jergason / hourglass

Client-side metrics library.

#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.

It uses jQuery for HTTP requests if it is defined, but you can pass in your own HTTP library if you want to use something different.

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.

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.
• httpLib - an alternative HTTP library that will be used instead of window.jQuery. It must have a .ajax() function that has the same api as jQuery.ajax()

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

The real answer is maybe, but I didn't do anything special to support it.

What do the metrics look like when sent to the server?

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]
  }
}

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.