grafserv/dist/websocketKeepalive.js

A highly optimized server for GraphQL, powered by Grafast

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.DEFAULT_WEBSOCKET_KEEPALIVE = void 0;
exports.handleWebSocketKeepalive = handleWebSocketKeepalive;
exports.DEFAULT_WEBSOCKET_KEEPALIVE = 12_000;
function handleWebSocketKeepalive(socket, preset) {
    const keepaliveInterval = preset.grafserv?.websocketKeepalive ?? exports.DEFAULT_WEBSOCKET_KEEPALIVE;
    if (!Number.isFinite(keepaliveInterval) || keepaliveInterval <= 0) {
        // Keepalive disabled
        return;
    }
    /**
     * Sending a ping and waiting for a pong are mutually exclusive, so this
     * timer is used for both.
     */
    let timer = null;
    /**
     * Cleans up the timer, always call this before re-assigning timer (to ensure
     * that an out-of-order pong doesn't cause two timers to run concurrently).
     */
    const stopTimer = () => {
        if (timer != null) {
            clearTimeout(timer);
            timer = null;
        }
    };
    /** First half of a heart beat - send ping */
    const sendPing = () => {
        stopTimer();
        // Schedule timeout
        timer = setTimeout(handleTimeout, keepaliveInterval);
        socket.ping();
    };
    /** Second half of a heart beat - receive pong */
    const handlePong = () => {
        stopTimer();
        // Schedule the next ping
        timer = setTimeout(sendPing, keepaliveInterval);
    };
    /** Terminal handler, due to timeout */
    const handleTimeout = () => {
        stopTimer();
        releaseListeners();
        // Kill the socket (after we've released the listeners)
        socket.terminate();
    };
    /** Terminal handler, due to natural socket close */
    const handleClose = (_code, _reason) => {
        stopTimer();
        releaseListeners();
    };
    const releaseListeners = () => {
        socket.off("pong", handlePong);
        socket.off("close", handleClose);
    };
    socket.on("pong", handlePong);
    socket.on("close", handleClose);
    // Schedule the first ping
    timer = setTimeout(sendPing, keepaliveInterval);
}
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