Introduce ping connecion handler

[yangbodong22011]

PingConnectionHandler will periodically send PING commands to Redis Server, and decide whether to reconnect based on whether it fails (the current strategy is to reconnect after three consecutive failures)

This is essentially because KeepAlive that only relies on TCP is unreliable, for details, please refer to: #2082

change

• Add PingConnectionHandler, and decide whether to enable it according to the size of pingConnectionInterval (default is 0, not enabled，unit: ms).

• If the sendPing command fails 3 times in a row (defined by MAX_PING_FAILED_TIMES and not user-configurable), it will trigger channel.close and then reconnect.

• The return result of the PING command ignores RedisLoadingException and RedisBusyException exceptions.

test

There is no good way to unit test, so I manually verified it using iptables as mentioned in the original issue and the test passed.

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[mp911de]

Thanks for reaching out. That isn't something we're interested in as we have better measures (keep-alive) that doesn't interfere with the Redis protocol.

[shelltea]

@mp911de Hi, There are lots of issues about this problem.
#1466
#1428
#1727
Since you have closed this PR, is there a more reasonable way for us to resolve this issue?

[yangbodong22011]

Update:

1. By adding BlockingCommands to identify blocking commands and avoid sending PING.
2. For the Module Blocking command, users can customize it through io.lettuce.core.BlockingCommands#addBlockingCommand.
3. Pass COMMANDS_STACK through Channel.attr.

@mp911de pls have a look when you have time.