Removed 1 alloc in channel validation (#251)

More work towards reducing the number of heap allocations in the hot path.

appveyor.yml

@@ -31,7 +31,7 @@ deploy:
   - provider: GitHub
     auth_token:
       secure: ImwOgsH/e1F+reDfqNIvoQ773FZHsjQt/4znrFdxUVrs1VNpFK9IUaW4hIL/yl4c
-    release: 'master'
+    release: 'edge'
     description: 'This is v$(appveyor_build_version) pre-release which is automatically built on every commit to master.'
     draft: false
     prerelease: true

internal/broker/bench_test.go

@@ -33,7 +33,7 @@ import (
 
 var benchInit sync.Once
 
-// BenchmarkSerial-8   	     100	  10084435 ns/op	    2183 B/op	      19 allocs/op
+// BenchmarkSerial-8   	     100	  10007938 ns/op	    2172 B/op	      17 allocs/op
 func BenchmarkSerial(b *testing.B) {
 	const port = 9995
 	benchInit.Do(func() {
@@ -64,7 +64,7 @@ func BenchmarkSerial(b *testing.B) {
 	}
 }
 
-// BenchmarkParallel-8   	  200000	      6801 ns/op	    1488 B/op	      16 allocs/op
+// BenchmarkParallel-8   	  200000	      8068 ns/op	    1331 B/op	      13 allocs/op
 func BenchmarkParallel(b *testing.B) {
 	const port = 9995
 	benchInit.Do(func() {

internal/security/channel_test.go

@@ -22,22 +22,22 @@ import (
 )
 
 func BenchmarkParseChannelWithOptions(b *testing.B) {
-	in := "xm54Sj0srWlSEctra-yU6ZA6Z2e6pp7c/a/roman/is/da/best/?opt1=true&opt2=false"
+	in := []byte("xm54Sj0srWlSEctra-yU6ZA6Z2e6pp7c/a/roman/is/da/best/?opt1=true&opt2=false")
 
 	b.ReportAllocs()
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
-		_ = ParseChannel([]byte(in))
+		_ = ParseChannel(in)
 	}
 }
 
 func BenchmarkParseChannelStatic(b *testing.B) {
-	in := "xm54Sj0srWlSEctra-yU6ZA6Z2e6pp7c/a/roman/is/da/best/"
+	in := []byte("xm54Sj0srWlSEctra-yU6ZA6Z2e6pp7c/a/roman/is/da/best/")
 
 	b.ReportAllocs()
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
-		_ = ParseChannel([]byte(in))
+		_ = ParseChannel(in)
 	}
 }
 

internal/security/key.go

@@ -117,6 +117,10 @@ func (k Key) SetPermissions(value uint8) {
 
 // ValidateChannel validates the channel string.
 func (k Key) ValidateChannel(ch *Channel) bool {
+	topic := ch.Channel
+	if len(topic) == 0 {
+		return false
+	}
 
 	// Bytes 16-17-18-19 contains target hash
 	target := uint32(k[16])<<24 | uint32(k[17])<<16 | uint32(k[18])<<8 | uint32(k[19])
@@ -130,8 +134,13 @@ func (k Key) ValidateChannel(ch *Channel) bool {
 		return target == ch.Target()
 	}
 
-	channel := string(ch.Channel)
-	channel = strings.TrimRight(channel, "/")
+	// Trim right `/`
+	if topic[len(topic)-1] == '/' {
+		topic = topic[:len(topic)-1]
+	}
+
+	// Split by `/`
+	channel := binaryToString(&topic)
 	parts := strings.Split(channel, "/")
 	wc := parts[len(parts)-1] == "#"
 	if wc {

internal/security/key_test.go

@@ -26,6 +26,19 @@ func TestKeyIsEmpty(t *testing.T) {
 	assert.True(t, true, key.IsEmpty())
 }
 
+// BenchmarkValidateChannel-8   	10000000	       126 ns/op	      48 B/op	       1 allocs/op
+func BenchmarkValidateChannel(b *testing.B) {
+	key := Key(make([]byte, 24))
+	key.SetTarget("a/")
+	v := ParseChannel([]byte(string(key) + "a/b/c/d/"))
+
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		key.ValidateChannel(v)
+	}
+}
+
 func validateChannel(k Key, c string) bool {
 	return k.ValidateChannel(&Channel{Channel: []byte(c)})
 }