Redis transactions demonstration

redis-transactions-demo.py

# Redis transactions demonstration.
# See the following thread on the Redis mailing list for background:
#     http://groups.google.com/group/redis-db/browse_thread/thread/8a981b3fd76f8f41
# Output is included in comments below the code.

import redis

def do(r):
    r.watch('mykey1')
    txn = r.pipeline()
    if r.get('mykey1') == 'xx':
        txn.set('mykey2', 'yy').incr('mykey3')
    else:
        txn.set('mykey2', 'zz').decr('mykey3')
    txn.execute()

def see(r):
    print 'mykey1: %s' % r.get('mykey1')
    print 'mykey2: %s' % r.get('mykey2')
    print 'mykey3: %s' % r.get('mykey3')

r = redis.Redis()

r.set('mykey1', 'foo')
r.set('mykey2', 'bar')
r.set('mykey3', 5)

do(r)
see(r)

r.set('mykey1', 'xx')
do(r)
see(r)

# >>> import redis
# >>> 
# >>> def do(r):
# ...     r.watch('mykey1')
# ...     txn = r.pipeline()
# ...     if r.get('mykey1') == 'xx':
# ...         txn.set('mykey2', 'yy').incr('mykey3')
# ...     else:
# ...         txn.set('mykey2', 'zz').decr('mykey3')
# ...     txn.execute()
# ... 
# >>> def see(r):
# ...     print 'mykey1: %s' % r.get('mykey1')
# ...     print 'mykey2: %s' % r.get('mykey2')
# ...     print 'mykey3: %s' % r.get('mykey3')
# ... 
# >>> r = redis.Redis()
# >>> 
# >>> r.set('mykey1', 'foo')
# True
# >>> r.set('mykey2', 'bar')
# True
# >>> r.set('mykey3', 5)
# True
# >>> 
# >>> do(r)
# >>> see(r)
# mykey1: foo
# mykey2: zz
# mykey3: 4
# >>> 
# >>> r.set('mykey1', 'xx')
# True
# >>> do(r)
# >>> see(r)
# mykey1: xx
# mykey2: yy
# mykey3: 5