ensure ReentrantLock is unlocked after being locked, and on same thread #2759
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westnordost
commented
Aug 23, 2024
platform/android/MapLibreAndroid/src/main/java/org/maplibre/android/storage/FileSource.java
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louwers
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Aug 26, 2024
TimSylvester
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Oct 15, 2024
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fixes #2432
The reentrant locks were engaged unconditionally on the then-main thread but the async task was only started conditionally. The unlocking of the locks was managed by the async task.
This lead to two issues:
if the condition checked for in
initializeFileDirsPathswas already met, the locks were engaged but never unlocked. Any subsequent attempt to lock would just block execution forever.(hypothetical, not tested:) the thread id of the app's main thread when the async task finished and thus calls
onPostExecuteoronCancelon that thread may differ from the thread id of the app's main thread wheninitializeFileDirsPathswas invoked: E.g. if the app was sent to background and effectively re-started later by the Android system. However, reentrant locks require to be locked/unlocked on the same thread, otherwise they will throw anIllegalMonitorStateException. The previous mechanism could not ensure this.In any case, I am pretty sure either of these two issues is the cause for #2432.