@buzuli/meter

Simple metrics collection utility with support for serialization and deserialization.

Usage

The package exports a function which creates a new Meter. It can also be used to collect results from multiple meters or other objects.

meter(src)

• src: string | Meter | object | Array | The source from which the new Meter should attempt to initialize.

Meter properties:

• isMeter: true
• add: (metric: string, value: number = 1) -> number | Increments a metric, initializing it if absent. Returns the updated metric's value.
• min: (metric: string, value: number) -> number | Update a metric of the supplied value is smaller or the metric is not set. Returns the updated metric's value.
• max: (metric: string, value: number) -> number | Update a metric of the supplied value is larger or the metric is not set. Returns the updated metric's value.
• set: (metric: string, value: number = 0) -> number | Set the value of a metric. Returns the new value.
• get: (metric: string) -> number | Get the value associated with a metric. Will be 0 if the metric was missing.
• clear: () -> nil | Removes all metrics from the Meter.
• forEach: ({ metric, count }) -> nil -> nil | Applies the supplied function to every metric in the Meter.
• entries: Iterator[[string, number]] | Supplies an iterator supplying each metric/count pair as an array of the form [metric, count].
• metrics: Iterator[string] | Supplies an iterator supplying all of the metric names.
• map: `({ metric, count }) -> T -> Array[T] | Maps all entries into a new array via the supplied mapper function
• asObject: ({ sort = false, desc = false }) -> object | Converts this meter into a simple object. With each metric key as a field name mapping to its count.
  • Unsorted by default, but may be sorted by keys (sort is true, keys, or metics), or sorted by values (sort is values or counts).
  • Defaults to ascending order, but order may be switched by setting desc to true.
• merge: (Meter) -> nil | Merges all of the metrics from another Meter into this Meter.
• mergeMap: (Map) -> nil | Merges all of a Map's valid fields (strings mapping to numbers) into this Meter.
• mergeObject: (object) -> nil | Merges all of an object's valid fields (strings mapping to numbers) into this Meter.
• serialize: () -> string | Returns a JSON structure which can be imported directly into a new Meter.
• size: () -> number | Returns the size of the meter (the number of distinct metric keys with associated counts).

Example

const meter = require('@buzuli/meter')
const metrics = meter()
metrics.add('calls')
metrics.set('age', 275)
metrics.add('calls')
metrics.add('age', 25)
metrics.forEach(({ metric, count }) => console.info(`${metric} => ${count}`))
// Outputs:
//calls => 2
//age => 300