netwerk/base/AutoClose.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=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 file,
   5  * You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef mozilla_net_AutoClose_h
   8 #define mozilla_net_AutoClose_h
   9
  10 #include "nsCOMPtr.h"
  11 #include "mozilla/Mutex.h"
  12
  13 namespace mozilla {
  14 namespace net {
  15
  16 // A container for XPCOM streams (e.g. nsIAsyncInputStream) and other
  17 // refcounted classes that need to have the Close() method called explicitly
  18 // before they are destroyed.
  19 template <typename T>
  20 class AutoClose {
  21  public:
  22   AutoClose() : mMutex("net::AutoClose.mMutex") {}
  23   ~AutoClose() { CloseAndRelease(); }
  24
  25   explicit operator bool() {
  26     MutexAutoLock lock(mMutex);
  27     return mPtr;
  28   }
  29
  30   already_AddRefed<T> forget() {
  31     MutexAutoLock lock(mMutex);
  32     return mPtr.forget();
  33   }
  34
  35   void takeOver(nsCOMPtr<T>& rhs) { TakeOverInternal(rhs.forget()); }
  36
  37   void CloseAndRelease() { TakeOverInternal(nullptr); }
  38
  39  private:
  40   void TakeOverInternal(already_AddRefed<T>&& aOther) {
  41     nsCOMPtr<T> ptr(std::move(aOther));
  42     {
  43       MutexAutoLock lock(mMutex);
  44       ptr.swap(mPtr);
  45     }
  46
  47     if (ptr) {
  48       ptr->Close();
  49     }
  50   }
  51
  52   void operator=(const AutoClose<T>&) = delete;
  53   AutoClose(const AutoClose<T>&) = delete;
  54
  55   nsCOMPtr<T> mPtr;
  56   Mutex mMutex MOZ_UNANNOTATED;
  57 };
  58
  59 }  // namespace net
  60 }  // namespace mozilla
  61
  62 #endif  // mozilla_net_AutoClose_h