cc: Allow the main thread to cancel commits

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"
 
 namespace cc {
 
 SchedulerStateMachine::SchedulerStateMachine(const SchedulerSettings& settings)
     : settings_(settings),
       commit_state_(COMMIT_STATE_IDLE),
       commit_count_(0),
       current_frame_number_(0),
+      last_frame_number_where_begin_frame_sent_to_main_thread_(-1),
       last_frame_number_where_draw_was_called_(-1),
       last_frame_number_where_tree_activation_attempted_(-1),
       last_frame_number_where_update_visible_tiles_was_called_(-1),
       consecutive_failed_draws_(0),
       maximum_number_of_failed_draws_before_draw_is_forced_(3),
       needs_redraw_(false),
       swap_used_incomplete_tile_(false),
       needs_forced_redraw_(false),
       needs_forced_redraw_after_next_commit_(false),
+      needs_redraw_after_next_commit_(false),
       needs_commit_(false),
       needs_forced_commit_(false),
       expect_immediate_begin_frame_for_main_thread_(false),
       main_thread_needs_layer_textures_(false),
       inside_begin_frame_(false),
       visible_(false),
       can_start_(false),
       can_draw_(false),
       has_pending_tree_(false),
       draw_if_possible_failed_(false),
@@ skipping 72 matching lines @@
 bool SchedulerStateMachine::HasAttemptedTreeActivationThisFrame() const {
   return current_frame_number_ ==
          last_frame_number_where_tree_activation_attempted_;
 }
 
 bool SchedulerStateMachine::HasUpdatedVisibleTilesThisFrame() const {
   return current_frame_number_ ==
          last_frame_number_where_update_visible_tiles_was_called_;
 }
 
+void SchedulerStateMachine::SetPostCommitFlags() {
+  // This post-commit work is common to both completed and aborted commits.
+  if (needs_forced_redraw_after_next_commit_) {
+    needs_forced_redraw_after_next_commit_ = false;
+    needs_forced_redraw_ = true;
+  }
+  if (needs_redraw_after_next_commit_) {
+    needs_redraw_after_next_commit_ = false;
+    needs_redraw_ = true;
+  }
+  texture_state_ = LAYER_TEXTURE_STATE_ACQUIRED_BY_IMPL_THREAD;
+}
+
 bool SchedulerStateMachine::DrawSuspendedUntilCommit() const {
   if (!can_draw_)
     return true;
   if (!visible_)
     return true;
   if (texture_state_ == LAYER_TEXTURE_STATE_ACQUIRED_BY_MAIN_THREAD)
     return true;
   return false;
 }
 
@@ skipping 48 matching lines @@
   if (!BeginFrameNeededToDrawByImplThread())
     return true;
   return false;
 }
 
 SchedulerStateMachine::Action SchedulerStateMachine::NextAction() const {
   if (ShouldAcquireLayerTexturesForMainThread())
     return ACTION_ACQUIRE_LAYER_TEXTURES_FOR_MAIN_THREAD;
 
   switch (commit_state_) {
-    case COMMIT_STATE_IDLE:
+    case COMMIT_STATE_IDLE: {
       if (output_surface_state_ != OUTPUT_SURFACE_ACTIVE &&
           needs_forced_redraw_)
         return ACTION_DRAW_FORCED;
       if (output_surface_state_ != OUTPUT_SURFACE_ACTIVE &&
           needs_forced_commit_)
         // TODO(enne): Should probably drop the active tree on force commit.
         return has_pending_tree_ ? ACTION_NONE
                                  : ACTION_SEND_BEGIN_FRAME_TO_MAIN_THREAD;
       if (output_surface_state_ == OUTPUT_SURFACE_LOST && can_start_)
         return ACTION_BEGIN_OUTPUT_SURFACE_CREATION;
       if (output_surface_state_ == OUTPUT_SURFACE_CREATING)
         return ACTION_NONE;
       if (ShouldUpdateVisibleTiles())
         return ACTION_UPDATE_VISIBLE_TILES;
       if (ShouldAttemptTreeActivation())
         return ACTION_ACTIVATE_PENDING_TREE_IF_NEEDED;
       if (ShouldDraw()) {
         return needs_forced_redraw_ ? ACTION_DRAW_FORCED
                                     : ACTION_DRAW_IF_POSSIBLE;
       }
-      if (needs_commit_ &&
-          ((visible_ && output_surface_state_ == OUTPUT_SURFACE_ACTIVE)
-           || needs_forced_commit_))
+      bool can_commit_this_frame =
+          visible_ &&
+          current_frame_number_ >
+              last_frame_number_where_begin_frame_sent_to_main_thread_;
+      if (needs_commit_ && ((can_commit_this_frame &&
+                             output_surface_state_ == OUTPUT_SURFACE_ACTIVE) ||
+                            needs_forced_commit_))
         // TODO(enne): Should probably drop the active tree on force commit.
         return has_pending_tree_ ? ACTION_NONE
                                  : ACTION_SEND_BEGIN_FRAME_TO_MAIN_THREAD;
       return ACTION_NONE;
-
+    }
     case COMMIT_STATE_FRAME_IN_PROGRESS:
       if (ShouldUpdateVisibleTiles())
         return ACTION_UPDATE_VISIBLE_TILES;
       if (ShouldAttemptTreeActivation())
         return ACTION_ACTIVATE_PENDING_TREE_IF_NEEDED;
       if (ShouldDraw()) {
         return needs_forced_redraw_ ? ACTION_DRAW_FORCED
                                     : ACTION_DRAW_IF_POSSIBLE;
       }
       return ACTION_NONE;
 
     case COMMIT_STATE_READY_TO_COMMIT:
       return ACTION_COMMIT;
 
     case COMMIT_STATE_WAITING_FOR_FIRST_DRAW: {
       if (ShouldUpdateVisibleTiles())
         return ACTION_UPDATE_VISIBLE_TILES;
       if (ShouldAttemptTreeActivation())
         return ACTION_ACTIVATE_PENDING_TREE_IF_NEEDED;
       if (ShouldDraw() || output_surface_state_ == OUTPUT_SURFACE_LOST) {
         return needs_forced_redraw_ ? ACTION_DRAW_FORCED
                                     : ACTION_DRAW_IF_POSSIBLE;
       }
       // COMMIT_STATE_WAITING_FOR_FIRST_DRAW wants to enforce a draw. If
       // can_draw_ is false or textures are not available, proceed to the next
       // step (similar as in COMMIT_STATE_IDLE).
-      bool can_commit = visible_ || needs_forced_commit_;
+      bool can_commit =
+          needs_forced_commit_ ||
+          (visible_ &&
+           current_frame_number_ >
+               last_frame_number_where_begin_frame_sent_to_main_thread_);
       if (needs_commit_ && can_commit && DrawSuspendedUntilCommit())
         return has_pending_tree_ ? ACTION_NONE
                                  : ACTION_SEND_BEGIN_FRAME_TO_MAIN_THREAD;
       return ACTION_NONE;
     }
 
     case COMMIT_STATE_WAITING_FOR_FIRST_FORCED_DRAW:
       if (ShouldUpdateVisibleTiles())
         return ACTION_UPDATE_VISIBLE_TILES;
       if (ShouldAttemptTreeActivation())
@@ skipping 16 matching lines @@
           current_frame_number_;
       return;
 
     case ACTION_ACTIVATE_PENDING_TREE_IF_NEEDED:
       last_frame_number_where_tree_activation_attempted_ =
           current_frame_number_;
       return;
 
     case ACTION_SEND_BEGIN_FRAME_TO_MAIN_THREAD:
       DCHECK(!has_pending_tree_);
-      DCHECK(visible_ || needs_forced_commit_);
+      if (!needs_forced_commit_) {
+        DCHECK(visible_);
+        DCHECK_GT(current_frame_number_,
+                  last_frame_number_where_begin_frame_sent_to_main_thread_);
+      }
       commit_state_ = COMMIT_STATE_FRAME_IN_PROGRESS;
       needs_commit_ = false;
       needs_forced_commit_ = false;
+      last_frame_number_where_begin_frame_sent_to_main_thread_ =
+          current_frame_number_;
       return;
 
     case ACTION_COMMIT:
       commit_count_++;
       if (expect_immediate_begin_frame_for_main_thread_)
         commit_state_ = COMMIT_STATE_WAITING_FOR_FIRST_FORCED_DRAW;
       else
         commit_state_ = COMMIT_STATE_WAITING_FOR_FIRST_DRAW;
       // When impl-side painting, we draw on activation instead of on commit.
       if (!settings_.impl_side_painting)
         needs_redraw_ = true;
       if (draw_if_possible_failed_)
         last_frame_number_where_draw_was_called_ = -1;
-
-      if (needs_forced_redraw_after_next_commit_) {
-        needs_forced_redraw_after_next_commit_ = false;
-        needs_forced_redraw_ = true;
-      }
-
-      texture_state_ = LAYER_TEXTURE_STATE_ACQUIRED_BY_IMPL_THREAD;
+      SetPostCommitFlags();
       return;
 
     case ACTION_DRAW_FORCED:
     case ACTION_DRAW_IF_POSSIBLE:
       needs_redraw_ = false;
       needs_forced_redraw_ = false;
       draw_if_possible_failed_ = false;
       swap_used_incomplete_tile_ = false;
       if (inside_begin_frame_)
         last_frame_number_where_draw_was_called_ = current_frame_number_;
@@ skipping 47 matching lines @@
   if (!visible_ || output_surface_state_ != OUTPUT_SURFACE_ACTIVE)
     return false;
 
   // We should proactively request a BeginFrame if a commit or a tree activation
   // is pending.
   return (needs_commit_ || needs_forced_commit_ ||
           commit_state_ != COMMIT_STATE_IDLE || has_pending_tree_);
 }
 
 void SchedulerStateMachine::DidEnterBeginFrame(const BeginFrameArgs& args) {
+  current_frame_number_++;
   inside_begin_frame_ = true;
   last_begin_frame_args_ = args;
 }
 
 void SchedulerStateMachine::DidLeaveBeginFrame() {
-  current_frame_number_++;
   inside_begin_frame_ = false;
 }
 
 void SchedulerStateMachine::SetVisible(bool visible) { visible_ = visible; }
 
 void SchedulerStateMachine::SetNeedsRedraw() { needs_redraw_ = true; }
 
 void SchedulerStateMachine::DidSwapUseIncompleteTile() {
   swap_used_incomplete_tile_ = true;
 }
@@ skipping 29 matching lines @@
 }
 
 void SchedulerStateMachine::FinishCommit() {
   DCHECK(commit_state_ == COMMIT_STATE_FRAME_IN_PROGRESS ||
          (expect_immediate_begin_frame_for_main_thread_ &&
           commit_state_ != COMMIT_STATE_IDLE))
       << ToString();
   commit_state_ = COMMIT_STATE_READY_TO_COMMIT;
 }
 
-void SchedulerStateMachine::BeginFrameAbortedByMainThread() {
+void SchedulerStateMachine::BeginFrameAbortedByMainThread(bool did_handle) {
   DCHECK_EQ(commit_state_, COMMIT_STATE_FRAME_IN_PROGRESS);
   if (expect_immediate_begin_frame_for_main_thread_) {
     expect_immediate_begin_frame_for_main_thread_ = false;
+  } else if (did_handle) {
+    commit_state_ = COMMIT_STATE_IDLE;
+    SetPostCommitFlags();
   } else {
     commit_state_ = COMMIT_STATE_IDLE;
     SetNeedsCommit();
   }
 }
 
 void SchedulerStateMachine::DidLoseOutputSurface() {
   if (output_surface_state_ == OUTPUT_SURFACE_LOST ||
       output_surface_state_ == OUTPUT_SURFACE_CREATING)
     return;
@@ skipping 12 matching lines @@
 
   if (did_create_and_initialize_first_output_surface_) {
     // TODO(boliu): See if we can remove this when impl-side painting is always
     // on. Does anything on the main thread need to update after recreate?
     needs_commit_ = true;
     // If anything has requested a redraw, we don't want to actually draw
     // when the output surface is restored until things have a chance to
     // sort themselves out with a commit.
     needs_redraw_ = false;
   }
+  needs_redraw_after_next_commit_ = true;
   did_create_and_initialize_first_output_surface_ = true;
 }
 
 bool SchedulerStateMachine::HasInitializedOutputSurface() const {
   return output_surface_state_ == OUTPUT_SURFACE_ACTIVE;
 }
 
 void SchedulerStateMachine::SetMaximumNumberOfFailedDrawsBeforeDrawIsForced(
     int num_draws) {
   maximum_number_of_failed_draws_before_draw_is_forced_ = num_draws;
 }
 
 }  // namespace cc