Exploring Processes and OTP behaviours in Erlang

Dive into Erlang processes and the most used OTP behaviours

Transcript

1. Exploring Processes and OTP
   behaviours in
   17 ottobre
   Erlang - Elixir meetup Bologna
   

   View Slide

2. @pdincau
   

   View Slide

3. Funzionale
   General purpose
   Dinamico
   Concorrente
   Garbage collected
   - 1 -
   Erlang Run-Time System
   Ideato da Ericsson per la necessità di Business reali
   

   View Slide

4. Soluzione ai problemi odierni e futuri
   Programmare diversamente
   - 2 -
   PERCHÈ USARLO?
   

   View Slide

5. “If we want to write programs that behave as other objects behave in the
   real world, then these programs will have a concurrent structure.
   Use a language that was designed for writing concurrent applications,
   and development becomes a lot easier.
   Erlang programs model how we think and interact.”
   Joe Armstrong
   Programming Erlang - 1st Edition
   - 3 -
   

   View Slide

6. - 4 -
   Moduli o Classi
   “It’s OO, but pretend it isn’t, please”
   Fred Hebert
   Joe Armstrong / Ralph Johnson
   infoq.com/interviews/johnson-armstrong-oop
   ferd.ca/an-open-letter-to-the-erlang-beginner-or-onlooker.html
   VENITE DAL MONDO OOP?
   

   View Slide

7. - 5 -
   Actor Model
   TASK = fun(message)
   http:/
   /learnyousomeerlang.com/the-hitchhikers-guide-to-concurrency
   LA REALTÀ
   

   View Slide

8. - 6 -
   Green Threads e message passing
   - 6 -
   - 6 -
   PROCESSI
   

   View Slide

9. - 7 -
   UN ESEMPIO PRATICO?
   

   View Slide

10. - 8 -
    P1 P2
    P2 ! {increment, N}
    COUNTER SERVER
    

    View Slide

11. - 9 -
    COUNTER CODICE
    

    View Slide

12. P1 P2
    P2 ! {self(), {increment, N}}
    - 10 -
    P1 ! {Pid2, Result}
    CHIAMATA SINCRONA
    

    View Slide

13. - 11 -
    COUNTER MIGLIORATO
    

    View Slide

14. P1
    P2
    m1
    P3
    P4
    P5
    m2
    m3
    m4
    - 12 -
    COUNTERS
    

    View Slide

15. - xx -
    PROVIAMO!
    

    View Slide

16. P1
    P2
    P3
    P4
    - 13 -
    CRASH!
    

    View Slide

17. - 14 -
    PRIMITIVE DI ERLANG
    spawn link spawn_link monitor
    

    View Slide

18. NON COSÌ
    - 15 -
    

    View Slide

19. {'EXIT', From, Reason}
    crash!
    crash!
    crash!
    - 16 -
    CRASH! CRASH! CHRASH!
    P1
    P2
    P3
    P4
    

    View Slide

20. trap_exit
    - 17 -
    

    View Slide

21. “…OTP, the 800-pound gorilla
    of process architecture”
    Dave Thomas
    Programming Elixir
    - 18 -
    

    View Slide

22. Librerie con pattern comuni che ci consentono di
    sviluppare applicazioni:
    - xx -
    DISTRIBUITE e FAULT TOLERANT
    - 18 -
    

    View Slide

23. - 19 -
    Modella il server di una relazione di tipo client-server
    Server
    Client
    Client
    Client Query
    Reply
    http:/
    /www.erlang.org/doc/design_principles/gen_server_concepts.html
    GEN_SERVER
    

    View Slide

24. - 20 -
    GEN_SERVER
    

    View Slide

25. - 21 -
    GEN_SERVER
    

    View Slide

26. - 22 -
    State(S) x Event(E) -> Actions(A), State(S')
    Lobby Idle
    Disconnected
    Reconnected
    timeout
    Stop
    GEN_FSM
    

    View Slide

27. Wander Pursue
    Act
    Eat
    Act Act
    Act
    Act
    Act
    Act
    - 23 -
    GEN_FSM
    

    View Slide

28. - 24 -
    GEN_EVENT
    server
    event
    manager
    g(event)
    f(event)
    h(event)
    event
    “Profiling and Debugging Erlang Systems”
    Martin Kjellin, Roberto Aloi
    youtube.com/watch?v=4u6c2FNauYE
    

    View Slide

29. - 25 -
    SUPERVISOR
    Main
    Sup.
    GCM 2
    GCM 1
    Il cuore della affidabilità di Erlang
    

    View Slide

30. - 26 -
    SUPERVISOR
    Sup.
    Main
    Sup.
    Seq.
    Worker
    Stash
    Worker
    “OTP: Supervisors”
    Programming Elixir
    Dave Thomas
    

    View Slide

31. - 27 -
    APPLICATION
    Raccoglie codice comune a una funzionalità
    start/stop
    Organizzazione dei file
    Gestione delle configurazioni
    Riutilizzabile
    

    View Slide

32. - 28 -
    RELEASE
    Una "release" è un insieme di applicazioni Erlang
    deployate ed eseguite assieme
    rebar3 è un grande passo avanti
    Gestione configurazioni
    

    View Slide

33. - 29 -
    Erlang in production: "I wish I'd known that when I started"
    Bernard Duggan
    youtube.com/watch?v=G0eBDWigORY
    Thinking like an Erlanger
    Torben Hoffmann
    youtube.com/watch?v=_fgaPGLGZI0
    RISORSE UTILI
    

    View Slide

34. Grazie
    

    View Slide