boost thread - mutex.lock() doesn't throw exception

[anonymous]

lock() member function of mutex object doesn't throw any exception on error. There is no error handling capabilities because lock() doesn't return any value.

[Steven Watanabe]

What errors do you expect from pthread_mutex_lock?

[anonymous]

Replying to steven_watanabe:

What errors do you expect from pthread_mutex_lock?

mutex.lock() call may fail - and it sometimes does (according, for example, to POSIX mutexes), so we need to know that something went wrong. One way to report an error is to throw system_error exception, like for example just::thread library does: ​http://www.stdthread.co.uk/doc/headers/mutex/mutex/lock.html

[Steven Watanabe]

Well, it doesn't fail randomly. Most of the possible failures either cannot happen with boost::mutex or are a result of undefined behavior. However, EAGAIN and ENOMEM appear to be possible.

[anonymous]

Replying to steven_watanabe:

Well, it doesn't fail randomly. Most of the possible failures either cannot happen with boost::mutex or are a result of undefined behavior. However, EAGAIN and ENOMEM appear to be possible.

On QNX pthread_mutex_lock may also return EDEADLK - if mutex was not set as recursive, or ETIMEDOUT if "A kernel timeout unblocked the call", and all this return values including EAGAIN are possible. At least this errors should be logged somewhere and execution of the thread should be cancelled.

[Steven Watanabe]

Relocking a mutex that is already locked by the current thread is undefined behavior, so EDEADLK is irrelevant.

[viboes]

I propose to resolve as invalid as works as designed.

[Anthony Williams]

Fixed on trunk