A mutex is an exclusive lock. At any moment, zero or one threads may own a mutex. If a thread attempts to acquire a mutex, and the mutex is already owned by some other thread, then the acquiring thread will block until the mutex becomes available.
Emacs Lisp mutexes are of a type called recursive, which means that a thread can re-acquire a mutex it owns any number of times. A mutex keeps a count of how many times it has been acquired, and each acquisition of a mutex must be paired with a release. The last release by a thread of a mutex reverts it to the unowned state, potentially allowing another thread to acquire the mutex.
This function returns
t if object represents an Emacs
Create a new mutex and return it. If name is specified, it is a name given to the mutex. It must be a string. The name is for debugging purposes only; it has no meaning to Emacs.
Return the name of mutex, as specified to
This will block until this thread acquires mutex, or until this
thread is signaled using
thread-signal. If mutex is
already owned by this thread, this simply returns.
Release mutex. If mutex is not owned by this thread, this will signal an error.
This macro is the simplest and safest way to evaluate forms while holding a mutex. It acquires mutex, invokes body, and then releases mutex. It returns the result of body.