTriggers();
-  ProcessScheduledActions();
-  state_machine_.DidLeavePollForAnticipatedDrawTriggers();
-}
 
 void Scheduler::PollToAdvanceCommitState() {
   TRACE_EVENT0("cc", "Scheduler::PollToAdvanceCommitState");
   advance_commit_state_task_.Cancel();
   ProcessScheduledActions();
 }
 
 void Scheduler::DrawAndSwapIfPossible() {
   DrawResult result = client_->ScheduledActionDrawAndSwapIfPossible();
   state_machine_.DidDrawIfPossibleCompleted(result);
 }
 
 void Scheduler::ProcessScheduledActions() {
   // We do not allow ProcessScheduledActions to be recursive.
   // The top-level call will iteratively execute the next action for us anyway.
   if (inside_process_scheduled_actions_)
     return;
+  {
+    // Separate scope for mark_inside.

[brianderson, 2014/12/20 00:34:13]

Do you only need this to allow re-entrancy when ScheduleBeginImplFrameDeadline
calls the deadline synchronously?

Would it be easier to read if this block is split out into a private method?

+    base::AutoReset<bool> mark_inside(&inside_process_scheduled_actions_, true);
 
-  base::AutoReset<bool> mark_inside(&inside_process_scheduled_actions_, true);
-
-  SchedulerStateMachine::Action action;
-  do {
-    action = state_machine_.NextAction();
-    TRACE_EVENT1(TRACE_DISABLED_BY_DEFAULT("cc.debug.scheduler"),
-                 "SchedulerStateMachine",
-                 "state",
-                 AsValue());
-    VLOG(2) << "Scheduler::ProcessScheduledActions: "
-            << SchedulerStateMachine::ActionToString(action) << " "
-            << state_machine_.GetStatesForDebugging();
-    state_machine_.UpdateState(action);
-    base::AutoReset<SchedulerStateMachine::Action>
-        mark_inside_action(&inside_action_, action);
-    switch (action) {
-      case SchedulerStateMachine::ACTION_NONE:
-        break;
-      case SchedulerStateMachine::ACTION_ANIMATE:
-        client_->ScheduledActionAnimate();
-        break;
-      case SchedulerStateMachine::ACTION_SEND_BEGIN_MAIN_FRAME:
-        client_->ScheduledActionSendBeginMainFrame();
-        break;
-      case SchedulerStateMachine::ACTION_COMMIT:
-        client_->ScheduledActionCommit();
-        break;
-      case SchedulerStateMachine::ACTION_ACTIVATE_SYNC_TREE:
-        client_->ScheduledActionActivateSyncTree();
-        break;
-      case SchedulerStateMachine::ACTION_DRAW_AND_SWAP_IF_POSSIBLE:
-        DrawAndSwapIfPossible();
-        break;
-      case SchedulerStateMachine::ACTION_DRAW_AND_SWAP_FORCED:
-        client_->ScheduledActionDrawAndSwapForced();
-        break;
-      case SchedulerStateMachine::ACTION_DRAW_AND_SWAP_ABORT:
-        // No action is actually performed, but this allows the state machine to
-        // advance out of its waiting to draw state without actually drawing.
-        break;
-      case SchedulerStateMachine::ACTION_BEGIN_OUTPUT_SURFACE_CREATION:
-        client_->ScheduledActionBeginOutputSurfaceCreation();
-        break;
-      case SchedulerStateMachine::ACTION_PREPARE_TILES:
-        client_->ScheduledActionPrepareTiles();
-        break;
-    }
-  } while (action != SchedulerStateMachine::ACTION_NONE);
+    SchedulerStateMachine::Action action;
+    do {
+      action = state_machine_.NextAction();
+      TRACE_EVENT1(TRACE_DISABLED_BY_DEFAULT("cc.debug.scheduler"),
+                   "SchedulerStateMachine",
+                   "state",
+                   AsValue());
+      VLOG(2) << "Scheduler::ProcessScheduledActions: "
+              << SchedulerStateMachine::ActionToString(action) << " "
+              << state_machine_.GetStatesForDebugging();
+      state_machine_.UpdateState(action);
+      base::AutoReset<SchedulerStateMachine::Action>
+          mark_inside_action(&inside_action_, action);
+      switch (action) {
+        case SchedulerStateMachine::ACTION_NONE:
+          break;
+        case SchedulerStateMachine::ACTION_ANIMATE:
+          client_->ScheduledActionAnimate();
+          break;
+        case SchedulerStateMachine::ACTION_SEND_BEGIN_MAIN_FRAME:
+          client_->ScheduledActionSendBeginMainFrame();
+          break;
+        case SchedulerStateMachine::ACTION_COMMIT:
+          client_->ScheduledActionCommit();
+          break;
+        case SchedulerStateMachine::ACTION_ACTIVATE_SYNC_TREE:
+          client_->ScheduledActionActivateSyncTree();
+          break;
+        case SchedulerStateMachine::ACTION_DRAW_AND_SWAP_IF_POSSIBLE:
+          DrawAndSwapIfPossible();
+          break;
+        case SchedulerStateMachine::ACTION_DRAW_AND_SWAP_FORCED:
+          client_->ScheduledActionDrawAndSwapForced();
+          break;
+        case SchedulerStateMachine::ACTION_DRAW_AND_SWAP_ABORT:
+          // No action is actually performed, but this allows the state machine
+          // to advance out of it's waiting to draw state without actually 

[brianderson, 2014/12/20 00:34:13]

it's -> its

[sunnyps, 2014/12/20 00:39:30]

Acknowledged.

+          // drawing.
+          break;
+        case SchedulerStateMachine::ACTION_BEGIN_OUTPUT_SURFACE_CREATION:
+          client_->ScheduledActionBeginOutputSurfaceCreation();
+          break;
+        case SchedulerStateMachine::ACTION_PREPARE_TILES:
+          client_->ScheduledActionPrepareTiles();
+          break;
+        case SchedulerStateMachine::ACTION_INVALIDATE_OUTPUT_SURFACE:
+          client_->ScheduledActionInvalidateOutputSurface();
+          break;
+      }
+    } while (action != SchedulerStateMachine::ACTION_NONE);
+  }
 
   SetupNextBeginFrameIfNeeded();
   client_->DidAnticipatedDrawTimeChange(AnticipatedDrawTime());
 
-  RescheduleBeginImplFrameDeadlineIfNeeded();
+  ScheduleBeginImplFrameDeadlineIfNeeded();
 }
 
 bool Scheduler::WillDrawIfNeeded() const {
   return !state_machine_.PendingDrawsShouldBeAborted();
 }
 
 scoped_refptr<base::debug::ConvertableToTraceFormat> Scheduler::AsValue()
     const {
   scoped_refptr<base::debug::TracedValue> state =
       new base::debug::TracedValue();
@@ skipping 21 matching lines @@
   state->SetDouble("time_until_anticipated_draw_time_ms",
                    (AnticipatedDrawTime() - Now()).InMillisecondsF());
   state->SetDouble("estimated_parent_draw_time_ms",
                    estimated_parent_draw_time_.InMillisecondsF());
   state->SetBoolean("last_set_needs_begin_frame_",
                     frame_source_->NeedsBeginFrames());
   state->SetBoolean("begin_retro_frame_posted_", begin_retro_frame_posted_);
   state->SetInteger("begin_retro_frame_args_", begin_retro_frame_args_.size());
   state->SetBoolean("begin_impl_frame_deadline_task_",
                     !begin_impl_frame_deadline_task_.IsCancelled());
-  state->SetBoolean("poll_for_draw_triggers_task_",
-                    !poll_for_draw_triggers_task_.IsCancelled());
   state->SetBoolean("advance_commit_state_task_",
                     !advance_commit_state_task_.IsCancelled());
   state->BeginDictionary("begin_impl_frame_args");
   begin_impl_frame_args_.AsValueInto(state);
   state->EndDictionary();
 
   state->EndDictionary();
 
   state->BeginDictionary("client_state");
   state->SetDouble("draw_duration_estimate_ms",
@@ skipping 27 matching lines @@
 }
 
 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