1 files changed, 147 insertions, 0 deletions
diff --git a/browser/devtools/performance/modules/io.js b/browser/devtools/performance/modules/io.js
new file mode 100644
index 000000000..6239d5a00
--- /dev/null
+++ b/browser/devtools/performance/modules/io.js
@@ -0,0 +1,147 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+"use strict";
+
+const { Cc, Ci, Cu, Cr } = require("chrome");
+
+loader.lazyRequireGetter(this, "Services");
+loader.lazyRequireGetter(this, "promise");
+
+loader.lazyImporter(this, "FileUtils",
+  "resource://gre/modules/FileUtils.jsm");
+loader.lazyImporter(this, "NetUtil",
+  "resource://gre/modules/NetUtil.jsm");
+
+// This identifier string is used to tentatively ascertain whether or not
+// a JSON loaded from disk is actually something generated by this tool.
+// It isn't, of course, a definitive verification, but a Good Enough™
+// approximation before continuing the import. Don't localize this.
+const PERF_TOOL_SERIALIZER_IDENTIFIER = "Recorded Performance Data";
+const PERF_TOOL_SERIALIZER_LEGACY_VERSION = 1;
+const PERF_TOOL_SERIALIZER_CURRENT_VERSION = 2;
+
+/**
+ * Helpers for importing/exporting JSON.
+ */
+let PerformanceIO = {
+  /**
+   * Gets a nsIScriptableUnicodeConverter instance with a default UTF-8 charset.
+   * @return object
+   */
+  getUnicodeConverter: function() {
+    let className = "@mozilla.org/intl/scriptableunicodeconverter";
+    let converter = Cc[className].createInstance(Ci.nsIScriptableUnicodeConverter);
+    converter.charset = "UTF-8";
+    return converter;
+  },
+
+  /**
+   * Saves a recording as JSON to a file. The provided data is assumed to be
+   * acyclical, so that it can be properly serialized.
+   *
+   * @param object recordingData
+   *        The recording data to stream as JSON.
+   * @param nsILocalFile file
+   *        The file to stream the data into.
+   * @return object
+   *         A promise that is resolved once streaming finishes, or rejected
+   *         if there was an error.
+   */
+  saveRecordingToFile: function(recordingData, file) {
+    let deferred = promise.defer();
+
+    recordingData.fileType = PERF_TOOL_SERIALIZER_IDENTIFIER;
+    recordingData.version = PERF_TOOL_SERIALIZER_CURRENT_VERSION;
+
+    let string = JSON.stringify(recordingData);
+    let inputStream = this.getUnicodeConverter().convertToInputStream(string);
+    let outputStream = FileUtils.openSafeFileOutputStream(file);
+
+    NetUtil.asyncCopy(inputStream, outputStream, deferred.resolve);
+    return deferred.promise;
+  },
+
+  /**
+   * Loads a recording stored as JSON from a file.
+   *
+   * @param nsILocalFile file
+   *        The file to import the data from.
+   * @return object
+   *         A promise that is resolved once importing finishes, or rejected
+   *         if there was an error.
+   */
+  loadRecordingFromFile: function(file) {
+    let deferred = promise.defer();
+
+    let channel = NetUtil.newChannel(file);
+    channel.contentType = "text/plain";
+
+    NetUtil.asyncFetch(channel, (inputStream, status) => {
+      try {
+        let string = NetUtil.readInputStreamToString(inputStream, inputStream.available());
+        var recordingData = JSON.parse(string);
+      } catch (e) {
+        deferred.reject(new Error("Could not read recording data file."));
+        return;
+      }
+      if (recordingData.fileType != PERF_TOOL_SERIALIZER_IDENTIFIER) {
+        deferred.reject(new Error("Unrecognized recording data file."));
+        return;
+      }
+      if (!isValidSerializerVersion(recordingData.version)) {
+        deferred.reject(new Error("Unsupported recording data file version."));
+        return;
+      }
+      if (recordingData.version === PERF_TOOL_SERIALIZER_LEGACY_VERSION) {
+        recordingData = convertLegacyData(recordingData);
+      }
+      deferred.resolve(recordingData);
+    });
+
+    return deferred.promise;
+  }
+};
+
+exports.PerformanceIO = PerformanceIO;
+
+/**
+ * Returns a boolean indicating whether or not the passed in `version`
+ * is supported by this serializer.
+ *
+ * @param number version
+ * @return boolean
+ */
+function isValidSerializerVersion (version) {
+  return !!~[
+    PERF_TOOL_SERIALIZER_LEGACY_VERSION,
+    PERF_TOOL_SERIALIZER_CURRENT_VERSION
+  ].indexOf(version);
+}
+
+/**
+ * Takes recording data (with version `1`, from the original profiler tool), and
+ * massages the data to be line with the current performance tool's property names
+ * and values.
+ *
+ * @param object legacyData
+ * @return object
+ */
+function convertLegacyData (legacyData) {
+  let { profilerData, ticksData, recordingDuration } = legacyData;
+
+  // The `profilerData` and `ticksData` stay, but the previously unrecorded
+  // fields just are empty arrays or objects.
+  let data = {
+    label: profilerData.profilerLabel,
+    duration: recordingDuration,
+    markers: [],
+    frames: [],
+    memory: [],
+    ticks: ticksData,
+    allocations: { sites: [], timestamps: [], frames: [], counts: [] },
+    profile: profilerData.profile
+  };
+
+  return data;
+}