commit 3fcfd8b6d7d222ec6b220debf806733e36d6d285
author Ady Abraham <adyabr@google.com> Tue Jul 12 12:31:00 2022 -0700
committer Ady Abraham <adyabr@google.com> Tue Aug 09 23:39:48 2022 +0000
tree 5c5cf1a670112808719745cbb4f9703758dc8d17
parent fdff5cded8c1cc5c86a77947e0d1c6b3c1179abb

SF: avoid dispatching close vsyncs

When the vsync period changes, the next vsync callback might be targeting
the same vsync event, that now has a newer time based on the current
period. This means that the client might be woken up for 2 frames within
the same vsync. This change tries to avoid that by making sure that the
vsync callbacks are at least a vsync period apart minus a safe distance.

Test: new unit test
Bug: 235566681
Change-Id: Ifb9b3f8b726976452d5131c8b758d1d5ca0e3639

services/surfaceflinger/tests/unittests/VSyncDispatchTimerQueueTest.cpp

diff --git a/services/surfaceflinger/tests/unittests/VSyncDispatchTimerQueueTest.cpp b/services/surfaceflinger/tests/unittests/VSyncDispatchTimerQueueTest.cpp
index b7f968d..f660753 100644
--- a/services/surfaceflinger/tests/unittests/VSyncDispatchTimerQueueTest.cpp
+++ b/services/surfaceflinger/tests/unittests/VSyncDispatchTimerQueueTest.cpp
@@ -44,6 +44,8 @@
         ON_CALL(*this, nextAnticipatedVSyncTimeFrom(_))
                 .WillByDefault(Invoke(this, &MockVSyncTracker::nextVSyncTime));
         ON_CALL(*this, addVsyncTimestamp(_)).WillByDefault(Return(true));
+        ON_CALL(*this, currentPeriod())
+                .WillByDefault(Invoke(this, &MockVSyncTracker::getCurrentPeriod));
     }
 
     MOCK_METHOD1(addVsyncTimestamp, bool(nsecs_t));
@@ -62,6 +64,8 @@
         return (timePoint - (timePoint % mPeriod) + mPeriod);
     }
 
+    nsecs_t getCurrentPeriod() const { return mPeriod; }
+
 protected:
     nsecs_t const mPeriod;
 };
@@ -393,6 +397,43 @@
     EXPECT_THAT(cb1.mCalls[0], Eq(1063));
 }
 
+TEST_F(VSyncDispatchTimerQueueTest, noCloseCallbacksAfterPeriodChange) {
+    EXPECT_CALL(mStubTracker, nextAnticipatedVSyncTimeFrom(_))
+            .Times(4)
+            .WillOnce(Return(1000))
+            .WillOnce(Return(2000))
+            .WillOnce(Return(2500))
+            .WillOnce(Return(4000));
+
+    Sequence seq;
+    EXPECT_CALL(mMockClock, alarmAt(_, 900)).InSequence(seq);
+    EXPECT_CALL(mMockClock, alarmAt(_, 1900)).InSequence(seq);
+    EXPECT_CALL(mMockClock, alarmAt(_, 3900)).InSequence(seq);
+
+    CountingCallback cb(mDispatch);
+
+    mDispatch.schedule(cb, {.workDuration = 100, .readyDuration = 0, .earliestVsync = 0});
+
+    advanceToNextCallback();
+
+    ASSERT_THAT(cb.mCalls.size(), Eq(1));
+    EXPECT_THAT(cb.mCalls[0], Eq(1000));
+
+    mDispatch.schedule(cb, {.workDuration = 100, .readyDuration = 0, .earliestVsync = 1000});
+
+    advanceToNextCallback();
+
+    ASSERT_THAT(cb.mCalls.size(), Eq(2));
+    EXPECT_THAT(cb.mCalls[1], Eq(2000));
+
+    mDispatch.schedule(cb, {.workDuration = 100, .readyDuration = 0, .earliestVsync = 2000});
+
+    advanceToNextCallback();
+
+    ASSERT_THAT(cb.mCalls.size(), Eq(3));
+    EXPECT_THAT(cb.mCalls[2], Eq(4000));
+}
+
 TEST_F(VSyncDispatchTimerQueueTest, rearmsFaroutTimeoutWhenCancellingCloseOne) {
     EXPECT_CALL(mStubTracker, nextAnticipatedVSyncTimeFrom(_))
             .Times(4)