source: src/tests/concurrent/waitfor/recurse.c @ 04570c7

//----------------------------------------------------------------
// Recursion test
// Ensures that proper ordering occurs between the nested waitfors
//-----------------------------------------------------------------

#include <fstream>
#include <kernel>
#include <monitor>
#include <stdlib>
#include <thread>

#include <stdbool.h>
#include <time.h>

static const unsigned long N = 5_000ul;

static inline void rand_yield() { yield(random( 10 )); }

enum state_t { FIRST, SECOND, THIRD, LAST, STOP };
void shuffle(enum state_t * array)
{
        int i;
        for (i = 0; i < 4; i++)
        {
                int j = random( 4 );
                enum state_t t = array[j];
                array[j] = array[i];
                array[i] = t;
        }
}


monitor global_t {
        int counter;
        volatile bool ready;
        state_t actions[4];
};

void ?{} ( global_t & this ) {
        this.counter = 0;
        this.ready = false;
        this.actions[0] = FIRST;
        this.actions[1] = SECOND;
        this.actions[2] = THIRD;
        this.actions[3] = LAST;
        shuffle( this.actions );
}

void ^?{} ( global_t & mutex this ) {}

global_t global;

state_t call4( global_t & mutex this, int idx ) {
        sout | "Last";

        rand_yield();
        this.counter++;
        this.ready = false;
        shuffle( this.actions );

        return this.counter < N ? (state_t)this.actions[idx] : (state_t)STOP;
}

state_t call3( global_t & mutex this, int idx ) {
        sout | "3rd";

        rand_yield();
        waitfor( call4, this );
        rand_yield();

        sout | "3rd";

        return this.counter < N ? (state_t)this.actions[idx] : (state_t)STOP;
}

state_t call2( global_t & mutex this, int idx ) {
        sout | "2nd";

        rand_yield();
        waitfor( call3, this );
        rand_yield();

        sout | "2nd";

        return this.counter < N ? (state_t)this.actions[idx] : (state_t)STOP;
}

state_t call1( global_t & mutex this, int idx ) {
        this.ready = true;

        sout | this.counter | "1st";

        rand_yield();
        waitfor( call2, this );
        rand_yield();

        sout | "1st" | endl;

        return this.counter < N ? (state_t)this.actions[idx] : (state_t)STOP;
}

thread waiter_t{
        int     idx;
        state_t state;
};

void ^?{} ( waiter_t & mutex this ) {}
void ?{} ( waiter_t & this ) {}

void ?{}( waiter_t & this, int idx, state_t state ) {
        this.idx   = idx;
        this.state = state;
}


void main( waiter_t & this ) {
        while( this.state != STOP ) {
                rand_yield();

                switch( this.state ) {
                        case FIRST  :                                     this.state = call1( global, this.idx ); break;
                        case SECOND : while( !global.ready ) { yield(); } this.state = call2( global, this.idx ); break;
                        case THIRD  : while( !global.ready ) { yield(); } this.state = call3( global, this.idx ); break;
                        case LAST   : while( !global.ready ) { yield(); } this.state = call4( global, this.idx ); break;
                        case STOP   : serr | "This should not happen" | endl;
                }
        }
}

static waiter_t * volatile the_threads;

int main() {
        srandom( time(NULL) );
        sout | "Starting" | endl;
        {
                waiter_t waiters[4] = {
                        { 0, FIRST  },
                        { 1, SECOND },
                        { 2, THIRD  },
                        { 3, LAST   }
                };
                the_threads = waiters;
        }
        sout | "Stopping" | endl;
}