Get graphs directly from codahale/metrics

README.md

Get metrics from codahale/metrics in realtime.

Requires obfuscurity/tasseo#64

tasseo-coda-realtime-metrics.js

function MetricsDatasource(metricsUrl, options) {
  this.metricCache = new MetricCache(new MetricFetcher(metricsUrl));
}

MetricsDatasource.prototype = {
  refresh: function(metrics, period) {
    var self = this;

    self.metricCache.setPeriod(period * 60);

    self.metricCache.refresh(function() {
      _.each(metrics, function(metric) {
        var dataset = self.metricCache.get(metric.target);
        metric.update(_.map(dataset, function(datum) {
          return { x: datum.time, y: datum.value }
        }))
      })
    })
  }
}

function MetricFetcher(url) {
  this.url = url;
}

MetricFetcher.prototype = {
  refresh: function(cb) {
    $.ajax({
      dataType: 'json',
      error: function(xhr, textStatus, errorThrown) { console.log(errorThrown); },
      url: this.url,
      success: _.bind(function(data) {
        this.latestMetrics = this.flattenMetrics(data)
        cb.call(this.latestMetrics)
      }, this)
    })
  },

  flattenMetrics: function(data, prefix) {
    var result = {};
    var hasType = _.has(data, 'type');

    _.each(data, function(value, key) {
      var metricName = _.isUndefined(prefix) ? key :  prefix + "." + key;
      if (hasType) {
        if (_.isNumber(value)) {
          result[metricName] = value;
        }
      } else if (_.isObject(value)) {
        _.extend(result, this.flattenMetrics(value, metricName))
      }
    }, this);

    return result;
  }
}

function MetricCache(metricFetcher, options) {
  this.metricFetcher = metricFetcher;
  this.options = _.extend({}, {
    period: 60 * 5 // 5 minutes
  }, options)
  this.period = this.options.period
  this.cache = {}
  this._metricNames = {}
}

MetricCache.prototype = {
  refresh: function(callback) {
    var self = this;
    this.metricFetcher.refresh(function() {
      self.update()
      if (callback) {
        callback.call()
      }
    })
  },

  setPeriod: function(period) {
    this.period = period;
  },

  get: function(name) {
    if (!_.has(this.cache, name)) {
      this.cache[name] = this.blankData();
    }

    return this.cache[name];
  },

  metricNames: function() {
    return _.keys(this._metricNames);
  },

  update: function() {
    var now = this.unixtime();
    var oldest = now - this.period;
    var newMetric = false;

    _.each(this.metricFetcher.latestMetrics, function(value, name) {
      if (!this._metricNames[name]) {
        this._metricNames[name] = true
        newMetric = true;
      }

      // Only fill in metrics that we've had requests for
      if (_.has(this.cache, name)) {
        this.cache[name].push({ value: value, time: now })
        this.cache[name] = _.reject(this.cache[name], function(record) {
          return record.time < oldest;
        })
      }
    }, this)

    if (newMetric) {
      $(this).trigger("metric:added")
    }
  },

  unixtime: function() {
    return Math.floor(new Date() / 1000)
  },

  blankData: function() {
    var now = this.unixtime();
    var data = []

    for (var i = now - this.period; i < now; i += 5) {
      data.push({ value: 0, time: i })
    }
    return data;
  }
}