SF: avoid rearming Timer during cancel
Averts a rare race condition by which a callback would be moved back a
vsync period inappropriately by rearming the callback-dispatching timer
only when the next-up callback was the one that was cancelled.
This was an analagous problem (but through the cancel() path) to
I0e7e2e3698ed6d1765082db20d9cf25f6e6c2db2
Test: 2 new unit tests
Test: boot to home, inspect for problems
Test: dogfood patch on device
Test: A/B uibench sanity check
Fixes: 154303580
Change-Id: I02b2ba12623ac683d9b1c592fdc35e7c7494261a
diff --git a/services/surfaceflinger/tests/unittests/VSyncDispatchTimerQueueTest.cpp b/services/surfaceflinger/tests/unittests/VSyncDispatchTimerQueueTest.cpp
index 793cb8b..d940dc5 100644
--- a/services/surfaceflinger/tests/unittests/VSyncDispatchTimerQueueTest.cpp
+++ b/services/surfaceflinger/tests/unittests/VSyncDispatchTimerQueueTest.cpp
@@ -701,6 +701,52 @@
EXPECT_THAT(cb.mCalls.size(), Eq(1));
}
+// b/154303580.
+TEST_F(VSyncDispatchTimerQueueTest, skipsRearmingWhenNotNextScheduled) {
+ Sequence seq;
+ EXPECT_CALL(mMockClock, alarmIn(_, 600)).InSequence(seq);
+ EXPECT_CALL(mMockClock, alarmCancel()).InSequence(seq);
+ CountingCallback cb1(mDispatch);
+ CountingCallback cb2(mDispatch);
+
+ EXPECT_EQ(mDispatch.schedule(cb1, 400, 1000), ScheduleResult::Scheduled);
+ EXPECT_EQ(mDispatch.schedule(cb2, 100, 2000), ScheduleResult::Scheduled);
+
+ mMockClock.setLag(100);
+ mMockClock.advanceBy(620);
+
+ EXPECT_EQ(mDispatch.cancel(cb2), CancelResult::Cancelled);
+
+ mMockClock.advanceBy(80);
+
+ EXPECT_THAT(cb1.mCalls.size(), Eq(1));
+ EXPECT_THAT(cb2.mCalls.size(), Eq(0));
+}
+
+TEST_F(VSyncDispatchTimerQueueTest, rearmsWhenCancelledAndIsNextScheduled) {
+ Sequence seq;
+ EXPECT_CALL(mMockClock, alarmIn(_, 600)).InSequence(seq);
+ EXPECT_CALL(mMockClock, alarmIn(_, 1280)).InSequence(seq);
+ EXPECT_CALL(mMockClock, alarmCancel()).InSequence(seq);
+ CountingCallback cb1(mDispatch);
+ CountingCallback cb2(mDispatch);
+
+ EXPECT_EQ(mDispatch.schedule(cb1, 400, 1000), ScheduleResult::Scheduled);
+ EXPECT_EQ(mDispatch.schedule(cb2, 100, 2000), ScheduleResult::Scheduled);
+
+ mMockClock.setLag(100);
+ mMockClock.advanceBy(620);
+
+ EXPECT_EQ(mDispatch.cancel(cb1), CancelResult::Cancelled);
+
+ EXPECT_THAT(cb1.mCalls.size(), Eq(0));
+ EXPECT_THAT(cb2.mCalls.size(), Eq(0));
+ mMockClock.advanceToNextCallback();
+
+ EXPECT_THAT(cb1.mCalls.size(), Eq(0));
+ EXPECT_THAT(cb2.mCalls.size(), Eq(1));
+}
+
class VSyncDispatchTimerQueueEntryTest : public testing::Test {
protected:
nsecs_t const mPeriod = 1000;