[NEW] Negative filtering for client command filters

[hpatro]

          does this PR support negative filtering?

Originally posted by @soloestoy in #1466 (comment)

[madolson]

Maybe we should get alignment we want negative alignment first before adding good first issue, I would rather us not have someone pick it up and then it get rejected.

[hpatro]

Maybe we should get alignment we want negative alignment first before adding good first issue, I would rather us not have someone pick it up and then it get rejected.

That makes sense.

@soloestoy / @zuiderkwast were already proposing on how to implement it. I guess they are ok with it. @madolson Could you also add your thoughts for the above issue?

@valkey-io/core-team Please add your thoughts. Thanks

[yangbodong22011]

Client kill/list negative filtering syntax proposal

Use ~ as first option to indicate negative filtering

127.0.0.1:6379> client kill ADDR ~ 127.0.0.1:23456  // Kill all clients except 127.0.0.1:23456
127.0.0.1:6379> client kill TYPE ~ NORMAL  // Kill all clients except NORMAL type
127.0.0.1:6379> client kill USER ~ user1  // Kill all clients except user1
127.0.0.1:6379> client kill NAME ~ valkey  // Kill all clients except named valkey
127.0.0.1:6379> client kill SKIPME YES/NO // Do not need filtering
127.0.0.1:6379> client kill ID ~ client-id-1 client-id-2  // Kill all clients except id-1 and id-2
127.0.0.1:6379> client kill MAXAGE maxage // Do not need filtering, but we can add new option like: client kill AGE >10|<=600
127.0.0.1:6379> client kill FLAGS ~ flag // Kill all clients except flag

@valkey-io/core-team Please have a look when you have time.

[PingXie]

negative filtering as a feature makes sense to me on a high level.

~ is already used in ACL to specify key patterns so I wonder if we should consider some other options for the not operator. how about NOT, !, -, or EXCLUDE? btw, ! might need to be escaped when sent on the command line using valkey-cli.

[yangbodong22011]

~ is already used in ACL to specify key patterns

I don’t think it matters; they are different commands. But I don't insist on using ~.

[soloestoy]

Considering special cases where the client's name or ACL user might start with ~ or !, or even be a single ~ or ! character, we can adjust the filter's naming convention. For example: client kill !NAME abc

[zuiderkwast]

If the negation is a separate token, the syntax can be simpler maybe. I suggested in the previous issue NOT NAME abc.