timeout.js

import initialParams from './internal/initialParams';

/**
 * Sets a time limit on an asynchronous function. If the function does not call
 * its callback within the specified milliseconds, it will be called with a
 * timeout error. The code property for the error object will be `'ETIMEDOUT'`.
 *
 * @name timeout
 * @static
 * @memberOf module:Utils
 * @method
 * @category Util
 * @param {Function} asyncFn - The asynchronous function you want to set the
 * time limit.
 * @param {number} milliseconds - The specified time limit.
 * @param {*} [info] - Any variable you want attached (`string`, `object`, etc)
 * to timeout Error for more information..
 * @returns {Function} Returns a wrapped function that can be used with any of
 * the control flow functions. Invoke this function with the same
 * parameters as you would `asyncFunc`.
 * @example
 *
 * function myFunction(foo, callback) {
 *     doAsyncTask(foo, function(err, data) {
 *         // handle errors
 *         if (err) return callback(err);
 *
 *         // do some stuff ...
 *
 *         // return processed data
 *         return callback(null, data);
 *     });
 * }
 *
 * var wrapped = async.timeout(myFunction, 1000);
 *
 * // call `wrapped` as you would `myFunction`
 * wrapped({ bar: 'bar' }, function(err, data) {
 *     // if `myFunction` takes < 1000 ms to execute, `err`
 *     // and `data` will have their expected values
 *
 *     // else `err` will be an Error with the code 'ETIMEDOUT'
 * });
 */
export default function timeout(asyncFn, milliseconds, info) {
    var originalCallback, timer;
    var timedOut = false;

    function injectedCallback() {
        if (!timedOut) {
            originalCallback.apply(null, arguments);
            clearTimeout(timer);
        }
    }

    function timeoutCallback() {
        var name = asyncFn.name || 'anonymous';
        var error  = new Error('Callback function "' + name + '" timed out.');
        error.code = 'ETIMEDOUT';
        if (info) {
            error.info = info;
        }
        timedOut = true;
        originalCallback(error);
    }

    return initialParams(function (args, origCallback) {
        originalCallback = origCallback;
        // setup timer and call original function
        timer = setTimeout(timeoutCallback, milliseconds);
        asyncFn.apply(null, args.concat(injectedCallback));
    });
}