1 files changed, 191 insertions, 0 deletions
diff --git a/ipc/mscom/WeakRef.cpp b/ipc/mscom/WeakRef.cpp
new file mode 100644
index 000000000..f19310264
--- /dev/null
+++ b/ipc/mscom/WeakRef.cpp
@@ -0,0 +1,191 @@
+/* -*- 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/Assertions.h"
+#include "mozilla/DebugOnly.h"
+#include "mozilla/RefPtr.h"
+#include "nsThreadUtils.h"
+#include "nsWindowsHelpers.h"
+#include "nsProxyRelease.h"
+
+namespace mozilla {
+namespace mscom {
+
+WeakReferenceSupport::WeakReferenceSupport(Flags aFlags)
+  : mRefCnt(1)
+  , mFlags(aFlags)
+{
+  ::InitializeCriticalSectionAndSpinCount(&mCS, 4000);
+}
+
+WeakReferenceSupport::~WeakReferenceSupport()
+{
+  MOZ_ASSERT(mWeakRefs.IsEmpty());
+  ::DeleteCriticalSection(&mCS);
+}
+
+HRESULT
+WeakReferenceSupport::QueryInterface(REFIID riid, void** ppv)
+{
+  AutoCriticalSection lock(&mCS);
+  RefPtr<IUnknown> punk;
+  if (!ppv) {
+    return E_INVALIDARG;
+  }
+  *ppv = nullptr;
+
+  // Raise the refcount for stabilization purposes during aggregation
+  RefPtr<IUnknown> kungFuDeathGrip(static_cast<IUnknown*>(this));
+
+  if (riid == IID_IUnknown || riid == IID_IWeakReferenceSource) {
+    punk = static_cast<IUnknown*>(this);
+  } else {
+    HRESULT hr = ThreadSafeQueryInterface(riid, getter_AddRefs(punk));
+    if (FAILED(hr)) {
+      return hr;
+    }
+  }
+
+  if (!punk) {
+    return E_NOINTERFACE;
+  }
+
+  punk.forget(ppv);
+  return S_OK;
+}
+
+ULONG
+WeakReferenceSupport::AddRef()
+{
+  AutoCriticalSection lock(&mCS);
+  return ++mRefCnt;
+}
+
+ULONG
+WeakReferenceSupport::Release()
+{
+  ULONG newRefCnt;
+  { // Scope for lock
+    AutoCriticalSection lock(&mCS);
+    newRefCnt = --mRefCnt;
+    if (newRefCnt == 0) {
+      ClearWeakRefs();
+    }
+  }
+  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(self.forget());
+    }
+  }
+  return newRefCnt;
+}
+
+void
+WeakReferenceSupport::ClearWeakRefs()
+{
+  for (uint32_t i = 0, len = mWeakRefs.Length(); i < len; ++i) {
+    mWeakRefs[i]->Clear();
+    mWeakRefs[i]->Release();
+  }
+  mWeakRefs.Clear();
+}
+
+HRESULT
+WeakReferenceSupport::GetWeakReference(IWeakReference** aOutWeakRef)
+{
+  if (!aOutWeakRef) {
+    return E_INVALIDARG;
+  }
+  *aOutWeakRef = nullptr;
+
+  AutoCriticalSection lock(&mCS);
+  RefPtr<WeakRef> weakRef = MakeAndAddRef<WeakRef>(this);
+
+  HRESULT hr = weakRef->QueryInterface(IID_IWeakReference, (void**)aOutWeakRef);
+  if (FAILED(hr)) {
+    return hr;
+  }
+
+  mWeakRefs.AppendElement(weakRef.get());
+  weakRef->AddRef();
+  return S_OK;
+}
+
+WeakRef::WeakRef(WeakReferenceSupport* aSupport)
+  : mRefCnt(1)
+  , mMutex("mozilla::mscom::WeakRef::mMutex")
+  , mSupport(aSupport)
+{
+  MOZ_ASSERT(aSupport);
+}
+
+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()
+{
+  return (ULONG) InterlockedIncrement((LONG*)&mRefCnt);
+}
+
+ULONG
+WeakRef::Release()
+{
+  ULONG newRefCnt = (ULONG) InterlockedDecrement((LONG*)&mRefCnt);
+  if (newRefCnt == 0) {
+    delete this;
+  }
+  return newRefCnt;
+}
+
+HRESULT
+WeakRef::Resolve(REFIID aIid, void** aOutStrongReference)
+{
+  MutexAutoLock lock(mMutex);
+  if (!mSupport) {
+    return E_FAIL;
+  }
+  return mSupport->QueryInterface(aIid, aOutStrongReference);
+}
+
+void
+WeakRef::Clear()
+{
+  MutexAutoLock lock(mMutex);
+  MOZ_ASSERT(mSupport);
+  mSupport = nullptr;
+}
+
+} // namespace mscom
+} // namespace mozilla
+