Interface RWMutex

A RWMutex is a reader/writer mutual exclusion lock. The lock can be held by an arbitrary number of readers or a single writer. The zero value for a RWMutex is an unlocked mutex.

A RWMutex must not be copied after first use.

If any goroutine calls [RWMutex.Lock] while the lock is already held by one or more readers, concurrent calls to [RWMutex.RLock] will block until the writer has acquired (and released) the lock, to ensure that the lock eventually becomes available to the writer. Note that this prohibits recursive read-locking.

In the terminology of the Go memory model, the n'th call to [RWMutex.Unlock] “synchronizes before” the m'th call to Lock for any n < m, just as for [Mutex]. For any call to RLock, there exists an n such that the n'th call to Unlock “synchronizes before” that call to RLock, and the corresponding call to [RWMutex.RUnlock] “synchronizes before” the n+1'th call to Lock.

Hierarchy

  • RWMutex

Methods

lock rLock rLocker rUnlock tryLock tryRLock unlock

Methods

lock

  • Lock locks rw for writing. If the lock is already locked for reading or writing, Lock blocks until the lock is available.

    Returns void

rLock

  • RLock locks rw for reading.

    It should not be used for recursive read locking; a blocked Lock call excludes new readers from acquiring the lock. See the documentation on the [RWMutex] type.

    Returns void

rLocker

  • RLocker returns a [Locker] interface that implements the [Locker.Lock] and [Locker.Unlock] methods by calling rw.RLock and rw.RUnlock.

    Returns Locker

rUnlock

  • RUnlock undoes a single [RWMutex.RLock] call; it does not affect other simultaneous readers. It is a run-time error if rw is not locked for reading on entry to RUnlock.

    Returns void

tryLock

  • TryLock tries to lock rw for writing and reports whether it succeeded.

    Note that while correct uses of TryLock do exist, they are rare, and use of TryLock is often a sign of a deeper problem in a particular use of mutexes.

    Returns boolean

tryRLock

  • TryRLock tries to lock rw for reading and reports whether it succeeded.

    Note that while correct uses of TryRLock do exist, they are rare, and use of TryRLock is often a sign of a deeper problem in a particular use of mutexes.

    Returns boolean

unlock

  • Unlock unlocks rw for writing. It is a run-time error if rw is not locked for writing on entry to Unlock.

    As with Mutexes, a locked [RWMutex] is not associated with a particular goroutine. One goroutine may [RWMutex.RLock] ([RWMutex.Lock]) a RWMutex and then arrange for another goroutine to [RWMutex.RUnlock] ([RWMutex.Unlock]) it.

    Returns void

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