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'use strict';
const {
ObjectAssign,
ObjectCreate,
ObjectDefineProperty,
ObjectGetOwnPropertyDescriptors,
ObjectGetPrototypeOf,
ObjectSetPrototypeOf,
Symbol,
} = primordials;
const {
handle_onclose: handleOnCloseSymbol,
oninit: onInitSymbol,
no_message_symbol: noMessageSymbol
} = internalBinding('symbols');
const {
MessagePort,
MessageChannel,
drainMessagePort,
moveMessagePortToContext,
receiveMessageOnPort: receiveMessageOnPort_,
stopMessagePort
} = internalBinding('messaging');
const {
getEnvMessagePort
} = internalBinding('worker');
const { Readable, Writable } = require('stream');
const {
Event,
NodeEventTarget,
defineEventHandler,
initNodeEventTarget,
kCreateEvent,
kNewListener,
kRemoveListener,
} = require('internal/event_target');
const { inspect } = require('internal/util/inspect');
const kIncrementsPortRef = Symbol('kIncrementsPortRef');
const kName = Symbol('kName');
const kPort = Symbol('kPort');
const kWaitingStreams = Symbol('kWaitingStreams');
const kWritableCallbacks = Symbol('kWritableCallbacks');
const kStartedReading = Symbol('kStartedReading');
const kStdioWantsMoreDataCallback = Symbol('kStdioWantsMoreDataCallback');
const messageTypes = {
UP_AND_RUNNING: 'upAndRunning',
COULD_NOT_SERIALIZE_ERROR: 'couldNotSerializeError',
ERROR_MESSAGE: 'errorMessage',
STDIO_PAYLOAD: 'stdioPayload',
STDIO_WANTS_MORE_DATA: 'stdioWantsMoreData',
LOAD_SCRIPT: 'loadScript'
};
// We have to mess with the MessagePort prototype a bit, so that a) we can make
// it inherit from NodeEventTarget, even though it is a C++ class, and b) we do
// not provide methods that are not present in the Browser and not documented
// on our side (e.g. hasRef).
// Save a copy of the original set of methods as a shallow clone.
const MessagePortPrototype = ObjectCreate(
ObjectGetPrototypeOf(MessagePort.prototype),
ObjectGetOwnPropertyDescriptors(MessagePort.prototype));
// Set up the new inheritance chain.
ObjectSetPrototypeOf(MessagePort, NodeEventTarget);
ObjectSetPrototypeOf(MessagePort.prototype, NodeEventTarget.prototype);
// Copy methods that are inherited from HandleWrap, because
// changing the prototype of MessagePort.prototype implicitly removed them.
MessagePort.prototype.ref = MessagePortPrototype.ref;
MessagePort.prototype.unref = MessagePortPrototype.unref;
class MessageEvent extends Event {
constructor(data, target, type) {
super(type);
this.data = data;
}
}
ObjectDefineProperty(
MessagePort.prototype,
kCreateEvent,
{
value: function(data, type) {
return new MessageEvent(data, this, type);
},
configurable: false,
writable: false,
enumerable: false,
});
// This is called from inside the `MessagePort` constructor.
function oninit() {
initNodeEventTarget(this);
// TODO(addaleax): This should be on MessagePort.prototype, but
// defineEventHandler() does not support that.
defineEventHandler(this, 'message');
defineEventHandler(this, 'messageerror');
setupPortReferencing(this, this, 'message');
}
ObjectDefineProperty(MessagePort.prototype, onInitSymbol, {
enumerable: true,
writable: false,
value: oninit
});
class MessagePortCloseEvent extends Event {
constructor() {
super('close');
}
}
// This is called after the underlying `uv_async_t` has been closed.
function onclose() {
this.dispatchEvent(new MessagePortCloseEvent());
}
ObjectDefineProperty(MessagePort.prototype, handleOnCloseSymbol, {
enumerable: false,
writable: false,
value: onclose
});
MessagePort.prototype.close = function(cb) {
if (typeof cb === 'function')
this.once('close', cb);
MessagePortPrototype.close.call(this);
};
ObjectDefineProperty(MessagePort.prototype, inspect.custom, {
enumerable: false,
writable: false,
value: function inspect() { // eslint-disable-line func-name-matching
let ref;
try {
// This may throw when `this` does not refer to a native object,
// e.g. when accessing the prototype directly.
ref = MessagePortPrototype.hasRef.call(this);
} catch { return this; }
return ObjectAssign(ObjectCreate(MessagePort.prototype),
ref === undefined ? {
active: false,
} : {
active: true,
refed: ref
},
this);
}
});
function setupPortReferencing(port, eventEmitter, eventName) {
// Keep track of whether there are any workerMessage listeners:
// If there are some, ref() the channel so it keeps the event loop alive.
// If there are none or all are removed, unref() the channel so the worker
// can shutdown gracefully.
port.unref();
eventEmitter.on('newListener', function(name) {
if (name === eventName) newListener(eventEmitter.listenerCount(name));
});
eventEmitter.on('removeListener', function(name) {
if (name === eventName) removeListener(eventEmitter.listenerCount(name));
});
const origNewListener = eventEmitter[kNewListener];
eventEmitter[kNewListener] = function(size, type, ...args) {
if (type === eventName) newListener(size - 1);
return origNewListener.call(this, size, type, ...args);
};
const origRemoveListener = eventEmitter[kRemoveListener];
eventEmitter[kRemoveListener] = function(size, type, ...args) {
if (type === eventName) removeListener(size);
return origRemoveListener.call(this, size, type, ...args);
};
function newListener(size) {
if (size === 0) {
port.ref();
MessagePortPrototype.start.call(port);
}
}
function removeListener(size) {
if (size === 0) {
stopMessagePort(port);
port.unref();
}
}
}
class ReadableWorkerStdio extends Readable {
constructor(port, name) {
super();
this[kPort] = port;
this[kName] = name;
this[kIncrementsPortRef] = true;
this[kStartedReading] = false;
this.on('end', () => {
if (this[kStartedReading] && this[kIncrementsPortRef]) {
if (--this[kPort][kWaitingStreams] === 0)
this[kPort].unref();
}
});
}
_read() {
if (!this[kStartedReading] && this[kIncrementsPortRef]) {
this[kStartedReading] = true;
if (this[kPort][kWaitingStreams]++ === 0)
this[kPort].ref();
}
this[kPort].postMessage({
type: messageTypes.STDIO_WANTS_MORE_DATA,
stream: this[kName]
});
}
}
class WritableWorkerStdio extends Writable {
constructor(port, name) {
super({ decodeStrings: false });
this[kPort] = port;
this[kName] = name;
this[kWritableCallbacks] = [];
}
_writev(chunks, cb) {
this[kPort].postMessage({
type: messageTypes.STDIO_PAYLOAD,
stream: this[kName],
chunks: chunks.map(({ chunk, encoding }) => ({ chunk, encoding }))
});
this[kWritableCallbacks].push(cb);
if (this[kPort][kWaitingStreams]++ === 0)
this[kPort].ref();
}
_final(cb) {
this[kPort].postMessage({
type: messageTypes.STDIO_PAYLOAD,
stream: this[kName],
chunks: [ { chunk: null, encoding: '' } ]
});
cb();
}
[kStdioWantsMoreDataCallback]() {
const cbs = this[kWritableCallbacks];
this[kWritableCallbacks] = [];
for (const cb of cbs)
cb();
if ((this[kPort][kWaitingStreams] -= cbs.length) === 0)
this[kPort].unref();
}
}
function createWorkerStdio() {
const port = getEnvMessagePort();
port[kWaitingStreams] = 0;
return {
stdin: new ReadableWorkerStdio(port, 'stdin'),
stdout: new WritableWorkerStdio(port, 'stdout'),
stderr: new WritableWorkerStdio(port, 'stderr')
};
}
function receiveMessageOnPort(port) {
const message = receiveMessageOnPort_(port);
if (message === noMessageSymbol) return undefined;
return { message };
}
module.exports = {
drainMessagePort,
messageTypes,
kPort,
kIncrementsPortRef,
kWaitingStreams,
kStdioWantsMoreDataCallback,
moveMessagePortToContext,
MessagePort,
MessageChannel,
receiveMessageOnPort,
setupPortReferencing,
ReadableWorkerStdio,
WritableWorkerStdio,
createWorkerStdio
};
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