Refactors PdfDataLister buffering.

extensions/firefox/content/PdfStreamConverter.jsm

@@ -177,46 +177,38 @@ function makeContentReadable(obj, window) {
 // PDF data storage
 function PdfDataListener(length) {
   this.length = length; // less than 0, if length is unknown
-  this.data = new Uint8Array(length >= 0 ? length : 0x10000);
-  this.position = 0;
+  this.buffer = null;
   this.loaded = 0;
 }
 
 PdfDataListener.prototype = {
   append: function PdfDataListener_append(chunk) {
-    var willBeLoaded = this.loaded + chunk.length;
-    if (this.length >= 0 && this.length < willBeLoaded) {
-      this.length = -1; // reset the length, server is giving incorrect one
+    // In most of the cases we will pass data as we receive it, but at the
+    // beginning of the loading we may accumulate some data.
+    if (!this.buffer) {
+      this.buffer = new Uint8Array(chunk);
+    } else {
+      var buffer = this.buffer;
+      var newBuffer = new Uint8Array(buffer.length + chunk.length);
+      newBuffer.set(buffer);
+      newBuffer.set(chunk, buffer.length);
+      this.buffer = newBuffer;
     }
-    if (this.length < 0 && this.data.length < willBeLoaded) {
-      // data length is unknown and new chunk will not fit in the existing
-      // buffer, resizing the buffer by doubling the its last length
-      var newLength = this.data.length;
-      for (; newLength < willBeLoaded; newLength *= 2) {}
-      var newData = new Uint8Array(newLength);
-      newData.set(this.data);
-      this.data = newData;
+    this.loaded += chunk.length;
+    if (this.length >= 0 && this.length < this.loaded) {
+      this.length = -1; // reset the length, server is giving incorrect one
     }
-    this.data.set(chunk, this.loaded);
-    this.loaded = willBeLoaded;
     this.onprogress(this.loaded, this.length >= 0 ? this.length : void(0));
   },
   readData: function PdfDataListener_readData() {
-    var data = this.data.subarray(this.position, this.loaded);
-    this.position = this.loaded;
-    return data;
-  },
-  getData: function PdfDataListener_getData() {
-    var data = this.data;
-    if (this.loaded != data.length)
-      data = data.subarray(0, this.loaded);
-    delete this.data; // releasing temporary storage
-    return data;
+    var result = this.buffer;
+    this.buffer = null;
+    return result;
   },
   finish: function PdfDataListener_finish() {
     this.isDataReady = true;
     if (this.oncompleteCallback) {
-      this.oncompleteCallback(this.getData());
+      this.oncompleteCallback(this.readData());
     }
   },
   error: function PdfDataListener_error(errorCode) {
@@ -232,7 +224,7 @@ PdfDataListener.prototype = {
   set oncomplete(value) {
     this.oncompleteCallback = value;
     if (this.isDataReady) {
-      value(this.getData());
+      value(this.readData());
     }
     if (this.errorCode) {
       value(null, this.errorCode);
@@ -607,7 +599,7 @@ var RangedChromeActions = (function RangedChromeActionsClosure() {
     if (!this.streamingEnabled) {
       this.originalRequest.cancel(Cr.NS_BINDING_ABORTED);
       this.originalRequest = null;
-      data = this.dataListener.getData();
+      data = this.dataListener.readData();
       this.dataListener = null;
     } else {
       data = this.dataListener.readData();