faster encapsulation + join

multiaddr.go

@@ -84,10 +84,10 @@ func (m *multiaddr) Encapsulate(o Multiaddr) Multiaddr {
 	mb := m.bytes
 	ob := o.Bytes()
 
-	var b bytes.Buffer
-	b.Write(mb)
-	b.Write(ob)
-	return &multiaddr{bytes: b.Bytes()}
+	b := make([]byte, len(mb)+len(ob))
+	copy(b, mb)
+	copy(b[len(mb):], ob)
+	return &multiaddr{bytes: b}
 }
 
 // Decapsulate unwraps Multiaddr up until the given Multiaddr is found.

util.go

 package multiaddr
 
-import (
-	"bytes"
-	"fmt"
-)
+import "fmt"
 
 // Split returns the sub-address portions of a multiaddr.
 func Split(m Multiaddr) []Multiaddr {
@@ -21,11 +18,23 @@ func Split(m Multiaddr) []Multiaddr {
 
 // Join returns a combination of addresses.
 func Join(ms ...Multiaddr) Multiaddr {
-	var b bytes.Buffer
-	for _, m := range ms {
-		b.Write(m.Bytes())
+
+	length := 0
+	bs := make([][]byte, len(ms))
+	for i, m := range ms {
+		bs[i] = m.Bytes()
+		length += len(bs[i])
+	}
+
+	bidx := 0
+	b := make([]byte, length)
+	for _, mb := range bs {
+		for i := range mb {
+			b[bidx] = mb[i]
+			bidx++
 		}
-	return &multiaddr{bytes: b.Bytes()}
+	}
+	return &multiaddr{bytes: b}
 }
 
 // Cast re-casts a byte slice as a multiaddr. will panic if it fails to parse.