[TimeStats] Expose pathological latch counters

* Missed latch because the acquire fence didn't fire
* Latched early because the desired present time was bad

Bug: 135478131
Test: libsurfaceflinger_unittest

Change-Id: Id02a62c222cb497c05889dd198be5fea6d64893a

1 files changed, 12 insertions, 1 deletions

diff --git a/services/surfaceflinger/BufferQueueLayer.cpp b/services/surfaceflinger/BufferQueueLayer.cpp
index b55e62b88c..bd8eafe683 100644
--- a/services/surfaceflinger/BufferQueueLayer.cpp
+++ b/services/surfaceflinger/BufferQueueLayer.cpp
@@ -117,6 +117,10 @@ bool BufferQueueLayer::shouldPresentNow(nsecs_t expectedPresentTime) const {
              "relative to expectedPresent %" PRId64,
              getDebugName(), addedTime, expectedPresentTime);
 
+    if (!isPlausible) {
+        mFlinger->mTimeStats->incrementBadDesiredPresent(getSequence());
+    }
+
     const bool isDue = addedTime < expectedPresentTime;
     return isDue || !isPlausible;
 }
@@ -154,7 +158,14 @@ bool BufferQueueLayer::fenceHasSignaled() const {
         // able to be latched. To avoid this, grab this buffer anyway.
         return true;
     }
-    return mQueueItems[0].mFenceTime->getSignalTime() != Fence::SIGNAL_TIME_PENDING;
+    const bool fenceSignaled =
+            mQueueItems[0].mFenceTime->getSignalTime() != Fence::SIGNAL_TIME_PENDING;
+    if (!fenceSignaled) {
+        mFlinger->mTimeStats->incrementLatchSkipped(getSequence(),
+                                                    TimeStats::LatchSkipReason::LateAcquire);
+    }
+
+    return fenceSignaled;
 }
 
 bool BufferQueueLayer::framePresentTimeIsCurrent(nsecs_t expectedPresentTime) const {