Fully delete duplicate entries inside LatencyTracker
Inside LatencyTracker, we use 2 collections that must always be in sync:
mTimelines and mEventTimes.
However, when duplicate input events are encountered, we do not treat
these collections equally. In one of them, we fully remove all data
associated with the duplicate inputEventId. In the other one, however,
we only remove the entry that matches both the inputEventId and the
eventTime. This means that the two collections will get out of sync,
because the entry with the mismatching eventTime will be kept in
mEventTimes.
To fix this, fully remove all entries with the duplicate inputEventId,
no matter what the eventTime is. Unfortunately, it means that we have to
traverse the entire collection of mEventTimes. However, since this event
should not occur often, it should not impact performance.
This issue was discovered via the use of the newly added fuzzer for
LatencyTracker. The fuzzer would hit this condition in about 2 seconds
after the run has started. This issue could have been identified the
fuzzer was in place from the start.
The removal of api 'reportNow':
The api 'reportNow' was added for convenience of writing tests. However,
this api has reduced the code coverage, since we would now short-circuit
the code around 'trackListener' that was responsible for event
reporting. This is why, when the issue was first being worked on, the
tests for duplicate events did not yield any crashes. To avoid such
problems in the future, fully remove this api and replace with a
'triggerEventReporting' method that's defined in the tests. This way,
the api's that are used by production code and by tests are identical.
Bug: 169866723
Test: m inputflinger_latencytracker_fuzzer && adb sync data && adb shell /data/fuzz/arm64/inputflinger_latencytracker_fuzzer/inputflinger_latencytracker_fuzzer
Test: atest inputflinger_tests:LatencyTrackerTest
Change-Id: I04069cf2c9eb1154e3324b25c8c4bdff32d84d3f
6 files changed