Mutex has two states: locked and unlocked. It is non-reentrant, that is invoking lock even from the same thread/coroutine that currently holds the lock still suspends the invoker.
JVM API note: Memory semantic of the Mutex is similar to synchronized block on JVM: An unlock operation on a Mutex happens-before every subsequent successful lock on that Mutex. Unsuccessful call to tryLock do not have any memory effects.
Clause for select expression of lock suspending function that selects when the mutex is locked. Additional parameter for the clause in the owner (see lock) and when the clause is selected the reference to this mutex is passed into the corresponding block.