cc: Introduce BeginFrame sequence numbers and acknowledgements.

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"
 #include "base/trace_event/trace_event_argument.h"
 #include "base/values.h"
 
 namespace cc {
 
 namespace {
 // Surfaces and CompositorTimingHistory don't support more than 1 pending swap.
 const int kMaxPendingSubmitFrames = 1;
 }  // namespace
 
 SchedulerStateMachine::SchedulerStateMachine(const SchedulerSettings& settings)
     : settings_(settings),
       compositor_frame_sink_state_(COMPOSITOR_FRAME_SINK_NONE),
       begin_impl_frame_state_(BEGIN_IMPL_FRAME_STATE_IDLE),
       begin_main_frame_state_(BEGIN_MAIN_FRAME_STATE_IDLE),
       forced_redraw_state_(FORCED_REDRAW_STATE_IDLE),
       commit_count_(0),
+      begin_frame_source_id_(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),
+      last_frame_number_submit_performed_(0),
+      last_frame_number_draw_performed_(0),
+      last_frame_number_begin_main_frame_sent_(0),
+      last_frame_number_invalidate_compositor_frame_sink_performed_(0),
+      last_frame_number_pending_tree_was_fresh_(0),
+      last_frame_number_active_tree_was_fresh_(0),
+      last_frame_number_compositor_frame_was_fresh_(0),
       draw_funnel_(false),
       send_begin_main_frame_funnel_(true),
       invalidate_compositor_frame_sink_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),
@@ skipping 157 matching lines @@
                    BeginMainFrameStateToString(begin_main_frame_state_));
   state->SetString(
       "compositor_frame_sink_state_",
       CompositorFrameSinkStateToString(compositor_frame_sink_state_));
   state->SetString("forced_redraw_state",
                    ForcedRedrawOnTimeoutStateToString(forced_redraw_state_));
   state->EndDictionary();
 
   state->BeginDictionary("minor_state");
   state->SetInteger("commit_count", commit_count_);
+  state->SetInteger("begin_frame_source_id", begin_frame_source_id_);
   state->SetInteger("current_frame_number", current_frame_number_);
   state->SetInteger("last_frame_number_submit_performed",
                     last_frame_number_submit_performed_);
   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->SetInteger("last_frame_number_pending_tree_was_fresh",
+                    last_frame_number_pending_tree_was_fresh_);
+  state->SetInteger("last_frame_number_active_tree_was_fresh",
+                    last_frame_number_active_tree_was_fresh_);
+  state->SetInteger("last_frame_number_compositor_frame_was_fresh",
+                    last_frame_number_compositor_frame_was_fresh_);
   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->SetInteger("consecutive_checkerboard_animations",
                     consecutive_checkerboard_animations_);
   state->SetInteger("pending_submit_frames_", pending_submit_frames_);
   state->SetInteger("submit_frames_with_current_compositor_frame_sink",
@@ skipping 355 matching lines @@
 }
 
 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) {
-    // Pending tree only exists if commit had updates.
+  if (commit_has_no_updates) {
+    // Pending tree might still exist from prior commit.
+    if (has_pending_tree_) {
+      DCHECK(settings_.main_frame_before_activation_enabled);
+      last_frame_number_pending_tree_was_fresh_ =
+          last_frame_number_begin_main_frame_sent_;
+    } else {
+      last_frame_number_active_tree_was_fresh_ =
+          last_frame_number_begin_main_frame_sent_;
+    }
+  } else {
+    // We have a new pending tree.
     has_pending_tree_ = true;
     pending_tree_is_ready_for_activation_ = false;
+    last_frame_number_pending_tree_was_fresh_ =
+        last_frame_number_begin_main_frame_sent_;
     wait_for_ready_to_draw_ = settings_.commit_to_active_tree;
   }
 
   // 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;
   }
 
@@ skipping 211 matching lines @@
     return true;
 
   // If the last commit was aborted because of early out (no updates), we should
   // still want a begin frame in case there is a commit coming again.
   if (last_commit_had_no_updates_)
     return true;
 
   return false;
 }
 
-void SchedulerStateMachine::OnBeginImplFrame() {
+void SchedulerStateMachine::OnBeginImplFrame(uint64_t source_id,
+                                             uint64_t sequence_number) {
+  if (source_id != begin_frame_source_id_) {
+    begin_frame_source_id_ = source_id;
+    current_frame_number_ = sequence_number;
+
+    // Consider us up to date up to the previous BeginFrame.
+    last_frame_number_active_tree_was_fresh_ =
+        current_frame_number_ > 0 ? current_frame_number_ - 1 : 0;

[Sami, 2016/12/06 12:41:07]

Ditto about 1-based sequence numbers if we decide to start using them.

[Eric Seckler, 2016/12/06 17:34:00]

Done.

+    last_frame_number_pending_tree_was_fresh_ =
+        last_frame_number_active_tree_was_fresh_;
+    last_frame_number_compositor_frame_was_fresh_ =
+        last_frame_number_active_tree_was_fresh_;
+  }
+
+  DCHECK_GE(sequence_number, current_frame_number_);
+
   begin_impl_frame_state_ = BEGIN_IMPL_FRAME_STATE_INSIDE_BEGIN_FRAME;
-  current_frame_number_++;
+  current_frame_number_ = sequence_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;
 
   // "Drain" the PrepareTiles funnel.
   if (prepare_tiles_funnel_ > 0)
     prepare_tiles_funnel_--;
+
+  // Update frame numbers for freshness if no updates are requested.
+  if (!needs_begin_main_frame_) {
+    if (has_pending_tree_) {
+      last_frame_number_pending_tree_was_fresh_ = current_frame_number_;
+    } else {
+      last_frame_number_active_tree_was_fresh_ = current_frame_number_;
+
+      if (!needs_redraw_)
+        last_frame_number_compositor_frame_was_fresh_ = current_frame_number_;
+    }
+  }
 }
 
 void SchedulerStateMachine::OnBeginImplFrameDeadline() {
   begin_impl_frame_state_ = BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE;
 
   // Clear funnels for any actions we perform during the deadline.
   draw_funnel_ = false;
 
   // Allow one PrepareTiles per draw for synchronous compositor.
   if (settings_.using_synchronous_renderer_compositor) {
@@ skipping 125 matching lines @@
 void SchedulerStateMachine::DidSubmitCompositorFrame() {
   TRACE_EVENT_ASYNC_BEGIN1("cc", "Scheduler:pending_submit_frames", this,
                            "pending_frames", pending_submit_frames_);
   DCHECK_LT(pending_submit_frames_, kMaxPendingSubmitFrames);
 
   pending_submit_frames_++;
   submit_frames_with_current_compositor_frame_sink_++;
 
   did_submit_in_last_frame_ = true;
   last_frame_number_submit_performed_ = current_frame_number_;
+  last_frame_number_compositor_frame_was_fresh_ =
+      last_frame_number_active_tree_was_fresh_;
 }
 
 void SchedulerStateMachine::DidReceiveCompositorFrameAck() {
   TRACE_EVENT_ASYNC_END1("cc", "Scheduler:pending_submit_frames", this,
                          "pending_frames", pending_submit_frames_);
   pending_submit_frames_--;
 }
 
 void SchedulerStateMachine::SetTreePrioritiesAndScrollState(
     TreePriority tree_priority,
@@ skipping 114 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