New in version 5.14.
QRecursiveMutexclass is a mutex, like
QMutex, with which it is API-compatible. It differs from
lock()calls from the same thread any number of times.
QMutexwould deadlock in this situation.
QRecursiveMutexis much more expensive to construct and operate on, so use a plain
QMutexwhenever you can. Sometimes, one public function, however, calls another public function, and they both need to lock the same mutex. In this case, you have two options:
Factor the code that needs mutex protection into private functions, which assume that the mutex is held when they are called, and lock a plain
QMutexin the public functions before you call the private implementation ones.
Or use a recursive mutex, so it doesn’t matter that the first public function has already locked the mutex when the second one wishes to do so.
Constructs a new recursive mutex. The mutex is created in an unlocked state.
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