Bug 870100 (part 1) - regenerate stale page thumbnails on demand, and send notification when done. r=adw

toolkit/components/thumbnails/PageThumbs.jsm

@@ -17,6 +17,11 @@ const LATEST_STORAGE_VERSION = 3;
 const EXPIRATION_MIN_CHUNK_SIZE = 50;
 const EXPIRATION_INTERVAL_SECS = 3600;
 
+// If a request for a thumbnail comes in and we find one that is "stale"
+// (or don't find one at all) we automatically queue a request to generate a
+// new one.
+const MAX_THUMBNAIL_AGE_SECS = 172800; // 2 days == 60*60*24*2 == 172800 secs.
+
 /**
  * Name of the directory in the profile that contains the thumbnails.
  */
@@ -180,6 +185,26 @@ this.PageThumbs = {
            "?url=" + encodeURIComponent(aUrl);
   },
 
+  /**
+   * Checks if an existing thumbnail for the specified URL is either missing
+   * or stale, and if so, queues a background request to capture it.  That
+   * capture process will send a notification via the observer service on
+   * capture, so consumers should watch for such observations if they want to
+   * be notified of an updated thumbnail.
+   */
+  captureIfStale: function PageThumbs_captureIfStale(aUrl) {
+    let filePath = PageThumbsStorage.getFilePathForURL(aUrl);
+    PageThumbsWorker.post("isFileRecent", [filePath, MAX_THUMBNAIL_AGE_SECS]
+    ).then(result => {
+      if (!result.ok) {
+        // Sadly there is currently a circular dependency between this module
+        // and BackgroundPageThumbs, so do the import locally.
+        let BPT = Cu.import("resource://gre/modules/BackgroundPageThumbs.jsm", {}).BackgroundPageThumbs;
+        BPT.capture(aUrl);
+      }
+    });
+  },
+
   /**
    * Captures a thumbnail for the given window.
    * @param aWindow The DOM window to capture a thumbnail from.
@@ -310,6 +335,7 @@ this.PageThumbs = {
       Services.telemetry.getHistogramById("FX_THUMBNAILS_STORE_TIME_MS")
         .add(new Date() - telemetryStoreTime);
 
+      Services.obs.notifyObservers(null, "page-thumbnail:create", aFinalURL);
       // We've been redirected. Create a copy of the current thumbnail for
       // the redirect source. We need to do this because:
       //
@@ -321,8 +347,10 @@ this.PageThumbs = {
       //    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 (aFinalURL != aOriginalURL)
+      if (aFinalURL != aOriginalURL) {
         yield PageThumbsStorage.copy(aFinalURL, aOriginalURL);
+        Services.obs.notifyObservers(null, "page-thumbnail:create", aOriginalURL);
+      }
     });
   },
 

toolkit/components/thumbnails/PageThumbsWorker.js

@@ -53,6 +53,20 @@ self.onmessage = function onmessage(msg) {
 
 
 let Agent = {
+  // Checks if the specified file exists and has an age less than as
+  // specifed (in seconds).
+  isFileRecent: function Agent_isFileRecent(path, maxAge) {
+    try {
+      let stat = OS.File.stat(path);
+      let maxDate = new Date();
+      maxDate.setSeconds(maxDate.getSeconds() - maxAge);
+      return stat.lastModificationDate > maxDate;
+    } catch (ex if ex instanceof OS.File.Error) {
+      // file doesn't exist (or can't be stat'd) - must be stale.
+      return false;
+    }
+  },
+
   remove: function Agent_removeFile(path) {
     try {
       OS.File.remove(path);

toolkit/components/thumbnails/test/Makefile.in

@@ -20,6 +20,7 @@ MOCHITEST_BROWSER_FILES := \
 	browser_thumbnails_storage_migrate3.js \
 	browser_thumbnails_bug726727.js \
 	browser_thumbnails_bug727765.js \
+	browser_thumbnails_update.js \
 	head.js \
 	background_red.html \
 	background_red_scroll.html \

toolkit/components/thumbnails/test/browser_thumbnails_update.js

@@ -0,0 +1,50 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/**
+ * These tests check the auto-update facility of the thumbnail service.
+ */
+
+let numNotifications = 0;
+const URL = "data:text/html;charset=utf-8,<body%20bgcolor=ff0000></body>";
+
+function observe(subject, topic, data) {
+  is(topic, "page-thumbnail:create", "got expected topic");
+  is(data, URL, "data is our test URL");
+  if (++numNotifications == 2) {
+    // This is the final notification and signals test success...
+    Services.obs.removeObserver(observe, "page-thumbnail:create");
+    next();
+  }
+}
+
+function runTests() {
+  Services.obs.addObserver(observe, "page-thumbnail:create", false);
+  // Create a tab with a red background.
+  yield addTab(URL);
+  let browser = gBrowser.selectedBrowser;
+
+  // Capture the screenshot.
+  PageThumbs.captureAndStore(browser, function () {
+    // We've got a capture so should have seen the observer.
+    is(numNotifications, 1, "got notification of item being created.");
+    // The capture is now "fresh" - so requesting the URL should not cause
+    // a new capture.
+    PageThumbs.captureIfStale(URL);
+    is(numNotifications, 1, "still only 1 notification of item being created.");
+
+    // Now we will go behind the back of the thumbnail service and change the
+    // mtime of the file to be in the past.
+    let fname = PageThumbsStorage.getFilePathForURL(URL);
+    let file = Cc["@mozilla.org/file/local;1"].createInstance(Ci.nsIFile);
+    file.initWithPath(fname);
+    ok(file.exists(), fname + " doesn't exist");
+    // Set it as very stale...
+    file.lastModifiedTime = Date.now() - 1000000000;
+    // Ask for it to be updated.
+    PageThumbs.captureIfStale(URL);
+    // But it's async, so wait - our observer above will call next() when
+    // the notification comes.
+  });
+  yield undefined; // wait for callbacks to call 'next'...
+}