1 files changed, 136 insertions, 0 deletions
diff --git a/dom/base/nsWrapperCache.cpp b/dom/base/nsWrapperCache.cpp
new file mode 100644
index 0000000000..1744eec545
--- /dev/null
+++ b/dom/base/nsWrapperCache.cpp
@@ -0,0 +1,136 @@
+/* -*- 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/. */
+
+#include "nsWrapperCacheInlines.h"
+
+#include "jsfriendapi.h"
+#include "js/Class.h"
+#include "js/Proxy.h"
+#include "mozilla/CycleCollectedJSRuntime.h"
+#include "mozilla/HoldDropJSObjects.h"
+#include "nsCycleCollectionTraversalCallback.h"
+#include "nsCycleCollector.h"
+
+using namespace mozilla;
+using namespace mozilla::dom;
+
+#ifdef DEBUG
+/* static */
+bool nsWrapperCache::HasJSObjectMovedOp(JSObject* aWrapper) {
+  return js::HasObjectMovedOp(aWrapper);
+}
+#endif
+
+void nsWrapperCache::HoldJSObjects(void* aScriptObjectHolder,
+                                   nsScriptObjectTracer* aTracer,
+                                   JS::Zone* aWrapperZone) {
+  cyclecollector::HoldJSObjectsImpl(aScriptObjectHolder, aTracer, aWrapperZone);
+  if (mWrapper && !JS::ObjectIsTenured(mWrapper)) {
+    CycleCollectedJSRuntime::Get()->NurseryWrapperPreserved(mWrapper);
+  }
+}
+
+void nsWrapperCache::SetWrapperJSObject(JSObject* aWrapper) {
+  mWrapper = aWrapper;
+  UnsetWrapperFlags(kWrapperFlagsMask);
+
+  if (aWrapper && !JS::ObjectIsTenured(aWrapper)) {
+    CycleCollectedJSRuntime::Get()->NurseryWrapperAdded(this);
+  }
+}
+
+void nsWrapperCache::ReleaseWrapper(void* aScriptObjectHolder) {
+  // If the behavior here changes in a substantive way, you may need
+  // to update css::Rule::UnlinkDeclarationWrapper as well.
+  if (PreservingWrapper()) {
+    SetPreservingWrapper(false);
+    cyclecollector::DropJSObjectsImpl(aScriptObjectHolder);
+  }
+}
+
+#ifdef DEBUG
+
+void nsWrapperCache::AssertUpdatedWrapperZone(const JSObject* aNewObject,
+                                              const JSObject* aOldObject) {
+  MOZ_ASSERT(js::GetObjectZoneFromAnyThread(aNewObject) ==
+             js::GetObjectZoneFromAnyThread(aOldObject));
+}
+
+class DebugWrapperTraversalCallback
+    : public nsCycleCollectionTraversalCallback {
+ public:
+  explicit DebugWrapperTraversalCallback(JSObject* aWrapper)
+      : mFound(false), mWrapper(JS::GCCellPtr(aWrapper)) {
+    mFlags = WANT_ALL_TRACES;
+  }
+
+  NS_IMETHOD_(void)
+  DescribeRefCountedNode(nsrefcnt aRefCount, const char* aObjName) override {}
+  NS_IMETHOD_(void)
+  DescribeGCedNode(bool aIsMarked, const char* aObjName,
+                   uint64_t aCompartmentAddress) override {}
+
+  NS_IMETHOD_(void) NoteJSChild(const JS::GCCellPtr& aChild) override {
+    if (aChild == mWrapper) {
+      mFound = true;
+    }
+  }
+  NS_IMETHOD_(void) NoteXPCOMChild(nsISupports* aChild) override {}
+  NS_IMETHOD_(void)
+  NoteNativeChild(void* aChild,
+                  nsCycleCollectionParticipant* aHelper) override {}
+
+  NS_IMETHOD_(void) NoteNextEdgeName(const char* aName) override {}
+
+  bool mFound;
+
+ private:
+  JS::GCCellPtr mWrapper;
+};
+
+static void DebugWrapperTraceCallback(JS::GCCellPtr aPtr, const char* aName,
+                                      void* aClosure) {
+  DebugWrapperTraversalCallback* callback =
+      static_cast<DebugWrapperTraversalCallback*>(aClosure);
+  if (aPtr.is<JSObject>()) {
+    callback->NoteJSChild(aPtr);
+  }
+}
+
+void nsWrapperCache::CheckCCWrapperTraversal(void* aScriptObjectHolder,
+                                             nsScriptObjectTracer* aTracer) {
+  JSObject* wrapper = GetWrapperPreserveColor();
+  if (!wrapper) {
+    return;
+  }
+
+  // Temporarily make this a preserving wrapper so that TraceWrapper() traces
+  // it.
+  bool wasPreservingWrapper = PreservingWrapper();
+  SetPreservingWrapper(true);
+
+  DebugWrapperTraversalCallback callback(wrapper);
+
+  // The CC traversal machinery cannot trigger GC; however, the analysis cannot
+  // see through the COM layer, so we use a suppression to help it.
+  JS::AutoSuppressGCAnalysis suppress;
+
+  aTracer->TraverseNativeAndJS(aScriptObjectHolder, callback);
+  MOZ_ASSERT(callback.mFound,
+             "Cycle collection participant didn't traverse to preserved "
+             "wrapper! This will probably crash.");
+
+  callback.mFound = false;
+  aTracer->Trace(aScriptObjectHolder,
+                 TraceCallbackFunc(DebugWrapperTraceCallback), &callback);
+  MOZ_ASSERT(callback.mFound,
+             "Cycle collection participant didn't trace preserved wrapper! "
+             "This will probably crash.");
+
+  SetPreservingWrapper(wasPreservingWrapper);
+}
+
+#endif  // DEBUG