Class Lock

Lib/asyncio/locks.py:23–155

Primitive lock objects. A primitive lock is a synchronization primitive that is not owned by a particular task when locked. A primitive lock is in one of two states, 'locked' or 'unlocked'. It is created in the unlocked state. It has two basic methods, acquire() and release()

class Lock(_ContextManagerMixin, mixins._LoopBoundMixin):
    """Primitive lock objects.

    A primitive lock is a synchronization primitive that is not owned
    by a particular task when locked.  A primitive lock is in one
    of two states, 'locked' or 'unlocked'.

    It is created in the unlocked state.  It has two basic methods,
    acquire() and release().  When the state is unlocked, acquire()
    changes the state to locked and returns immediately.  When the
    state is locked, acquire() blocks until a call to release() in
    another task changes it to unlocked, then the acquire() call
    resets it to locked and returns.  The release() method should only
    be called in the locked state; it changes the state to unlocked
    and returns immediately.  If an attempt is made to release an
    unlocked lock, a RuntimeError will be raised.

    When more than one task is blocked in acquire() waiting for
    the state to turn to unlocked, only one task proceeds when a
    release() call resets the state to unlocked; successive release()
    calls will unblock tasks in FIFO order.

    Locks also support the asynchronous context management protocol.
    'async with lock' statement should be used.

    Usage:

        lock = Lock()
        ...
        await lock.acquire()
        try:
            ...
        finally:
            lock.release()

    Context manager usage:

        lock = Lock()
        ...
        async with lock:
             ...

    Lock objects can be tested for locking state:

        if not lock.locked():
           await lock.acquire()
        else:
           # lock is acquired
           ...

    """

    def __init__(self):
        self._waiters = None
        self._locked = False

    def __repr__(self):
        res = super().__repr__()