transport: pool, stop shard refill faster when context is done

[Kulezi]

Checking if context is done should be checked in the loop, returning early without relying on the result of OpenShardConn.

scylla-go-driver/transport/pool.go

Lines 221 to 264 in 88fc8ef

	func (r *PoolRefiller) fill(ctx context.Context) {
	if !r.needsFilling() {
	return
	}
	si := ShardInfo{
	NrShards: uint16(r.pool.nrShards),
	MsbIgnore: r.pool.msbIgnore,
	}
	for i := 0; i < r.pool.nrShards; i++ {
	if r.pool.loadConn(i) != nil {
	continue
	}
	si.Shard = uint16(i)
	span := startSpan()
	conn, err := OpenShardConn(ctx, r.addr, si, r.cfg)
	span.stop()
	if err != nil {
	if r.pool.connObs != nil {
	r.pool.connObs.OnConnect(ConnectEvent{ConnEvent: ConnEvent{Addr: r.addr, Shard: si.Shard}, span: span, Err: err})
	}
	if conn != nil {
	conn.Close()
	}
	continue
	}
	if r.pool.connObs != nil {
	r.pool.connObs.OnConnect(ConnectEvent{ConnEvent: conn.Event(), span: span})
	}
	if conn.Shard() != i {
	log.Fatalf("opened conn to wrong shard: expected %d got %d", i, conn.Shard())
	}
	conn.setOnClose(r.onConnClose)
	r.pool.storeConn(conn)
	r.active++
	if !r.needsFilling() {
	return
	}
	}
	}