Store only current pack and beyond in parser

Changes.md

@@ -4,6 +4,10 @@ This file is a manually maintained list of changes for each release. Feel free
 to add your changes here when sending pull requests. Also send corrections if
 you spot any mistakes.
 
+## HEAD
+
+* Store only current pack and beyond in parser
+
 ## v2.5.1 (2014-09-22)
 
 * Fix `pool.end` race conditions #915

lib/protocol/Parser.js

@@ -98,25 +98,36 @@ Parser.prototype.write = function(buffer) {
   }
 };
 
-Parser.prototype.append = function(newBuffer) {
-  // If resume() is called, we don't pass a buffer to write()
-  if (!newBuffer) {
+Parser.prototype.append = function append(chunk) {
+  if (!chunk || chunk.length === 0) {
     return;
   }
 
-  var oldBuffer = this._buffer;
-  var bytesRemaining = this._bytesRemaining();
-  var newLength = bytesRemaining + newBuffer.length;
+  var buffer      = chunk;
+  var sliceEnd    = this._buffer.length;
+  var sliceStart  = this._packetOffset === null
+    ? this._offset
+    : this._packetOffset;
+  var sliceLength = sliceEnd - sliceStart;
 
-  var combinedBuffer = (this._offset > newLength)
-    ? oldBuffer.slice(0, newLength)
-    : new Buffer(newLength);
+  if (sliceLength !== 0) {
+    // Create a new Buffer
+    buffer = new Buffer(sliceLength + chunk.length);
 
-  oldBuffer.copy(combinedBuffer, 0, this._offset);
-  newBuffer.copy(combinedBuffer, bytesRemaining);
+    // Copy data
+    this._buffer.copy(buffer, 0, sliceStart, sliceEnd);
+    chunk.copy(buffer, sliceLength);
+  }
 
-  this._buffer = combinedBuffer;
-  this._offset = 0;
+  // Adjust data-tracking pointers
+  this._buffer       = buffer;
+  this._offset       = this._offset - sliceStart;
+  this._packetEnd    = this._packetEnd !== null
+    ? this._packetEnd - sliceStart
+    : null;
+  this._packetOffset = this._packetOffset !== null
+    ? this._packetOffset - sliceStart
+    : null;
 };
 
 Parser.prototype.pause = function() {