python-redisRedis watch example
Pipelines use transactions by default, so we have to watch() our key from pipeline:
r = redis.Redis()
val = r.get('some_counter')
p = r.pipeline()
p.watch('some_counter')
p.set('some_counter', val + 10)
p.execute()ctrl + credis.Redisconnect to Redis server | r.get('some_counter')get value of some key from Redis (assume it has numeric value stored in it already) |
r.pipeline()create Redis pipeline to execute batch commands | p.watchwatch specified key within pipeline transaction |
p.setset key value within pipeline | p.execute()execute pipeline |
Usage example
import redis, time
r = redis.Redis()
val = r.get('some_counter')
p = r.pipeline()
p.watch('some_counter')
time.sleep(10)
p.set('some_counter', val + 10)
p.execute()output
Traceback (most recent call last):
...
redis.exceptions.WatchError: Watched variable changed.