gecko-dev/ipc/mscom/Ptr.h
Aaron Klotz 62f0203838 Bug 1263224: Smart pointers for passing COM interface pointers around in other apartments; r=jimm
MozReview-Commit-ID: 377VvQ5PMCJ

--HG--
extra : rebase_source : c64ed8690ee42141ebe6aa97ef0b750c7e058647
2016-07-19 13:13:31 -06:00

112 lines
2.5 KiB
C++

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef mozilla_mscom_Ptr_h
#define mozilla_mscom_Ptr_h
#include "mozilla/Assertions.h"
#include "mozilla/DebugOnly.h"
#include "mozilla/mscom/EnsureMTA.h"
#include "mozilla/UniquePtr.h"
#include "nsError.h"
#include "nsThreadUtils.h"
#include "nsXULAppAPI.h"
/**
* The glue code in mozilla::mscom often needs to pass around interface pointers
* belonging to a different apartment from the current one. We must not touch
* the reference counts of those objects on the wrong apartment. By using these
* UniquePtr specializations, we may ensure that the reference counts are always
* handled correctly.
*/
namespace mozilla {
namespace mscom {
namespace detail {
template <typename T>
struct MainThreadRelease
{
void operator()(T* aPtr)
{
if (!aPtr) {
return;
}
if (NS_IsMainThread()) {
aPtr->Release();
return;
}
DebugOnly<nsresult> rv =
NS_DispatchToMainThread(NewNonOwningRunnableMethod(aPtr,
&T::Release));
MOZ_ASSERT(NS_SUCCEEDED(rv));
}
};
template <typename T>
struct MTARelease
{
void operator()(T* aPtr)
{
if (!aPtr) {
return;
}
EnsureMTA([&]() -> void
{
aPtr->Release();
});
}
};
template <typename T>
struct MTAReleaseInChildProcess
{
void operator()(T* aPtr)
{
if (!aPtr) {
return;
}
if (XRE_IsParentProcess()) {
MOZ_ASSERT(NS_IsMainThread());
aPtr->Release();
return;
}
EnsureMTA([&]() -> void
{
aPtr->Release();
});
}
};
struct InterceptorTargetDeleter
{
void operator()(IUnknown* aPtr)
{
// We intentionally do not touch the refcounts of interceptor targets!
}
};
} // namespace detail
template <typename T>
using STAUniquePtr = mozilla::UniquePtr<T, detail::MainThreadRelease<T>>;
template <typename T>
using MTAUniquePtr = mozilla::UniquePtr<T, detail::MTARelease<T>>;
template <typename T>
using ProxyUniquePtr = mozilla::UniquePtr<T, detail::MTAReleaseInChildProcess<T>>;
using InterceptorTargetPtr =
mozilla::UniquePtr<IUnknown, detail::InterceptorTargetDeleter>;
} // namespace mscom
} // namespace mozilla
#endif // mozilla_mscom_Ptr_h