Redis client for Python asyncio.

Redis client for the PEP 3156 Python event loop.

This Redis library is a completely asynchronous, non-blocking client for a Redis server. It depends on asyncio (PEP 3156) and therefor it requires Python 3.3 or 3.4. If you're new to asyncio, it can be helpful to check out the asyncio documentation first.

Features

• Works for the asyncio (PEP3156) event loop
• No dependencies except asyncio
• Connection pooling
• Automatic conversion from unicode (Python) to bytes (inside Redis.)
• Bytes and str protocols.
• Completely tested
• Blocking calls and transactions supported
• Streaming of some multi bulk replies
• Pubsub support

Installation

pip install asyncio_redis

Documentation

View documentation at read-the-docs

The connection class

A asyncio_redis.Connection instance will take care of the connection and will automatically reconnect, using a new transport when the connection drops. This connection class also acts as a proxy to a asyncio_redis.RedisProtocol instance; any Redis command of the protocol can be called directly at the connection.

import asyncio
import asyncio_redis

@asyncio.coroutine
def example():
    # Create Redis connection
    connection = yield from asyncio_redis.Connection.create(host='localhost', port=6379)

    # Set a key
    yield from connection.set('my_key', 'my_value')

    # When finished, close the connection.
    connection.close()

if __name__ == '__main__':
    loop = asyncio.get_event_loop()
    loop.run_until_complete(example())

Connection pooling

Requests will automatically be distributed among all connections in a pool. If a connection is blocking because of --for instance-- a blocking rpop, another connection will be used for new commands.

import asyncio
import asyncio_redis

@asyncio.coroutine
def example():
    # Create Redis connection
    connection = yield from asyncio_redis.Pool.create(host='localhost', port=6379, poolsize=10)

    # Set a key
    yield from connection.set('my_key', 'my_value')

    # When finished, close the connection pool.
    connection.close()

Transactions example

import asyncio
import asyncio_redis

@asyncio.coroutine
def example():
    # Create Redis connection
    connection = yield from asyncio_redis.Pool.create(host='localhost', port=6379, poolsize=10)

    # Create transaction
    transaction = yield from connection.multi()

    # Run commands in transaction (they return future objects)
    f1 = yield from transaction.set('key', 'value')
    f2 = yield from transaction.set('another_key', 'another_value')

    # Commit transaction
    yield from transaction.exec()

    # Retrieve results
    result1 = yield from f1
    result2 = yield from f2

    # When finished, close the connection pool.
    connection.close()

It's recommended to use a large enough poolsize. A connection will be occupied as long as there's a transaction running in there.

Pubsub example

import asyncio
import asyncio_redis

@asyncio.coroutine
def example():
    # Create connection
    connection = yield from asyncio_redis.Connection.create(host='localhost', port=6379)

    # Create subscriber.
    subscriber = yield from connection.start_subscribe()

    # Subscribe to channel.
    yield from subscriber.subscribe([ 'our-channel' ])

    # Inside a while loop, wait for incoming events.
    while True:
        reply = yield from subscriber.next_published()
        print('Received: ', repr(reply.value), 'on channel', reply.channel)

    # When finished, close the connection.
    connection.close()

LUA Scripting example

import asyncio
import asyncio_redis

code = \
"""
local value = redis.call('GET', KEYS[1])
value = tonumber(value)
return value * ARGV[1]
"""

@asyncio.coroutine
def example():
    connection = yield from asyncio_redis.Connection.create(host='localhost', port=6379)

    # Set a key
    yield from connection.set('my_key', '2')

    # Register script
    multiply = yield from connection.register_script(code)

    # Run script
    script_reply = yield from multiply.run(keys=['my_key'], args=['5'])
    result = yield from script_reply.return_value()
    print(result) # prints 2 * 5

    # When finished, close the connection.
    connection.close()

Example using the Protocol class

import asyncio
import asyncio_redis

@asyncio.coroutine
def example():
    loop = asyncio.get_event_loop()

    # Create Redis connection
    transport, protocol = yield from loop.create_connection(
                asyncio_redis.RedisProtocol, 'localhost', 6379)

    # Set a key
    yield from protocol.set('my_key', 'my_value')

    # Get a key
    result = yield from protocol.get('my_key')
    print(result)

    # Close transport when finished.
    transport.close()

if __name__ == '__main__':
    asyncio.get_event_loop().run_until_complete(example())