image/ShutdownTracker.cpp

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #include "ShutdownTracker.h"
   7
   8 #include "mozilla/Services.h"
   9 #include "nsIObserver.h"
  10 #include "nsIObserverService.h"
  11
  12 namespace mozilla {
  13 namespace image {
  14
  15 class ShutdownTrackerImpl;
  16
  17 ///////////////////////////////////////////////////////////////////////////////
  18 // Static Data
  19 ///////////////////////////////////////////////////////////////////////////////
  20
  21 // Whether we've observed shutdown starting yet.
  22 static bool sShutdownHasStarted = false;
  23
  24 ///////////////////////////////////////////////////////////////////////////////
  25 // Implementation
  26 ///////////////////////////////////////////////////////////////////////////////
  27
  28 struct ShutdownObserver : public nsIObserver {
  29   NS_DECL_ISUPPORTS
  30
  31   NS_IMETHOD Observe(nsISupports*, const char* aTopic,
  32                      const char16_t*) override {
  33     if (strcmp(aTopic, "xpcom-will-shutdown") != 0) {
  34       return NS_OK;
  35     }
  36
  37     nsCOMPtr<nsIObserverService> os = services::GetObserverService();
  38     if (os) {
  39       os->RemoveObserver(this, "xpcom-will-shutdown");
  40     }
  41
  42     sShutdownHasStarted = true;
  43     return NS_OK;
  44   }
  45
  46  private:
  47   virtual ~ShutdownObserver() {}
  48 };
  49
  50 NS_IMPL_ISUPPORTS(ShutdownObserver, nsIObserver)
  51
  52 ///////////////////////////////////////////////////////////////////////////////
  53 // Public API
  54 ///////////////////////////////////////////////////////////////////////////////
  55
  56 /* static */
  57 void ShutdownTracker::Initialize() {
  58   nsCOMPtr<nsIObserverService> os = services::GetObserverService();
  59   if (os) {
  60     os->AddObserver(new ShutdownObserver, "xpcom-will-shutdown", false);
  61   }
  62 }
  63
  64 /* static */
  65 bool ShutdownTracker::ShutdownHasStarted() { return sShutdownHasStarted; }
  66
  67 }  // namespace image
  68 }  // namespace mozilla