Merge pull request #167 from go-redis/fix/clarify-thread-safety

Clarify thread safety. Fixes #166.

cluster.go

@@ -9,6 +9,9 @@ import (
 	"time"
 )
 
+// ClusterClient is a Redis Cluster client representing a pool of zero
+// or more underlying connections. It's safe for concurrent use by
+// multiple goroutines.
 type ClusterClient struct {
 	commandable
 
@@ -26,7 +29,7 @@ type ClusterClient struct {
 	reloading uint32
 }
 
-// NewClusterClient returns a new Redis Cluster client as described in
+// NewClusterClient returns a Redis Cluster client as described in
 // http://redis.io/topics/cluster-spec.
 func NewClusterClient(opt *ClusterOptions) *ClusterClient {
 	client := &ClusterClient{
@@ -43,8 +46,8 @@ func NewClusterClient(opt *ClusterOptions) *ClusterClient {
 
 // Close closes the cluster client, releasing any open resources.
 //
-// It is rare to Close a Client, as the Client is meant to be
+// It is rare to Close a ClusterClient, as the ClusterClient is meant
-// long-lived and shared between many goroutines.
+// to be long-lived and shared between many goroutines.
 func (c *ClusterClient) Close() error {
 	defer c.clientsMx.Unlock()
 	c.clientsMx.Lock()

cluster_pipeline.go

@@ -10,7 +10,8 @@ type ClusterPipeline struct {
 }
 
 // Pipeline creates a new pipeline which is able to execute commands
-// against multiple shards.
+// against multiple shards. It's NOT safe for concurrent use by
+// multiple goroutines.
 func (c *ClusterClient) Pipeline() *ClusterPipeline {
 	pipe := &ClusterPipeline{
 		cluster: c,
@@ -82,7 +83,7 @@ func (pipe *ClusterPipeline) Exec() (cmds []Cmder, retErr error) {
 	return cmds, retErr
 }
 
-// Close marks the pipeline as closed
+// Close closes the pipeline, releasing any open resources.
 func (pipe *ClusterPipeline) Close() error {
 	pipe.Discard()
 	pipe.closed = true

multi.go

@@ -9,7 +9,8 @@ import (
 var errDiscard = errors.New("redis: Discard can be used only inside Exec")
 
 // Multi implements Redis transactions as described in
-// http://redis.io/topics/transactions.
+// http://redis.io/topics/transactions. It's NOT safe for concurrent
+// use by multiple goroutines.
 type Multi struct {
 	commandable
 

pipeline.go

@@ -1,9 +1,8 @@
 package redis
 
 // Pipeline implements pipelining as described in
-// http://redis.io/topics/pipelining.
+// http://redis.io/topics/pipelining. It's NOT safe for concurrent use
-//
+// by multiple goroutines.
-// Pipeline is not thread-safe.
 type Pipeline struct {
 	commandable
 
@@ -36,6 +35,7 @@ func (pipe *Pipeline) process(cmd Cmder) {
 	pipe.cmds = append(pipe.cmds, cmd)
 }
 
+// Close closes the pipeline, releasing any open resources.
 func (pipe *Pipeline) Close() error {
 	pipe.Discard()
 	pipe.closed = true

pubsub.go

@@ -15,7 +15,8 @@ func (c *Client) Publish(channel, message string) *IntCmd {
 }
 
 // PubSub implements Pub/Sub commands as described in
-// http://redis.io/topics/pubsub.
+// http://redis.io/topics/pubsub. It's NOT safe for concurrent use by
+// multiple goroutines.
 type PubSub struct {
 	*baseClient
 

redis.go

@@ -80,6 +80,9 @@ func (c *baseClient) process(cmd Cmder) {
 }
 
 // Close closes the client, releasing any open resources.
+//
+// It is rare to Close a Client, as the Client is meant to be
+// long-lived and shared between many goroutines.
 func (c *baseClient) Close() error {
 	return c.connPool.Close()
 }
@@ -173,6 +176,9 @@ func (opt *Options) getIdleTimeout() time.Duration {
 
 //------------------------------------------------------------------------------
 
+// Client is a Redis client representing a pool of zero or more
+// underlying connections. It's safe for concurrent use by multiple
+// goroutines.
 type Client struct {
 	*baseClient
 	commandable
@@ -186,6 +192,7 @@ func newClient(opt *Options, pool pool) *Client {
 	}
 }
 
+// NewClient returns a client to the Redis Server specified by Options.
 func NewClient(opt *Options) *Client {
 	pool := newConnPool(opt)
 	return newClient(opt, pool)

ring.go

@@ -92,7 +92,8 @@ func (shard *ringShard) Vote(up bool) bool {
 }
 
 // Ring is a Redis client that uses constistent hashing to distribute
-// keys across multiple Redis servers (shards).
+// keys across multiple Redis servers (shards). It's safe for
+// concurrent use by multiple goroutines.
 //
 // It monitors the state of each shard and removes dead shards from
 // the ring. When shard comes online it is added back to the ring. This
@@ -215,8 +216,8 @@ func (ring *Ring) heartbeat() {
 
 // Close closes the ring client, releasing any open resources.
 //
-// It is rare to Close a Client, as the Client is meant to be
+// It is rare to Close a Ring, as the Ring is meant to be long-lived
-// long-lived and shared between many goroutines.
+// and shared between many goroutines.
 func (ring *Ring) Close() (retErr error) {
 	defer ring.mx.Unlock()
 	ring.mx.Lock()
@@ -238,7 +239,8 @@ func (ring *Ring) Close() (retErr error) {
 }
 
 // RingPipeline creates a new pipeline which is able to execute commands
-// against multiple shards.
+// against multiple shards. It's NOT safe for concurrent use by
+// multiple goroutines.
 type RingPipeline struct {
 	commandable
 
@@ -342,6 +344,7 @@ func (pipe *RingPipeline) Exec() (cmds []Cmder, retErr error) {
 	return cmds, retErr
 }
 
+// Close closes the pipeline, releasing any open resources.
 func (pipe *RingPipeline) Close() error {
 	pipe.Discard()
 	pipe.closed = true

sentinel.go

@@ -54,8 +54,9 @@ func (opt *FailoverOptions) options() *Options {
 	}
 }
 
-// NewFailoverClient returns a Redis client with automatic failover
+// NewFailoverClient returns a Redis client that uses Redis Sentinel
-// capabilities using Redis Sentinel.
+// for automatic failover. It's safe for concurrent use by multiple
+// goroutines.
 func NewFailoverClient(failoverOpt *FailoverOptions) *Client {
 	opt := failoverOpt.options()
 	failover := &sentinelFailover{