commit 7c03ce6508a7887e732abe03dc2dd53e146c008e
author Ady Abraham <adyabr@google.com> Fri Jul 19 10:59:45 2019 -0700
committer Ady Abraham <adyabr@google.com> Tue Jul 23 09:35:29 2019 -0700
tree a62c9789330b0fb3c5703fcd0140b93a9dd7b4ca
parent ddb5f84005c03cb000d9f2ad042347e8d0e336de

SurfaceFlinger: calculate expected present once

Calculate the expected present time in the beginning of the frame
and use the same value across the frame composition.

Bug: 137873466
Test: App transitions
Change-Id: I0b41c62796f6150702e8d50ec7d28838d3a5aa87

services/surfaceflinger/SurfaceFlinger.cpp

diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 0c9263b..56cccfb 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -1686,22 +1686,26 @@
     return fence != Fence::NO_FENCE && (fence->getStatus() == Fence::Status::Unsignaled);
 }
 
-nsecs_t SurfaceFlinger::getExpectedPresentTime() NO_THREAD_SAFETY_ANALYSIS {
+void SurfaceFlinger::populateExpectedPresentTime() NO_THREAD_SAFETY_ANALYSIS {
     DisplayStatInfo stats;
     mScheduler->getDisplayStatInfo(&stats);
     const nsecs_t presentTime = mScheduler->getDispSyncExpectedPresentTime();
     // Inflate the expected present time if we're targetting the next vsync.
-    const nsecs_t correctedTime =
+    mExpectedPresentTime =
             mVsyncModulator.getOffsets().sf < mPhaseOffsets->getOffsetThresholdForNextVsync()
             ? presentTime
             : presentTime + stats.vsyncPeriod;
-    return correctedTime;
 }
 
 void SurfaceFlinger::onMessageReceived(int32_t what) NO_THREAD_SAFETY_ANALYSIS {
     ATRACE_CALL();
     switch (what) {
         case MessageQueue::INVALIDATE: {
+            // calculate the expected present time once and use the cached
+            // value throughout this frame to make sure all layers are
+            // seeing this same value.
+            populateExpectedPresentTime();
+
             bool frameMissed = previousFrameMissed();
             bool hwcFrameMissed = mHadDeviceComposition && frameMissed;
             bool gpuFrameMissed = mHadClientComposition && frameMissed;