node/lib/internal/worker/js_transferable.js
Chengzhong Wu 38dee8a1c0
src: distinguish HTML transferable and cloneable
The HTML structured serialize algorithm treats transferable and
serializable as two different bits. A web platform interface can be
both transferable and serializable.

Splits BaseObject::TransferMode to be able to compose the two bits
and distinguishes the transferable and cloneable.

PR-URL: https://github.com/nodejs/node/pull/47956
Refs: cf13b9b465
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>
Reviewed-By: Daeyeon Jeong <daeyeon.dev@gmail.com>
2023-07-07 17:00:00 +00:00

101 lines
3.1 KiB
JavaScript

'use strict';
const {
Error,
StringPrototypeSplit,
} = primordials;
const {
messaging_deserialize_symbol,
messaging_transfer_symbol,
messaging_clone_symbol,
messaging_transfer_list_symbol,
} = internalBinding('symbols');
const {
setDeserializerCreateObjectFunction,
} = internalBinding('messaging');
const {
privateSymbols: {
transfer_mode_private_symbol,
},
constants: {
kDisallowCloneAndTransfer,
kTransferable,
kCloneable,
},
} = internalBinding('util');
function setup() {
// Register the handler that will be used when deserializing JS-based objects
// from .postMessage() calls. The format of `deserializeInfo` is generally
// 'module:Constructor', e.g. 'internal/fs/promises:FileHandle'.
setDeserializerCreateObjectFunction((deserializeInfo) => {
const { 0: module, 1: ctor } = StringPrototypeSplit(deserializeInfo, ':');
const Ctor = require(module)[ctor];
if (typeof Ctor !== 'function' ||
typeof Ctor.prototype[messaging_deserialize_symbol] !== 'function') {
// Not one of the official errors because one should not be able to get
// here without messing with Node.js internals.
// eslint-disable-next-line no-restricted-syntax
throw new Error(`Unknown deserialize spec ${deserializeInfo}`);
}
return new Ctor();
});
}
/**
* Mark an object as being transferable or customized cloneable in
* `.postMessage()`.
* This should only applied to host objects like Web API interfaces, Node.js'
* built-in objects.
* Objects marked as cloneable and transferable should implement the method
* `@@kClone` and `@@kTransfer` respectively. Method `@@kDeserialize` is
* required to deserialize the data to a new instance.
*
* Example implementation of a cloneable interface (assuming its located in
* `internal/my_interface.js`):
*
* ```
* class MyInterface {
* constructor(...args) {
* markTransferMode(this, true);
* this.args = args;
* }
* [kDeserialize](data) {
* this.args = data.args;
* }
* [kClone]() {
* return {
* data: { args: this.args },
* deserializeInfo: 'internal/my_interface:MyInterface',
* }
* }
* }
*
* module.exports = {
* MyInterface,
* };
* ```
* @param {object} obj Host objects that can be either cloned or transferred.
* @param {boolean} [cloneable] if the object can be cloned and `@@kClone` is
* implemented.
* @param {boolean} [transferable] if the object can be transferred and
* `@@kTransfer` is implemented.
*/
function markTransferMode(obj, cloneable = false, transferable = false) {
if ((typeof obj !== 'object' && typeof obj !== 'function') || obj === null)
return; // This object is a primitive and therefore already untransferable.
let mode = kDisallowCloneAndTransfer;
if (cloneable) mode |= kCloneable;
if (transferable) mode |= kTransferable;
obj[transfer_mode_private_symbol] = mode;
}
module.exports = {
markTransferMode,
setup,
kClone: messaging_clone_symbol,
kDeserialize: messaging_deserialize_symbol,
kTransfer: messaging_transfer_symbol,
kTransferList: messaging_transfer_list_symbol,
};