#ifndef SRC_NODE_MESSAGING_H_

#define SRC_NODE_MESSAGING_H_

#if defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS

#include "env.h"

#include "node_mutex.h"

#include "sharedarraybuffer_metadata.h"

#include <list>

namespace node {

namespace worker {

class MessagePortData;

class MessagePort;

// Represents a single communication message.

class Message : public MemoryRetainer {

public:

explicit Message(MallocedBuffer<char>&& payload = MallocedBuffer<char>());

Message(Message&& other) = default;

Message& operator=(Message&& other) = default;

Message& operator=(const Message&) = delete;

Message(const Message&) = delete;

// Deserialize the contained JS value. May only be called once, and only

// after Serialize() has been called (e.g. by another thread).

v8::MaybeLocal<v8::Value> Deserialize(Environment* env,

v8::Local<v8::Context> context);

// Serialize a JS value, and optionally transfer objects, into this message.

// The Message object retains ownership of all transferred objects until

// deserialization.

// The source_port parameter, if provided, will make Serialize() throw a

// "DataCloneError" DOMException if source_port is found in transfer_list.

v8::Maybe<bool> Serialize(Environment* env,

v8::Local<v8::Context> context,

v8::Local<v8::Value> input,

v8::Local<v8::Value> transfer_list,

v8::Local<v8::Object> source_port =

v8::Local<v8::Object>());

// Internal method of Message that is called when a new SharedArrayBuffer

// object is encountered in the incoming value's structure.

void AddSharedArrayBuffer(const SharedArrayBufferMetadataReference& ref);

// Internal method of Message that is called once serialization finishes

// and that transfers ownership of `data` to this message.

void AddMessagePort(std::unique_ptr<MessagePortData>&& data);

// Internal method of Message that is called when a new WebAssembly.Module

// object is encountered in the incoming value's structure.

uint32_t AddWASMModule(v8::WasmModuleObject::TransferrableModule&& mod);

// The MessagePorts that will be transferred, as recorded by Serialize().

// Used for warning user about posting the target MessagePort to itself,

// which will as a side effect destroy the communication channel.

const std::vector<std::unique_ptr<MessagePortData>>& message_ports() const {

return message_ports_;

}

void MemoryInfo(MemoryTracker* tracker) const override;

SET_MEMORY_INFO_NAME(Message)

SET_SELF_SIZE(Message)

private:

MallocedBuffer<char> main_message_buf_;

std::vector<MallocedBuffer<char>> array_buffer_contents_;

std::vector<SharedArrayBufferMetadataReference> shared_array_buffers_;

std::vector<std::unique_ptr<MessagePortData>> message_ports_;

std::vector<v8::WasmModuleObject::TransferrableModule> wasm_modules_;

friend class MessagePort;

};

// This contains all data for a `MessagePort` instance that is not tied to

// a specific Environment/Isolate/event loop, for easier transfer between those.

class MessagePortData : public MemoryRetainer {

public:

explicit MessagePortData(MessagePort* owner);

~MessagePortData() override;

MessagePortData(MessagePortData&& other) = delete;

MessagePortData& operator=(MessagePortData&& other) = delete;

MessagePortData(const MessagePortData& other) = delete;

MessagePortData& operator=(const MessagePortData& other) = delete;

// Add a message to the incoming queue and notify the receiver.

// This may be called from any thread.

void AddToIncomingQueue(Message&& message);

// Returns true if and only this MessagePort is currently not entangled

// with another message port.

bool IsSiblingClosed() const;

// Turns `a` and `b` into siblings, i.e. connects the sending side of one

// to the receiving side of the other. This is not thread-safe.

static void Entangle(MessagePortData* a, MessagePortData* b);

// Removes any possible sibling. This is thread-safe (it acquires both

// `sibling_mutex_` and `mutex_`), and has to be because it is called once

// the corresponding JS handle handle wants to close

// which can happen on either side of a worker.

void Disentangle();

void MemoryInfo(MemoryTracker* tracker) const override;

SET_MEMORY_INFO_NAME(MessagePortData)

SET_SELF_SIZE(MessagePortData)

private:

// After disentangling this message port, the owner handle (if any)

// is asynchronously triggered, so that it can close down naturally.

void PingOwnerAfterDisentanglement();

// This mutex protects all fields below it, with the exception of

// sibling_.

mutable Mutex mutex_;

bool receiving_messages_ = false;

std::list<Message> incoming_messages_;

MessagePort* owner_ = nullptr;

// This mutex protects the sibling_ field and is shared between two entangled

// MessagePorts. If both mutexes are acquired, this one needs to be

// acquired first.

std::shared_ptr<Mutex> sibling_mutex_ = std::make_shared<Mutex>();

MessagePortData* sibling_ = nullptr;

friend class MessagePort;

};

// A message port that receives messages from other threads, including

// the uv_async_t handle that is used to notify the current event loop of

// new incoming messages.

class MessagePort : public HandleWrap {

public:

// Create a new MessagePort. The `context` argument specifies the Context

// instance that is used for creating the values emitted from this port.

MessagePort(Environment* env,

v8::Local<v8::Context> context,

v8::Local<v8::Object> wrap);

~MessagePort() override;

// Create a new message port instance, optionally over an existing

// `MessagePortData` object.

static MessagePort* New(Environment* env,

v8::Local<v8::Context> context,

std::unique_ptr<MessagePortData> data = nullptr);

// Send a message, i.e. deliver it into the sibling's incoming queue.

// If this port is closed, or if there is no sibling, this message is

// serialized with transfers, then silently discarded.

v8::Maybe<bool> PostMessage(Environment* env,

v8::Local<v8::Value> message,

v8::Local<v8::Value> transfer);

// Start processing messages on this port as a receiving end.

void Start();

// Stop processing messages on this port as a receiving end.

void Stop();

/* constructor */

static void New(const v8::FunctionCallbackInfo<v8::Value>& args);

/* prototype methods */

static void PostMessage(const v8::FunctionCallbackInfo<v8::Value>& args);

static void Start(const v8::FunctionCallbackInfo<v8::Value>& args);

static void Stop(const v8::FunctionCallbackInfo<v8::Value>& args);

static void Drain(const v8::FunctionCallbackInfo<v8::Value>& args);

/* static */

static void MoveToContext(const v8::FunctionCallbackInfo<v8::Value>& args);

// Turns `a` and `b` into siblings, i.e. connects the sending side of one

// to the receiving side of the other. This is not thread-safe.

static void Entangle(MessagePort* a, MessagePort* b);

static void Entangle(MessagePort* a, MessagePortData* b);

// Detach this port's data for transferring. After this, the MessagePortData

// is no longer associated with this handle, although it can still receive

// messages.

std::unique_ptr<MessagePortData> Detach();

bool IsSiblingClosed() const;

void Close(

v8::Local<v8::Value> close_callback = v8::Local<v8::Value>()) override;

// Returns true if either data_ has been freed, or if the handle is being

// closed. Equivalent to the [[Detached]] internal slot in the HTML Standard.

//

// If checking if a JavaScript MessagePort object is detached, this method

// alone is often not enough, since the backing C++ MessagePort object may

// have been deleted already. For all intents and purposes, an object with a

// NULL pointer to the C++ MessagePort object is also detached.

inline bool IsDetached() const;

void MemoryInfo(MemoryTracker* tracker) const override {

tracker->TrackField("data", data_);

}

SET_MEMORY_INFO_NAME(MessagePort)

SET_SELF_SIZE(MessagePort)

private:

void OnClose() override;

void OnMessage();

void TriggerAsync();

std::unique_ptr<MessagePortData> data_ = nullptr;

uv_async_t async_;

friend class MessagePortData;

};

v8::MaybeLocal<v8::Function> GetMessagePortConstructor(

Environment* env, v8::Local<v8::Context> context);

} // namespace worker

} // namespace node

#endif // defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS

#endif // SRC_NODE_MESSAGING_H_