Measured Core

The core measured library that has the Metric interfaces and implementations.


Install

``
npm install measured-core
`

What is in this package

$3

The core library has the following metrics classes:

#### Gauge
Values that can be read instantly via a supplied call back.

#### SettableGauge
Just like a Gauge but its value is set directly rather than supplied by a callback.

#### CachedGauge
Like a mix of the regular and settable Gauge it takes a call back that returns a promise that will resolve the cached value and an interval that it should call the callback on to update its cached value.

#### Counter
Counters are things that increment or decrement.

#### Timer
Timers are a combination of Meters and Histograms. They measure the rate as well as distribution of scalar events.

#### Histogram
Keeps a reservoir of statistically relevant values to explore their distribution.

#### Meter
Things that are measured as events / interval.

$3

The core library comes with a basic registry class

#### Collection

that is not aware of dimensions / tags and leaves reporting up to you.

#### See the measured-reporting module for more advanced and featured registries.

$3

See The measured-core modules for the full list of exports for require('measured-core').

Usage

Step 1: Add measurements to your code. For example, lets track the
requests/sec of a http server:

`js
var http = require('http');
var stats = require('measured').createCollection();

http.createServer(function(req, res) {
stats.meter('requestsPerSecond').mark();
res.end('Thanks');
}).listen(3000);
`

Step 2: Show the collected measurements (more advanced examples follow later):

`js
setInterval(function() {
console.log(stats.toJSON());
}, 1000);
`

This will output something like this every second:

`
{ requestsPerSecond:
{ mean: 1710.2180279856818,
count: 10511,
'currentRate': 1941.4893498239829,
'1MinuteRate': 168.08263156623656,
'5MinuteRate': 34.74630977619571,
'15MinuteRate': 11.646507524106095 } }
``

Step 3: Aggregate the data into your backend of choice.
Here are a few time series data aggregators.
- Graphite
- A free and open source, self hosted and managed solution for time series data.
- SignalFx
- An enterprise SASS offering for time series data.
- Datadog
- An enterprise SASS offering for time series data.