def get_and_lock(self,
id, # type: str
expiration, # type: int
*options, # type: GetAndLockOptions
**kwargs
):
# type: (...)->GetResult
final_options=forward_args(kwargs, *options)
x = _Base.get(self.bucket, id, expiration, **final_options)
_Base.lock(self.bucket, id, options)
return ResultPrecursor(x, options)
def lock(self, # type: CBCollection
key, # type: str
*options, # type: LockOptions
**kwargs # type: Any
):
"""Lock and retrieve a key-value entry in Couchbase.
:param key: A string which is the key to lock.
:param ttl: a TTL for which the lock should be valid.
While the lock is active, attempts to access the key (via
other :meth:`lock`, :meth:`upsert` or other mutation calls)
will fail with an :exc:`.KeyExistsError`. Note that the
value for this option is limited by the maximum allowable
lock time determined by the server (currently, this is 30
seconds). If passed a higher value, the server will silently
lower this to its maximum limit.
This function otherwise functions similarly to :meth:`get`;
specifically, it will return the value upon success. Note the
:attr:`~.MutationResult.cas` value from the :class:`.MutationResult` object.
This will be needed to :meth:`unlock` the key.
Note the lock will also be implicitly released if modified by
one of the :meth:`upsert` family of functions when the valid CAS
is supplied
:raise: :exc:`.TemporaryFailError` if the key is already locked.
:raise: See :meth:`get` for possible exceptions
Lock a key ::
rv = cb.lock("locked_key", ttl=5)
# This key is now locked for the next 5 seconds.
# attempts to access this key will fail until the lock
# is released.
# do important stuff...
cb.unlock("locked_key", rv.cas)
Lock a key, implicitly unlocking with :meth:`upsert` with CAS ::
rv = self.cb.lock("locked_key", ttl=5)
new_value = rv.value.upper()
cb.upsert("locked_key", new_value, rv.cas)
Poll and Lock ::
rv = None
begin_time = time.time()
while time.time() - begin_time < 15:
try:
rv = cb.lock("key", ttl=10)
break
except TemporaryFailError:
print("Key is currently locked.. waiting")
time.sleep(1)
if not rv:
raise Exception("Waited too long..")
# Do stuff..
cb.unlock("key", rv.cas)
.. seealso:: :meth:`get`, :meth:`unlock`
"""
final_options = forward_args(kwargs, *options)
return _Base.lock(self.bucket, key, **final_options)
