elio

elio means event loop io library.
This library allows you to quickly write epoll-based servers.

Apps written using elio library

🚀 Running Echo

Echo is a simple echo server.

🚀 Running Herald

Herald is a simple MQTT pub/sub test client.

• Docker Hub: cppis/herald

Under the Hood of Echo

app/echo is simple echo server written by elio.
This is the main function of app/echo:

package main

import (
	"github.com/cppis/elio"
)

func main() {
	app := elio.Elio()

	echo := NewEcho(app)
	app.Register(echo)

	app.Run()

	app.Wait()
}

The echo generated by NewEcho is a implementation of elio service interface:
elio service interface has following method signatures:

package elio

import (
	"context"
	"time"
)

// Service service
type Service interface {
	Name() string
	OnInit(ctx context.Context, cancel context.CancelFunc) error
	OnExit()
	OnOpen(s *Session) error
	OnClose(s *Session, err error)
	OnError(s *Session, err error)
	OnRead(s *Session, in []byte) int
	OnWrite(s *Session, out []byte)
	OnLoop(host *IoHost, t time.Time, d time.Duration)
}

If network I/O event happens, elio calls proper event method of service.

This is a event implementations of echo service:

func (e *Echo) OnOpen(s *elio.Session) error {
	fmt.Printf("o")

	return nil
}

func (e *Echo) OnClose(s *elio.Session, err error) {
	fmt.Printf("c")
}

func (e *Echo) OnError(s *elio.Session, err error) {
	fmt.Printf("e")
}

func (e *Echo) OnRead(s *elio.Session, in []byte) (processed int) {
	fmt.Printf("+%d", len(in))

	s.Write(in)

	if 'q' == in[0] {
		elio.Elio().End()
	}

	return processed
}

func (e *Echo) OnWrite(s *elio.Session, out []byte) {
	fmt.Printf("-%d", len(out))
}

Service also has loop callback for running logics at regular intervals:

const (
	// defaultFetchLimit default fetch limit
	defaultFetchLimit int = 2000
)

func (e *Echo) OnLoop(host *elio.IoHost, t time.Time, d time.Duration) {
	//host.RunDivision(t, r.callbackDivision)

	_, _ = host.Dispatching(t, defaultFetchLimit)

	e.prev = t
}