Feature: support connection lifetime

[terut]

Hi, thank you for writing great library. It is working well for now !

Recently I noticed that request is unbalanced when its replica failover on a cloud service if the connection keeps. So I consider about connection lifetime to reconnect to redis endpoint because existing connection are not rerouted when a node reintroduced.

Here is the document about archtecture and connection balance manegement.

https://cloud.google.com/memorystore/docs/redis/about-read-replicas#architecture
https://cloud.google.com/memorystore/docs/redis/about-read-replicas#connection_balance_management

Other library like go-redis and redigo has a option such as MaxConnectionLifetime to drop expired connection from connection pool. So I tried to writing the implement of connection lifetime, but rueidis has auto pipelining is working background and detecting to finish all commands is difficult for me. Background worker for auto piplining keep going to received commands until error occurred, right?

I'm glad if I know the wire is safe to close like the following.

# mux.go

func (m *mux) _pipe(i uint16) (w wire, err error) {
	if w = m.wire[i].Load().(wire); w != m.init && !w.IsExpired() {
		return w, nil
	}
        if w.IsExpired() {
                 m.wire[i].CompareAndSwap(w, w.init)
                 ew := w
                 go func() {
                      <- ew.Done()
                      ew.close()
                 }
        }
      //...
}

Please tell me you have any solution about that. Thanks!

[rueian]

Hi @terut,

I believe it is safe to do .IsExpired() and swap the connection out, but that requires comparing the current time for each operation which is too costly.

Maybe scheduling a timer to close the pipe is a better way. The timer can be scheduled before this line

rueidis/pipe.go

Line 329 in bd17103

return p, nil