@nestjs/platform-fastify/adapters/utils/on-response-close.util.js

Run NestJS on Fastify: the HTTP adapter with Fastify's plugins, JSON schemas and serialization.

import { finished } from 'stream';
/**
 * The listeners waiting for each connection to close. A client may pipeline
 * any number of requests on one connection, so they share a single "close"
 * listener of it.
 */
const listenersByConnection = new WeakMap();
function isConnection(socket) {
    return (typeof socket?.once === 'function');
}
/**
 * Calls `listener` once, when `response` has finished, failed or closed, or
 * when the connection of its request has closed.
 *
 * `finished()` alone may never report the latter for the response of a
 * pipelined request (e.g. on Node.js 22): until the responses queued before it
 * are out, it has no socket, and it gets no "close" when the connection goes.
 */
export function onResponseClose(response, listener) {
    let listeners;
    let isSettled = false;
    const settle = () => {
        if (isSettled) {
            return;
        }
        isSettled = true;
        listeners?.delete(settle);
        listener();
    };
    finished(response, settle);
    const connection = response.req?.socket;
    if (!isConnection(connection)) {
        return;
    }
    if (connection.destroyed) {
        // Asynchronously, as finished() reports a response that has closed
        process.nextTick(settle);
        return;
    }
    listeners = listenersByConnection.get(connection);
    if (!listeners) {
        const connectionListeners = new Set();
        listenersByConnection.set(connection, connectionListeners);
        connection.once('close', () => {
            listenersByConnection.delete(connection);
            connectionListeners.forEach(notify => notify());
        });
        listeners = connectionListeners;
    }
    listeners.add(settle);
}