String HeapSnapshotBuilder::json(std::function<bool (const HeapSnapshotNode&)> allowNodeCallback)
{
VM& vm = m_profiler.vm();
DeferGCForAWhile deferGC(vm.heap);
// Build a node to identifier map of allowed nodes to use when serializing edges.
HashMap<JSCell*, unsigned> allowedNodeIdentifiers;
// Build a list of used class names.
HashMap<const char*, unsigned> classNameIndexes;
classNameIndexes.set("<root>", 0);
unsigned nextClassNameIndex = 1;
// Build a list of used edge names.
HashMap<UniquedStringImpl*, unsigned> edgeNameIndexes;
unsigned nextEdgeNameIndex = 0;
StringBuilder json;
auto appendNodeJSON = [&] (const HeapSnapshotNode& node) {
// Let the client decide if they want to allow or disallow certain nodes.
if (!allowNodeCallback(node))
return;
allowedNodeIdentifiers.set(node.cell, node.identifier);
auto result = classNameIndexes.add(node.cell->classInfo()->className, nextClassNameIndex);
if (result.isNewEntry)
nextClassNameIndex++;
unsigned classNameIndex = result.iterator->value;
bool isInternal = false;
if (!node.cell->isString()) {
Structure* structure = node.cell->structure(vm);
isInternal = !structure || !structure->globalObject();
}
// <nodeId>, <sizeInBytes>, <className>, <optionalInternalBoolean>
json.append(',');
json.appendNumber(node.identifier);
json.append(',');
json.appendNumber(node.cell->estimatedSizeInBytes());
json.append(',');
json.appendNumber(classNameIndex);
json.append(',');
json.append(isInternal ? '1' : '0');
};
bool firstEdge = true;
auto appendEdgeJSON = [&] (const HeapSnapshotEdge& edge) {
if (!firstEdge)
json.append(',');
firstEdge = false;
// <fromNodeId>, <toNodeId>, <edgeTypeIndex>, <edgeExtraData>
json.appendNumber(edge.from.identifier);
json.append(',');
json.appendNumber(edge.to.identifier);
json.append(',');
json.appendNumber(edgeTypeToNumber(edge.type));
json.append(',');
switch (edge.type) {
case EdgeType::Property:
case EdgeType::Variable: {
auto result = edgeNameIndexes.add(edge.u.name, nextEdgeNameIndex);
if (result.isNewEntry)
nextEdgeNameIndex++;
unsigned edgeNameIndex = result.iterator->value;
json.appendNumber(edgeNameIndex);
break;
}
case EdgeType::Index:
json.appendNumber(edge.u.index);
break;
default:
// No data for this edge type.
json.append('0');
break;
}
};
json.append('{');
// version
json.appendLiteral("\"version\":1");
// nodes
json.append(',');
json.appendLiteral("\"nodes\":");
json.append('[');
json.appendLiteral("0,0,0,0"); // <root>
for (HeapSnapshot* snapshot = m_profiler.mostRecentSnapshot(); snapshot; snapshot = snapshot->previous()) {
for (auto& node : snapshot->m_nodes)
appendNodeJSON(node);
}
json.append(']');
// node class names
json.append(',');
json.appendLiteral("\"nodeClassNames\":");
json.append('[');
Vector<const char *> orderedClassNames(classNameIndexes.size());
for (auto& entry : classNameIndexes)
orderedClassNames[entry.value] = entry.key;
classNameIndexes.clear();
bool firstClassName = true;
for (auto& className : orderedClassNames) {
if (!firstClassName)
json.append(',');
firstClassName = false;
json.appendQuotedJSONString(className);
}
orderedClassNames.clear();
json.append(']');
// Process edges.
// Replace pointers with identifiers.
// Remove any edges that we won't need.
m_edges.removeAllMatching([&] (HeapSnapshotEdge& edge) {
// If the from cell is null, this means a <root> edge.
if (!edge.from.cell)
edge.from.identifier = 0;
else {
auto fromLookup = allowedNodeIdentifiers.find(edge.from.cell);
if (fromLookup == allowedNodeIdentifiers.end())
return true;
edge.from.identifier = fromLookup->value;
}
if (!edge.to.cell)
edge.to.identifier = 0;
else {
auto toLookup = allowedNodeIdentifiers.find(edge.to.cell);
if (toLookup == allowedNodeIdentifiers.end())
return true;
edge.to.identifier = toLookup->value;
}
return false;
});
allowedNodeIdentifiers.clear();
m_edges.shrinkToFit();
// Sort edges based on from identifier.
std::sort(m_edges.begin(), m_edges.end(), [&] (const HeapSnapshotEdge& a, const HeapSnapshotEdge& b) {
return a.from.identifier < b.from.identifier;
});
// edges
json.append(',');
json.appendLiteral("\"edges\":");
json.append('[');
for (auto& edge : m_edges)
appendEdgeJSON(edge);
json.append(']');
// edge types
json.append(',');
json.appendLiteral("\"edgeTypes\":");
json.append('[');
json.appendQuotedJSONString(edgeTypeToString(EdgeType::Internal));
json.append(',');
json.appendQuotedJSONString(edgeTypeToString(EdgeType::Property));
json.append(',');
json.appendQuotedJSONString(edgeTypeToString(EdgeType::Index));
json.append(',');
json.appendQuotedJSONString(edgeTypeToString(EdgeType::Variable));
json.append(']');
// edge names
json.append(',');
json.appendLiteral("\"edgeNames\":");
json.append('[');
Vector<UniquedStringImpl*> orderedEdgeNames(edgeNameIndexes.size());
for (auto& entry : edgeNameIndexes)
orderedEdgeNames[entry.value] = entry.key;
edgeNameIndexes.clear();
bool firstEdgeName = true;
for (auto& edgeName : orderedEdgeNames) {
if (!firstEdgeName)
json.append(',');
firstEdgeName = false;
json.appendQuotedJSONString(edgeName);
}
orderedEdgeNames.clear();
json.append(']');
json.append('}');
return json.toString();
}
String HeapSnapshotBuilder::json(Function<bool (const HeapSnapshotNode&)> allowNodeCallback)
{
VM& vm = m_profiler.vm();
DeferGCForAWhile deferGC(vm.heap);
// Build a node to identifier map of allowed nodes to use when serializing edges.
HashMap<JSCell*, NodeIdentifier> allowedNodeIdentifiers;
// Build a list of used class names.
HashMap<String, unsigned> classNameIndexes;
classNameIndexes.set("<root>"_s, 0);
unsigned nextClassNameIndex = 1;
// Build a list of labels (this is just a string table).
HashMap<String, unsigned> labelIndexes;
labelIndexes.set(emptyString(), 0);
unsigned nextLabelIndex = 1;
// Build a list of used edge names.
HashMap<UniquedStringImpl*, unsigned> edgeNameIndexes;
unsigned nextEdgeNameIndex = 0;
StringBuilder json;
auto appendNodeJSON = [&] (const HeapSnapshotNode& node) {
// Let the client decide if they want to allow or disallow certain nodes.
if (!allowNodeCallback(node))
return;
unsigned flags = 0;
allowedNodeIdentifiers.set(node.cell, node.identifier);
String className = node.cell->classInfo(vm)->className;
if (node.cell->isObject() && className == JSObject::info()->className) {
flags |= static_cast<unsigned>(NodeFlags::ObjectSubtype);
// Skip calculating a class name if this object has a `constructor` own property.
// These cases are typically F.prototype objects and we want to treat these as
// "Object" in snapshots and not get the name of the prototype's parent.
JSObject* object = asObject(node.cell);
if (JSGlobalObject* globalObject = object->globalObject(vm)) {
ExecState* exec = globalObject->globalExec();
PropertySlot slot(object, PropertySlot::InternalMethodType::VMInquiry);
if (!object->getOwnPropertySlot(object, exec, vm.propertyNames->constructor, slot))
className = JSObject::calculatedClassName(object);
}
}
auto result = classNameIndexes.add(className, nextClassNameIndex);
if (result.isNewEntry)
nextClassNameIndex++;
unsigned classNameIndex = result.iterator->value;
void* wrappedAddress = 0;
unsigned labelIndex = 0;
if (!node.cell->isString()) {
Structure* structure = node.cell->structure(vm);
if (!structure || !structure->globalObject())
flags |= static_cast<unsigned>(NodeFlags::Internal);
if (m_snapshotType == SnapshotType::GCDebuggingSnapshot) {
String nodeLabel;
auto it = m_cellLabels.find(node.cell);
if (it != m_cellLabels.end())
nodeLabel = it->value;
if (nodeLabel.isEmpty()) {
if (auto* object = jsDynamicCast<JSObject*>(vm, node.cell)) {
if (auto* function = jsDynamicCast<JSFunction*>(vm, object))
nodeLabel = function->calculatedDisplayName(vm);
}
}
String description = descriptionForCell(node.cell);
if (description.length()) {
if (nodeLabel.length())
nodeLabel.append(' ');
nodeLabel.append(description);
}
if (!nodeLabel.isEmpty() && m_snapshotType == SnapshotType::GCDebuggingSnapshot) {
auto result = labelIndexes.add(nodeLabel, nextLabelIndex);
if (result.isNewEntry)
nextLabelIndex++;
labelIndex = result.iterator->value;
}
wrappedAddress = m_wrappedObjectPointers.get(node.cell);
}
}
// <nodeId>, <sizeInBytes>, <nodeClassNameIndex>, <flags>, [<labelIndex>, <cellEddress>, <wrappedAddress>]
json.append(',');
json.appendNumber(node.identifier);
json.append(',');
json.appendNumber(node.cell->estimatedSizeInBytes(vm));
json.append(',');
json.appendNumber(classNameIndex);
json.append(',');
json.appendNumber(flags);
if (m_snapshotType == SnapshotType::GCDebuggingSnapshot) {
json.append(',');
json.appendNumber(labelIndex);
json.appendLiteral(",\"0x");
appendUnsignedAsHex(reinterpret_cast<uintptr_t>(node.cell), json, Lowercase);
json.appendLiteral("\",\"0x");
appendUnsignedAsHex(reinterpret_cast<uintptr_t>(wrappedAddress), json, Lowercase);
json.append('"');
}
};
bool firstEdge = true;
auto appendEdgeJSON = [&] (const HeapSnapshotEdge& edge) {
if (!firstEdge)
json.append(',');
firstEdge = false;
// <fromNodeId>, <toNodeId>, <edgeTypeIndex>, <edgeExtraData>
json.appendNumber(edge.from.identifier);
json.append(',');
json.appendNumber(edge.to.identifier);
json.append(',');
json.appendNumber(edgeTypeToNumber(edge.type));
json.append(',');
switch (edge.type) {
case EdgeType::Property:
case EdgeType::Variable: {
auto result = edgeNameIndexes.add(edge.u.name, nextEdgeNameIndex);
if (result.isNewEntry)
nextEdgeNameIndex++;
unsigned edgeNameIndex = result.iterator->value;
json.appendNumber(edgeNameIndex);
break;
}
case EdgeType::Index:
json.appendNumber(edge.u.index);
break;
default:
// No data for this edge type.
json.append('0');
break;
}
};
json.append('{');
// version
json.appendLiteral("\"version\":2");
// type
json.append(',');
json.appendLiteral("\"type\":");
json.appendQuotedJSONString(snapshotTypeToString(m_snapshotType));
// nodes
json.append(',');
json.appendLiteral("\"nodes\":");
json.append('[');
// <root>
if (m_snapshotType == SnapshotType::GCDebuggingSnapshot)
json.appendLiteral("0,0,0,0,0,\"0x0\",\"0x0\"");
else
json.appendLiteral("0,0,0,0");
for (HeapSnapshot* snapshot = m_profiler.mostRecentSnapshot(); snapshot; snapshot = snapshot->previous()) {
for (auto& node : snapshot->m_nodes)
appendNodeJSON(node);
}
json.append(']');
// node class names
json.append(',');
json.appendLiteral("\"nodeClassNames\":");
json.append('[');
Vector<String> orderedClassNames(classNameIndexes.size());
for (auto& entry : classNameIndexes)
orderedClassNames[entry.value] = entry.key;
classNameIndexes.clear();
bool firstClassName = true;
for (auto& className : orderedClassNames) {
if (!firstClassName)
json.append(',');
firstClassName = false;
json.appendQuotedJSONString(className);
}
orderedClassNames.clear();
json.append(']');
// Process edges.
// Replace pointers with identifiers.
// Remove any edges that we won't need.
m_edges.removeAllMatching([&] (HeapSnapshotEdge& edge) {
// If the from cell is null, this means a <root> edge.
if (!edge.from.cell)
edge.from.identifier = 0;
else {
auto fromLookup = allowedNodeIdentifiers.find(edge.from.cell);
if (fromLookup == allowedNodeIdentifiers.end()) {
if (m_snapshotType == SnapshotType::GCDebuggingSnapshot)
WTFLogAlways("Failed to find node for from-edge cell %p", edge.from.cell);
return true;
}
edge.from.identifier = fromLookup->value;
}
if (!edge.to.cell)
edge.to.identifier = 0;
else {
auto toLookup = allowedNodeIdentifiers.find(edge.to.cell);
if (toLookup == allowedNodeIdentifiers.end()) {
if (m_snapshotType == SnapshotType::GCDebuggingSnapshot)
WTFLogAlways("Failed to find node for to-edge cell %p", edge.to.cell);
return true;
}
edge.to.identifier = toLookup->value;
}
return false;
});
allowedNodeIdentifiers.clear();
m_edges.shrinkToFit();
// Sort edges based on from identifier.
std::sort(m_edges.begin(), m_edges.end(), [&] (const HeapSnapshotEdge& a, const HeapSnapshotEdge& b) {
return a.from.identifier < b.from.identifier;
});
// edges
json.append(',');
json.appendLiteral("\"edges\":");
json.append('[');
for (auto& edge : m_edges)
appendEdgeJSON(edge);
json.append(']');
// edge types
json.append(',');
json.appendLiteral("\"edgeTypes\":");
json.append('[');
json.appendQuotedJSONString(edgeTypeToString(EdgeType::Internal));
json.append(',');
json.appendQuotedJSONString(edgeTypeToString(EdgeType::Property));
json.append(',');
json.appendQuotedJSONString(edgeTypeToString(EdgeType::Index));
json.append(',');
json.appendQuotedJSONString(edgeTypeToString(EdgeType::Variable));
json.append(']');
// edge names
json.append(',');
json.appendLiteral("\"edgeNames\":");
json.append('[');
Vector<UniquedStringImpl*> orderedEdgeNames(edgeNameIndexes.size());
for (auto& entry : edgeNameIndexes)
orderedEdgeNames[entry.value] = entry.key;
edgeNameIndexes.clear();
bool firstEdgeName = true;
for (auto& edgeName : orderedEdgeNames) {
if (!firstEdgeName)
json.append(',');
firstEdgeName = false;
json.appendQuotedJSONString(edgeName);
}
orderedEdgeNames.clear();
json.append(']');
if (m_snapshotType == SnapshotType::GCDebuggingSnapshot) {
json.append(',');
json.appendLiteral("\"roots\":");
json.append('[');
HeapSnapshot* snapshot = m_profiler.mostRecentSnapshot();
bool firstNode = true;
for (auto it : m_rootData) {
auto snapshotNode = snapshot->nodeForCell(it.key);
if (!snapshotNode) {
WTFLogAlways("Failed to find snapshot node for cell %p", it.key);
continue;
}
if (!firstNode)
json.append(',');
firstNode = false;
json.appendNumber(snapshotNode.value().identifier);
// Maybe we should just always encode the root names.
const char* rootName = rootTypeToString(it.value.markReason);
auto result = labelIndexes.add(rootName, nextLabelIndex);
if (result.isNewEntry)
nextLabelIndex++;
unsigned labelIndex = result.iterator->value;
json.append(',');
json.appendNumber(labelIndex);
unsigned reachabilityReasonIndex = 0;
if (it.value.reachabilityFromOpaqueRootReasons) {
auto result = labelIndexes.add(it.value.reachabilityFromOpaqueRootReasons, nextLabelIndex);
if (result.isNewEntry)
nextLabelIndex++;
reachabilityReasonIndex = result.iterator->value;
}
json.append(',');
json.appendNumber(reachabilityReasonIndex);
}
json.append(']');
}
if (m_snapshotType == SnapshotType::GCDebuggingSnapshot) {
// internal node descriptions
json.append(',');
json.appendLiteral("\"labels\":");
json.append('[');
Vector<String> orderedLabels(labelIndexes.size());
for (auto& entry : labelIndexes)
orderedLabels[entry.value] = entry.key;
labelIndexes.clear();
bool firstLabel = true;
for (auto& label : orderedLabels) {
if (!firstLabel)
json.append(',');
firstLabel = false;
json.appendQuotedJSONString(label);
}
orderedLabels.clear();
json.append(']');
}
json.append('}');
return json.toString();
}