Shulou(Shulou.com)06/01 Report--

Using Python+Redis to realize distributed Lock

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Common relational databases (Oracle+MySQL+PG+GP) + highly available enterprise solutions + distributed locks

Use the scene:

Completely solve the problem of brain fissure in HA

A scenario in which only one process is allowed to execute between multiple servers

Class MyDLock (object):

Def _ _ init__ (self, lockID,timeout):

Self.connection = redis.Redis (host=cfg.REDIS_SERVER_IP

, port=cfg.REDIS_SERVER_PORT

, password=cfg.REDIS_SERVER_PWD

, db=cfg.REDIS_SERVER_DB_NUM

, decode_responses=True)

Self.__lockID = lockID

Self.__timeout = timeout

Def tryLock (self, appid):

# To_Main

Try:

Val=self.connection.get (self.__lockID)

If val is None:

Logging.info ("The app (% s) try lock (% s) ok." (appid, self.__lockID))

Self.connection.set (self.__lockID, appid, ex=self.__timeout)

Return True

Else:

Logging.info ("The owner of lock (% s) is% s. You (% s) can not get it"% (self.__lockID, val, appid))

Return False

Except Exception as e:

Logging.error ("Warning: Can't write log. (% s)"% e)

Return False

Def activeLock (self, appid):

# heartbeat, activate periodically

Val = self.connection.get (self.__lockID)

If val is None:

Logging.info ("There is no lock (% s)."% (self.__lockID))

Return False

Else:

If appid = = val:

# only activate your own locks

Logging.info ("Application (% s) active lock (% s) ok." (appid, self.__lockID))

Self.connection.set (self.__lockID, appid, ex=self.__timeout)

Return True

Else:

# cannot activate locks that are not your own

Logging.info ("Application (% s) can not active lock (% s) .The owner is (% s)" (appid, self.__lockID, val))

Return False

Def releaseLock (self, key, appid):

Val = self.connection.get (self.__lockID)

If val is None:

Return False

Else:

If appid = = val:

# you can only delete your own locks

Self.connection.delete (self.__lockID)

Return True

Else:

# you cannot delete locks that are not your own

Return False

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