/* -*- 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 "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)

{

  cyclecollector::HoldJSObjectsImpl(aScriptObjectHolder, aTracer);

  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);

  }

  if (mozilla::recordreplay::IsReplaying()) {

    mozilla::recordreplay::SetWeakPointerJSRoot(this, aWrapper);

  }

}

void

nsWrapperCache::ReleaseWrapper(void* aScriptObjectHolder)

{

  if (PreservingWrapper()) {

    SetPreservingWrapper(false);

    cyclecollector::DropJSObjectsImpl(aScriptObjectHolder);

  }

}

#ifdef DEBUG

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)

{

  // Skip checking if we are recording or replaying, as calling

  // GetWrapperPreserveColor() can cause the cache's wrapper to be cleared.

  if (recordreplay::IsRecordingOrReplaying()) {

    return;

  }

  JSObject* wrapper = GetWrapperPreserveColor();

  if (!wrapper) {

    return;

  }

  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.");

}

#endif // DEBUG