Pthreads. How to check is mutex locked already

Question

I need to write bicycle function that would be equals to pthread_mutex_trylock(...)
How can I do this?
I could not find the source code of this function, and I'm afraid, even if I find them, they are too complex for copy-paste. But I'll upvote for the link anyway.
I need to write simple function which could just take the mutex if it's not locked or return if it's not.

Answer 1

My feeling is that you haven't provided enough information in your question. The actual pthread mutex implementation in glibc is a very complex beast (it's meant to support many use cases and policies) and is hardly suitable for training assignments.

Therefore, you may actually be required to do something different then digging into pthread mutex internals.

One possibility: it may be enough for you to use an alternative to pthread_mutex_trylock. Such alternative surely exists and is called pthread_mutex_timedlock (invoke it with timeout of 0).

Another possibility: you may need to come with your own mutex implementation (based on low level primitives, such as futex on Linux). This is not too complicated either: http://locklessinc.com/articles/mutex_cv_futex/.