Fix bookkeeping of ongoing calls for recursive calls to CallbackQueue::callAvailable() #2378
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…::callAvailable() When copying over pending calls to the thread-local callback queue held in tls->callbacks, the calling_ member was not updated correctly with the number of added callbacks if tls->callbacks was not empty before. This may be the case if callAvailable() is called recursively, e.g. from within another callback. The issue should only affect the empty() and isEmpty() member functions, which apparently are unused within the CallbackQueue class or within roscpp itself, but may be used by external code. Signed-off-by: Johannes Meyer <[email protected]>
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While investigating a segmentation fault in one of our applications, and while working on #2377 yesterday, I found another small possible bug in the implementation of
ros::CallbackQueue::callAvailable()in the way it keeps track of how many callbacks are currently being executed in any spinner thread, namely thecalling_variable.When copying over pending calls to the thread-local callback queue held in
tls->callbacks, thecalling_member was not updated correctly with the number of added callbacks iftls->callbackswas not empty before. This may be the case ifcallAvailable()is called recursively, e.g. from within another callback.The issue should only affect the
calling_member andempty()andisEmpty()member functions, which apparently are unused within roscpp itself, but may be used by external code.