Crawler frontend

lib/storage.js

Index: lib/storage.js
===================================================================
new file mode 100644
--- /dev/null
+++ b/lib/storage.js
@@ -0,0 +1,45 @@
+Cu.import("resource://gre/modules/FileUtils.jsm");
+
+let outputStream;
+let converterOutputStream;
+
+function createTemporaryFile(name)
+{
+  let file = FileUtils.getFile("TmpD", [name]);
+  file.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, FileUtils.PERMS_FILE);
+  return file;
+}
+
+function openOutputStream(file)
+{
+  let outputStream = FileUtils.openSafeFileOutputStream(file);
+  let converterOutputStream = Cc["@mozilla.org/intl/converter-output-stream;1"]
+      .createInstance(Ci.nsIConverterOutputStream);
+  converterOutputStream.init(outputStream, "UTF-8", 0, 0);
+  return [outputStream, converterOutputStream];
+}
+
+let Storage = exports.Storage = {};
+
+Storage.init = function()
+{
+  Storage.dataFile = createTemporaryFile("crawler-data");
+  [outputStream, converterOutputStream] = openOutputStream(Storage.dataFile);
+};
+
+Storage.write = function(data)
+{
+  let line = JSON.stringify(data) + "\n";
+  converterOutputStream.writeString(line);
+};
+
+Storage.finish = function()
+{
+  converterOutputStream.flush();
+  FileUtils.closeSafeFileOutputStream(outputStream);
+};
+
+Storage.destroy = function()
+{
+  Storage.dataFile.remove(true);
+};