swap writer for elasticbuffer for performance

lib/writer.js

@@ -1,66 +1,74 @@
-var Writer = function() {
-  this.buffers = [];
+var ElasticBuffer = function(size) {
+  this.size = size || 1024;
+  this.buffer = new Buffer(this.size);
+  this.offset = 0;
 };
 
-var p = Writer.prototype;
+var p = ElasticBuffer.prototype;
 
-p.add = function(buffer) {
-  this.buffers.push(buffer);
-  return this;
-};
+p._remaining = function() {
+  return this.buffer.length - this.offset;
+}
 
-p.addInt16 = function(val, front) {
-  return this.add(Buffer([
-    (val >>> 8),
-    (val >>> 0)
-  ]));
-};
+p._resize = function() {
+  var oldBuffer = this.buffer;
+  this.buffer = Buffer(oldBuffer.length + this.size);
+  oldBuffer.copy(this.buffer);
+}
 
-p.getByteLength = function(initial) {
-  var totalBufferLength = 0;
-  var buffers = this.buffers;
-  for(var i = 0, len = buffers.length; i < len; i++) {
-    totalBufferLength += buffers[i].length;
+//resizes internal buffer if not enough size left
+p._ensure = function(size) {
+  if(this._remaining() < size) {
+    this._resize()
   }
-  return totalBufferLength;
-};
+}
 
-p.addInt32 = function(val, first) {
-  return this.add(Buffer([
-    (val >>> 24 & 0xFF),
-    (val >>> 16 & 0xFF),
-    (val >>> 8 & 0xFF),
-    (val >>> 0 & 0xFF)
-  ]));
-};
+p.addInt32 = function(num) {
+  this._ensure(4)
+  this.buffer[this.offset++] = (num >>> 24 & 0xFF)
+  this.buffer[this.offset++] = (num >>> 16 & 0xFF)
+  this.buffer[this.offset++] = (num >>>  8 & 0xFF)
+  this.buffer[this.offset++] = (num >>>  0 & 0xFF)
+  return this;
+}
 
-p.addCString = function(val) {
-  var len = Buffer.byteLength(val);
-  var buffer = new Buffer(len+1);
-  buffer.write(val);
-  buffer[len] = 0;
-  return this.add(buffer);
-};
+p.addInt16 = function(num) {
+  this._ensure(2)
+  this.buffer[this.offset++] = (num >>>  8 & 0xFF)
+  this.buffer[this.offset++] = (num >>>  0 & 0xFF)
+  return this;
+}
 
-p.addChar = function(char, first) {
-  return this.add(Buffer(char,'utf8'), first);
-};
+p.addCString = function(string) {
+  var string = string || "";
+  var len = Buffer.byteLength(string) + 1;
+  this._ensure(len);
+  this.buffer.write(string, this.offset);
+  this.offset += len;
+  this.buffer[this.offset] = 0; //add null terminator
+  return this;  
+}
+
+p.addChar = function(char) {
+  this._ensure(1);
+  this.buffer.write(char, this.offset);
+  this.offset++;
+  return this;
+}
 
 p.join = function() {
-  var length = this.buffers.length;
-  if(length===1) {
-    return this.buffers[0]
-  }
-  var result = Buffer(this.getByteLength());
-  var index = 0;
-  var buffers = this.buffers;
-  for(var i = 0; i < length; i ++) {
-    var buffer = buffers[i];
-    buffer.copy(result, index, 0);
-    index += buffer.length;
-  }
-  return result;
-};
+  return this.buffer.slice(0, this.offset);
+}
 
-module.exports = Writer;
+p.getByteLength = function() {
+  return this.offset;
+}
 
+p.add = function(otherBuffer) {
+  this._ensure(otherBuffer.length);
+  otherBuffer.copy(this.buffer, this.offset);
+  this.offset += otherBuffer.length;
+  return this;
+}
+
+module.exports = ElasticBuffer;