ring: reduce HeartbeatFrequency.

options.go

@@ -18,43 +18,42 @@ type Options struct {
 	// Network and Addr options.
 	Dialer func() (net.Conn, error)
 
-	// An optional password. Must match the password specified in the
+	// Optional password. Must match the password specified in the
 	// requirepass server configuration option.
 	Password string
-	// A database to be selected after connecting to server.
+	// Database to be selected after connecting to the server.
 	DB int
 
-	// The maximum number of retries before giving up.
+	// Maximum number of retries before giving up.
 	// Default is to not retry failed commands.
 	MaxRetries int
 
-	// Sets the deadline for establishing new connections. If reached,
-	// dial will fail with a timeout.
+	// Dial timeout for establishing new connections.
 	// Default is 5 seconds.
 	DialTimeout time.Duration
-	// Sets the deadline for socket reads. If reached, commands will
-	// fail with a timeout instead of blocking.
+	// Timeout for socket reads. If reached, commands will fail
+	// with a timeout instead of blocking.
 	ReadTimeout time.Duration
-	// Sets the deadline for socket writes. If reached, commands will
-	// fail with a timeout instead of blocking.
+	// Timeout for socket writes. If reached, commands will fail
+	// with a timeout instead of blocking.
 	WriteTimeout time.Duration
 
-	// The maximum number of socket connections.
+	// Maximum number of socket connections.
 	// Default is 10 connections.
 	PoolSize int
-	// Specifies amount of time client waits for connection if all
-	// connections are busy before returning an error.
+	// Amount of time client waits for connection if all connections
+	// are busy before returning an error.
 	// Default is 1 second.
 	PoolTimeout time.Duration
-	// Specifies amount of time after which client closes idle
-	// connections. Should be less than server's timeout.
+	// Amount of time after which client closes idle connections.
+	// Should be less than server's timeout.
 	// Default is to not close idle connections.
 	IdleTimeout time.Duration
-	// The frequency of idle checks.
+	// Frequency of idle checks.
 	// Default is 1 minute.
 	IdleCheckFrequency time.Duration
 
-	// Enables read queries for a connection to a Redis Cluster slave node.
+	// Enables read only queries on slave nodes.
 	ReadOnly bool
 }
 

ring.go

@@ -12,16 +12,18 @@ import (
 	"gopkg.in/redis.v4/internal/pool"
 )
 
-var (
-	errRingShardsDown = errors.New("redis: all ring shards are down")
-)
+var errRingShardsDown = errors.New("redis: all ring shards are down")
 
 // RingOptions are used to configure a ring client and should be
 // passed to NewRing.
 type RingOptions struct {
-	// A map of name => host:port addresses of ring shards.
+	// Map of name => host:port addresses of ring shards.
 	Addrs map[string]string
 
+	// Frequency of PING commands sent to check shards availability.
+	// Shard is considered down after 3 subsequent failed checks.
+	HeartbeatFrequency time.Duration
+
 	// Following options are copied from Options struct.
 
 	DB       int
@@ -39,7 +41,11 @@ type RingOptions struct {
 	IdleCheckFrequency time.Duration
 }
 
-func (opt *RingOptions) init() {}
+func (opt *RingOptions) init() {
+	if opt.HeartbeatFrequency == 0 {
+		opt.HeartbeatFrequency = 500 * time.Millisecond
+	}
+}
 
 func (opt *RingOptions) clientOptions() *Options {
 	return &Options{
@@ -73,7 +79,7 @@ func (shard *ringShard) String() string {
 }
 
 func (shard *ringShard) IsDown() bool {
-	const threshold = 5
+	const threshold = 3
 	return shard.down >= threshold
 }
 
@@ -108,7 +114,7 @@ func (shard *ringShard) Vote(up bool) bool {
 // uses shards that are available to the client and does not do any
 // coordination when shard state is changed.
 //
-// Ring should be used when you use multiple Redis servers for caching
+// Ring should be used when you need multiple Redis servers for caching
 // and can tolerate losing data when one of the servers dies.
 // Otherwise you should use Redis Cluster.
 type Ring struct {
@@ -224,7 +230,7 @@ func (c *Ring) rebalance() {
 
 // heartbeat monitors state of each shard in the ring.
 func (c *Ring) heartbeat() {
-	ticker := time.NewTicker(100 * time.Millisecond)
+	ticker := time.NewTicker(c.opt.HeartbeatFrequency)
 	defer ticker.Stop()
 	for _ = range ticker.C {
 		var rebalance bool

ring_test.go

@@ -12,6 +12,7 @@ import (
 )
 
 var _ = Describe("Redis ring", func() {
+	const heartbeat = 100 * time.Millisecond
 	var ring *redis.Ring
 
 	setRingKeys := func() {
@@ -27,6 +28,7 @@ var _ = Describe("Redis ring", func() {
 				"ringShardOne": ":" + ringShard1Port,
 				"ringShardTwo": ":" + ringShard2Port,
 			},
+			HeartbeatFrequency: heartbeat,
 		})
 
 		// Shards should not have any keys.
@@ -53,10 +55,9 @@ var _ = Describe("Redis ring", func() {
 		// Stop ringShard2.
 		Expect(ringShard2.Close()).NotTo(HaveOccurred())
 
-		// Ring needs 5 * heartbeat time to detect that node is down.
+		// Ring needs 3 * heartbeat time to detect that node is down.
 		// Give it more to be sure.
-		heartbeat := 100 * time.Millisecond
-		time.Sleep(2 * 5 * heartbeat)
+		time.Sleep(2 * 3 * heartbeat)
 
 		setRingKeys()