cc: Single-threaded impl-side painting for unit tests

cc/trees/single_thread_proxy.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/trees/single_thread_proxy.h"
 
 #include "base/auto_reset.h"
 #include "base/debug/trace_event.h"
 #include "cc/debug/benchmark_instrumentation.h"
 #include "cc/output/context_provider.h"
@@ skipping 29 matching lines @@
       timing_history_(layer_tree_host->rendering_stats_instrumentation()),
       next_frame_is_newly_committed_frame_(false),
       inside_draw_(false),
       defer_commits_(false),
       commit_was_deferred_(false),
       commit_requested_(false),
       weak_factory_(this) {
   TRACE_EVENT0("cc", "SingleThreadProxy::SingleThreadProxy");
   DCHECK(Proxy::IsMainThread());
   DCHECK(layer_tree_host);
-
-  // Impl-side painting not supported without threaded compositing.
-  CHECK(!layer_tree_host->settings().impl_side_painting)
-      << "Threaded compositing must be enabled to use impl-side painting.";
 }
 
 void SingleThreadProxy::Start() {
   DebugScopedSetImplThread impl(this);
   layer_tree_host_impl_ = layer_tree_host_->CreateLayerTreeHostImpl(this);
 }
 
 SingleThreadProxy::~SingleThreadProxy() {
   TRACE_EVENT0("cc", "SingleThreadProxy::~SingleThreadProxy");
   DCHECK(Proxy::IsMainThread());
@@ skipping 163 matching lines @@
     DCHECK(!scroll_info->scrolls.size());
     DCHECK_EQ(1.f, scroll_info->page_scale_delta);
 #endif
 
     RenderingStatsInstrumentation* stats_instrumentation =
         layer_tree_host_->rendering_stats_instrumentation();
     benchmark_instrumentation::IssueMainThreadRenderingStatsEvent(
         stats_instrumentation->main_thread_rendering_stats());
     stats_instrumentation->AccumulateAndClearMainThreadStats();
   }
+
+  if (layer_tree_host_->settings().impl_side_painting) {
+    // TODO(enne): just commit directly to the active tree.
+    //
+    // Synchronously activate during commit to satisfy any potential
+    // SetNextCommitWaitsForActivation calls.  Unfortunately, the tree
+    // might not be ready to draw, so DidActivateSyncTree must set
+    // the flag to force the tree to not draw until textures are ready.
+    NotifyReadyToActivate();

[enne (OOO), 2014/08/27 23:53:38]

Unfortunateness #1: This works, but feels unsafe.

SetNextCommitWaitsForActivation really means that you want to activate
synchronously inside of commit.  I think that is the only way to make that logic
work in a single-threaded world.  Unfortunately, Because ScheduledActionCommit
is already inside of Scheduler::ProcessActions, NotifyReadyToActivate will not
cause ScheduledActionActivateSyncTree to happen.  So, it's impossible to tell
from inside of ScheduledActionCommit that ScheduledActionActivate will happen
immediately afterwards.  Looking at the code, it will, always.  However, I don't
know how to check this.

I could add some hokey "PleaseExplodeIfActivationHasntHappened" flag into
Scheduler and check that when returning from ScheduledActionCommit.  That's the
best I can come up with.

[danakj, 2014/09/03 17:01:32]

I'm confused, NotifyReadyToActivate won't cause it to happen? Do you mean it
will
happen when we unwind the stack to ProcessActions? That is what I am expecting.
You could DCHECK there's no pending tree in STP::CommitComplete?

[enne (OOO), 2014/09/03 19:41:28]

Yes, that's exactly it.  NotifyReadyToActivate will not cause a synchronous
activation; it will instead (hopefully) cause an activation during the stack
unwind.
Great suggestion! Done.

+  } else {
+    CommitComplete();
+  }
+}
+
+void SingleThreadProxy::CommitComplete() {
+  DebugScopedSetMainThread main(this);
+
   layer_tree_host_->CommitComplete();
   layer_tree_host_->DidBeginMainFrame();
   timing_history_.DidCommit();
 
   next_frame_is_newly_committed_frame_ = true;
 }
 
 void SingleThreadProxy::SetNeedsCommit() {
   DCHECK(Proxy::IsMainThread());
   DebugScopedSetImplThread impl(this);
   client_->ScheduleComposite();
   if (scheduler_on_impl_thread_)
     scheduler_on_impl_thread_->SetNeedsCommit();
   commit_requested_ = true;
 }
 
 void SingleThreadProxy::SetNeedsRedraw(const gfx::Rect& damage_rect) {
   TRACE_EVENT0("cc", "SingleThreadProxy::SetNeedsRedraw");
   DCHECK(Proxy::IsMainThread());
   DebugScopedSetImplThread impl(this);
   client_->ScheduleComposite();
   SetNeedsRedrawRectOnImplThread(damage_rect);
 }
 
 void SingleThreadProxy::SetNextCommitWaitsForActivation() {
-  // There is no activation here other than commit. So do nothing.
+  // Activation always forced in commit, so nothing to do.
   DCHECK(Proxy::IsMainThread());
 }
 
 void SingleThreadProxy::SetDeferCommits(bool defer_commits) {
   DCHECK(Proxy::IsMainThread());
   // Deferring commits only makes sense if there's a scheduler.
   if (!scheduler_on_impl_thread_)
     return;
   if (defer_commits_ == defer_commits)
     return;
@@ skipping 47 matching lines @@
 void SingleThreadProxy::OnCanDrawStateChanged(bool can_draw) {
   TRACE_EVENT1(
       "cc", "SingleThreadProxy::OnCanDrawStateChanged", "can_draw", can_draw);
   DCHECK(Proxy::IsImplThread());
   UpdateBackgroundAnimateTicking();
   if (scheduler_on_impl_thread_)
     scheduler_on_impl_thread_->SetCanDraw(can_draw);
 }
 
 void SingleThreadProxy::NotifyReadyToActivate() {
-  // Impl-side painting only.
-  NOTREACHED();
+  TRACE_EVENT0("cc", "SingleThreadProxy::NotifyReadyToActivate");
+  DebugScopedSetImplThread impl(this);
+  if (scheduler_on_impl_thread_)
+    scheduler_on_impl_thread_->NotifyReadyToActivate();
 }
 
 void SingleThreadProxy::SetNeedsRedrawOnImplThread() {
   client_->ScheduleComposite();
   if (scheduler_on_impl_thread_)
     scheduler_on_impl_thread_->SetNeedsRedraw();
 }
 
 void SingleThreadProxy::SetNeedsAnimateOnImplThread() {
   SetNeedsRedrawOnImplThread();
 }
 
 void SingleThreadProxy::SetNeedsManageTilesOnImplThread() {
-  // Impl-side painting only.
-  NOTREACHED();
+  TRACE_EVENT0("cc", "SingleThreadProxy::SetNeedsManageTilesOnImplThread");
+  if (scheduler_on_impl_thread_)
+    scheduler_on_impl_thread_->SetNeedsManageTiles();
 }
 
 void SingleThreadProxy::SetNeedsRedrawRectOnImplThread(
     const gfx::Rect& damage_rect) {
   layer_tree_host_impl_->SetViewportDamage(damage_rect);
   SetNeedsRedrawOnImplThread();
 }
 
 void SingleThreadProxy::DidInitializeVisibleTileOnImplThread() {
-  // Impl-side painting only.
-  NOTREACHED();
+  TRACE_EVENT0("cc", "SingleThreadProxy::DidInitializeVisibleTileOnImplThread");
+  if (scheduler_on_impl_thread_)
+    scheduler_on_impl_thread_->SetNeedsRedraw();
 }
 
 void SingleThreadProxy::SetNeedsCommitOnImplThread() {
   client_->ScheduleComposite();
   if (scheduler_on_impl_thread_)
     scheduler_on_impl_thread_->SetNeedsCommit();
 }
 
 void SingleThreadProxy::PostAnimationEventsToMainThreadOnImplThread(
     scoped_ptr<AnimationEventsVector> events) {
@@ skipping 16 matching lines @@
 
   if (!contents_texture_manager || !resource_provider)
     return false;
 
   return contents_texture_manager->ReduceMemoryOnImplThread(
       limit_bytes, priority_cutoff, resource_provider);
 }
 
 bool SingleThreadProxy::IsInsideDraw() { return inside_draw_; }
 
+void SingleThreadProxy::RenewTreePriority() {
+  // TODO(enne): Sync directly to the active tree in the future
+  // so that there isn't two trees.
+  if (scheduler_on_impl_thread_)
+    scheduler_on_impl_thread_->SetSmoothnessTakesPriority(false);

[danakj, 2014/09/03 17:01:32]

Is there really any need to do this? Should we just do this once at startup and
nothing in here?

[enne (OOO), 2014/09/03 19:41:28]

Done.

+}
+
+void SingleThreadProxy::DidActivateSyncTree() {
+  // Non-impl-side painting finishes commit in DoCommit.  Impl-side painting
+  // defers until here to simulate SetNextCommitWaitsForActivation.
+  if (layer_tree_host_impl_->settings().impl_side_painting) {
+    // This is required because NotifyReadyToActivate gets called when
+    // the pending tree is not actually ready in the SingleThreadProxy.
+    layer_tree_host_impl_->active_tree()->SetRequiresHighResToDraw();

[danakj, 2014/09/03 17:01:32]

This is going to be bad when we are OOM? We will skip frames cuz of this flag if
any tile is a checkerboard. I'm not sure what to suggest tho.. or am I wrong and
this is okay?

[enne (OOO), 2014/09/03 19:41:28]

I think the discussion we had today about raster-on-demand (or alternatively
calling it like "I can't get a resource for this so consider it high res", but
in a more pithy way) covers this case.

[danakj, 2014/09/03 19:49:30]

Hm, can you explain how? I can see how that would interact with activation. But
when this flag is true, then PrepareToDraw returns DRAW_ABORTED_MISSING_STUFF
which will cause frames to not be drawn?

[enne (OOO), 2014/09/03 20:02:48]

Looking at TileManager, we only set RasterOnDemand when the tile is required for
activation.  Should we be doing this for visible tiles as well?

Also, this is not a new problem with this patch.  This would already be a
problem for OOMing pages since we set this flag when a tab goes invisible.

+
+    // Since activation could cause tasks to run, post CommitComplete
+    // separately so that it runs after these tasks.  This is the loose
+    // equivalent of blocking commit until activation and also running
+    // all tasks posted during commit/activation before CommitComplete.
+    MainThreadTaskRunner()->PostTask(

[enne (OOO), 2014/08/27 23:53:39]

Unfortunateness #2: Because activation is controlled via the scheduler, there's
no stack frame where I can block all post tasks.  So, things like mailbox
returning gets posted during commit.  That means when DidActivateSyncTree is
called, they've been posted but haven't run.  So, CommitComplete can't be called
directly or it will happen before those tasks (incorrectly).  To fix this
ordering, I just PostTask CommitComplete here.  Given that commit -> activation
-> DidActivateSyncTree have all happened synchronously, I think this is legit,
but it's weird.

I could potentially create a member variable blocked task runner and create it
in commit and destroy it here, rather than the scoped version that exists inside
of commit today.  Maybe?

[danakj, 2014/09/03 17:01:32]

Ya, creating a CaptureTasks and holding it thru the activation would be more
performant.

[enne (OOO), 2014/09/03 19:41:28]

Done.

+        FROM_HERE,
+        base::Bind(&SingleThreadProxy::CommitComplete,
+                   weak_factory_.GetWeakPtr()));
+  }
+
+  UpdateBackgroundAnimateTicking();
+  timing_history_.DidActivateSyncTree();
+}
+
+void SingleThreadProxy::DidManageTiles() {
+  DCHECK(layer_tree_host_impl_->settings().impl_side_painting);
+  DCHECK(Proxy::IsImplThread());
+  if (scheduler_on_impl_thread_)
+    scheduler_on_impl_thread_->DidManageTiles();
+}
+
 void SingleThreadProxy::UpdateRendererCapabilitiesOnImplThread() {
   DCHECK(IsImplThread());
   renderer_capabilities_for_main_thread_ =
       layer_tree_host_impl_->GetRendererCapabilities().MainThreadCapabilities();
 }
 
-void SingleThreadProxy::DidManageTiles() {
-  // Impl-side painting only.
-  NOTREACHED();
-}
-
 void SingleThreadProxy::DidLoseOutputSurfaceOnImplThread() {
   TRACE_EVENT0("cc", "SingleThreadProxy::DidLoseOutputSurfaceOnImplThread");
   {
     DebugScopedSetMainThread main(this);
     // This must happen before we notify the scheduler as it may try to recreate
     // the output surface if already in BEGIN_IMPL_FRAME_STATE_IDLE.
     layer_tree_host_->DidLoseOutputSurface();
   }
   client_->DidAbortSwapBuffers();
   if (scheduler_on_impl_thread_)
@@ skipping 22 matching lines @@
 
 void SingleThreadProxy::CompositeImmediately(base::TimeTicks frame_begin_time) {
   TRACE_EVENT0("cc", "SingleThreadProxy::CompositeImmediately");
   DCHECK(Proxy::IsMainThread());
   DCHECK(!layer_tree_host_->output_surface_lost());
 
   BeginFrameArgs begin_frame_args = BeginFrameArgs::Create(
       frame_begin_time, base::TimeTicks(), BeginFrameArgs::DefaultInterval());
   DoCommit(begin_frame_args);
 
+  DCHECK(!layer_tree_host_impl_->settings().impl_side_painting)
+      << "Impl-side painting and synchronous compositing are not supported.";
+
   LayerTreeHostImpl::FrameData frame;
   DoComposite(frame_begin_time, &frame);
 }
 
 void SingleThreadProxy::AsValueInto(base::debug::TracedValue* state) const {
   // The following line casts away const modifiers because it is just
   // setting debug state. We still want the AsValue() function and its
   // call chain to be const throughout.
   DebugScopedSetImplThread impl(const_cast<SingleThreadProxy*>(this));
 
@@ skipping 180 matching lines @@
   DoCommit(layer_tree_host_impl_->CurrentBeginFrameArgs());
 }
 
 void SingleThreadProxy::ScheduledActionAnimate() {
   TRACE_EVENT0("cc", "ScheduledActionAnimate");
   layer_tree_host_impl_->Animate(
       layer_tree_host_impl_->CurrentBeginFrameArgs().frame_time);
 }
 
 void SingleThreadProxy::ScheduledActionUpdateVisibleTiles() {
-  // Impl-side painting only.
-  NOTREACHED();
+  DebugScopedSetImplThread impl(this);
+  layer_tree_host_impl_->UpdateVisibleTiles();
 }
 
 void SingleThreadProxy::ScheduledActionActivateSyncTree() {
+  DebugScopedSetImplThread impl(this);
+  layer_tree_host_impl_->ActivateSyncTree();
 }
 
 void SingleThreadProxy::ScheduledActionBeginOutputSurfaceCreation() {
   DebugScopedSetMainThread main(this);
   DCHECK(scheduler_on_impl_thread_);
   // If possible, create the output surface in a post task.  Synchronously
   // creating the output surface makes tests more awkward since this differs
   // from the ThreadProxy behavior.  However, sometimes there is no
   // task runner.
   if (Proxy::MainThreadTaskRunner()) {
     MainThreadTaskRunner()->PostTask(
         FROM_HERE,
         base::Bind(&SingleThreadProxy::CreateAndInitializeOutputSurface,
                    weak_factory_.GetWeakPtr()));
   } else {
     CreateAndInitializeOutputSurface();
   }
 }
 
 void SingleThreadProxy::ScheduledActionManageTiles() {
-  // Impl-side painting only.
-  NOTREACHED();
+  TRACE_EVENT0("cc", "SingleThreadProxy::ScheduledActionManageTiles");
+  DCHECK(layer_tree_host_impl_->settings().impl_side_painting);
+  DebugScopedSetImplThread impl(this);
+  layer_tree_host_impl_->ManageTiles();
 }
 
 void SingleThreadProxy::DidAnticipatedDrawTimeChange(base::TimeTicks time) {
 }
 
 base::TimeDelta SingleThreadProxy::DrawDurationEstimate() {
   return timing_history_.DrawDurationEstimate();
 }
 
 base::TimeDelta SingleThreadProxy::BeginMainFrameToCommitDurationEstimate() {
   return timing_history_.BeginMainFrameToCommitDurationEstimate();
 }
 
 base::TimeDelta SingleThreadProxy::CommitToActivateDurationEstimate() {
   return timing_history_.CommitToActivateDurationEstimate();
 }
 
 void SingleThreadProxy::DidBeginImplFrameDeadline() {
   layer_tree_host_impl_->ResetCurrentBeginFrameArgsForNextFrame();
 }
 
 }  // namespace cc