cc: Implement deadine scheduling disabled by default

cc/scheduler/scheduler.cc

Index: cc/scheduler/scheduler.cc
diff --git a/cc/scheduler/scheduler.cc b/cc/scheduler/scheduler.cc
index 14f6c7fe2f1d1d9eb9a1a7bddb078101631569e4..17a72f149d77afcaa3d29a6237c9fa559ca95cf2 100644
--- a/cc/scheduler/scheduler.cc
+++ b/cc/scheduler/scheduler.cc
@@ -4,6 +4,7 @@
 
 #include "cc/scheduler/scheduler.h"
 
+#include <algorithm>
 #include "base/auto_reset.h"
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
@@ -21,12 +22,10 @@ Scheduler::Scheduler(SchedulerClient* client,
       inside_process_scheduled_actions_(false),
       inside_action_(SchedulerStateMachine::ACTION_NONE) {
   DCHECK(client_);
-  DCHECK(!state_machine_.BeginFrameNeededToDrawByImplThread());
+  DCHECK(!state_machine_.BeginFrameNeededByImplThread());
 }
 
-Scheduler::~Scheduler() {
-  client_->SetNeedsBeginFrameOnImplThread(false);
-}
+Scheduler::~Scheduler() {}
 
 void Scheduler::SetCanStart() {
   state_machine_.SetCanStart();
@@ -48,6 +47,12 @@ void Scheduler::NotifyReadyToActivate() {
   ProcessScheduledActions();
 }
 
+void Scheduler::ActivatePendingTree() {
+  client_->ScheduledActionActivatePendingTree();
+  if (state_machine_.ShouldTriggerBeginFrameDeadlineEarly())
+    PostBeginFrameDeadline(base::TimeTicks());
+}
+
 void Scheduler::SetNeedsCommit() {
   state_machine_.SetNeedsCommit();
   ProcessScheduledActions();
@@ -84,6 +89,9 @@ void Scheduler::FinishCommit() {
   TRACE_EVENT0("cc", "Scheduler::FinishCommit");
   state_machine_.FinishCommit();
   ProcessScheduledActions();
+
+  if (state_machine_.ShouldTriggerBeginFrameDeadlineEarly())
+    PostBeginFrameDeadline(base::TimeTicks());
 }
 
 void Scheduler::BeginFrameAbortedByMainThread(bool did_handle) {
@@ -94,14 +102,17 @@ void Scheduler::BeginFrameAbortedByMainThread(bool did_handle) {
 
 void Scheduler::DidLoseOutputSurface() {
   TRACE_EVENT0("cc", "Scheduler::DidLoseOutputSurface");
+  last_set_needs_begin_frame_ = false;
+  begin_frame_deadline_closure_.Cancel();
   state_machine_.DidLoseOutputSurface();
   ProcessScheduledActions();
 }
 
 void Scheduler::DidCreateAndInitializeOutputSurface() {
   TRACE_EVENT0("cc", "Scheduler::DidCreateAndInitializeOutputSurface");
+  DCHECK(!last_set_needs_begin_frame_);
+  DCHECK(begin_frame_deadline_closure_.IsCancelled());
   state_machine_.DidCreateAndInitializeOutputSurface();
-  last_set_needs_begin_frame_ = false;
   ProcessScheduledActions();
 }
 
@@ -112,12 +123,11 @@ base::TimeTicks Scheduler::AnticipatedDrawTime() {
       last_begin_frame_args_.interval <= base::TimeDelta())
     return base::TimeTicks();
 
-  // TODO(brianderson): Express this in terms of the deadline.
   base::TimeTicks now = base::TimeTicks::Now();
-  int64 intervals = 1 + ((now - last_begin_frame_args_.frame_time) /
-                         last_begin_frame_args_.interval);
-  return last_begin_frame_args_.frame_time +
-      (last_begin_frame_args_.interval * intervals);
+  base::TimeTicks timebase = std::max(last_begin_frame_args_.frame_time,
+                                      last_begin_frame_args_.deadline);
+  int64 intervals = 1 + ((now - timebase) / last_begin_frame_args_.interval);
+  return timebase + (last_begin_frame_args_.interval * intervals);
 }
 
 base::TimeTicks Scheduler::LastBeginFrameOnImplThreadTime() {
@@ -125,22 +135,15 @@ base::TimeTicks Scheduler::LastBeginFrameOnImplThreadTime() {
 }
 
 void Scheduler::SetupNextBeginFrameIfNeeded() {
-  bool needs_begin_frame_to_draw =
-      state_machine_.BeginFrameNeededToDrawByImplThread();
-  // We want to avoid proactive begin frames with the synchronous compositor
-  // because every SetNeedsBeginFrame will force a redraw.
-  bool proactive_begin_frame_wanted =
-      state_machine_.ProactiveBeginFrameWantedByImplThread() &&
-      !settings_.using_synchronous_renderer_compositor &&
-      settings_.throttle_frame_production;
-  bool needs_begin_frame = needs_begin_frame_to_draw ||
-                           proactive_begin_frame_wanted;
+  bool needs_begin_frame =
+      state_machine_.BeginFrameNeededByImplThread();
 
   bool should_call_set_needs_begin_frame =
       // Always request the BeginFrame immediately if it wasn't needed before.
       (needs_begin_frame && !last_set_needs_begin_frame_) ||
       // We always need to explicitly request our next BeginFrame.
-      state_machine_.inside_begin_frame();
+      (state_machine_.begin_frame_state() ==

[danakj, 2013/09/17 20:26:19]

bool at_end_of_deadline = "this thing" might help clarify things?

[brianderson, 2013/09/17 21:08:24]

Good suggestion. Done.

+          SchedulerStateMachine::BEGIN_FRAME_STATE_INSIDE_DEADLINE);
 
   if (should_call_set_needs_begin_frame) {
     client_->SetNeedsBeginFrameOnImplThread(needs_begin_frame);
@@ -149,8 +152,8 @@ void Scheduler::SetupNextBeginFrameIfNeeded() {
 
   // Setup PollForAnticipatedDrawTriggers for cases where we want a proactive
   // BeginFrame but aren't requesting one.
-  if (!needs_begin_frame &&
-      state_machine_.ProactiveBeginFrameWantedByImplThread()) {
+  if (!last_set_needs_begin_frame_ &&
+      state_machine_.ShouldPollForAnticipatedDrawTriggers()) {
     if (poll_for_draw_triggers_closure_.IsCancelled()) {

[danakj, 2013/09/17 20:26:19]

As discussed, DCHECK(!needs_begin_frame) with a comment that we should only poll
if BeingFrameNeededByImplThread() is false.

[brianderson, 2013/09/17 21:08:24]

Done.

       poll_for_draw_triggers_closure_.Reset(
           base::Bind(&Scheduler::PollForAnticipatedDrawTriggers,
@@ -167,11 +170,62 @@ void Scheduler::SetupNextBeginFrameIfNeeded() {
 
 void Scheduler::BeginFrame(const BeginFrameArgs& args) {
   TRACE_EVENT0("cc", "Scheduler::BeginFrame");
-  DCHECK(!state_machine_.inside_begin_frame());

[danakj, 2013/09/17 20:26:19]

Can we dcheck against the begin_frame_state() instead?

[brianderson, 2013/09/17 21:08:24]

I moved DCHECKS to OnBeginFrame, OnBeginFrameDeadlinePending, etc - but I can
add them here for more clarity.

   last_begin_frame_args_ = args;
-  state_machine_.DidEnterBeginFrame(args);
+  last_begin_frame_args_.deadline -= client_->DrawDurationEstimate();
+  state_machine_.OnBeginFrame(last_begin_frame_args_);
+  ProcessScheduledActions();
+  state_machine_.OnBeginFrameDeadlinePending();
+
+  if (settings_.using_synchronous_renderer_compositor) {
+    // The synchronous renderer compositor has to make its GL calls
+    // within this call to BeginFrame.
+    // TODO(brianderson): Have the OutputSurface initiate the deadline tasks
+    // so the sychronous renderer compoistor can take advantage of splitting
+    // up the BeginFrame and deadline as well.
+    OnBeginFrameDeadline();
+  } else if (!settings_.deadline_scheduling_enabled) {
+    // We emulate the old non-deadline scheduler here by posting the
+    // deadline task without any delay.
+    PostBeginFrameDeadline(base::TimeTicks());
+  } else if (state_machine_.ShouldTriggerBeginFrameDeadlineEarly()) {
+    // We are ready to draw a new active tree immediately.
+    PostBeginFrameDeadline(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.
+    PostBeginFrameDeadline(last_begin_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 BeginFrame start. This allows us to draw immediately when
+    // there is a new active tree, instead of waiting for the next BeginFrame.
+    // TODO(brianderson): Handle long deadlines (that are past the next frame's
+    // frame time) properly instead of using this hack.
+    PostBeginFrameDeadline(last_begin_frame_args_.frame_time +
+                           last_begin_frame_args_.interval);
+  }
+}
+
+void Scheduler::PostBeginFrameDeadline(base::TimeTicks deadline) {
+  begin_frame_deadline_closure_.Cancel();
+  begin_frame_deadline_closure_.Reset(
+      base::Bind(&Scheduler::OnBeginFrameDeadline, weak_factory_.GetWeakPtr()));
+  client_->PostBeginFrameDeadline(begin_frame_deadline_closure_.callback(),
+                                  deadline);
+}
+
+void Scheduler::OnBeginFrameDeadline() {
+  TRACE_EVENT0("cc", "Scheduler::OnBeginFrameDeadline");
+  begin_frame_deadline_closure_.Cancel();
+  state_machine_.OnBeginFrameDeadline();
   ProcessScheduledActions();
-  state_machine_.DidLeaveBeginFrame();
+  // We only transition out of BEGIN_FRAME_STATE_INSIDE_DEADLINE when all
+  // actions that occur back-to-back in response to entering
+  // BEGIN_FRAME_STATE_INSIDE_DEADLINE have completed. This is important
+  // because sending the BeginFrame to the main thread will not occur if
+  // we transition to BEGIN_FRAME_STATE_IDLE too early.
+  state_machine_.OnBeginFrameIdle();
+  client_->DidBeginFrameDeadlineOnImplThread();
 }
 
 void Scheduler::PollForAnticipatedDrawTriggers() {
@@ -228,7 +282,7 @@ void Scheduler::ProcessScheduledActions() {
         client_->ScheduledActionUpdateVisibleTiles();
         break;
       case SchedulerStateMachine::ACTION_ACTIVATE_PENDING_TREE:
-        client_->ScheduledActionActivatePendingTree();
+        ActivatePendingTree();
         break;
       case SchedulerStateMachine::ACTION_DRAW_AND_SWAP_IF_POSSIBLE:
         DrawAndSwapIfPossible();