Fix race condition when waiting for functions #304
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Without the added lock of the message mutex it can happen that the calling thread wakes up and checks the completion condition in waitForMessagesInternal(), but the runner engine finishes and signals the condition variable in processFunctions() before the calling thread enters waiting state again. Signed-off-by: Johannes Meyer <johannes@intermodalics.eu>
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Without the added lock of the message mutex it can happen that the calling thread wakes up and checks the completion condition in
waitForMessagesInternal(), but the runner engine finishes and signals the condition variable inprocessFunctions()before the calling thread enters waiting state again.This is a race condition and it is hard to catch it in a unit test.
This lock was already introduced in 58cb4bb as part of #91, but has been reverted in b9f2f34 before the merge. There was a comment in psoetens#3 (comment) that explains why the revert was needed, which also leaves the question open whether to keep the lock in
processFunctions():