def user_lock_acquire(context, user_id, action_id, engine=None,
forced=False):
"""Try to lock the specified user.
:param context: the context used for DB operations;
:param user_id: ID of the user to be locked.
:param action_id: ID of the action that attempts to lock the user.
:param engine: ID of the engine that attempts to lock the user.
:param forced: set to True to cancel current action that owns the lock,
if any.
:returns: True if lock is acquired, or False otherwise.
"""
owner = db_api.user_lock_acquire(user_id, action_id)
if action_id == owner:
return True
retries = cfg.CONF.lock_retry_times
retry_interval = cfg.CONF.lock_retry_interval
while retries > 0:
sleep(retry_interval)
LOG.debug(_('Acquire lock for user %s again'), user_id)
owner = db_api.user_lock_acquire(user_id, action_id)
if action_id == owner:
return True
retries = retries - 1
if forced:
owner = db_api.user_lock_steal(user_id, action_id)
return action_id == owner
action = db_api.action_get(context, owner)
if (action and action.owner and action.owner != engine and
is_engine_dead(context, action.owner)):
LOG.info(_LI('The user %(u)s is locked by dead action %(a)s, '
'try to steal the lock.'), {
'u': user_id,
'a': owner
})
reason = _('Engine died when executing this action.')
db_api.action_mark_failed(context, action.id, time.time(),
reason=reason)
db_api.user_lock_steal(user_id, action_id)
return True
LOG.error(_LE('User is already locked by action %(old)s, '
'action %(new)s failed grabbing the lock'),
{'old': owner, 'new': action_id})
return False
def load(cls, context, action_id=None, db_action=None):
"""Retrieve an action from database.
:param context: Instance of request context.
:param action_id: An UUID for the action to deserialize.
:param db_action: An action object for the action to deserialize.
:return: A `Action` object instance.
"""
if db_action is None:
db_action = db_api.action_get(context, action_id)
if db_action is None:
raise exception.ActionNotFound(action=action_id)
return cls._from_db_record(db_action)
