Asyncio Examples#
All commands are coroutine functions.
Connecting and Disconnecting#
Utilizing asyncio Redis requires an explicit disconnect of the connection since there is no asyncio deconstructor magic method. By default, a connection pool is created on redis.Redis()
and attached to this Redis
instance. The connection pool closes automatically on the call to Redis.close
which disconnects all connections.
[1]:
import redis.asyncio as redis
connection = redis.Redis()
print(f"Ping successful: {await connection.ping()}")
await connection.close()
Ping successful: True
If you supply a custom ConnectionPool
that is supplied to several Redis
instances, you may want to disconnect the connection pool explicitly. Disconnecting the connection pool simply disconnects all connections hosted in the pool.
[2]:
import redis.asyncio as redis
connection = redis.Redis(auto_close_connection_pool=False)
await connection.close()
# Or: await connection.close(close_connection_pool=False)
await connection.connection_pool.disconnect()
Transactions (Multi/Exec)#
The aioredis.Redis.pipeline will return a aioredis.Pipeline object, which will buffer all commands in-memory and compile them into batches using the Redis Bulk String protocol. Additionally, each command will return the Pipeline instance, allowing you to chain your commands, i.e., p.set(‘foo’, 1).set(‘bar’, 2).mget(‘foo’, ‘bar’).
The commands will not be reflected in Redis until execute() is called & awaited.
Usually, when performing a bulk operation, taking advantage of a “transaction” (e.g., Multi/Exec) is to be desired, as it will also add a layer of atomicity to your bulk operation.
[3]:
import redis.asyncio as redis
r = await redis.from_url("redis://localhost")
async with r.pipeline(transaction=True) as pipe:
ok1, ok2 = await (pipe.set("key1", "value1").set("key2", "value2").execute())
assert ok1
assert ok2
Pub/Sub Mode#
Subscribing to specific channels:
[4]:
import asyncio
import redis.asyncio as redis
STOPWORD = "STOP"
async def reader(channel: redis.client.PubSub):
while True:
message = await channel.get_message(ignore_subscribe_messages=True)
if message is not None:
print(f"(Reader) Message Received: {message}")
if message["data"].decode() == STOPWORD:
print("(Reader) STOP")
break
r = redis.from_url("redis://localhost")
async with r.pubsub() as pubsub:
await pubsub.subscribe("channel:1", "channel:2")
future = asyncio.create_task(reader(pubsub))
await r.publish("channel:1", "Hello")
await r.publish("channel:2", "World")
await r.publish("channel:1", STOPWORD)
await future
(Reader) Message Received: {'type': 'message', 'pattern': None, 'channel': b'channel:1', 'data': b'Hello'}
(Reader) Message Received: {'type': 'message', 'pattern': None, 'channel': b'channel:2', 'data': b'World'}
(Reader) Message Received: {'type': 'message', 'pattern': None, 'channel': b'channel:1', 'data': b'STOP'}
(Reader) STOP
Subscribing to channels matching a glob-style pattern:
[5]:
import asyncio
import redis.asyncio as redis
STOPWORD = "STOP"
async def reader(channel: redis.client.PubSub):
while True:
message = await channel.get_message(ignore_subscribe_messages=True)
if message is not None:
print(f"(Reader) Message Received: {message}")
if message["data"].decode() == STOPWORD:
print("(Reader) STOP")
break
r = await redis.from_url("redis://localhost")
async with r.pubsub() as pubsub:
await pubsub.psubscribe("channel:*")
future = asyncio.create_task(reader(pubsub))
await r.publish("channel:1", "Hello")
await r.publish("channel:2", "World")
await r.publish("channel:1", STOPWORD)
await future
(Reader) Message Received: {'type': 'pmessage', 'pattern': b'channel:*', 'channel': b'channel:1', 'data': b'Hello'}
(Reader) Message Received: {'type': 'pmessage', 'pattern': b'channel:*', 'channel': b'channel:2', 'data': b'World'}
(Reader) Message Received: {'type': 'pmessage', 'pattern': b'channel:*', 'channel': b'channel:1', 'data': b'STOP'}
(Reader) STOP
Sentinel Client#
The Sentinel client requires a list of Redis Sentinel addresses to connect to and start discovering services.
Calling aioredis.sentinel.Sentinel.master_for or aioredis.sentinel.Sentinel.slave_for methods will return Redis clients connected to specified services monitored by Sentinel.
Sentinel client will detect failover and reconnect Redis clients automatically.
[ ]:
import asyncio
from redis.asyncio.sentinel import Sentinel
sentinel = Sentinel([("localhost", 26379), ("sentinel2", 26379)])
r = sentinel.master_for("mymaster")
ok = await r.set("key", "value")
assert ok
val = await r.get("key")
assert val == b"value"