redis_lock

exception redis_lock.AlreadyAcquired

exception redis_lock.AlreadyStarted

exception redis_lock.InvalidTimeout

class redis_lock.Lock(redis_client, name, expire=None, id=None, auto_renewal=False, signal_expire=1000, blocking=True)

A Lock context manager implemented via redis SETNX/BLPOP.

__init__(redis_client, name, expire=None, id=None, auto_renewal=False, signal_expire=1000, blocking=True)

Parameters:

• redis_client – An instance of StrictRedis.

• name – The name (redis key) the lock should have.

• expire – The lock expiry time in seconds. If left at the default (None) the lock will not expire.

• id –

  The ID (redis value) the lock should have. A random value is generated when left at the default.

  Note that if you specify this then the lock is marked as “held”. Acquires won’t be possible.

• auto_renewal –

  If set to True, Lock will automatically renew the lock so that it doesn’t expire for as long as the lock is held (acquire() called or running in a context manager).

  Implementation note: Renewal will happen using a daemon thread with an interval of expire*2/3. If wishing to use a different renewal time, subclass Lock, call super().__init__() then set self._lock_renewal_interval to your desired interval.

• signal_expire – Advanced option to override signal list expiration in milliseconds. Increase it for very slow clients. Default: 1000.

• blocking – Boolean value specifying whether lock should be blocking or not. Used in __enter__ method.

acquire(blocking=True, timeout=None)

Parameters:

• blocking – Boolean value specifying whether lock should be blocking or not.

• timeout – An integer value specifying the maximum number of seconds to block.

blocking = None

extend(expire=None)

Extends expiration time of the lock.

Parameters:

expire – New expiration time. If None - expire provided during lock initialization will be taken.

extend_script = None

get_owner_id()

property id

locked()

Return true if the lock is acquired.

Checks that lock with same name already exists. This method returns true, even if lock have another id.

classmethod register_scripts(redis_client)

release()

Releases the lock, that was acquired with the same object.

Note

If you want to release a lock that you acquired in a different place you have two choices:

• Use Lock("name", id=id_from_other_place).release()

• Use Lock("name").reset()

reset()

Forcibly deletes the lock. Use this with care.

reset_all_script = None

reset_script = None

unlock_script = None

exception redis_lock.NotAcquired

exception redis_lock.NotExpirable

exception redis_lock.TimeoutNotUsable

exception redis_lock.TimeoutTooLarge

redis_lock.reset_all(redis_client)

Forcibly deletes all locks if its remains (like a crash reason). Use this with care.

Parameters:

redis_client – An instance of StrictRedis.