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sentinel pool backed read and write redis client

Project description

read and write sentinel connection pool backed redis client

when using a redis connection backed by a SentinelConnectionPool, the pool is initialized to connect to either the master or slaves. this is annoying if you want to read from slaves and occasionally write to the master. TwiceRedis solves this by having two clients, one for master and one for slaves:

  • tr.master also aliased as tr.write
  • tr.slave also aliased as tr.read

these clients are each backed by a separate SentinelConnectionPool initialized to connect to the master or slaves respectively

TwiceRedis also uses a DisconnectingSentinel class to drastically reduce the number of active connections to the redis sentinel service(s). This class drops connection to the chosen sentinel once the master or slave has been chosen.

The DisconnectionSentinel class also filters slaves a little more intelligently than the base Sentinel class does. In addition to insuring slaves are not sdown or odown it makes sure the slaves master-link-status is ‘ok’.

TwiceRedis randomizes the sentinel list so each TwiceRedis object will be connecting to a random sentinel in the list instead of them all connecting to the first one (for as long as it works). this shuffling is probably a bit superfluous used in conjunction with DisconnectingSentinel, but at worst will reduce the load on the first sentinel in the sentinels list

usage

from twiceredis import TwiceRedis
sentinels = [('10.10.10.10', 26379),
             ('10.10.10.11', 26379),
             ('10.10.10.12', 26379)]
tr = TwiceRedis('master01', sentinels, 'tötes_passowrd')
x = tr.slave.get('superkey')
tr.master.set('je mange', 'huehue')
x = tr.read.get('nous mangeons')
tr.write.del('superkey')

pipelines work great too, you just have decide whether you need to write during one or not, if write is needed, use tr.master, else use tr.slave

with tr.master.pipeline() as wpipe:
    wpipe.set('turle', 'power')
    wpipe.set('tr3buchet', 'tötes')
    wpipe.execute()

to connect, get a key, and then disconnect to reduce active connections

x = tr.slave.get('some key')
tr.disconnect()

and afterward reconnection will happen seamlessly as needed o/ and chances are you’ll hit a different slave

x = tr.slave.get('some other key')

it also disconnects any connection under tr.master as well, but you’ll end up back on the same node when you do anything with tr.master that connects unless the master has changed in the meantime

install

pip install twiceredis or clone the repo and python setup.py install

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