#hourglass

hourglass is a front end JavaScript performance monitoring tool. It gives you a time and timeEnd api for measuring how long things take, similar to the Chrome console API. It aggregates these times and POSTs them to a server, where you make magic happen with them.

AN EXAMPLE

var hourglass = new Hourglass({
  url: 'http://where.to.send.metrics.example.com'
  aggregationInterval: 10000
})

function someLongRunningThing() {
  hourglass.time('longRunningThing')
  someAsyncOperation(function() {
    hourglass.timeEnd('longRunningThing')
  })
}

Now every 10 seconds, hourglass will POST any metrics that were timeEnded to the url.

Metric Format

They get POSTed as JSON with this format:

{
  "timestamp": 123455434, // timestamp the metrics were posted
  "metrics": {
    "metricName": [10, 20, 500, 10], // arrays of times in millesecond between `time` and `timeEnd`.
    "metricName2": [12312, 1234, 5959]
  }
}

API

new Hourglass(opts)

Create a new instance of Hourglass. opts is a hash of options

• url - the URL to POST metrics to. This is the only required option. The constructor will throw an error if you don't provide a url.
• aggregationInterval - the number of milliseconds to wait between POSTing metrics to url. Defaults to 60000
• verbose - if true, debug info will be printed to the console.

Example

var hourglass = new Hourglass({url: 'http://my.server.endpoint.example.com/stats'})

hourglass.time(metricName)

Record a start time for a metric. If start is called multiple times with the same metricName, the metrics will be resolved in FIFO order.

• metricName String the name of the metric to record a start time for.

Example

hourglass.time('renderHomePage')
someFunctionToRenderHomePage(function() {
  hourglass.timeEnd('renderHomePage')
})

hourglass.timeEnd(metricName)

Finish recording a time for a metric. It will be sent off with the next aggregation cycle.

• metricName String name of the metric to resolve.

Example

hourglass.time('renderHomePage')
someFunctionToRenderHomePage(function() {
  hourglass.timeEnd('renderHomePage')
})

hourglass.startAggregation()

Start the aggregation setInterval. This is called automatically by the constructor, but if you want to manually start and stop aggregation, here it is.

hourglass.pauseAggregation()

Stop sending metrics to the server.

FAQ

Will this work on IE <= 8?

(╯°□°）╯︵ ƎI

How do I consume these on the server?

I am working on a project to intergrate with Graphite and statsd, but for now it is up to you to do something useful with this data.