Bug 706958 - Add ClearOnShutdown() function which will clear a smart pointer on shutdown. r=bsmedberg
authorJustin Lebar <justin.lebar@gmail.com>
Thu, 15 Dec 2011 10:51:11 -0500
changeset 84299 ab38cc8b58667c8d719135516ac76b8033e3acdb
parent 84298 53e708b8faa9c543c2e4c06c30a1229f6f7b3a27
child 84300 44777be250609c3f0e3ca390a7f597a4b22a3d04
push id519
push userakeybl@mozilla.com
push dateWed, 01 Feb 2012 00:38:35 +0000
treeherdermozilla-beta@788ea1ef610b [default view] [failures only]
perfherder[talos] [build metrics] [platform microbench] (compared to previous push)
reviewersbsmedberg
bugs706958
milestone11.0a1
first release with
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last release without
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Bug 706958 - Add ClearOnShutdown() function which will clear a smart pointer on shutdown. r=bsmedberg
hal/Hal.cpp
xpcom/base/ClearOnShutdown.h
xpcom/base/Makefile.in
--- a/hal/Hal.cpp
+++ b/hal/Hal.cpp
@@ -42,22 +42,21 @@
 #include "mozilla/dom/TabChild.h"
 #include "mozilla/Util.h"
 #include "nsThreadUtils.h"
 #include "nsXULAppAPI.h"
 #include "mozilla/Observer.h"
 #include "nsIDOMDocument.h"
 #include "nsIDOMWindow.h"
 #include "nsPIDOMWindow.h"
-#include "nsIObserver.h"
-#include "nsIObserverService.h"
 #include "mozilla/Services.h"
 #include "nsIWebNavigation.h"
 #include "nsITabChild.h"
 #include "nsIDocShell.h"
+#include "mozilla/ClearOnShutdown.h"
 
 using namespace mozilla::dom;
 using namespace mozilla::services;
 
 #define PROXY_IF_SANDBOXED(_call)                 \
   do {                                            \
     if (InSandbox()) {                            \
       hal_sandbox::_call;                         \
@@ -105,49 +104,20 @@ WindowIsActive(nsIDOMWindow *window)
 
   bool hidden = true;
   doc->GetMozHidden(&hidden);
   return !hidden;
 }
 
 nsAutoPtr<WindowIdentifier::IDArrayType> gLastIDToVibrate;
 
-// This observer makes sure we delete gLastIDToVibrate, so we don't
-// leak.
-class ShutdownObserver : public nsIObserver
-{
-public:
-  ShutdownObserver() {}
-  virtual ~ShutdownObserver() {}
-
-  NS_DECL_ISUPPORTS
-
-  NS_IMETHOD Observe(nsISupports *subject, const char *aTopic,
-                     const PRUnichar *aData)
-  {
-    MOZ_ASSERT(strcmp(aTopic, NS_XPCOM_SHUTDOWN_OBSERVER_ID) == 0);
-    gLastIDToVibrate = nsnull;
-    return NS_OK;
-  }
-};
-
-NS_IMPL_ISUPPORTS1(ShutdownObserver, nsIObserver);
-
 void InitLastIDToVibrate()
 {
   gLastIDToVibrate = new WindowIdentifier::IDArrayType();
-
-  nsCOMPtr<nsIObserverService> observerService = GetObserverService();
-  if (!observerService) {
-    NS_WARNING("Could not get observer service!");
-    return;
-  }
-
-  ShutdownObserver *obs = new ShutdownObserver();
-  observerService->AddObserver(obs, NS_XPCOM_SHUTDOWN_OBSERVER_ID, false);
+  ClearOnShutdown(&gLastIDToVibrate);
 }
 
 } // anonymous namespace
 
 WindowIdentifier::WindowIdentifier()
   : mWindow(nsnull)
   , mIsEmpty(true)
 {
new file mode 100644
--- /dev/null
+++ b/xpcom/base/ClearOnShutdown.h
@@ -0,0 +1,119 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et ft=cpp : */
+/* ***** 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 Mozilla Code.
+ *
+ * The Initial Developer of the Original Code is
+ *   The Mozilla Foundation
+ * Portions created by the Initial Developer are Copyright (C) 2011
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s):
+ *   Justin Lebar <justin.lebar@gmail.com>
+ *
+ * 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 ***** */
+
+#ifndef mozilla_ClearOnShutdown_h
+
+#include <nsAutoPtr.h>
+#include <nsCOMPtr.h>
+#include <nsIObserver.h>
+#include <nsIObserverService.h>
+#include <mozilla/Services.h>
+
+/*
+ * This header exports one method in the mozilla namespace:
+ *
+ *   template<class SmartPtr>
+ *   void ClearOnShutdown(SmartPtr *aPtr)
+ *
+ * This function takes a pointer to a smart pointer (i.e., nsCOMPtr<T>*,
+ * nsRefPtr<T>*, or nsAutoPtr<T>*) and nulls the smart pointer on shutdown.
+ *
+ * This is useful if you have a global smart pointer object which you don't
+ * want to "leak" on shutdown.
+ *
+ * There is no way to undo a call to ClearOnShutdown, so you can call it only
+ * on smart pointers which you know will live until the program shuts down.
+ */
+
+namespace mozilla {
+namespace ClearOnShutdown_Internal {
+
+template<class SmartPtr>
+class ShutdownObserver : public nsIObserver
+{
+public:
+  ShutdownObserver(SmartPtr *aPtr)
+    : mPtr(aPtr)
+  {}
+
+  virtual ~ShutdownObserver()
+  {}
+
+  NS_IMETHOD QueryInterface(REFNSIID aIID, void ** aInstancePtr);
+  NS_INLINE_DECL_REFCOUNTING(ShutdownObserver)
+
+  NS_IMETHOD Observe(nsISupports *aSubject, const char *aTopic,
+                     const PRUnichar *aData)
+  {
+    MOZ_ASSERT(strcmp(aTopic, NS_XPCOM_SHUTDOWN_OBSERVER_ID) == 0);
+
+    if (mPtr) {
+      *mPtr = NULL;
+    }
+
+    return NS_OK;
+  }
+
+private:
+  SmartPtr *mPtr;
+};
+
+// This is horrible, but I don't see a better way.
+template<class SmartPtr>
+NS_IMPL_QUERY_INTERFACE1(ShutdownObserver<SmartPtr>, nsIObserver)
+
+} // namespace ClearOnShutdown_Internal
+
+template<class SmartPtr>
+void ClearOnShutdown(SmartPtr *aPtr)
+{
+  nsRefPtr<ClearOnShutdown_Internal::ShutdownObserver<SmartPtr> > observer =
+    new ClearOnShutdown_Internal::ShutdownObserver<SmartPtr>(aPtr);
+
+  nsCOMPtr<nsIObserverService> os = services::GetObserverService();
+  if (!os) {
+    NS_WARNING("Could not get observer service!");
+    return;
+  }
+  os->AddObserver(observer, NS_XPCOM_SHUTDOWN_OBSERVER_ID, false);
+}
+
+} // namespace mozilla
+
+#endif
--- a/xpcom/base/Makefile.in
+++ b/xpcom/base/Makefile.in
@@ -95,16 +95,17 @@ EXPORTS		= \
 		dmd.h \
 		$(NULL)
 
 EXPORTS_NAMESPACES = mozilla
 
 EXPORTS_mozilla = \
 	FunctionTimer.h \
 	MapsMemoryReporter.h \
+	ClearOnShutdown.h \
 	$(NULL)
 
 ifeq (windows,$(MOZ_WIDGET_TOOLKIT))
 CPPSRCS += nsCrashOnException.cpp
 endif
 
 ifeq ($(OS_ARCH),WINNT)
 ifdef MOZ_DEBUG