cc: Add scheduler support for invalidating content on impl thread.

cc/scheduler/scheduler_state_machine.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_state_machine.h"
 
 #include "base/format_macros.h"
 #include "base/logging.h"
 #include "base/strings/stringprintf.h"
 #include "base/trace_event/trace_event.h"
@@ skipping 15 matching lines @@
       forced_redraw_state_(FORCED_REDRAW_STATE_IDLE),
       commit_count_(0),
       current_frame_number_(0),
       last_frame_number_submit_performed_(-1),
       last_frame_number_draw_performed_(-1),
       last_frame_number_begin_main_frame_sent_(-1),
       last_frame_number_invalidate_compositor_frame_sink_performed_(-1),
       draw_funnel_(false),
       send_begin_main_frame_funnel_(true),
       invalidate_compositor_frame_sink_funnel_(false),
+      impl_side_invalidation_funnel_(false),
       prepare_tiles_funnel_(0),
       consecutive_checkerboard_animations_(0),
       pending_submit_frames_(0),
       submit_frames_with_current_compositor_frame_sink_(0),
       needs_redraw_(false),
       needs_prepare_tiles_(false),
       needs_begin_main_frame_(false),
       needs_one_begin_impl_frame_(false),
       visible_(false),
       begin_frame_source_paused_(false),
       resourceless_draw_(false),
       can_draw_(false),
       has_pending_tree_(false),
       pending_tree_is_ready_for_activation_(false),
       active_tree_needs_first_draw_(false),
       did_create_and_initialize_first_compositor_frame_sink_(false),
       tree_priority_(NEW_CONTENT_TAKES_PRIORITY),
       scroll_handler_state_(
           ScrollHandlerState::SCROLL_DOES_NOT_AFFECT_SCROLL_HANDLER),
       critical_begin_main_frame_to_activate_is_fast_(true),
       main_thread_missed_last_deadline_(false),
       skip_next_begin_main_frame_to_reduce_latency_(false),
       defer_commits_(false),
       video_needs_begin_frames_(false),
       last_commit_had_no_updates_(false),
       wait_for_ready_to_draw_(false),
       did_draw_in_last_frame_(false),
-      did_submit_in_last_frame_(false) {}
+      did_submit_in_last_frame_(false),
+      needs_impl_side_invalidation_(false),
+      impl_side_invalidations_take_priority_(false) {}
 
 const char* SchedulerStateMachine::CompositorFrameSinkStateToString(
     CompositorFrameSinkState state) {
   switch (state) {
     case COMPOSITOR_FRAME_SINK_NONE:
       return "COMPOSITOR_FRAME_SINK_NONE";
     case COMPOSITOR_FRAME_SINK_ACTIVE:
       return "COMPOSITOR_FRAME_SINK_ACTIVE";
     case COMPOSITOR_FRAME_SINK_CREATING:
       return "COMPOSITOR_FRAME_SINK_CREATING";
@@ skipping 96 matching lines @@
     case ACTION_DRAW_FORCED:
       return "ACTION_DRAW_FORCED";
     case ACTION_DRAW_ABORT:
       return "ACTION_DRAW_ABORT";
     case ACTION_BEGIN_COMPOSITOR_FRAME_SINK_CREATION:
       return "ACTION_BEGIN_COMPOSITOR_FRAME_SINK_CREATION";
     case ACTION_PREPARE_TILES:
       return "ACTION_PREPARE_TILES";
     case ACTION_INVALIDATE_COMPOSITOR_FRAME_SINK:
       return "ACTION_INVALIDATE_COMPOSITOR_FRAME_SINK";
+    case ACTION_PERFORM_IMPL_SIDE_INVALIDATION:
+      return "ACTION_PERFORM_IMPL_SIDE_INVALIDATION";
   }
   NOTREACHED();
   return "???";
 }
 
 std::unique_ptr<base::trace_event::ConvertableToTraceFormat>
 SchedulerStateMachine::AsValue() const {
   std::unique_ptr<base::trace_event::TracedValue> state(
       new base::trace_event::TracedValue());
   AsValueInto(state.get());
@@ skipping 23 matching lines @@
   state->SetInteger("last_frame_number_draw_performed",
                     last_frame_number_draw_performed_);
   state->SetInteger("last_frame_number_begin_main_frame_sent",
                     last_frame_number_begin_main_frame_sent_);
   state->SetBoolean("funnel: draw_funnel", draw_funnel_);
   state->SetBoolean("funnel: send_begin_main_frame_funnel",
                     send_begin_main_frame_funnel_);
   state->SetInteger("funnel: prepare_tiles_funnel", prepare_tiles_funnel_);
   state->SetBoolean("funnel: invalidate_compositor_frame_sink_funnel",
                     invalidate_compositor_frame_sink_funnel_);
+  state->SetBoolean("funnel: impl_side_invalidation_funnel",
+                    impl_side_invalidation_funnel_);
   state->SetInteger("consecutive_checkerboard_animations",
                     consecutive_checkerboard_animations_);
   state->SetInteger("pending_submit_frames_", pending_submit_frames_);
   state->SetInteger("submit_frames_with_current_compositor_frame_sink",
                     submit_frames_with_current_compositor_frame_sink_);
   state->SetBoolean("needs_redraw", needs_redraw_);
   state->SetBoolean("needs_prepare_tiles", needs_prepare_tiles_);
   state->SetBoolean("needs_begin_main_frame", needs_begin_main_frame_);
   state->SetBoolean("needs_one_begin_impl_frame", needs_one_begin_impl_frame_);
   state->SetBoolean("visible", visible_);
@@ skipping 15 matching lines @@
                     critical_begin_main_frame_to_activate_is_fast_);
   state->SetBoolean("main_thread_missed_last_deadline",
                     main_thread_missed_last_deadline_);
   state->SetBoolean("skip_next_begin_main_frame_to_reduce_latency",
                     skip_next_begin_main_frame_to_reduce_latency_);
   state->SetBoolean("video_needs_begin_frames", video_needs_begin_frames_);
   state->SetBoolean("defer_commits", defer_commits_);
   state->SetBoolean("last_commit_had_no_updates", last_commit_had_no_updates_);
   state->SetBoolean("did_draw_in_last_frame", did_draw_in_last_frame_);
   state->SetBoolean("did_submit_in_last_frame", did_submit_in_last_frame_);
+  state->SetBoolean("needs_impl_side_invalidation",
+                    needs_impl_side_invalidation_);
+  state->SetBoolean("impl_side_invalidations_take_priority",
+                    impl_side_invalidations_take_priority_);
   state->EndDictionary();
 }
 
 bool SchedulerStateMachine::PendingDrawsShouldBeAborted() const {
   // Normally when |visible_| is false or |begin_frame_source_paused_| is true,
   // pending activations will be forced and draws will be aborted. However,
   // when the embedder is Android WebView, software draws could be scheduled by
   // the Android OS at any time and draws should not be aborted in this case.
   bool is_compositor_frame_sink_lost =
       (compositor_frame_sink_state_ == COMPOSITOR_FRAME_SINK_NONE);
@@ skipping 283 matching lines @@
       return ACTION_DRAW_ABORT;
     else if (forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_DRAW)
       return ACTION_DRAW_FORCED;
     else
       return ACTION_DRAW_IF_POSSIBLE;
   }
   if (ShouldPrepareTiles())
     return ACTION_PREPARE_TILES;
   if (ShouldSendBeginMainFrame())
     return ACTION_SEND_BEGIN_MAIN_FRAME;
+  if (ShouldPerformImplSideInvalidation())
+    return ACTION_PERFORM_IMPL_SIDE_INVALIDATION;
   if (ShouldInvalidateCompositorFrameSink())
     return ACTION_INVALIDATE_COMPOSITOR_FRAME_SINK;
   if (ShouldBeginCompositorFrameSinkCreation())
     return ACTION_BEGIN_COMPOSITOR_FRAME_SINK_CREATION;
   return ACTION_NONE;
 }
 
+bool SchedulerStateMachine::ShouldPerformImplSideInvalidation() const {
+  if (!needs_impl_side_invalidation_)
+    return false;
+
+  if (!CouldCreatePendingTree())
+    return false;
+
+  // If the main thread is ready to commit, the impl-side invalidations will be
+  // merged with the incoming main frame.
+  if (begin_main_frame_state_ == BEGIN_MAIN_FRAME_STATE_READY_TO_COMMIT)
+    return false;
+
+  // Don't invalidate too many times in the same frame.
+  if (impl_side_invalidation_funnel_)
+    return false;
+
+  // If invalidations go to the active tree and we are waiting for the previous
+  // frame to be drawn, submitted and acked.
+  if (settings_.commit_to_active_tree &&
+      (active_tree_needs_first_draw_ || IsDrawThrottled())) {
+    return false;
+  }
+
+  // Don't wait on the response to BeginMainFrame if we are prioritizing impl
+  // side invalidations.
+  if (impl_side_invalidations_take_priority_)
+    return true;
+
+  // If BeginMainFrame has been sent, let's wait for the main thread before
+  // pipelining impl-side invalidations.
+  // TODO(khushalsagar): If the main thread is high latency, may be run
+  // impl-side invalidations instead of waiting on the main thread?
+  // See crbug.com/691735.
+  if (begin_main_frame_state_ == BEGIN_MAIN_FRAME_STATE_SENT ||
+      begin_main_frame_state_ == BEGIN_MAIN_FRAME_STATE_STARTED)
+    return false;
+
+  // If a main frame request is pending, always prioritize sending a
+  // BeginMainFrame and receiving an update from the main thread before creating
+  // a pending tree for impl-side invalidations.
+  if (CouldSendBeginMainFrame() &&
+      begin_main_frame_state_ ==
+          BeginMainFrameState::BEGIN_MAIN_FRAME_STATE_IDLE)

[brianderson, 2017/02/21 23:34:59]

Given the preceding logic, I think the STATE_IDLE check can become a DCHECK.
Probably put the DCHECK within the if to maintain the relationship even though
it'll be true before the if.

[Khushal, 2017/02/22 20:24:02]

This code went away in the new patch, now that we just do it inside the
deadline, so the main frame state can be ignored.

+    return false;
+
+  // At this point, create a pending tree to run impl-side invalidations.
+  return true;
+}
+
+void SchedulerStateMachine::WillPerformImplSideInvalidation() {
+  WillPerformImplSideInvalidationInternal();
+}
+
+void SchedulerStateMachine::WillPerformImplSideInvalidationInternal() {
+  DCHECK(needs_impl_side_invalidation_);
+  DCHECK(!has_pending_tree_);
+
+  needs_impl_side_invalidation_ = false;
+  has_pending_tree_ = true;

[sunnyps, 2017/02/20 23:19:22]

For UI, has_pending_tree_ = true should never be true except between
SetNeedsCommit and ScheduledActionCommit.

[Khushal, 2017/02/21 09:43:44]

Good point. The impl-side invalidation should be done similar to a commit in
SingleThreadProxy. In ScheduledActionPerformImplSideInvalidation, right after we
invalidate the sync tree, it should immediately call NotifyReadyToActivate to
update the scheduler state correctly.

+  impl_side_invalidations_take_priority_ = false;
+  impl_side_invalidation_funnel_ = true;
+}
+
+bool SchedulerStateMachine::CouldCreatePendingTree() const {
+  // Can't create a new pending tree till the current one is activated.
+  if (has_pending_tree_)
+    return false;
+
+  // Can't make frames while we're invisible.
+  if (!visible_)
+    return false;
+
+  // If the BeginFrameSource is paused, we will not be able to make any impl
+  // frames.
+  if (begin_frame_source_paused_)
+    return false;
+
+  // Don't create a pending tree till a frame sink is initialized.
+  if (!HasInitializedCompositorFrameSink())
+    return false;
+
+  return true;
+}
+
 void SchedulerStateMachine::WillSendBeginMainFrame() {
   DCHECK(!has_pending_tree_ || settings_.main_frame_before_activation_enabled);
   DCHECK(visible_);
   DCHECK(!begin_frame_source_paused_);
   DCHECK(!send_begin_main_frame_funnel_);
   begin_main_frame_state_ = BEGIN_MAIN_FRAME_STATE_SENT;
   needs_begin_main_frame_ = false;
   send_begin_main_frame_funnel_ = true;
   last_frame_number_begin_main_frame_sent_ = current_frame_number_;
 }
 
 void SchedulerStateMachine::WillCommit(bool commit_has_no_updates) {
   DCHECK(!has_pending_tree_ ||
          (settings_.main_frame_before_activation_enabled &&
           commit_has_no_updates));
   commit_count_++;
   last_commit_had_no_updates_ = commit_has_no_updates;
   begin_main_frame_state_ = BEGIN_MAIN_FRAME_STATE_IDLE;
 
   if (!commit_has_no_updates) {
+    // If there was a commit, the impl-side invalidations will be merged with
+    // it. We always fill the impl-side invalidation funnel here, even if no
+    // request was currently pending, to defer creating another pending tree and
+    // performing PrepareTiles until the next frame, in case the invalidation
+    // request is received after the commit.
+    if (needs_impl_side_invalidation_)
+      WillPerformImplSideInvalidationInternal();
+    impl_side_invalidation_funnel_ = true;
+
     // Pending tree only exists if commit had updates.
     has_pending_tree_ = true;
     pending_tree_is_ready_for_activation_ = false;
     wait_for_ready_to_draw_ = settings_.commit_to_active_tree;
+  } else if (needs_impl_side_invalidation_) {
+    // If the main frame is getting aborted, the impl-side updates will end up
+    // continuously waiting on a commit. In this case, prioritize these over
+    // the main frame.
+    impl_side_invalidations_take_priority_ = true;
   }
 
   // Update state related to forced draws.
   if (forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_COMMIT) {
     forced_redraw_state_ = has_pending_tree_
                                ? FORCED_REDRAW_STATE_WAITING_FOR_ACTIVATION
                                : FORCED_REDRAW_STATE_WAITING_FOR_DRAW;
   }
 
   // Update the output surface state.
@@ skipping 80 matching lines @@
 
 void SchedulerStateMachine::WillDraw() {
   DCHECK(!draw_funnel_);
   WillDrawInternal();
 }
 
 void SchedulerStateMachine::DidDraw(DrawResult draw_result) {
   DidDrawInternal(draw_result);
 }
 
+void SchedulerStateMachine::SetNeedsImplSideInvalidation() {
+  needs_impl_side_invalidation_ = true;
+}
+
 void SchedulerStateMachine::AbortDraw() {
   // Pretend like the draw was successful.
   // Note: We may abort at any time and cannot DCHECK that
   // we haven't drawn in or swapped in the last frame here.
   WillDrawInternal();
   DidDrawInternal(DRAW_ABORTED_DRAINING_PIPELINE);
 }
 
 void SchedulerStateMachine::WillPrepareTiles() {
   needs_prepare_tiles_ = false;
@@ skipping 58 matching lines @@
 
 // These are the cases where we require a BeginFrame message to make progress
 // on requested actions.
 bool SchedulerStateMachine::BeginFrameRequiredForAction() const {
   // The forced draw respects our normal draw scheduling, so we need to
   // request a BeginImplFrame for it.
   if (forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_DRAW)
     return true;
 
   return needs_redraw_ || needs_one_begin_impl_frame_ ||
-         (needs_begin_main_frame_ && !defer_commits_);
+         (needs_begin_main_frame_ && !defer_commits_) ||
+         needs_impl_side_invalidation_;
 }
 
 // These are cases where we are very likely want a BeginFrame message in the
 // near future. Proactively requesting the BeginImplFrame helps hide the round
 // trip latency of the SetNeedsBeginFrame request that has to go to the
 // Browser.
 // This includes things like drawing soon, but might not actually have a new
 // frame to draw when we receive the next BeginImplFrame.
 bool SchedulerStateMachine::ProactiveBeginFrameWanted() const {
   // Do not be proactive when invisible.
@@ skipping 39 matching lines @@
   current_frame_number_++;
 
   last_commit_had_no_updates_ = false;
   did_draw_in_last_frame_ = false;
   did_submit_in_last_frame_ = false;
   needs_one_begin_impl_frame_ = false;
 
   // Clear funnels for any actions we perform during the frame.
   send_begin_main_frame_funnel_ = false;
   invalidate_compositor_frame_sink_funnel_ = false;
+  impl_side_invalidation_funnel_ = false;
 
   // "Drain" the PrepareTiles funnel.
   if (prepare_tiles_funnel_ > 0)
     prepare_tiles_funnel_--;
 }
 
 void SchedulerStateMachine::OnBeginImplFrameDeadline() {
   begin_impl_frame_state_ = BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE;
 
   // Clear funnels for any actions we perform during the deadline.
@@ skipping 263 matching lines @@
     case COMPOSITOR_FRAME_SINK_ACTIVE:
     case COMPOSITOR_FRAME_SINK_WAITING_FOR_FIRST_COMMIT:
     case COMPOSITOR_FRAME_SINK_WAITING_FOR_FIRST_ACTIVATION:
       return true;
   }
   NOTREACHED();
   return false;
 }
 
 }  // namespace cc