Fix java.lang.ArrayIndexOutOfBoundsException in java.util.ArrayList.fastRemove (ArrayList.java:557)

[scottleibrand]

Version 0.3(91)

Stacktrace

Reason

java.lang.ArrayIndexOutOfBoundsException

Link to App Center

• https://appcenter.ms/users/scottleibrand/apps/CoEpi-Android/crashes/errors/3825654970u

[duskoo]

@scottleibrand I am unable to assign the issue to myself: can you add me to the Android team?

[scottleibrand]

Done.

[duskoo]

Stacktrace:
java.util.ArrayList.fastRemove ArrayList.java:557 java.util.ArrayList.remove ArrayList.java:540 org.tcncoalition.tcnclient.bluetooth.TcnBluetoothManager.dequeueFromAdvertising TcnBluetoothManager.kt:128 org.tcncoalition.tcnclient.bluetooth.TcnBluetoothManager.access$dequeueFromAdvertising TcnBluetoothManager.kt:34 org.tcncoalition.tcnclient.bluetooth.TcnBluetoothManager$changeOwnTcn$1.run TcnBluetoothManager.kt:114 java.util.concurrent.ThreadPoolExecutor.processTask ThreadPoolExecutor.java:1187 java.util.concurrent.ThreadPoolExecutor.runWorker ThreadPoolExecutor.java:1152 java.util.concurrent.ThreadPoolExecutor$Worker.run ThreadPoolExecutor.java:641 java.lang.Thread.run Thread.java:929
Crash originates in tcnclient lib.
Likely cause is concurrent modification of 'tcnAdvertisingQueue' (explains index value of -1):

private fun dequeueFromAdvertising(tcn: ByteArray?) { tcn ?: return tcnAdvertisingQueue.remove(tcn) Log.i(TAG, "Dequeued TCN=${Base64.encodeToString(tcn, Base64.NO_WRAP)} from advertising") }

From ArrayList.java:

Note that this implementation is not synchronized. If multiple threads access an ArrayList instance concurrently, and at least one of the threads modifies the list structurally, it must be synchronized externally. (A structural modification is any operation that adds or deletes one or more elements, or explicitly resizes the backing array; merely setting the value of an element is not a structural modification.) This is typically accomplished by synchronizing on some object that naturally encapsulates the list.

Proposed solution: a PR for tcnclient adding synchronization when modifying tcnAdvertisingQueue.