Module Brassaia.Metrics

Type agnostics mechanisms to manipulate metrics.

Metrics defines primitives to handle metrics inside of Brassaia. Its purpose is to decouple the metrics type definition from the data manipulation.

A t can be modified in different ways, depending on the update_mode.

type origin = ..

An extensible type to get the location of the definition.

type 'a t

t is the object that describes how a t is gathered and store. The 'a parameter represents the type of the internal data.

val state : 'a t -> 'a

The internal state extracted from a t.

val set_state : 'a t -> 'a -> unit

set_state m v updates the value in the t object.

type 'a update_mode =
  1. | Mutate of 'a -> unit
  2. | Replace of 'a -> 'a

update_mode describes how the data will be handled by the update function.

  • Mutate: the value and the storage are not modified but the content of the value can be mutate.
  • Replace f: apply f to the value and updates its content.

It gives the possibility to handle the same metric in different ways.

val create : ?origin:origin -> name:string -> initial_state:'a -> 'a Repr.ty -> 'a t

create ~origin ~name ~initial_state repr create a new t.

  • origin can be set to give an hint about where the data are gathered
  • name is a name to describe this metrics
  • initial_state is the first value to store in the metric object
  • repr describes the type representation to allow serialization.
val update : 'a t -> 'a update_mode -> unit

update metrics mode updates the metric by taking in consideration mode to define how it acts on t according to their specication.