From c438d40377eab513f1e44232f320d890c93f29f9 Mon Sep 17 00:00:00 2001
From: Vladimir Mihailenco <vladimir.webdev@gmail.com>
Date: Tue, 7 Oct 2014 15:40:00 +0300
Subject: [PATCH] Add optimization for '*' pattern in PubSubChannels.

---
 commands.go   | 6 +++++-
 redis_test.go | 8 ++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/commands.go b/commands.go
index 01e758a7..99beb61f 100644
--- a/commands.go
+++ b/commands.go
@@ -1212,7 +1212,11 @@ func (c *Client) DebugObject(key string) *StringCmd {
 //------------------------------------------------------------------------------
 
 func (c *Client) PubSubChannels(pattern string) *StringSliceCmd {
-	cmd := NewStringSliceCmd("PUBSUB", "CHANNELS", pattern)
+	args := []string{"PUBSUB", "CHANNELS"}
+	if pattern != "*" {
+		args = append(args, pattern)
+	}
+	cmd := NewStringSliceCmd(args...)
 	c.Process(cmd)
 	return cmd
 }
diff --git a/redis_test.go b/redis_test.go
index 2407795a..5aef878e 100644
--- a/redis_test.go
+++ b/redis_test.go
@@ -2576,6 +2576,14 @@ func (t *RedisTest) TestPubSubChannels(c *C) {
 	channels, err = t.client.PubSubChannels("mychannel*").Result()
 	c.Assert(err, IsNil)
 	c.Assert(sortStrings(channels), DeepEquals, []string{"mychannel", "mychannel2"})
+
+	channels, err = t.client.PubSubChannels("").Result()
+	c.Assert(err, IsNil)
+	c.Assert(channels, HasLen, 0)
+
+	channels, err = t.client.PubSubChannels("*").Result()
+	c.Assert(err, IsNil)
+	c.Assert(len(channels) >= 2, Equals, true)
 }
 
 func (t *RedisTest) TestPubSubNumSub(c *C) {