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#ifndef SRC_NODE_SNAPSHOTABLE_H_
#define SRC_NODE_SNAPSHOTABLE_H_
#if defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS
#include "base_object.h"
#include "util.h"
namespace node {
class Environment;
struct RealmSerializeInfo;
struct SnapshotData;
class ExternalReferenceRegistry;
using SnapshotIndex = size_t;
struct PropInfo {
std::string name; // name for debugging
uint32_t id; // In the list - in case there are any empty entries
SnapshotIndex index; // In the snapshot
};
typedef size_t SnapshotIndex;
// When serializing an embedder object, we'll serialize the native states
// into a chunk that can be mapped into a subclass of InternalFieldInfoBase,
// and pass it into the V8 callback as the payload of StartupData.
// The memory chunk looks like this:
//
// [ type ] - EmbedderObjectType (a uint8_t)
// [ length ] - a size_t
// [ ... ] - custom bytes of size |length - header size|
struct InternalFieldInfoBase {
public:
EmbedderObjectType type;
size_t length;
template <typename T>
static T* New(EmbedderObjectType type) {
static_assert(std::is_base_of_v<InternalFieldInfoBase, T> ||
std::is_same_v<InternalFieldInfoBase, T>,
"Can only accept InternalFieldInfoBase subclasses");
void* buf = ::operator new[](sizeof(T));
T* result = new (buf) T;
result->type = type;
result->length = sizeof(T);
return result;
}
template <typename T>
T* Copy() const {
static_assert(std::is_base_of_v<InternalFieldInfoBase, T> ||
std::is_same_v<InternalFieldInfoBase, T>,
"Can only accept InternalFieldInfoBase subclasses");
static_assert(std::is_trivially_copyable_v<T>,
"Can only memcpy trivially copyable class");
void* buf = ::operator new[](sizeof(T));
T* result = new (buf) T;
memcpy(result, this, sizeof(T));
return result;
}
void Delete() { ::operator delete[](this); }
InternalFieldInfoBase() = default;
};
// An interface for snapshotable native objects to inherit from.
// Use the SERIALIZABLE_OBJECT_METHODS() macro in the class to define
// the following methods to implement:
//
// - PrepareForSerialization(): This would be run prior to context
// serialization. Use this method to e.g. release references that
// can be re-initialized, or perform property store operations
// that needs a V8 context.
// - Serialize(): This would be called during context serialization,
// once for each embedder field of the object.
// Allocate and construct an InternalFieldInfoBase object that contains
// data that can be used to deserialize native states.
// - Deserialize(): This would be called after the context is
// deserialized and the object graph is complete, once for each
// embedder field of the object. Use this to restore native states
// in the object.
class SnapshotableObject : public BaseObject {
public:
SnapshotableObject(Realm* realm,
v8::Local<v8::Object> wrap,
EmbedderObjectType type);
std::string GetTypeName() const;
// If returns false, the object will not be serialized.
virtual bool PrepareForSerialization(v8::Local<v8::Context> context,
v8::SnapshotCreator* creator) = 0;
virtual InternalFieldInfoBase* Serialize(int index) = 0;
bool is_snapshotable() const override { return true; }
// We'll make sure that the type is set in the constructor
EmbedderObjectType type() { return type_; }
private:
EmbedderObjectType type_;
};
#define SERIALIZABLE_OBJECT_METHODS() \
bool PrepareForSerialization(v8::Local<v8::Context> context, \
v8::SnapshotCreator* creator) override; \
InternalFieldInfoBase* Serialize(int index) override; \
static void Deserialize(v8::Local<v8::Context> context, \
v8::Local<v8::Object> holder, \
int index, \
InternalFieldInfoBase* info);
v8::StartupData SerializeNodeContextInternalFields(v8::Local<v8::Object> holder,
int index,
void* env);
void DeserializeNodeInternalFields(v8::Local<v8::Object> holder,
int index,
v8::StartupData payload,
void* env);
void SerializeSnapshotableObjects(Realm* realm,
v8::SnapshotCreator* creator,
RealmSerializeInfo* info);
} // namespace node
#endif // defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS
#endif // SRC_NODE_SNAPSHOTABLE_H_
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