// Copyright (C) The University of Melbourne 2012

digraph G {
//    rankdir=LR;

    { rank=source; startup };
    { rank=same; context; context_advice; worksteal_advice };
    //{ rank=same; stealing; sleeping; };
    { rank=sink; do_shutdown };
    { rank=same; working; idle; stealing; };

    // { rank=same; working; idle; sleeping; };

/*
    //subgraph cluster_working {

        //working;
        //idle;
        context_advice [label="context or worksteal advice" shape=rectangle];
        context_advice2 [label="context_advice" shape=rectangle];
        context [shape=rectangle];
        //worksteal [shape=rectangle];
    //    label = "counted as working";
    //}
*/

/*
    subgraph cluster_idle {

        stealing;
        sleeping;
        soft_was_stealing [label="context or worksteal advice" shape=rectangle];
        label = "counted as idle";
    };
*/

    // Styles for 'idle' states.
    sleeping [style=filled fillcolor=lightgrey];
    stealing [style=filled fillcolor=lightgrey];

    // Shapes for notifications
    shutdown [shape=rectangle];
    context [shape=rectangle];
    context_advice [shape=rectangle];
    worksteal_advice [shape=rectangle];

    // Illistrative only.
    worksteal_once [style=dashed];

    /*
     * Normal operation.
     */
    
    // Primordial engine.
    startup -> working;
    
    // Worker engines.
    startup -> idle;

    // Finished work.
    working -> idle [style=bold];

    // Looking for work.
    idle -> working [style=bold];
    stealing -> working [style=bold];
    // Other transitions use CAS below.

    // Respond to notifications.
    shutdown -> do_shutdown;

    // We do the same action as idle does anyway.
    context_advice -> idle;

    worksteal_advice -> worksteal_once;

    worksteal_once -> working;
    worksteal_once -> stealing;

    context -> working;

    /* CAS Transitions */
    edge [color=blue];
    idle -> stealing [style=bold];
    stealing -> sleeping;

    /* Locked transitions from other engines */
    edge [color=red];
    sleeping -> context;
    sleeping -> context_advice;
    sleeping -> worksteal_advice;
    sleeping -> shutdown;

    /* CAS transitions from other engines */
    edge [color=green];
    idle -> context_advice;
    idle -> worksteal_advice;
    stealing -> context_advice;
    stealing -> worksteal_advice;

    // safe because there will be no other work
    idle -> shutdown;
    stealing -> shutdown;

}