1 files changed, 225 insertions, 0 deletions
diff --git a/ipc/mscom/WeakRef.cpp b/ipc/mscom/WeakRef.cpp
new file mode 100644
index 0000000000..b15c027153
--- /dev/null
+++ b/ipc/mscom/WeakRef.cpp
@@ -0,0 +1,225 @@
+/* -*- 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/. */
+
+#define INITGUID
+#include "mozilla/mscom/WeakRef.h"
+
+#include "mozilla/DebugOnly.h"
+#include "mozilla/Mutex.h"
+#include "nsThreadUtils.h"
+#include "nsWindowsHelpers.h"
+#include "nsProxyRelease.h"
+
+static void InitializeCS(CRITICAL_SECTION& aCS) {
+  DWORD flags = 0;
+#if defined(RELEASE_OR_BETA)
+  flags |= CRITICAL_SECTION_NO_DEBUG_INFO;
+#endif
+  InitializeCriticalSectionEx(&aCS, 4000, flags);
+}
+
+namespace mozilla {
+namespace mscom {
+
+namespace detail {
+
+SharedRef::SharedRef(WeakReferenceSupport* aSupport) : mSupport(aSupport) {
+  ::InitializeCS(mCS);
+}
+
+SharedRef::~SharedRef() { ::DeleteCriticalSection(&mCS); }
+
+void SharedRef::Lock() { ::EnterCriticalSection(&mCS); }
+
+void SharedRef::Unlock() { ::LeaveCriticalSection(&mCS); }
+
+HRESULT
+SharedRef::ToStrongRef(IWeakReferenceSource** aOutStrongReference) {
+  RefPtr<IWeakReferenceSource> strongRef;
+
+  {  // Scope for lock
+    AutoCriticalSection lock(&mCS);
+    if (!mSupport) {
+      return E_POINTER;
+    }
+    strongRef = mSupport;
+  }
+
+  strongRef.forget(aOutStrongReference);
+  return S_OK;
+}
+
+HRESULT
+SharedRef::Resolve(REFIID aIid, void** aOutStrongReference) {
+  RefPtr<WeakReferenceSupport> strongRef;
+
+  {  // Scope for lock
+    AutoCriticalSection lock(&mCS);
+    if (!mSupport) {
+      return E_POINTER;
+    }
+    strongRef = mSupport;
+  }
+
+  return strongRef->QueryInterface(aIid, aOutStrongReference);
+}
+
+void SharedRef::Clear() {
+  AutoCriticalSection lock(&mCS);
+  mSupport = nullptr;
+}
+
+}  // namespace detail
+
+typedef mozilla::detail::BaseAutoLock<detail::SharedRef&> SharedRefAutoLock;
+typedef mozilla::detail::BaseAutoUnlock<detail::SharedRef&> SharedRefAutoUnlock;
+
+WeakReferenceSupport::WeakReferenceSupport(Flags aFlags)
+    : mRefCnt(0), mFlags(aFlags) {
+  mSharedRef = new detail::SharedRef(this);
+}
+
+HRESULT
+WeakReferenceSupport::QueryInterface(REFIID riid, void** ppv) {
+  RefPtr<IUnknown> punk;
+  if (!ppv) {
+    return E_INVALIDARG;
+  }
+  *ppv = nullptr;
+
+  // Raise the refcount for stabilization purposes during aggregation
+  StabilizeRefCount stabilize(*this);
+
+  if (riid == IID_IUnknown || riid == IID_IWeakReferenceSource) {
+    punk = static_cast<IUnknown*>(this);
+  } else {
+    HRESULT hr = WeakRefQueryInterface(riid, getter_AddRefs(punk));
+    if (FAILED(hr)) {
+      return hr;
+    }
+  }
+
+  if (!punk) {
+    return E_NOINTERFACE;
+  }
+
+  punk.forget(ppv);
+  return S_OK;
+}
+
+WeakReferenceSupport::StabilizeRefCount::StabilizeRefCount(
+    WeakReferenceSupport& aObject)
+    : mObject(aObject) {
+  SharedRefAutoLock lock(*mObject.mSharedRef);
+  ++mObject.mRefCnt;
+}
+
+WeakReferenceSupport::StabilizeRefCount::~StabilizeRefCount() {
+  // We directly access these fields instead of calling Release() because we
+  // want to adjust the ref count without the other side effects (such as
+  // deleting this if the count drops back to zero, which may happen during
+  // an initial QI during object creation).
+  SharedRefAutoLock lock(*mObject.mSharedRef);
+  --mObject.mRefCnt;
+}
+
+ULONG
+WeakReferenceSupport::AddRef() {
+  SharedRefAutoLock lock(*mSharedRef);
+  ULONG result = ++mRefCnt;
+  NS_LOG_ADDREF(this, result, "mscom::WeakReferenceSupport", sizeof(*this));
+  return result;
+}
+
+ULONG
+WeakReferenceSupport::Release() {
+  ULONG newRefCnt;
+  {  // Scope for lock
+    SharedRefAutoLock lock(*mSharedRef);
+    newRefCnt = --mRefCnt;
+    if (newRefCnt == 0) {
+      mSharedRef->Clear();
+    }
+  }
+  NS_LOG_RELEASE(this, newRefCnt, "mscom::WeakReferenceSupport");
+  if (newRefCnt == 0) {
+    if (mFlags != Flags::eDestroyOnMainThread || NS_IsMainThread()) {
+      delete this;
+    } else {
+      // We need to delete this object on the main thread, but we aren't on the
+      // main thread right now, so we send a reference to ourselves to the main
+      // thread to be re-released there.
+      RefPtr<WeakReferenceSupport> self = this;
+      NS_ReleaseOnMainThread("WeakReferenceSupport", self.forget());
+    }
+  }
+  return newRefCnt;
+}
+
+HRESULT
+WeakReferenceSupport::GetWeakReference(IWeakReference** aOutWeakRef) {
+  if (!aOutWeakRef) {
+    return E_INVALIDARG;
+  }
+
+  RefPtr<WeakRef> weakRef = MakeAndAddRef<WeakRef>(mSharedRef);
+  return weakRef->QueryInterface(IID_IWeakReference, (void**)aOutWeakRef);
+}
+
+WeakRef::WeakRef(RefPtr<detail::SharedRef>& aSharedRef)
+    : mRefCnt(0), mSharedRef(aSharedRef) {
+  MOZ_ASSERT(aSharedRef);
+}
+
+HRESULT
+WeakRef::QueryInterface(REFIID riid, void** ppv) {
+  IUnknown* punk = nullptr;
+  if (!ppv) {
+    return E_INVALIDARG;
+  }
+
+  if (riid == IID_IUnknown || riid == IID_IWeakReference) {
+    punk = static_cast<IUnknown*>(this);
+  }
+
+  *ppv = punk;
+  if (!punk) {
+    return E_NOINTERFACE;
+  }
+
+  punk->AddRef();
+  return S_OK;
+}
+
+ULONG
+WeakRef::AddRef() {
+  ULONG result = ++mRefCnt;
+  NS_LOG_ADDREF(this, result, "mscom::WeakRef", sizeof(*this));
+  return result;
+}
+
+ULONG
+WeakRef::Release() {
+  ULONG newRefCnt = --mRefCnt;
+  NS_LOG_RELEASE(this, newRefCnt, "mscom::WeakRef");
+  if (newRefCnt == 0) {
+    delete this;
+  }
+  return newRefCnt;
+}
+
+HRESULT
+WeakRef::ToStrongRef(IWeakReferenceSource** aOutStrongReference) {
+  return mSharedRef->ToStrongRef(aOutStrongReference);
+}
+
+HRESULT
+WeakRef::Resolve(REFIID aIid, void** aOutStrongReference) {
+  return mSharedRef->Resolve(aIid, aOutStrongReference);
+}
+
+}  // namespace mscom
+}  // namespace mozilla