go actor

actor.go

package actor

import (
	"context"
	"sync"

	"go.uber.org/zap"
)

var (
	MailboxSize = 100
)

type Actor interface {
	Receive(ctx context.Context, msg any)
	OnStop(ctx context.Context)
}

type PID struct {
	mailbox chan any
	cancel  context.CancelFunc
	wg      sync.WaitGroup
	actor   Actor
}

func Spawn(actor Actor) *PID {
	mailbox := make(chan any, MailboxSize)
	ctx, cancel := context.WithCancel(context.Background())
	pid := &PID{
		mailbox: mailbox,
		cancel:  cancel,
		actor:   actor,
	}
	pid.wg.Add(1)
	go pid.loop(ctx)
	return pid
}

func (p *PID) Stop() {
	p.cancel()
	p.actor.OnStop(context.Background())
	p.wg.Wait()
	close(p.mailbox)
}

func (p *PID) Send(msg any) bool {
	select {
	case p.mailbox <- msg:
		return true
	default:
		zap.L().Warn("actor mailbox full, dropping message", zap.Any("message", msg))
		return false
	}
}

func (p *PID) loop(ctx context.Context) {
	defer p.wg.Done()

	for {
		select {
		case msg := <-p.mailbox:
			p.actor.Receive(ctx, msg)
		case <-ctx.Done():
			return
		}
	}
}