import uuid
import time
import redis
from haipproxy.config.settings import (
REDIS_HOST, REDIS_PORT, REDIS_DB,
REDIS_PASSWORD, LOCKER_PREFIX)
def get_redis_conn(**kwargs):
host = kwargs.get('host', REDIS_HOST)
port = kwargs.get('port', REDIS_PORT)
db = kwargs.get('db', REDIS_DB)
password = kwargs.get('password', REDIS_PASSWORD)
return redis.StrictRedis(host, port, db, password)
def acquire_lock(conn, lock_name, acquire_timeout=10, lock_timeout=10):
"""inspired by the book 'redis in action' """
identifier = str(uuid.uuid4())
lock_name = LOCKER_PREFIX + lock_name
end = time.time() + acquire_timeout
while time.time() < end:
if conn.set(lock_name, identifier, lock_timeout, nx=True):
return identifier
elif not conn.ttl(lock_name) or conn.ttl(lock_name) == -1:
conn.expire(lock_name, lock_timeout)
time.sleep(0.1)
return False
def release_lock(conn, lock_name, identifier):
pipe = conn.pipeline(True)
lock_name = LOCKER_PREFIX + lock_name
while True:
try:
pipe.watch(lock_name)
identifier_origin = pipe.get(lock_name).decode()
if identifier_origin == identifier:
pipe.multi()
pipe.delete(lock_name)
pipe.execute()
return True
pipe.unwatch()
break
except redis.exceptions.WatchError:
pass
return False
