Optimise some special cases in StreamReader; return a new Buffer from read() immediately if there's enough buffered data, and if the read can be fulfilled entirely from the first queued buffer than take a slice rather than copying into a new buffer.

lib/websocket/driver/hybi/stream_reader.js

@@ -57,6 +57,9 @@ StreamReader.prototype.fork = function(length) {
 StreamReader.prototype.read = function(length, callback) {
   if (!this.writable) return;
 
+  if (this._queueSize >= length)
+    return callback.call(this._context, this._readBytes(length));
+
   var self = this;
 
   this.fork(length).pipe(new Concat(function(buffer) {
@@ -67,7 +70,7 @@ StreamReader.prototype.read = function(length, callback) {
 StreamReader.prototype._flush = function() {
   var streams = this._streams, stream, size, buffer;
 
-  while (streams.length > 0 && this._queueSize >= 0) {
+  while (streams.length > 0 && this._queueSize > 0) {
     stream = streams[0];
     size   = Math.min(stream._remaining, this._queueSize);
     buffer = this._readBytes(size);
@@ -84,12 +87,26 @@ StreamReader.prototype._flush = function() {
 };
 
 StreamReader.prototype._readBytes = function(length) {
-  var buffer = new Buffer(length),
-      queue  = this._queue,
+  var queue  = this._queue,
       remain = length,
       n      = queue.length,
+      first  = queue[0],
       i      = 0,
-      chunk, size;
+      buffer, chunk, size;
+
+  if (length === 0) return new Buffer(0);
+
+  if (remain <= first.length - this._cursor) {
+    buffer = first.slice(this._cursor, this._cursor + remain);
+
+    this._queueSize -= remain;
+    this._cursor     = (this._cursor + remain) % first.length;
+    if (this._cursor === 0) this._queue.shift();
+
+    return buffer;
+  }
+
+  buffer = new Buffer(length);
 
   while (remain > 0 && i < n) {
     chunk = queue[i];