grandma/lib/runner.js

Load testing CLI tool

var EventEmitter = require('events');
var _ = require('lodash');

var modes = {
    rate: require('./run-mode-rate.js'),
    concurrent: require('./run-mode-concurrent.js')
};

var events = {
    START: 'start',
    RUN: 'task:run',
    RUN_INTERNAL: 'task:run:internal',
    COMPLETE: 'task:complete'
};

module.exports = function taskCreator(opts) {
    var mode = opts.mode;
    var paused = false;
    var running = 0;

    var modeFunc = modes[mode] || function() {
        return {
            _start: function(c, n) {
                process.nextTick(n);
            }
        };
    };

    var api = Object.defineProperties(new EventEmitter(), {
        paused: {
            enumerable: true,
            configurable: false,
            get: function() {
                return paused;
            }
        },
        runningCount: {
            enumerable: true,
            configurable: false,
            get: function() {
                return running;
            }
        },
        expectedCount: {
            enumerable: true,
            configurable: false,
            get: function() {
                var options = opts.options;

                if (!options.rate) {
                    return null;
                }

                return options.duration === 0 ?
                    null :
                    Math.floor(options.rate * (options.duration / 1000));
            }
        },
        EVENTS: {
            enumerable: false,
            configurable: false,
            value: events,
            writable: false
        }
    });

    // TODO I don't like these props... how should these
    // be handled in the new API?
    // Maybe add a 'debug' and 'metadata' events, which the runner
    // can translate to these functions?
    api.debug = opts.debug;
    api.writeOutput = opts.writeOutput;
    api.options = opts.options;

    // TODO handle #stop in this shared API, triggering
    // a terminate event for the run mode helpers to use

    // TODO maybe overload the emit event in order
    // to whitelist some public events that can be
    // emitted through this api

    api.on(events.RUN_INTERNAL, function(context) {
        if (paused) {
            // do not run tests while paused... any discrepancies
            // will be taken care of on resume
            return;
        }

        running += 1;

        api.emit(events.RUN, {
            context: context
        });
    });

    api.on(events.COMPLETE, function() {
        running -= 1;

        // TODO the underlying run helper should just
        // use complete
        api.emit('tick');
    });

    api.once(events.START, function() {
        api._start();
    });

    api.pause = function() {
        paused = true;
    };

    api.resume = function() {
        paused = false;
        var context;

        // if we are in concurrent mode, we may need to start more tests
        // (in rate mode, tests are started on a timer, so we don't care)
        if (mode === 'concurrent' && running < opts.options.concurrent) {
            var needToStart = opts.options.concurrent - running;

            _.times(needToStart, function() {
                api.emit(events.RUN, {
                    context: context
                });
            });
        }
    };

    modeFunc(api);

    api._start = function(o, done) {
        var ERR;
        var DATA;

        return api._startX(o, function checkDone(err, data) {
            ERR = ERR || err;
            DATA = DATA || data;

            if (running) {
                api.once('tick', checkDone);
            } else {
                done(ERR, DATA);
            }
        });
    };

    return api;
};