Allow FIFO pool in redis client (#1820)

* Initial commit for FIFO pool

* Change PoolType string to PoolFIFO bool

* Remove redundant type

* add PoolFIFO option to all clients

Signed-off-by: monkey92t <golang@88.com>

Co-authored-by: Kim Tae Kwon <taekwon.kim@shopee.com>
Co-authored-by: monkey92t <golang@88.com>

cluster.go

@@ -68,6 +68,9 @@ type ClusterOptions struct {
 	ReadTimeout  time.Duration
 	WriteTimeout time.Duration
 
+	// PoolFIFO uses FIFO mode for each node connection pool GET/PUT (default LIFO).
+	PoolFIFO bool
+
 	// PoolSize applies per cluster node and not for the whole cluster.
 	PoolSize           int
 	MinIdleConns       int
@@ -146,6 +149,7 @@ func (opt *ClusterOptions) clientOptions() *Options {
 		ReadTimeout:  opt.ReadTimeout,
 		WriteTimeout: opt.WriteTimeout,
 
+		PoolFIFO:           opt.PoolFIFO,
 		PoolSize:           opt.PoolSize,
 		MinIdleConns:       opt.MinIdleConns,
 		MaxConnAge:         opt.MaxConnAge,

internal/pool/pool.go

@@ -57,6 +57,7 @@ type Options struct {
 	Dialer  func(context.Context) (net.Conn, error)
 	OnClose func(*Conn) error
 
+	PoolFIFO           bool
 	PoolSize           int
 	MinIdleConns       int
 	MaxConnAge         time.Duration
@@ -308,13 +309,21 @@ func (p *ConnPool) freeTurn() {
 }
 
 func (p *ConnPool) popIdle() *Conn {
-	if len(p.idleConns) == 0 {
+	n := len(p.idleConns)
+	if n == 0 {
 		return nil
 	}
 
-	idx := len(p.idleConns) - 1
+	var cn *Conn
-	cn := p.idleConns[idx]
+	if p.opt.PoolFIFO {
+		cn = p.idleConns[0]
+		copy(p.idleConns, p.idleConns[1:])
+		p.idleConns = p.idleConns[:n-1]
+	} else {
+		idx := n - 1
+		cn = p.idleConns[idx]
 		p.idleConns = p.idleConns[:idx]
+	}
 	p.idleConnsLen--
 	p.checkMinIdleConns()
 	return cn

options.go

@@ -76,6 +76,10 @@ type Options struct {
 	// Default is ReadTimeout.
 	WriteTimeout time.Duration
 
+	// Type of connection pool.
+	// true for FIFO pool, false for LIFO pool.
+	// Note that fifo has higher overhead compared to lifo.
+	PoolFIFO bool
 	// Maximum number of socket connections.
 	// Default is 10 connections per every available CPU as reported by runtime.GOMAXPROCS.
 	PoolSize int
@@ -291,6 +295,7 @@ func newConnPool(opt *Options) *pool.ConnPool {
 		Dialer: func(ctx context.Context) (net.Conn, error) {
 			return opt.Dialer(ctx, opt.Network, opt.Addr)
 		},
+		PoolFIFO:           opt.PoolFIFO,
 		PoolSize:           opt.PoolSize,
 		MinIdleConns:       opt.MinIdleConns,
 		MaxConnAge:         opt.MaxConnAge,

ring.go

@@ -78,6 +78,9 @@ type RingOptions struct {
 	ReadTimeout  time.Duration
 	WriteTimeout time.Duration
 
+	// PoolFIFO uses FIFO mode for each node connection pool GET/PUT (default LIFO).
+	PoolFIFO bool
+
 	PoolSize           int
 	MinIdleConns       int
 	MaxConnAge         time.Duration
@@ -138,6 +141,7 @@ func (opt *RingOptions) clientOptions() *Options {
 		ReadTimeout:  opt.ReadTimeout,
 		WriteTimeout: opt.WriteTimeout,
 
+		PoolFIFO:           opt.PoolFIFO,
 		PoolSize:           opt.PoolSize,
 		MinIdleConns:       opt.MinIdleConns,
 		MaxConnAge:         opt.MaxConnAge,

sentinel.go

@@ -57,6 +57,9 @@ type FailoverOptions struct {
 	ReadTimeout  time.Duration
 	WriteTimeout time.Duration
 
+	// PoolFIFO uses FIFO mode for each node connection pool GET/PUT (default LIFO).
+	PoolFIFO bool
+
 	PoolSize           int
 	MinIdleConns       int
 	MaxConnAge         time.Duration
@@ -86,6 +89,7 @@ func (opt *FailoverOptions) clientOptions() *Options {
 		ReadTimeout:  opt.ReadTimeout,
 		WriteTimeout: opt.WriteTimeout,
 
+		PoolFIFO:           opt.PoolFIFO,
 		PoolSize:           opt.PoolSize,
 		PoolTimeout:        opt.PoolTimeout,
 		IdleTimeout:        opt.IdleTimeout,
@@ -115,6 +119,7 @@ func (opt *FailoverOptions) sentinelOptions(addr string) *Options {
 		ReadTimeout:  opt.ReadTimeout,
 		WriteTimeout: opt.WriteTimeout,
 
+		PoolFIFO:           opt.PoolFIFO,
 		PoolSize:           opt.PoolSize,
 		PoolTimeout:        opt.PoolTimeout,
 		IdleTimeout:        opt.IdleTimeout,
@@ -146,6 +151,7 @@ func (opt *FailoverOptions) clusterOptions() *ClusterOptions {
 		ReadTimeout:  opt.ReadTimeout,
 		WriteTimeout: opt.WriteTimeout,
 
+		PoolFIFO:           opt.PoolFIFO,
 		PoolSize:           opt.PoolSize,
 		PoolTimeout:        opt.PoolTimeout,
 		IdleTimeout:        opt.IdleTimeout,

universal.go

@@ -35,6 +35,9 @@ type UniversalOptions struct {
 	ReadTimeout  time.Duration
 	WriteTimeout time.Duration
 
+	// PoolFIFO uses FIFO mode for each node connection pool GET/PUT (default LIFO).
+	PoolFIFO bool
+
 	PoolSize           int
 	MinIdleConns       int
 	MaxConnAge         time.Duration
@@ -83,6 +86,7 @@ func (o *UniversalOptions) Cluster() *ClusterOptions {
 		DialTimeout:        o.DialTimeout,
 		ReadTimeout:        o.ReadTimeout,
 		WriteTimeout:       o.WriteTimeout,
+		PoolFIFO:           o.PoolFIFO,
 		PoolSize:           o.PoolSize,
 		MinIdleConns:       o.MinIdleConns,
 		MaxConnAge:         o.MaxConnAge,
@@ -120,6 +124,7 @@ func (o *UniversalOptions) Failover() *FailoverOptions {
 		ReadTimeout:  o.ReadTimeout,
 		WriteTimeout: o.WriteTimeout,
 
+		PoolFIFO:           o.PoolFIFO,
 		PoolSize:           o.PoolSize,
 		MinIdleConns:       o.MinIdleConns,
 		MaxConnAge:         o.MaxConnAge,
@@ -155,6 +160,7 @@ func (o *UniversalOptions) Simple() *Options {
 		ReadTimeout:  o.ReadTimeout,
 		WriteTimeout: o.WriteTimeout,
 
+		PoolFIFO:           o.PoolFIFO,
 		PoolSize:           o.PoolSize,
 		MinIdleConns:       o.MinIdleConns,
 		MaxConnAge:         o.MaxConnAge,