Current File : //lib64/python3.8/asyncio/__pycache__/locks.cpython-38.pyc
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This enables the following idiom for acquiring and releasing a
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S )r a� Primitive lock objects.
A primitive lock is a synchronization primitive that is not owned
by a particular coroutine 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 coroutine 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 coroutine is blocked in acquire() waiting for
the state to turn to unlocked, only one coroutine proceeds when a
release() call resets the state to unlocked; first coroutine which
is blocked in acquire() is being processed.
acquire() is a coroutine and should be called with 'await'.
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
...
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r� | j s�| � � � Y nX d| _ dS )z�Acquire a lock.
This method blocks until the lock is unlocked, then sets it to
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z Lock.acquirec C s" | j rd| _ | �� ntd��dS )aG Release a lock.
When the lock is locked, reset it to unlocked, and return.
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unlocked, allow exactly one of them to proceed.
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There is no return value.
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S )r a# Asynchronous equivalent to threading.Event.
Class implementing event objects. An event manages a flag that can be set
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The wait() method blocks until the flag is true. The flag is initially
false.
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zEvent.__repr__c C s | j S )z5Return True if and only if the internal flag is true.�r\ r r r r �is_set s z Event.is_setc C s. | j s*d| _ | jD ]}|�� s|�d� qdS )z�Set the internal flag to true. All coroutines waiting for it to
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dS | j�� }| j�|� z|I dH W �dS | j�|� X dS )z�Block until the internal flag is true.
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S )r a Asynchronous equivalent to threading.Condition.
This class implements condition variable objects. A condition variable
allows one or more coroutines to wait until they are notified by another
coroutine.
A new Lock object is created and used as the underlying lock.
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If the calling coroutine has not acquired the lock when this
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the same condition variable in another coroutine. Once
awakened, it re-acquires the lock and returns True.
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zCondition.waitc � s$ |� }|s | � � I dH |� }q|S )z�Wait until a predicate becomes true.
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zCondition.wait_forr c C sJ | � � std��d}| jD ]*}||kr* qF|�� s|d7 }|�d� qdS )a By default, wake up one coroutine waiting on this condition, if any.
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is called, a RuntimeError is raised.
This method wakes up at most n of the coroutines waiting for the
condition variable; it is a no-op if no coroutines are waiting.
Note: an awakened coroutine does not actually return from its
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zCondition.notifyc C s | � t| j�� dS )a Wake up all threads waiting on this condition. This method acts
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S )r a A Semaphore implementation.
A semaphore manages an internal counter which is decremented by each
acquire() call and incremented by each release() call. The counter
can never go below zero; when acquire() finds that it is zero, it blocks,
waiting until some other thread calls release().
Semaphores also support the context management protocol.
The optional argument gives the initial value for the internal
counter; it defaults to 1. If the value given is less than 0,
ValueError is raised.
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If the internal counter is larger than zero on entry,
decrement it by one and return True immediately. If it is
zero on entry, block, waiting until some other coroutine has
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True.
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zSemaphore.acquirec C s | j d7 _ | �� dS )z�Release a semaphore, incrementing the internal counter by one.
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r N)r\ rl r r r r r � s zSemaphore.release)r ) r r r r r rB rl r; r& r r[ r r rF r r � s
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This raises ValueError in release() if it would increase the value
above the initial value.
r Nr1 c s. |rt jdtdd� || _t� j||d� d S )Nr4 r r! r1 )r# r$ r% � _bound_valuerA r ri rF r r r
s �zBoundedSemaphore.__init__c s" | j | jkrtd��t� �� d S )Nz(BoundedSemaphore released too many times)r\ rm rb rA r r rF r r r s zBoundedSemaphore.release)r )r r r r r r r[ r r rF r r s r )r �__all__rM r/ r# � r r r
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