Transcript of "Way to do things" from Peter Bourgon

Actors.md

Ways to do things (from Peter Bourgon)

Actors

// Actor model (state machine)
type stateMachine struct {
    state string
    actionc chan func()
}

func newStateMachine() *stateMachine {
    return &stateMachine{
        state: "initial",
        actionc: make(chan func()),
    }
}

func (sm *stateMachine) Run(ctx context.Context) error {
    for {
        select {
            case f := <-sm.actionc:
                f()
            case <-ctx.Done():
                return ctx.Err()
        }
    }
}

func (sm *stateMachine) foo() int {
    c := make(chan int)
    sm.actionc <- func() {
        // Do some stuff inside
        sm.state = "processing foo"
        c <- 123
    }
    return <-c
}

Orchestrating actors (using group)

var g group.Group
{
    ctx, cancel := context.WithCancel(context.Background())
    g.Add(func() error {
        return sm.Run(ctx)
    }, func(error) {
        cancel()
    })
}
// Considering server as an actor too
{
    ln, _ := net.Listen("tcp", ":8080")
    g.Add(func() error {
        return http.Serve(ln, api)
    }, func(error) {
        ln.Close()
    })
}
// Other stuff too
{
    cancel := make(chan struct{})
    g.Add(func() error {
        return cronJobs(cancel, sm)
    }, func(error) {
        close(cancel)
    }
}

g.Run()