xpcom/glue/nsProxyRelease.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "nsProxyRelease.h"
   8 #include "nsThreadUtils.h"
   9 #include "nsAutoPtr.h"
  10
  11 class nsProxyReleaseEvent : public nsRunnable
  12 {
  13 public:
  14   explicit nsProxyReleaseEvent(nsISupports* aDoomed) : mDoomed(aDoomed) {}
  15
  16   NS_IMETHOD Run()
  17   {
  18     mDoomed->Release();
  19     return NS_OK;
  20   }
  21
  22 private:
  23   nsISupports* MOZ_OWNING_REF mDoomed;
  24 };
  25
  26 nsresult
  27 NS_ProxyRelease(nsIEventTarget* aTarget, nsISupports* aDoomed,
  28                 bool aAlwaysProxy)
  29 {
  30   nsresult rv;
  31
  32   if (!aDoomed) {
  33     // nothing to do
  34     return NS_OK;
  35   }
  36
  37   if (!aTarget) {
  38     NS_RELEASE(aDoomed);
  39     return NS_OK;
  40   }
  41
  42   if (!aAlwaysProxy) {
  43     bool onCurrentThread = false;
  44     rv = aTarget->IsOnCurrentThread(&onCurrentThread);
  45     if (NS_SUCCEEDED(rv) && onCurrentThread) {
  46       NS_RELEASE(aDoomed);
  47       return NS_OK;
  48     }
  49   }
  50
  51   nsRefPtr<nsIRunnable> ev = new nsProxyReleaseEvent(aDoomed);
  52   if (!ev) {
  53     // we do not release aDoomed here since it may cause a delete on the
  54     // wrong thread.  better to leak than crash.
  55     return NS_ERROR_OUT_OF_MEMORY;
  56   }
  57
  58   rv = aTarget->Dispatch(ev, NS_DISPATCH_NORMAL);
  59   if (NS_FAILED(rv)) {
  60     NS_WARNING("failed to post proxy release event");
  61     // again, it is better to leak the aDoomed object than risk crashing as
  62     // a result of deleting it on the wrong thread.
  63   }
  64   return rv;
  65 }