tm-apps-list-api/src/breaker.js

const { commandFactory } = require('hystrixjs');

const promisify = require('util.promisify');
const callbackify = require('util').callbackify || function (promiser) {
    return function (...args) {
        const callback = args.pop();
        promiser.apply(this, args).then(
            result => callback(null, result),
            error => callback(error)
        );
    };
};

module.exports = (redis, options) => {
    const service = promisify((command_obj, callback) => {
        command_obj.callback = callback;
    });

    const fallback = promisify((error, [command_obj], callback) => {
        command_obj.command = command_obj.callback = null;
        callback(error);
    });

    const breaker = commandFactory.getOrCreate(options.name)
        .circuitBreakerErrorThresholdPercentage(options.errorThreshold)
        .timeout(options.timeout)
        .run(service)
        .circuitBreakerRequestVolumeThreshold(options.volumeThreshold)
        .requestVolumeRejectionThreshold(options.rejectionThreshold)
        .circuitBreakerSleepWindowInMilliseconds(options.sleepWindow)
        .statisticalWindowLength(options.windowLength)
        .statisticalWindowNumberOfBuckets(options.windowBuckets)
        .fallbackTo(fallback)
        .build();

    const { createClient } = redis;

    redis.createClient = function () {
        const client = createClient.apply(this, arguments);

        const  { internal_send_command } = client;

        client.internal_send_command = function (command_obj) {
            const { command, callback = function () {} } = command_obj;

            if (!command) return true;

            callbackify(breaker.execute).call(breaker, command_obj, callback);

            return internal_send_command.call(this, command_obj);
        };

        return client;
    };

    return redis;
};