Add support to socket timeout, health check and keepalive

[guoyiang]

Hello,

When TCP connection lost without proper disconnection, existing redis connection may become broken and the next request may take a long time before it reaches system default socket timeout, which is around ~15 mins with default linux config ( https://stackoverflow.com/questions/20403118/tcp-ceases-retransmissions-before-reaching-the-default-of-15-attempts-after-phy ).
In this situation, redis operation will be blocked for a long time before an exception is thrown. This is observed in 1.3.1

  File "/home/bolt/.local/lib/python3.8/site-packages/example-0.0.0-py3.8.egg/example/registry.py", line 63, in get_redis
    get_redis= await self.redis_client.smembers(key)
  File "/home/bolt/.local/lib/python3.8/site-packages/aioredis/connection.py", line 186, in _read_data
    obj = await self._reader.readobj()
  File "/home/bolt/.local/lib/python3.8/site-packages/aioredis/stream.py", line 102, in readobj
    await self._wait_for_data('readobj')
  File "/usr/local/lib/python3.8/asyncio/streams.py", line 517, in _wait_for_data
    await self._waiter
  File "/usr/local/lib/python3.8/asyncio/selector_events.py", line 846, in _read_ready__data_received
    data = self._sock.recv(self.max_size)
TimeoutError: [Errno 110] Operation timed out

With issue #184 , connection timeout is added. It would be nice to support socket timeout, socket keepalive and health check to better handle connection loss.

Thanks!

[ppd0705]

i met the same problem when i use redis pool execute some command, it blocked。hope add timeout option too

[luisdamora]

I have the same error, it is related to the keepalive in the server configuration

[seandstewart]

@guoyiang -

Thank you for your submission! Would you be willing to submit proposed implementation in a PR? This would be a great addition to the library.

[Andrew-Chen-Wang]

@seandstewart I like copying others' code, so this is a perfect place to copy from: redis-py implements it in the exact same way we should: https://github.com/andymccurdy/redis-py/blob/8c176cdc7f36e2cbcd3254768766035a7b7cd8b3/redis/connection.py#L589-L593

We would add this kind of code (not the same but...) in aioredis.connection: https://github.com/aio-libs/aioredis/blob/f5907fa8631a6f36684e081ec78e4d9267c6a992/aioredis/connection.py#L128-L143

Passing in the methods would be the same as passing in timeout (for connection timeout) in create_redis or pool conn.

[seandstewart]

This issue should be resolved as of #891 - please feel free to pull in the latest master and test to ensure this is the case.