Bug 753768 - Moving Page Thumbs I/O fully off the main thread;r=ttaubert

toolkit/components/thumbnails/PageThumbs.jsm

@@ -27,7 +27,10 @@ const THUMBNAIL_DIRECTORY = "thumbnails";
  */
 const THUMBNAIL_BG_COLOR = "#fff";
 
-Cu.import("resource://gre/modules/XPCOMUtils.jsm");
+Cu.import("resource://gre/modules/XPCOMUtils.jsm", this);
+Cu.import("resource://gre/modules/osfile/_PromiseWorker.jsm", this);
+Cu.import("resource://gre/modules/commonjs/sdk/core/promise.js", this);
+Cu.import("resource://gre/modules/osfile.jsm", this);
 
 XPCOMUtils.defineLazyModuleGetter(this, "NetUtil",
   "resource://gre/modules/NetUtil.jsm");
@@ -55,6 +58,70 @@ XPCOMUtils.defineLazyGetter(this, "gUnicodeConverter", function () {
   return converter;
 });
 
+XPCOMUtils.defineLazyModuleGetter(this, "Task",
+  "resource://gre/modules/Task.jsm");
+
+/**
+ * Utilities for dealing with promises and Task.jsm
+ */
+const TaskUtils = {
+  /**
+   * Add logging to a promise.
+   *
+   * @param {Promise} promise
+   * @return {Promise} A promise behaving as |promise|, but with additional
+   * logging in case of uncaught error.
+   */
+  captureErrors: function captureErrors(promise) {
+    return promise.then(
+      null,
+      function onError(reason) {
+        Cu.reportError("Uncaught asynchronous error: " + reason + " at\n"
+          + reason.stack + "\n");
+        throw reason;
+      }
+    );
+  },
+
+  /**
+   * Spawn a new Task from a generator.
+   *
+   * This function behaves as |Task.spawn|, with the exception that it
+   * adds logging in case of uncaught error. For more information, see
+   * the documentation of |Task.jsm|.
+   *
+   * @param {generator} gen Some generator.
+   * @return {Promise} A promise built from |gen|, with the same semantics
+   * as |Task.spawn(gen)|.
+   */
+  spawn: function spawn(gen) {
+    return this.captureErrors(Task.spawn(gen));
+  },
+  /**
+   * Read the bytes from a blob, asynchronously.
+   *
+   * @return {Promise}
+   * @resolve {ArrayBuffer} In case of success, the bytes contained in the blob.
+   * @reject {DOMError} In case of error, the underlying DOMError.
+   */
+  readBlob: function readBlob(blob) {
+    let deferred = Promise.defer();
+    let reader = Cc["@mozilla.org/files/filereader;1"].createInstance(Ci.nsIDOMFileReader);
+    reader.onloadend = function onloadend() {
+      if (reader.readyState != Ci.nsIDOMFileReader.DONE) {
+        deferred.reject(reader.error);
+      } else {
+        deferred.resolve(reader.result);
+      }
+    };
+    reader.readAsArrayBuffer(blob);
+    return deferred.promise;
+  }
+};
+
+
+
+
 /**
  * Singleton providing functionality for capturing web page thumbnails and for
  * accessing them if already cached.
@@ -134,6 +201,33 @@ this.PageThumbs = {
     }.bind(this), Ci.nsIThread.DISPATCH_NORMAL);
   },
 
+
+  /**
+   * Captures a thumbnail for the given window.
+   *
+   * @param aWindow The DOM window to capture a thumbnail from.
+   * @return {Promise}
+   * @resolve {Blob} The thumbnail, as a Blob.
+   */
+  captureToBlob: function PageThumbs_captureToBlob(aWindow) {
+    if (!this._prefEnabled()) {
+      return null;
+    }
+
+    let canvas = this._createCanvas();
+    this.captureToCanvas(aWindow, canvas);
+
+    let deferred = Promise.defer();
+    let type = this.contentType;
+    // Fetch the canvas data on the next event loop tick so that we allow
+    // some event processing in between drawing to the canvas and encoding
+    // its data. We want to block the UI as short as possible. See bug 744100.
+    canvas.toBlob(function asBlob(blob) {
+      deferred.resolve(blob, type);
+    });
+    return deferred.promise;
+  },
+
   /**
    * Captures a thumbnail from a given window and draws it to the given canvas.
    * @param aWindow The DOM window to capture a thumbnail from.
@@ -177,35 +271,39 @@ this.PageThumbs = {
     let channel = aBrowser.docShell.currentDocumentChannel;
     let originalURL = channel.originalURI.spec;
 
-    this.capture(aBrowser.contentWindow, function (aInputStream) {
-      let telemetryStoreTime = new Date();
+    TaskUtils.spawn((function task() {
+      let isSuccess = true;
+      try {
+        let blob = yield this.captureToBlob(aBrowser.contentWindow);
+        let buffer = yield TaskUtils.readBlob(blob);
 
-      function finish(aSuccessful) {
-        if (aSuccessful) {
-          Services.telemetry.getHistogramById("FX_THUMBNAILS_STORE_TIME_MS")
-            .add(new Date() - telemetryStoreTime);
+        let telemetryStoreTime = new Date();
+        yield PageThumbsStorage.writeData(url, new Uint8Array(buffer));
 
-          // We've been redirected. Create a copy of the current thumbnail for
-          // the redirect source. We need to do this because:
-          //
-          // 1) Users can drag any kind of links onto the newtab page. If those
-          //    links redirect to a different URL then we want to be able to
-          //    provide thumbnails for both of them.
-          //
-          // 2) The newtab page should actually display redirect targets, only.
-          //    Because of bug 559175 this information can get lost when using
-          //    Sync and therefore also redirect sources appear on the newtab
-          //    page. We also want thumbnails for those.
-          if (url != originalURL)
-            PageThumbsStorage.copy(url, originalURL);
+        Services.telemetry.getHistogramById("FX_THUMBNAILS_STORE_TIME_MS")
+          .add(new Date() - telemetryStoreTime);
+
+        // We've been redirected. Create a copy of the current thumbnail for
+        // the redirect source. We need to do this because:
+        //
+        // 1) Users can drag any kind of links onto the newtab page. If those
+        //    links redirect to a different URL then we want to be able to
+        //    provide thumbnails for both of them.
+        //
+        // 2) The newtab page should actually display redirect targets, only.
+        //    Because of bug 559175 this information can get lost when using
+        //    Sync and therefore also redirect sources appear on the newtab
+        //    page. We also want thumbnails for those.
+        if (url != originalURL) {
+          yield PageThumbsStorage.copy(url, originalURL);
         }
-
-        if (aCallback)
-          aCallback(aSuccessful);
+      } catch (_) {
+        isSuccess = false;
       }
-
-      PageThumbsStorage.write(url, aInputStream, finish);
-    });
+      if (aCallback) {
+        aCallback(isSuccess);
+      }
+    }).bind(this));
   },
 
   /**
@@ -314,55 +412,99 @@ this.PageThumbs = {
 };
 
 this.PageThumbsStorage = {
-  getDirectory: function Storage_getDirectory(aCreate = true) {
-    return FileUtils.getDir("ProfLD", [THUMBNAIL_DIRECTORY], aCreate);
+  // The path for the storage
+  _path: null,
+  get path() {
+    if (!this._path) {
+      this._path = OS.Path.join(OS.Constants.Path.localProfileDir, THUMBNAIL_DIRECTORY);
+    }
+    return this._path;
+  },
+
+  ensurePath: function Storage_ensurePath() {
+    // Create the directory (ignore any error if the directory
+    // already exists). As all writes are done from the PageThumbsWorker
+    // thread, which serializes its operations, this ensures that
+    // future operations can proceed without having to check whether
+    // the directory exists.
+    return PageThumbsWorker.post("makeDir",
+      [this.path, {ignoreExisting: true}]).then(
+        null,
+        function onError(aReason) {
+          Components.utils.reportError("Could not create thumbnails directory" + aReason);
+        });
   },
 
   getLeafNameForURL: function Storage_getLeafNameForURL(aURL) {
+    if (typeof aURL != "string") {
+      throw new TypeError("Expecting a string");
+    }
     let hash = this._calculateMD5Hash(aURL);
     return hash + ".png";
   },
 
-  getFileForURL: function Storage_getFileForURL(aURL) {
-    let file = this.getDirectory();
-    file.append(this.getLeafNameForURL(aURL));
-    return file;
+  getFilePathForURL: function Storage_getFilePathForURL(aURL) {
+    return OS.Path.join(this.path, this.getLeafNameForURL(aURL));
   },
 
-  write: function Storage_write(aURL, aDataStream, aCallback) {
-    let file = this.getFileForURL(aURL);
-    let fos = FileUtils.openSafeFileOutputStream(file);
-
-    NetUtil.asyncCopy(aDataStream, fos, function (aResult) {
-      FileUtils.closeSafeFileOutputStream(fos);
-      aCallback(Components.isSuccessCode(aResult));
-    });
+  /**
+   * Write the contents of a thumbnail, off the main thread.
+   *
+   * @param {string} aURL The url for which to store a thumbnail.
+   * @param {string} aData The data to store in the thumbnail, as
+   * an ArrayBuffer. This array buffer is neutered and cannot be
+   * reused after the copy.
+   *
+   * @return {Promise}
+   */
+  writeData: function Storage_write(aURL, aData) {
+    let path = this.getFilePathForURL(aURL);
+    this.ensurePath();
+    let msg = [
+      path,
+      aData,
+      {
+        tmpPath: path + ".tmp",
+        bytes: aData.byteLength,
+        flush: false /*thumbnails do not require the level of guarantee provided by flush*/
+      }];
+    return PageThumbsWorker.post("writeAtomic", msg,
+      msg /*we don't want that message garbage-collected,
+           as OS.Shared.Type.void_t.in_ptr.toMsg uses C-level
+           memory tricks to enforce zero-copy*/);
   },
 
+  /**
+   * Copy a thumbnail, off the main thread.
+   *
+   * @param {string} aSourceURL The url of the thumbnail to copy.
+   * @param {string} aTargetURL The url of the target thumbnail.
+   *
+   * @return {Promise}
+   */
   copy: function Storage_copy(aSourceURL, aTargetURL) {
-    let sourceFile = this.getFileForURL(aSourceURL);
-    let targetFile = this.getFileForURL(aTargetURL);
-
-    try {
-      sourceFile.copyTo(targetFile.parent, targetFile.leafName);
-    } catch (e) {
-      /* We might not be permitted to write to the file. */
-    }
+    this.ensurePath();
+    let sourceFile = this.getFilePathForURL(aSourceURL);
+    let targetFile = this.getFilePathForURL(aTargetURL);
+    return PageThumbsWorker.post("copy", [sourceFile, targetFile]);
   },
 
+  /**
+   * Remove a single thumbnail, off the main thread.
+   *
+   * @return {Promise}
+   */
   remove: function Storage_remove(aURL) {
-    let file = this.getFileForURL(aURL);
-    PageThumbsWorker.postMessage({type: "removeFile", path: file.path});
+    return PageThumbsWorker.post("remove", [this.getFilePathForURL(aURL)]);
   },
 
+  /**
+   * Remove all thumbnails, off the main thread.
+   *
+   * @return {Promise}
+   */
   wipe: function Storage_wipe() {
-    let dir = this.getDirectory(false);
-    dir.followLinks = false;
-    try {
-      dir.remove(true);
-    } catch (e) {
-      /* The directory might not exist or we're not permitted to remove it. */
-    }
+    return PageThumbsWorker.post("wipe", [this.path]);
   },
 
   _calculateMD5Hash: function Storage_calculateMD5Hash(aValue) {
@@ -423,18 +565,20 @@ let PageThumbsStorageMigrator = {
    * try to move the old thumbnails to their new location. If that's not
    * possible (because ProfD might be on a different file system than
    * ProfLD) we'll just discard them.
+   *
+   * @param {string*} local The path to the local profile directory.
+   * Used for testing. Default argument is good for all non-testing uses.
+   * @param {string*} roaming The path to the roaming profile directory.
+   * Used for testing. Default argument is good for all non-testing uses.
    */
-  migrateToVersion3: function Migrator_migrateToVersion3() {
-    let local = FileUtils.getDir("ProfLD", [THUMBNAIL_DIRECTORY], true);
-    let roaming = FileUtils.getDir("ProfD", [THUMBNAIL_DIRECTORY]);
-
-    if (!roaming.equals(local)) {
-      PageThumbsWorker.postMessage({
-        type: "moveOrDeleteAllThumbnails",
-        from: roaming.path,
-        to: local.path
-      });
-    }
+  migrateToVersion3: function Migrator_migrateToVersion3(
+    local = OS.Constants.Path.localProfileDir,
+    roaming = OS.Constants.Path.profileDir) {
+    PageThumbsWorker.post(
+      "moveOrDeleteAllThumbnails",
+      [OS.Path.join(roaming, THUMBNAIL_DIRECTORY),
+       OS.Path.join(local, THUMBNAIL_DIRECTORY)]
+    );
   }
 };
 
@@ -484,60 +628,46 @@ let PageThumbsExpiration = {
     }
   },
 
-  expireThumbnails: function Expiration_expireThumbnails(aURLsToKeep, aCallback) {
-    PageThumbsWorker.postMessage({
-      type: "expireFilesInDirectory",
-      minChunkSize: EXPIRATION_MIN_CHUNK_SIZE,
-      path: PageThumbsStorage.getDirectory().path,
-      filesToKeep: [PageThumbsStorage.getLeafNameForURL(url) for (url of aURLsToKeep)]
-    }, aCallback);
+  expireThumbnails: function Expiration_expireThumbnails(aURLsToKeep) {
+    let path = this.path;
+    let keep = [PageThumbsStorage.getLeafNameForURL(url) for (url of aURLsToKeep)];
+    let msg = [
+      PageThumbsStorage.path,
+      keep,
+      EXPIRATION_MIN_CHUNK_SIZE
+    ];
+
+    return PageThumbsWorker.post(
+      "expireFilesInDirectory",
+      msg
+    );
   }
 };
 
 /**
  * Interface to a dedicated thread handling I/O
  */
-let PageThumbsWorker = {
-  /**
-   * A (fifo) queue of callbacks registered for execution
-   * upon completion of calls to the worker.
-   */
-  _callbacks: [],
 
-  /**
-   * Get the worker, spawning it if necessary.
-   * Code of the worker is in companion file PageThumbsWorker.js
-   */
-  get _worker() {
-    delete this._worker;
-    this._worker = new ChromeWorker("resource://gre/modules/PageThumbsWorker.js");
-    this._worker.addEventListener("message", this);
-    return this._worker;
-  },
-
-  /**
-   * Post a message to the dedicated thread, registering a callback
-   * to be executed once the reply has been received.
-   *
-   * See PageThumbsWorker.js for the format of messages and replies.
-   *
-   * @param {*} message A JSON message.
-   * @param {Function=} callback An optional callback.
-   */
-  postMessage: function Worker_postMessage(message, callback) {
-    this._callbacks.push(callback);
-    this._worker.postMessage(message);
-  },
-
-  /**
-   * Handle a message from the dedicated thread.
-   */
-  handleEvent: function Worker_handleEvent(aEvent) {
-    let callback = this._callbacks.shift();
-    if (callback)
-      callback(aEvent.data);
-  }
-};
+let PageThumbsWorker = (function() {
+  let worker = new PromiseWorker("resource://gre/modules/PageThumbsWorker.js",
+    OS.Shared.LOG.bind("PageThumbs"));
+  return {
+    post: function post(...args) {
+      let promise = worker.post.apply(worker, args);
+      return promise.then(
+        null,
+        function onError(error) {
+          // Decode any serialized error
+          if (error instanceof PromiseWorker.WorkerError) {
+            throw OS.File.Error.fromMsg(error.data);
+          } else {
+            throw error;
+          }
+        }
+      );
+    }
+  };
+})();
 
 let PageThumbsHistoryObserver = {
   onDeleteURI: function Thumbnails_onDeleteURI(aURI, aGUID) {

toolkit/components/thumbnails/PageThumbsProtocol.js

@@ -27,6 +27,8 @@ Cu.import("resource://gre/modules/XPCOMUtils.jsm");
 
 XPCOMUtils.defineLazyModuleGetter(this, "Services",
   "resource://gre/modules/Services.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "FileUtils",
+  "resource://gre/modules/FileUtils.jsm");
 
 /**
  * Implements the thumbnail protocol handler responsible for moz-page-thumb: URIs.
@@ -73,8 +75,8 @@ Protocol.prototype = {
    */
   newChannel: function Proto_newChannel(aURI) {
     let {url} = parseURI(aURI);
-    let file = PageThumbsStorage.getFileForURL(url);
-    let fileuri = Services.io.newFileURI(file);
+    let file = PageThumbsStorage.getFilePathForURL(url);
+    let fileuri = Services.io.newFileURI(new FileUtils.File(file));
     return Services.io.newChannelFromURI(fileuri);
   },
 

toolkit/components/thumbnails/PageThumbsWorker.js

@@ -13,45 +13,62 @@
 
 importScripts("resource://gre/modules/osfile.jsm");
 
-let PageThumbsWorker = {
-  handleMessage: function Worker_handleMessage(aEvent) {
-    let msg = aEvent.data;
-    let data = {result: null, data: null};
+let File = OS.File;
+let Type = OS.Shared.Type;
 
-    switch (msg.type) {
-      case "removeFile":
-        data.result = this.removeFile(msg);
-        break;
-      case "expireFilesInDirectory":
-        data.result = this.expireFilesInDirectory(msg);
-        break;
-      case "moveOrDeleteAllThumbnails":
-        data.result = this.moveOrDeleteAllThumbnails(msg);
-        break;
-      default:
-        data.result = false;
-        data.detail = "message not understood";
-        break;
-    }
+/**
+ * Communications with the controller.
+ *
+ * Accepts messages:
+ * {fun:function_name, args:array_of_arguments_or_null}
+ *
+ * Sends messages:
+ * {ok: result} / {fail: serialized_form_of_OS.File.Error}
+ */
+self.onmessage = function onmessage(msg) {
+  let data = msg.data;
+  let id = data.id;
+  let result;
+  if (!(data.fun in Agent)) {
+    throw new Error("Cannot find method " + data.fun);
+  }
+  try {
+    result = Agent[data.fun].apply(Agent, data.args);
+  } catch (ex if ex instanceof StopIteration) {
+    // StopIteration cannot be serialized automatically
+    self.postMessage({StopIteration: true, id: id});
+    return;
+  } catch (ex if ex instanceof OS.File.Error) {
+    // Instances of OS.File.Error know how to serialize themselves
+    // (deserialization ensures that we end up with OS-specific
+    // instances of |OS.File.Error|)
+    self.postMessage({fail: OS.File.Error.toMsg(ex), id:id});
+    return;
+  }
+  // Other exceptions do not, and should be propagated through DOM's
+  // built-in mechanism for uncaught errors, although this mechanism
+  // may lose interesting information.
+  self.postMessage({ok: result, id:id});
+};
 
-    self.postMessage(data);
-  },
 
-  removeFile: function Worker_removeFile(msg) {
+let Agent = {
+  remove: function Agent_removeFile(path) {
     try {
-      OS.File.remove(msg.path);
+      OS.File.remove(path);
       return true;
     } catch (e) {
       return false;
     }
   },
 
-  expireFilesInDirectory: function Worker_expireFilesInDirectory(msg) {
-    let entries = this.getFileEntriesInDirectory(msg.path, msg.filesToKeep);
-    let limit = Math.max(msg.minChunkSize, Math.round(entries.length / 2));
+  expireFilesInDirectory:
+  function Agent_expireFilesInDirectory(path, filesToKeep, minChunkSize) {
+    let entries = this.getFileEntriesInDirectory(path, filesToKeep);
+    let limit = Math.max(minChunkSize, Math.round(entries.length / 2));
 
     for (let entry of entries) {
-      this.removeFile(entry);
+      this.remove(entry.path);
 
       // Check if we reached the limit of files to remove.
       if (--limit <= 0) {
@@ -63,9 +80,13 @@ let PageThumbsWorker = {
   },
 
   getFileEntriesInDirectory:
-  function Worker_getFileEntriesInDirectory(aPath, aSkipFiles) {
-    let skip = new Set(aSkipFiles);
-    let iter = new OS.File.DirectoryIterator(aPath);
+  function Agent_getFileEntriesInDirectory(path, skipFiles) {
+    let iter = new OS.File.DirectoryIterator(path);
+    if (!iter.exists()) {
+      return [];
+    }
+
+    let skip = new Set(skipFiles);
 
     return [entry
             for (entry in iter)
@@ -73,36 +94,74 @@ let PageThumbsWorker = {
   },
 
   moveOrDeleteAllThumbnails:
-  function Worker_moveOrDeleteAllThumbnails(msg) {
-    if (!OS.File.exists(msg.from))
+  function Agent_moveOrDeleteAllThumbnails(pathFrom, pathTo) {
+    OS.File.makeDir(pathTo, {ignoreExisting: true});
+    if (pathFrom == pathTo) {
       return true;
+    }
+    let iter = new OS.File.DirectoryIterator(pathFrom);
+    if (iter.exists()) {
+      for (let entry in iter) {
+        if (entry.isDir || entry.isSymLink) {
+          continue;
+        }
 
-    let iter = new OS.File.DirectoryIterator(msg.from);
-    for (let entry in iter) {
-      if (entry.isDir || entry.isSymLink) {
-        continue;
-      }
 
-      let from = OS.Path.join(msg.from, entry.name);
-      let to = OS.Path.join(msg.to, entry.name);
+        let from = OS.Path.join(pathFrom, entry.name);
+        let to = OS.Path.join(pathTo, entry.name);
 
-      try {
-        OS.File.move(from, to, {noOverwrite: true, noCopy: true});
-      } catch (e) {
-        OS.File.remove(from);
+        try {
+          OS.File.move(from, to, {noOverwrite: true, noCopy: true});
+        } catch (e) {
+          OS.File.remove(from);
+        }
       }
     }
     iter.close();
 
     try {
-      OS.File.removeEmptyDir(msg.from);
+      OS.File.removeEmptyDir(pathFrom);
     } catch (e) {
       // This could fail if there's something in
       // the folder we're not permitted to remove.
     }
 
     return true;
-  }
+  },
+
+  writeAtomic: function Agent_writeAtomic(path, buffer, options) {
+    return File.writeAtomic(path,
+      buffer,
+      options);
+  },
+
+  makeDir: function Agent_makeDir(path, options) {
+    return File.makeDir(path, options);
+  },
+
+  copy: function Agent_copy(source, dest) {
+    return File.copy(source, dest);
+  },
+
+  wipe: function Agent_wipe(path) {
+    let iterator = new File.DirectoryIterator(path);
+    try {
+      for (let entry in iterator) {
+        try {
+          File.remove(entry.path);
+        } catch (ex) {
+          // If a file cannot be removed, we should still continue.
+          // This can happen at least for any of the following reasons:
+          // - access denied;
+          // - file has been removed recently during a previous wipe
+          //  and the file system has not flushed that yet (yes, this
+          //  can happen under Windows);
+          // - file has been removed by the user or another process.
+        }
+      }
+    } finally {
+      iterator.close();
+    }
+   }
 };
 
-self.onmessage = PageThumbsWorker.handleMessage.bind(PageThumbsWorker);

toolkit/components/thumbnails/test/browser_thumbnails_expiration.js

@@ -6,9 +6,6 @@ const URL1 = URL + "#1";
 const URL2 = URL + "#2";
 const URL3 = URL + "#3";
 
-XPCOMUtils.defineLazyModuleGetter(this, "FileUtils",
-  "resource://gre/modules/FileUtils.jsm");
-
 let tmp = {};
 Cc["@mozilla.org/moz/jssubscript-loader;1"]
   .getService(Ci.mozIJSSubScriptLoader)
@@ -18,13 +15,13 @@ const {EXPIRATION_MIN_CHUNK_SIZE, PageThumbsExpiration} = tmp;
 
 function runTests() {
   // Create three thumbnails.
-  createDummyThumbnail(URL1);
+  yield createDummyThumbnail(URL1);
   ok(thumbnailExists(URL1), "first thumbnail created");
 
-  createDummyThumbnail(URL2);
+  yield createDummyThumbnail(URL2);
   ok(thumbnailExists(URL2), "second thumbnail created");
 
-  createDummyThumbnail(URL3);
+  yield createDummyThumbnail(URL3);
   ok(thumbnailExists(URL3), "third thumbnail created");
 
   // Remove the third thumbnail.
@@ -45,10 +42,11 @@ function runTests() {
   // Create some more files than the min chunk size.
   let urls = [];
   for (let i = 0; i < EXPIRATION_MIN_CHUNK_SIZE + 10; i++) {
-    urls.push(URL + "#dummy" + i);
+    let url = URL + "#dummy" + i;
+    urls.push(url);
+    yield createDummyThumbnail(url);
   }
 
-  urls.forEach(createDummyThumbnail);
   ok(urls.every(thumbnailExists), "all dummy thumbnails created");
 
   // Make sure our dummy thumbnails aren't expired too early.
@@ -71,16 +69,30 @@ function runTests() {
 }
 
 function createDummyThumbnail(aURL) {
-  let file = PageThumbsStorage.getFileForURL(aURL);
-  let fos = FileUtils.openSafeFileOutputStream(file);
-
-  let data = "dummy";
-  fos.write(data, data.length);
-  FileUtils.closeSafeFileOutputStream(fos);
+  info("Creating dummy thumbnail for " + aURL);
+  let dummy = new Uint8Array(10);
+  for (let i = 0; i < 10; ++i) {
+    dummy[i] = i;
+  }
+  PageThumbsStorage.writeData(aURL, dummy).then(
+    function onSuccess() {
+      info("createDummyThumbnail succeeded");
+      executeSoon(next);
+    },
+    function onFailure(error) {
+      ok(false, "createDummyThumbnail failed " + error);
+    }
+  );
 }
 
 function expireThumbnails(aKeep) {
-  PageThumbsExpiration.expireThumbnails(aKeep, function () {
-    executeSoon(next);
-  });
+  PageThumbsExpiration.expireThumbnails(aKeep).then(
+    function onSuccess() {
+      info("expireThumbnails succeeded");
+      executeSoon(next);
+    },
+    function onFailure(error) {
+      ok(false, "expireThumbnails failed " + error);
+    }
+  );
 }

toolkit/components/thumbnails/test/browser_thumbnails_storage.js

@@ -22,16 +22,16 @@ function runTests() {
   yield createThumbnail();
 
   // Make sure Storage.copy() updates an existing file.
-  PageThumbsStorage.copy(URL, URL_COPY);
-  let copy = PageThumbsStorage.getFileForURL(URL_COPY);
+  yield PageThumbsStorage.copy(URL, URL_COPY);
+  let copy = new FileUtils.File(PageThumbsStorage.getFilePathForURL(URL_COPY));
   let mtime = copy.lastModifiedTime -= 60;
 
-  PageThumbsStorage.copy(URL, URL_COPY);
-  isnot(PageThumbsStorage.getFileForURL(URL_COPY).lastModifiedTime, mtime,
+  yield PageThumbsStorage.copy(URL, URL_COPY);
+  isnot(new FileUtils.File(PageThumbsStorage.getFilePathForURL(URL_COPY)).lastModifiedTime, mtime,
         "thumbnail file was updated");
 
-  let file = PageThumbsStorage.getFileForURL(URL);
-  let fileCopy = PageThumbsStorage.getFileForURL(URL_COPY);
+  let file = new FileUtils.File(PageThumbsStorage.getFilePathForURL(URL));
+  let fileCopy = new FileUtils.File(PageThumbsStorage.getFilePathForURL(URL_COPY));
 
   // Clear the browser history. Retry until the files are gone because Windows
   // locks them sometimes.

toolkit/components/thumbnails/test/browser_thumbnails_storage_migrate3.js

@@ -13,9 +13,6 @@ Cc["@mozilla.org/moz/jssubscript-loader;1"]
   .loadSubScript("resource://gre/modules/PageThumbs.jsm", tmp);
 let {PageThumbsStorageMigrator} = tmp;
 
-XPCOMUtils.defineLazyModuleGetter(this, "FileUtils",
-  "resource://gre/modules/FileUtils.jsm");
-
 XPCOMUtils.defineLazyServiceGetter(this, "gDirSvc",
   "@mozilla.org/file/directory_service;1", "nsIProperties");
 
@@ -55,7 +52,7 @@ function runTests() {
   writeDummyFile(file, "no-overwrite-plz");
 
   // Kick off thumbnail storage migration.
-  PageThumbsStorageMigrator.migrateToVersion3();
+  PageThumbsStorageMigrator.migrateToVersion3(localProfile.path);
   ok(true, "migration finished");
 
   // Wait until the first thumbnail was moved to its new location.

toolkit/components/thumbnails/test/head.js

@@ -4,7 +4,9 @@
 let tmp = {};
 Cu.import("resource://gre/modules/PageThumbs.jsm", tmp);
 Cu.import("resource:///modules/sessionstore/SessionStore.jsm", tmp);
-let {PageThumbs, PageThumbsStorage, SessionStore} = tmp;
+Cu.import("resource://gre/modules/FileUtils.jsm", tmp);
+Cu.import("resource://gre/modules/osfile.jsm", tmp);
+let {PageThumbs, PageThumbsStorage, SessionStore, FileUtils, OS} = tmp;
 
 Cu.import("resource://gre/modules/PlacesUtils.jsm");
 
@@ -45,7 +47,9 @@ let TestRunner = {
    */
   next: function () {
     try {
-      TestRunner._iter.next();
+      let value = TestRunner._iter.next();
+      if (value && typeof value.then == "function")
+        value.then(next);
     } catch (e if e instanceof StopIteration) {
       finish();
     }
@@ -85,10 +89,10 @@ function navigateTo(aURI) {
  * @param aElement The DOM element to listen on.
  * @param aCallback The function to call when the load event was dispatched.
  */
-function whenLoaded(aElement, aCallback) {
+function whenLoaded(aElement, aCallback = next) {
   aElement.addEventListener("load", function onLoad() {
     aElement.removeEventListener("load", onLoad, true);
-    executeSoon(aCallback || next);
+    executeSoon(aCallback);
   }, true);
 }
 
@@ -143,7 +147,7 @@ function retrieveImageDataForURL(aURL, aCallback) {
  * @param aURL The url associated to the thumbnail.
  */
 function thumbnailExists(aURL) {
-  let file = PageThumbsStorage.getFileForURL(aURL);
+  let file = new FileUtils.File(PageThumbsStorage.getFilePathForURL(aURL));
   return file.exists() && file.fileSize;
 }
 
@@ -211,13 +215,13 @@ function addVisits(aPlaceInfo, aCallback) {
  * @param [optional] aCallback
  *        Function to be invoked on completion.
  */
-function whenFileExists(aURL, aCallback) {
+function whenFileExists(aURL, aCallback = next) {
   let callback = aCallback;
   if (!thumbnailExists(aURL)) {
     callback = function () whenFileExists(aURL, aCallback);
   }
 
-  executeSoon(callback || next);
+  executeSoon(callback);
 }
 
 /**