Bug 447951 - Gmail displays wrong/previous URL on session restore after heavy usage (50 hash changes). r=dietrich

browser/components/sessionstore/src/nsSessionStore.js

@@ -200,6 +200,10 @@ SessionStoreService.prototype = {
     
     // observe prefs changes so we can modify stored data to match
     this._prefBranch.addObserver("sessionstore.max_tabs_undo", this, true);
+    
+    // this pref is only read at startup, so no need to observe it
+    this._sessionhistory_max_entries =
+      this._prefBranch.getIntPref("sessionhistory.max_entries");
 
     // get file references
     var dirService = Cc["@mozilla.org/file/directory_service;1"].
@@ -1007,8 +1011,11 @@ SessionStoreService.prototype = {
     }
     catch (ex) { } // this could happen if we catch a tab during (de)initialization
     
+    // XXXzeniko anchor navigation doesn't reset __SS_data, so we could reuse
+    //           data even when we shouldn't (e.g. Back, different anchor)
     if (history && browser.parentNode.__SS_data &&
-        browser.parentNode.__SS_data.entries[history.index] && !aFullData) {
+        browser.parentNode.__SS_data.entries[history.index] &&
+        history.index < this._sessionhistory_max_entries - 1 && !aFullData) {
       tabData = browser.parentNode.__SS_data;
       tabData.index = history.index + 1;
     }

browser/components/sessionstore/test/browser/Makefile.in

@@ -58,6 +58,8 @@ _BROWSER_TEST_FILES = \
 	browser_393716.js \
 	browser_408470.js \
 	browser_408470_sample.html \
+	browser_447951.js \
+	browser_447951_sample.html \
 	browser_448741.js \
 	browser_454908.js \
 	browser_454908_sample.html \

browser/components/sessionstore/test/browser/browser_447951.js

@@ -0,0 +1,84 @@
+/* ***** BEGIN LICENSE BLOCK *****
+ * Version: MPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is sessionstore test code.
+ *
+ * The Initial Developer of the Original Code is
+ * Simon Bünzli <zeniko@gmail.com>.
+ * Portions created by the Initial Developer are Copyright (C) 2008
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s):
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either the GNU General Public License Version 2 or later (the "GPL"), or
+ * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the MPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the MPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+
+function test() {
+  /** Test for Bug 447951 **/
+  
+  // test setup
+  let ss = Cc["@mozilla.org/browser/sessionstore;1"].getService(Ci.nsISessionStore);
+  waitForExplicitFinish();
+  const baseURL = "http://localhost:8888/browser/" +
+    "browser/components/sessionstore/test/browser/browser_447951_sample.html#";
+    
+  let tab = gBrowser.addTab();
+  tab.linkedBrowser.addEventListener("load", function(aEvent) {
+    this.removeEventListener("load", arguments.callee, true);
+    
+    let tabState = { entries: [] };
+    let max_entries = gPrefService.getIntPref("browser.sessionhistory.max_entries");
+    for (let i = 0; i < max_entries; i++)
+      tabState.entries.push({ url: baseURL + i });
+    
+    ss.setTabState(tab, JSON.stringify(tabState));
+    tab.addEventListener("SSTabRestored", function(aEvent) {
+      this.removeEventListener("SSTabRestored", arguments.callee, false);
+      tabState = eval("(" + ss.getTabState(tab) + ")");
+      is(tabState.entries.length, max_entries, "session history filled to the limit");
+      is(tabState.entries[0].url, baseURL + 0, "... but not more");
+      
+      // visit yet another anchor (appending it to session history)
+      let doc = tab.linkedBrowser.contentDocument;
+      let event = doc.createEvent("MouseEvents");
+      event.initMouseEvent("click", true, true, doc.defaultView, 1,
+                           0, 0, 0, 0, false, false, false, false, 0, null);
+      doc.querySelector("a").dispatchEvent(event);
+      
+      executeSoon(function() {
+        tabState = eval("(" + ss.getTabState(tab) + ")");
+        is(tab.linkedBrowser.currentURI.spec, baseURL + "end",
+           "the new anchor was loaded");
+        is(tabState.entries[tabState.entries.length - 1].url, baseURL + "end",
+           "... and ignored");
+        is(tabState.entries[0].url, baseURL + 1,
+           "... and the first item was removed");
+        
+        // clean up
+        gBrowser.removeTab(tab);
+        finish();
+      });
+    }, false);
+  }, true);
+}

browser/components/sessionstore/test/browser/browser_447951_sample.html

@@ -0,0 +1,4 @@
+<!DOCTYPE html>
+<title>Testcase for bug 447951</title>
+
+<a href="#end">click me</a>