WebKit/Source/JavaScriptCore/API/JSMarkingConstraintPrivate.cpp at main · WebKit/WebKit · GitHub

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#include "config.h"

#include "JSMarkingConstraintPrivate.h"

#include "APICast.h"

#include "JSCellInlines.h"

#include "SimpleMarkingConstraint.h"

using namespace JSC;

namespace {

Atomic<unsigned> constraintCounter;

struct Marker : JSMarker {

AbstractSlotVisitor* visitor;

};

bool isMarked(JSMarkerRef markerRef, JSObjectRef objectRef)

{

if (!objectRef)

return true; // Null is an immortal object.

return static_cast<Marker*>(markerRef)->visitor->isMarked(toJS(objectRef));

}

void mark(JSMarkerRef markerRef, JSObjectRef objectRef)

{

if (!objectRef)

return;

static_cast<Marker*>(markerRef)->visitor->appendHiddenUnbarriered(toJS(objectRef));

}

} // anonymous namespace

void JSContextGroupAddMarkingConstraint(JSContextGroupRef group, JSMarkingConstraint constraintCallback, void *userData)

{

VM& vm = *toJS(group);

JSLockHolder locker(vm);

unsigned constraintIndex = constraintCounter.exchangeAdd(1);

// This is a guess. The algorithm should be correct no matter what we pick. This means

// that we expect this constraint to mark things even during a stop-the-world full GC, but

// we don't expect it to be able to mark anything at the very start of a GC before anything

// else gets marked.

ConstraintVolatility volatility = ConstraintVolatility::GreyedByMarking;

auto constraint = makeUnique<SimpleMarkingConstraint>(

toCString("Amc", constraintIndex, "(", RawPointer(constraintCallback), ")"),

toCString("API Marking Constraint #", constraintIndex, " (", RawPointer(constraintCallback), ", ", RawPointer(userData), ")"),

MAKE_MARKING_CONSTRAINT_EXECUTOR_PAIR(([constraintCallback, userData] (AbstractSlotVisitor& visitor) {

Marker marker;

marker.IsMarked = isMarked;

marker.Mark = mark;

marker.visitor = &visitor;

constraintCallback(&marker, userData);

})),

volatility,

ConstraintConcurrency::Sequential);

vm.heap.addMarkingConstraint(WTF::move(constraint));

}

WebKit/Source/JavaScriptCore/API/JSMarkingConstraintPrivate.cpp at main · WebKit/WebKit · GitHub

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