README.md

PeeVee - Go 1.18+ only (requires Go generics)

PEEVEE lets you peek into what is happening in real time through Golang channels. It can automatically generate Prometheus metrics about the throughput of channels. Think of it like Unix's "pv" (https://linux.die.net/man/1/pv) but in Golang.

Examples

Using PeeVee to create both reader and writer channels

package main

import (
	"fmt"
	"time"
	"log"

	"github.com/migueleliasweb/peevee"
	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promhttp"
)

func runMetricsEndpoint() {
	http.Handle("/metrics", promhttp.HandlerFor(
		prometheus.DefaultGatherer,
		promhttp.HandlerOpts{},
	))
	log.Fatal(http.ListenAndServe(":8080", nil))
}

func main() {
	pv := peevee.New("myWorkChannel", WithPromMetrics[int]())

	// mimic an asynchronous channel writer
	go func() {
		for {
			pv.GetWritableChan() <- rand.Int()
			time.Sleep(time.Millisecond * 250)
		}
	}()

	// mimic an asynchronous channel reader
	go func() {
		for {
			fmt.Printnl("int:", <-pv.GetReadableChan())
		}
	}()

	runMetricsEndpoint()
	
	// Leave the example running and open "localhost:8080/metrics" on your browser.
	// You will see a metric called "peevee" that is generated in real time
	// when the channel is being read/written.
}

Using PeeVee to wrap an existing channel for reading

package main

import (
	"fmt"
	"time"
	"log"

	"github.com/migueleliasweb/peevee"
	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promhttp"
)

func runMetricsEndpoint() {
	http.Handle("/metrics", promhttp.HandlerFor(
		prometheus.DefaultGatherer,
		promhttp.HandlerOpts{},
	))
	log.Fatal(http.ListenAndServe(":8080", nil))
}

func main() {
	// this is a channel that gets returned
	// from an SDK or a third party lib, for example
	channelYouDontControl := make(chan bool)

	go func() {
		for {
			// this would be something happening inside the SDK or lib
			channelYouDontControl <- true
			time.Sleep(time.Millisecond * 250)
		}
	}()

	pv := peevee.NewReaderWrap(
		"boolwrap",
		channelYouDontControl, // this time you can pass the existing channel
	)

	// mimic an asynchronous channel reader
	go func() {
		for {
			fmt.Printnl("got:", <-pv.GetReadableChan())
		}
	}()

	runMetricsEndpoint()
	
	// Leave the example running and open "localhost:8080/metrics" on your browser.
	// You will see a metric called "peevee" that is generated in real time
	// when the channel is being read/written.
}