The Tor Browser: dom/base/nsWrapperCache.cpp@b8a032363ba2

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

     1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

     2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */

     3 /* This Source Code Form is subject to the terms of the Mozilla Public

     4  * License, v. 2.0. If a copy of the MPL was not distributed with this

     5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

     7 #include "nsWrapperCacheInlines.h"

     9 #include "jsproxy.h"

    10 #include "mozilla/dom/DOMJSProxyHandler.h"

    11 #include "mozilla/HoldDropJSObjects.h"

    12 #include "nsCycleCollectionTraversalCallback.h"

    13 #include "nsCycleCollector.h"

    15 using namespace mozilla;

    16 using namespace mozilla::dom;

    18 /* static */ void

    19 nsWrapperCache::HoldJSObjects(void* aScriptObjectHolder,

    20                               nsScriptObjectTracer* aTracer)

    21 {

    22   cyclecollector::HoldJSObjectsImpl(aScriptObjectHolder, aTracer);

    23 }

    25 void

    26 nsWrapperCache::ReleaseWrapper(void* aScriptObjectHolder)

    27 {

    28   if (PreservingWrapper()) {

    29     // PreserveWrapper puts new DOM bindings in the JS holders hash, but they

    30     // can also be in the DOM expando hash, so we need to try to remove them

    31     // from both here.

    32     JSObject* obj = GetWrapperPreserveColor();

    33     if (IsDOMBinding() && obj && js::IsProxy(obj)) {

    34       DOMProxyHandler::GetAndClearExpandoObject(obj);

    35     }

    36     SetPreservingWrapper(false);

    37     cyclecollector::DropJSObjectsImpl(aScriptObjectHolder);

    38   }

    39 }

    41 #ifdef DEBUG

    43 class DebugWrapperTraversalCallback : public nsCycleCollectionTraversalCallback

    44 {

    45 public:

    46   DebugWrapperTraversalCallback(void* aWrapper)

    47     : mFound(false)

    48     , mWrapper(aWrapper)

    49   {

    50     mFlags = WANT_ALL_TRACES;

    51   }

    53   NS_IMETHOD_(void) DescribeRefCountedNode(nsrefcnt aRefCount,

    54                                            const char* aObjName)

    55   {

    56   }

    57   NS_IMETHOD_(void) DescribeGCedNode(bool aIsMarked,

    58                                      const char* aObjName,

    59                                      uint64_t aCompartmentAddress)

    60   {

    61   }

    63   NS_IMETHOD_(void) NoteJSChild(void* aChild)

    64   {

    65     if (aChild == mWrapper) {

    66       mFound = true;

    67     }

    68   }

    69   NS_IMETHOD_(void) NoteXPCOMChild(nsISupports* aChild)

    70   {

    71   }

    72   NS_IMETHOD_(void) NoteNativeChild(void* aChild,

    73                                     nsCycleCollectionParticipant* aHelper)

    74   {

    75   }

    77   NS_IMETHOD_(void) NoteNextEdgeName(const char* aName)

    78   {

    79   }

    81   bool mFound;

    83 private:

    84   void* mWrapper;

    85 };

    87 static void

    88 DebugWrapperTraceCallback(void* aP, const char* aName, void* aClosure)

    89 {

    90   DebugWrapperTraversalCallback* callback =

    91     static_cast<DebugWrapperTraversalCallback*>(aClosure);

    92   callback->NoteJSChild(aP);

    93 }

    95 void

    96 nsWrapperCache::CheckCCWrapperTraversal(void* aScriptObjectHolder,

    97                                         nsScriptObjectTracer* aTracer)

    98 {

    99   JSObject* wrapper = GetWrapper();

   100   if (!wrapper) {

   101     return;

   102   }

   104   DebugWrapperTraversalCallback callback(wrapper);

   106   aTracer->Traverse(aScriptObjectHolder, callback);

   107   MOZ_ASSERT(callback.mFound,

   108              "Cycle collection participant didn't traverse to preserved "

   109              "wrapper! This will probably crash.");

   111   callback.mFound = false;

   112   aTracer->Trace(aScriptObjectHolder,

   113                  TraceCallbackFunc(DebugWrapperTraceCallback), &callback);

   114   MOZ_ASSERT(callback.mFound,

   115              "Cycle collection participant didn't trace preserved wrapper! "

   116              "This will probably crash.");

   117 }

   119 #endif // DEBUG

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