commit 8d76518011390067943d1a42cd83b1bfbeaf06c9
author Kaushik Iska <iska.kaushik@gmail.com> Mon May 11 14:52:22 2020 -0700
committer GitHub <noreply@github.com> Mon May 11 14:52:22 2020 -0700
tree cfae3a0f075980c2407fa17219d7479098d6e70f
parent 044f2542d485f4bd73d64790bebb22ff806ce065

Fix latest_frame_target_time race (#18279)

There are some cases where onAnimatorDraw gets called before
onAnimatorBeginFrame, in these cases we need to update the
latest_frame_target_time to be the target time for the current frame.

This manifested as an issue in release mode Android builds:
https://firebase.corp.google.com/project/flutter-infra/testlab/histories/bh.27c33c672e9b01f2/matrices/4903344583855476919/executions/bs.ee4f6f7ad8671a34

shell/common/animator.cc

diff --git a/shell/common/animator.cc b/shell/common/animator.cc
index 004069b..7e581c0 100644
--- a/shell/common/animator.cc
+++ b/shell/common/animator.cc
@@ -190,7 +190,7 @@
     FML_DLOG(INFO) << "No pending continuation to commit";
   }
 
-  delegate_.OnAnimatorDraw(layer_tree_pipeline_);
+  delegate_.OnAnimatorDraw(layer_tree_pipeline_, last_frame_target_time_);
 }
 
 bool Animator::CanReuseLastLayerTree() {

shell/common/animator.h

diff --git a/shell/common/animator.h b/shell/common/animator.h
index f96acb7..0bab577 100644
--- a/shell/common/animator.h
+++ b/shell/common/animator.h
@@ -35,7 +35,8 @@
     virtual void OnAnimatorNotifyIdle(int64_t deadline) = 0;
 
     virtual void OnAnimatorDraw(
-        fml::RefPtr<Pipeline<flutter::LayerTree>> pipeline) = 0;
+        fml::RefPtr<Pipeline<flutter::LayerTree>> pipeline,
+        fml::TimePoint frame_target_time) = 0;
 
     virtual void OnAnimatorDrawLastLayerTree() = 0;
   };

shell/common/shell.cc

diff --git a/shell/common/shell.cc b/shell/common/shell.cc
index 8d27853..d83fadb 100644
--- a/shell/common/shell.cc
+++ b/shell/common/shell.cc
@@ -952,9 +952,20 @@
 }
 
 // |Animator::Delegate|
-void Shell::OnAnimatorDraw(fml::RefPtr<Pipeline<flutter::LayerTree>> pipeline) {
+void Shell::OnAnimatorDraw(fml::RefPtr<Pipeline<flutter::LayerTree>> pipeline,
+                           fml::TimePoint frame_target_time) {
   FML_DCHECK(is_setup_);
 
+  // record the target time for use by rasterizer.
+  {
+    std::scoped_lock time_recorder_lock(time_recorder_mutex_);
+    if (!latest_frame_target_time_) {
+      latest_frame_target_time_ = frame_target_time;
+    } else if (latest_frame_target_time_ < frame_target_time) {
+      latest_frame_target_time_ = frame_target_time;
+    }
+  }
+
   task_runners_.GetRasterTaskRunner()->PostTask(
       [&waiting_for_first_frame = waiting_for_first_frame_,
        &waiting_for_first_frame_condition = waiting_for_first_frame_condition_,

shell/common/shell.h

diff --git a/shell/common/shell.h b/shell/common/shell.h
index 3c904d8..a39884a 100644
--- a/shell/common/shell.h
+++ b/shell/common/shell.h
@@ -489,8 +489,8 @@
   void OnAnimatorNotifyIdle(int64_t deadline) override;
 
   // |Animator::Delegate|
-  void OnAnimatorDraw(
-      fml::RefPtr<Pipeline<flutter::LayerTree>> pipeline) override;
+  void OnAnimatorDraw(fml::RefPtr<Pipeline<flutter::LayerTree>> pipeline,
+                      fml::TimePoint frame_target_time) override;
 
   // |Animator::Delegate|
   void OnAnimatorDrawLastLayerTree() override;