Merge pull request #788 from Endeavourken/master

[CHANGED] avoid unnecessary data copy in processMsg

nats.go

@@ -2629,8 +2629,11 @@ func (nc *Conn) processMsg(data []byte) {
 	// It's possible that we end-up not using the message, but that's ok.
 
 	// FIXME(dlc): Need to copy, should/can do COW?
-	msgPayload := make([]byte, len(data))
-	copy(msgPayload, data)
+	var msgPayload = data
+	if !nc.ps.msgCopied {
+		msgPayload = make([]byte, len(data))
+		copy(msgPayload, data)
+	}
 
 	// Check if we have headers encoded here.
 	var h Header

parser.go

@@ -28,14 +28,15 @@ type msgArg struct {
 const MAX_CONTROL_LINE_SIZE = 4096
 
 type parseState struct {
-	state   int
-	as      int
-	drop    int
-	hdr     int
-	ma      msgArg
-	argBuf  []byte
-	msgBuf  []byte
-	scratch [MAX_CONTROL_LINE_SIZE]byte
+	state     int
+	as        int
+	drop      int
+	hdr       int
+	ma        msgArg
+	argBuf    []byte
+	msgBuf    []byte
+	msgCopied bool
+	scratch   [MAX_CONTROL_LINE_SIZE]byte
 }
 
 const (
@@ -167,7 +168,7 @@ func (nc *Conn) parse(buf []byte) error {
 			if nc.ps.msgBuf != nil {
 				if len(nc.ps.msgBuf) >= nc.ps.ma.size {
 					nc.processMsg(nc.ps.msgBuf)
-					nc.ps.argBuf, nc.ps.msgBuf, nc.ps.state = nil, nil, MSG_END
+					nc.ps.argBuf, nc.ps.msgBuf, nc.ps.msgCopied, nc.ps.state = nil, nil, false, MSG_END
 				} else {
 					// copy as much as we can to the buffer and skip ahead.
 					toCopy := nc.ps.ma.size - len(nc.ps.msgBuf)
@@ -190,7 +191,7 @@ func (nc *Conn) parse(buf []byte) error {
 				}
 			} else if i-nc.ps.as >= nc.ps.ma.size {
 				nc.processMsg(buf[nc.ps.as:i])
-				nc.ps.argBuf, nc.ps.msgBuf, nc.ps.state = nil, nil, MSG_END
+				nc.ps.argBuf, nc.ps.msgBuf, nc.ps.msgCopied, nc.ps.state = nil, nil, false, MSG_END
 			}
 		case MSG_END:
 			switch b {
@@ -403,6 +404,7 @@ func (nc *Conn) parse(buf []byte) error {
 
 			nc.ps.msgBuf = make([]byte, lrem, nc.ps.ma.size)
 			copy(nc.ps.msgBuf, buf[nc.ps.as:])
+			nc.ps.msgCopied = true
 		} else {
 			nc.ps.msgBuf = nc.ps.scratch[len(nc.ps.argBuf):len(nc.ps.argBuf)]
 			nc.ps.msgBuf = append(nc.ps.msgBuf, (buf[nc.ps.as:])...)