Add exception handling for mutex or condition variable failures #268
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Signed-off-by: Johannes Meyer <[email protected]>
…ations There are several things that could go wrong when trying to initialize, lock, unlock, signal or wait on pthread mutexes and condition variables. RTT should check the return value of low-level OS abstraction functions and throw an exception (or at least assert) in case of an unexpected error. Signed-off-by: Johannes Meyer <[email protected]>
Xenomai mutexes are always recursive. Signed-off-by: Johannes Meyer <[email protected]>
Signed-off-by: Johannes Meyer <[email protected]>
pthread mutexes in normal mode do not provide deadlock detection. It would be possible to the mutex type to PTHREAD_MUTEX_ERRORCHECK, which would trigger the EDEADLK exception, but it comes with a performance penalty. Might be a candidate for a compile-time option. Signed-off-by: Johannes Meyer <[email protected]>
…y us If a Mutex or MutexResursive instance is still locked by another thread upon destruction, the handle becomes dangling. Signed-off-by: Johannes Meyer <[email protected]>
…ndition-exceptions
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RTT - or more specifically the
RTT::os::Mutex,RTT::os::MutexRecursiveandRTT::os::Conditionimplementations - were not checking for errors returned by the underlying OS system calls, which I think is a serious issue. As a consequence errors in using those primitives within RTT or in user code remain undetected which may lead to unpredictable and hard to debug behavior of Orocos applications.This pull request introduces exception handling in the
Mutex,MutexRecursiveandConditionimplementations. In order to avoid ambiguity if the return value of a OS abstraction method (rtos_*()) represents an error or not they now return negative values in the error case consistently and the absolute value holds the error code.I added a unit test (as part of the
core_test) for the single thread behavior ofMutexandMutexRecursive. The test currently fails for the xenomai target, which might reveal a problem in the implementation ofrtos_mutex_unlock():Futhermore the IPC tests fail with this patch because the CORBA transport implementations tries to lock RTT mutexes from ORB threads, which is not allowed in Xenomai and triggers an exception now.