57 lines
1.9 KiB
JavaScript
57 lines
1.9 KiB
JavaScript
import {EventEmitter} from 'node:events';
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import {onMessage, onDisconnect} from './incoming.js';
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import {undoAddedReferences} from './reference.js';
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// Forward the `message` and `disconnect` events from the process and subprocess to a proxy emitter.
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// This prevents the `error` event from stopping IPC.
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// This also allows debouncing the `message` event.
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export const getIpcEmitter = (anyProcess, channel, isSubprocess) => {
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if (IPC_EMITTERS.has(anyProcess)) {
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return IPC_EMITTERS.get(anyProcess);
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}
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// Use an `EventEmitter`, like the `process` that is being proxied
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// eslint-disable-next-line unicorn/prefer-event-target
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const ipcEmitter = new EventEmitter();
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ipcEmitter.connected = true;
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IPC_EMITTERS.set(anyProcess, ipcEmitter);
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forwardEvents({
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ipcEmitter,
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anyProcess,
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channel,
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isSubprocess,
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});
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return ipcEmitter;
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};
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const IPC_EMITTERS = new WeakMap();
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// The `message` and `disconnect` events are buffered in the subprocess until the first listener is setup.
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// However, unbuffering happens after one tick, so this give enough time for the caller to setup the listener on the proxy emitter first.
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// See https://github.com/nodejs/node/blob/2aaeaa863c35befa2ebaa98fb7737ec84df4d8e9/lib/internal/child_process.js#L721
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const forwardEvents = ({ipcEmitter, anyProcess, channel, isSubprocess}) => {
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const boundOnMessage = onMessage.bind(undefined, {
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anyProcess,
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channel,
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isSubprocess,
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ipcEmitter,
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});
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anyProcess.on('message', boundOnMessage);
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anyProcess.once('disconnect', onDisconnect.bind(undefined, {
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anyProcess,
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channel,
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isSubprocess,
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ipcEmitter,
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boundOnMessage,
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}));
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undoAddedReferences(channel, isSubprocess);
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};
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// Check whether there might still be some `message` events to receive
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export const isConnected = anyProcess => {
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const ipcEmitter = IPC_EMITTERS.get(anyProcess);
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return ipcEmitter === undefined
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? anyProcess.channel !== null
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: ipcEmitter.connected;
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};
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