librato-express/lib/metrics.js

Middleware for expressjs to send metrics to Librato.

var util = require('util');

const PREFIX_COUNT  = 'count_';
const PREFIX_TIMER  = 'timing_';

var Metrics;
module.exports = function (base) {

    Metrics = base;
    return {
        Counter : Counter,
        Timing : Timing
    }
};

/* Common constructor routine. */
function MetricsController (opt, prefix) {

	if (!Metrics.collector) {
		throw new Error('librato-metrics module not initialized before use.');
	}

	if (!opt.name) {
		throw 'Metrics options must have name';
	}

	var options = util._extend({}, opt);
	options.source = options.source ? options.source : Metrics.source;
	this.name = options.name = Metrics.prefix + prefix + options.name;
    return options;
}

MetricsController.deleteMetrics = function (cb) {
    Metrics.transport.deleteMetrics({names: [this.name + '*']}, cb);
};

/**
 * Counter
 * @param opt
 * @constructor
 */
function Counter (opt) {
    var modifiedOptions = MetricsController.call(this, opt, PREFIX_COUNT);
    Metrics.collector.initCounter(modifiedOptions);
}

Counter.prototype.increment = function (step, filter) {
    var self = this;
    Metrics.queue.push(
        function (cb) {
            Metrics.collector.count(self.name, step || 1, filter, cb);
        },
        1
    );
};

Counter.prototype.deleteMetrics = MetricsController.deleteMetrics;

/**
 * Timer
 * @param opt
 * @constructor
 */
function Timing (opt) {
    var modifiedOptions = MetricsController.call(this, opt, PREFIX_TIMER);
    Metrics.collector.initTiming(modifiedOptions);
}

Timing.prototype.measure = function (time, filter) {
    var self = this;
    Metrics.queue.push(
        function (cb) {
            Metrics.collector.timing(self.name, (Date.now() - time), filter, cb)
        },
        1
    );
};

Timing.prototype.deleteMetrics = MetricsController.deleteMetrics;