зеркало из https://github.com/mozilla/gecko-dev.git
357 строки
11 KiB
C++
357 строки
11 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
|
|
/* 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/. */
|
|
|
|
#ifndef nsWrapperCache_h___
|
|
#define nsWrapperCache_h___
|
|
|
|
#include "nsCycleCollectionParticipant.h"
|
|
#include "mozilla/Assertions.h"
|
|
#include "js/Id.h" // must come before js/RootingAPI.h
|
|
#include "js/Value.h" // must come before js/RootingAPI.h
|
|
#include "js/RootingAPI.h"
|
|
#include "js/TracingAPI.h"
|
|
|
|
class XPCWrappedNativeScope;
|
|
|
|
#define NS_WRAPPERCACHE_IID \
|
|
{ 0x6f3179a1, 0x36f7, 0x4a5c, \
|
|
{ 0x8c, 0xf1, 0xad, 0xc8, 0x7c, 0xde, 0x3e, 0x87 } }
|
|
|
|
/**
|
|
* Class to store the wrapper for an object. This can only be used with objects
|
|
* that only have one non-security wrapper at a time (for an XPCWrappedNative
|
|
* this is usually ensured by setting an explicit parent in the PreCreate hook
|
|
* for the class).
|
|
*
|
|
* An instance of nsWrapperCache can be gotten from an object that implements
|
|
* a wrapper cache by calling QueryInterface on it. Note that this breaks XPCOM
|
|
* rules a bit (this object doesn't derive from nsISupports).
|
|
*
|
|
* The cache can store objects other than wrappers. We allow wrappers to use a
|
|
* separate JSObject to store their state (mostly expandos). If the wrapper is
|
|
* collected and we want to preserve this state we actually store the state
|
|
* object in the cache.
|
|
*
|
|
* The cache can store 2 types of objects:
|
|
*
|
|
* If WRAPPER_IS_DOM_BINDING is not set (IsDOMBinding() returns false):
|
|
* - a slim wrapper or the JSObject of an XPCWrappedNative wrapper
|
|
*
|
|
* If WRAPPER_IS_DOM_BINDING is set (IsDOMBinding() returns true):
|
|
* - a DOM binding object (regular JS object or proxy)
|
|
*
|
|
* The finalizer for the wrapper clears the cache.
|
|
*
|
|
* A number of the methods are implemented in nsWrapperCacheInlines.h because we
|
|
* have to include some JS headers that don't play nicely with the rest of the
|
|
* codebase. Include nsWrapperCacheInlines.h if you need to call those methods.
|
|
*/
|
|
class nsWrapperCache
|
|
{
|
|
public:
|
|
NS_DECLARE_STATIC_IID_ACCESSOR(NS_WRAPPERCACHE_IID)
|
|
|
|
nsWrapperCache() : mWrapper(nullptr), mFlags(0)
|
|
{
|
|
}
|
|
~nsWrapperCache()
|
|
{
|
|
MOZ_ASSERT(!PreservingWrapper(),
|
|
"Destroying cache with a preserved wrapper!");
|
|
}
|
|
|
|
/**
|
|
* Get the cached wrapper.
|
|
*
|
|
* This getter clears the gray bit before handing out the JSObject which means
|
|
* that the object is guaranteed to be kept alive past the next CC.
|
|
*/
|
|
JSObject* GetWrapper() const;
|
|
|
|
/**
|
|
* Get the cached wrapper.
|
|
*
|
|
* This getter does not change the color of the JSObject meaning that the
|
|
* object returned is not guaranteed to be kept alive past the next CC.
|
|
*
|
|
* This should only be called if you are certain that the return value won't
|
|
* be passed into a JS API function and that it won't be stored without being
|
|
* rooted (or otherwise signaling the stored value to the CC).
|
|
*/
|
|
JSObject* GetWrapperPreserveColor() const
|
|
{
|
|
return GetWrapperJSObject();
|
|
}
|
|
|
|
void SetWrapper(JSObject* aWrapper)
|
|
{
|
|
MOZ_ASSERT(!PreservingWrapper(), "Clearing a preserved wrapper!");
|
|
MOZ_ASSERT(aWrapper, "Use ClearWrapper!");
|
|
|
|
SetWrapperJSObject(aWrapper);
|
|
}
|
|
|
|
/**
|
|
* Clear the wrapper. This should be called from the finalizer for the
|
|
* wrapper.
|
|
*/
|
|
void ClearWrapper()
|
|
{
|
|
MOZ_ASSERT(!PreservingWrapper(), "Clearing a preserved wrapper!");
|
|
|
|
SetWrapperJSObject(nullptr);
|
|
}
|
|
|
|
bool PreservingWrapper()
|
|
{
|
|
return HasWrapperFlag(WRAPPER_BIT_PRESERVED);
|
|
}
|
|
|
|
void SetIsDOMBinding()
|
|
{
|
|
MOZ_ASSERT(!mWrapper && !(GetWrapperFlags() & ~WRAPPER_IS_DOM_BINDING),
|
|
"This flag should be set before creating any wrappers.");
|
|
SetWrapperFlags(WRAPPER_IS_DOM_BINDING);
|
|
}
|
|
|
|
bool IsDOMBinding() const
|
|
{
|
|
return HasWrapperFlag(WRAPPER_IS_DOM_BINDING);
|
|
}
|
|
|
|
/**
|
|
* Wrap the object corresponding to this wrapper cache. If non-null is
|
|
* returned, the object has already been stored in the wrapper cache.
|
|
*/
|
|
virtual JSObject* WrapObject(JSContext* cx)
|
|
{
|
|
MOZ_ASSERT(!IsDOMBinding(), "Someone forgot to override WrapObject");
|
|
return nullptr;
|
|
}
|
|
|
|
/**
|
|
* Returns true if the object has a non-gray wrapper.
|
|
*/
|
|
bool IsBlack();
|
|
|
|
/**
|
|
* Returns true if the object has a black wrapper,
|
|
* and all the GC things it is keeping alive are black too.
|
|
*/
|
|
bool IsBlackAndDoesNotNeedTracing(nsISupports* aThis);
|
|
|
|
bool HasNothingToTrace(nsISupports* aThis);
|
|
|
|
// Only meant to be called by code that preserves a wrapper.
|
|
void SetPreservingWrapper(bool aPreserve)
|
|
{
|
|
if(aPreserve) {
|
|
SetWrapperFlags(WRAPPER_BIT_PRESERVED);
|
|
}
|
|
else {
|
|
UnsetWrapperFlags(WRAPPER_BIT_PRESERVED);
|
|
}
|
|
}
|
|
|
|
void TraceWrapper(const TraceCallbacks& aCallbacks, void* aClosure)
|
|
{
|
|
if (PreservingWrapper() && mWrapper) {
|
|
aCallbacks.Trace(&mWrapper, "Preserved wrapper", aClosure);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* The following methods for getting and manipulating flags allow the unused
|
|
* bits of mFlags to be used by derived classes.
|
|
*/
|
|
|
|
uint32_t GetFlags() const
|
|
{
|
|
return mFlags & ~kWrapperFlagsMask;
|
|
}
|
|
|
|
bool HasFlag(uint32_t aFlag) const
|
|
{
|
|
MOZ_ASSERT((aFlag & kWrapperFlagsMask) == 0, "Bad flag mask");
|
|
return !!(mFlags & aFlag);
|
|
}
|
|
|
|
void SetFlags(uint32_t aFlagsToSet)
|
|
{
|
|
MOZ_ASSERT((aFlagsToSet & kWrapperFlagsMask) == 0, "Bad flag mask");
|
|
mFlags |= aFlagsToSet;
|
|
}
|
|
|
|
void UnsetFlags(uint32_t aFlagsToUnset)
|
|
{
|
|
MOZ_ASSERT((aFlagsToUnset & kWrapperFlagsMask) == 0, "Bad flag mask");
|
|
mFlags &= ~aFlagsToUnset;
|
|
}
|
|
|
|
void PreserveWrapper(nsISupports* aScriptObjectHolder)
|
|
{
|
|
if (PreservingWrapper()) {
|
|
return;
|
|
}
|
|
|
|
nsISupports* ccISupports;
|
|
aScriptObjectHolder->QueryInterface(NS_GET_IID(nsCycleCollectionISupports),
|
|
reinterpret_cast<void**>(&ccISupports));
|
|
MOZ_ASSERT(ccISupports);
|
|
|
|
nsXPCOMCycleCollectionParticipant* participant;
|
|
CallQueryInterface(ccISupports, &participant);
|
|
PreserveWrapper(ccISupports, participant);
|
|
}
|
|
|
|
void PreserveWrapper(void* aScriptObjectHolder, nsScriptObjectTracer* aTracer)
|
|
{
|
|
if (PreservingWrapper()) {
|
|
return;
|
|
}
|
|
|
|
HoldJSObjects(aScriptObjectHolder, aTracer);
|
|
SetPreservingWrapper(true);
|
|
#ifdef DEBUG
|
|
// Make sure the cycle collector will be able to traverse to the wrapper.
|
|
CheckCCWrapperTraversal(aScriptObjectHolder, aTracer);
|
|
#endif
|
|
}
|
|
|
|
void ReleaseWrapper(void* aScriptObjectHolder);
|
|
|
|
protected:
|
|
void TraceWrapper(JSTracer* aTrc, const char* name)
|
|
{
|
|
if (mWrapper) {
|
|
JS_CallHeapObjectTracer(aTrc, &mWrapper, name);
|
|
}
|
|
}
|
|
|
|
void PoisonWrapper()
|
|
{
|
|
if (mWrapper) {
|
|
mWrapper.setToCrashOnTouch();
|
|
}
|
|
}
|
|
|
|
private:
|
|
JSObject *GetWrapperJSObject() const
|
|
{
|
|
return mWrapper;
|
|
}
|
|
|
|
void SetWrapperJSObject(JSObject* aWrapper)
|
|
{
|
|
mWrapper = aWrapper;
|
|
UnsetWrapperFlags(kWrapperFlagsMask & ~WRAPPER_IS_DOM_BINDING);
|
|
}
|
|
|
|
void TraceWrapperJSObject(JSTracer* aTrc, const char* aName);
|
|
|
|
uint32_t GetWrapperFlags() const
|
|
{
|
|
return mFlags & kWrapperFlagsMask;
|
|
}
|
|
|
|
bool HasWrapperFlag(uint32_t aFlag) const
|
|
{
|
|
MOZ_ASSERT((aFlag & ~kWrapperFlagsMask) == 0, "Bad wrapper flag bits");
|
|
return !!(mFlags & aFlag);
|
|
}
|
|
|
|
void SetWrapperFlags(uint32_t aFlagsToSet)
|
|
{
|
|
MOZ_ASSERT((aFlagsToSet & ~kWrapperFlagsMask) == 0, "Bad wrapper flag bits");
|
|
mFlags |= aFlagsToSet;
|
|
}
|
|
|
|
void UnsetWrapperFlags(uint32_t aFlagsToUnset)
|
|
{
|
|
MOZ_ASSERT((aFlagsToUnset & ~kWrapperFlagsMask) == 0, "Bad wrapper flag bits");
|
|
mFlags &= ~aFlagsToUnset;
|
|
}
|
|
|
|
static void HoldJSObjects(void* aScriptObjectHolder,
|
|
nsScriptObjectTracer* aTracer);
|
|
|
|
#ifdef DEBUG
|
|
void CheckCCWrapperTraversal(void* aScriptObjectHolder,
|
|
nsScriptObjectTracer* aTracer);
|
|
#endif // DEBUG
|
|
|
|
/**
|
|
* If this bit is set then we're preserving the wrapper, which in effect ties
|
|
* the lifetime of the JS object stored in the cache to the lifetime of the
|
|
* native object. We rely on the cycle collector to break the cycle that this
|
|
* causes between the native object and the JS object, so it is important that
|
|
* any native object that supports preserving of its wrapper
|
|
* traces/traverses/unlinks the cached JS object (see
|
|
* NS_IMPL_CYCLE_COLLECTION_TRACE_PRESERVED_WRAPPER,
|
|
* NS_IMPL_CYCLE_COLLECTION_TRAVERSE_SCRIPT_OBJECTS and
|
|
* NS_IMPL_CYCLE_COLLECTION_UNLINK_PRESERVED_WRAPPER).
|
|
*/
|
|
enum { WRAPPER_BIT_PRESERVED = 1 << 0 };
|
|
|
|
/**
|
|
* If this bit is set then the wrapper for the native object is a DOM binding
|
|
* (regular JS object or proxy).
|
|
*/
|
|
enum { WRAPPER_IS_DOM_BINDING = 1 << 1 };
|
|
|
|
enum { kWrapperFlagsMask = (WRAPPER_BIT_PRESERVED | WRAPPER_IS_DOM_BINDING) };
|
|
|
|
JS::Heap<JSObject*> mWrapper;
|
|
uint32_t mFlags;
|
|
};
|
|
|
|
enum { WRAPPER_CACHE_FLAGS_BITS_USED = 2 };
|
|
|
|
NS_DEFINE_STATIC_IID_ACCESSOR(nsWrapperCache, NS_WRAPPERCACHE_IID)
|
|
|
|
#define NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY \
|
|
if ( aIID.Equals(NS_GET_IID(nsWrapperCache)) ) { \
|
|
*aInstancePtr = static_cast<nsWrapperCache*>(this); \
|
|
return NS_OK; \
|
|
}
|
|
|
|
|
|
// Cycle collector macros for wrapper caches.
|
|
|
|
#define NS_IMPL_CYCLE_COLLECTION_TRACE_PRESERVED_WRAPPER \
|
|
tmp->TraceWrapper(aCallbacks, aClosure);
|
|
|
|
#define NS_IMPL_CYCLE_COLLECTION_UNLINK_PRESERVED_WRAPPER \
|
|
tmp->ReleaseWrapper(p);
|
|
|
|
#define NS_IMPL_CYCLE_COLLECTION_TRACE_WRAPPERCACHE(_class) \
|
|
NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN(_class) \
|
|
NS_IMPL_CYCLE_COLLECTION_TRACE_PRESERVED_WRAPPER \
|
|
NS_IMPL_CYCLE_COLLECTION_TRACE_END
|
|
|
|
#define NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE_0(_class) \
|
|
NS_IMPL_CYCLE_COLLECTION_CLASS(_class) \
|
|
NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(_class) \
|
|
NS_IMPL_CYCLE_COLLECTION_UNLINK_PRESERVED_WRAPPER \
|
|
NS_IMPL_CYCLE_COLLECTION_UNLINK_END \
|
|
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(_class) \
|
|
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_SCRIPT_OBJECTS \
|
|
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END \
|
|
NS_IMPL_CYCLE_COLLECTION_TRACE_WRAPPERCACHE(_class)
|
|
|
|
#define NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(_class, ...) \
|
|
NS_IMPL_CYCLE_COLLECTION_CLASS(_class) \
|
|
NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(_class) \
|
|
NS_IMPL_CYCLE_COLLECTION_UNLINK(__VA_ARGS__) \
|
|
NS_IMPL_CYCLE_COLLECTION_UNLINK_PRESERVED_WRAPPER \
|
|
NS_IMPL_CYCLE_COLLECTION_UNLINK_END \
|
|
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(_class) \
|
|
NS_IMPL_CYCLE_COLLECTION_TRAVERSE(__VA_ARGS__) \
|
|
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_SCRIPT_OBJECTS \
|
|
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END \
|
|
NS_IMPL_CYCLE_COLLECTION_TRACE_WRAPPERCACHE(_class)
|
|
|
|
#endif /* nsWrapperCache_h___ */
|