source: src/tests/concurrent/signal/block.c@ 1a3eab8

//---------------------------------------------------------
// Barging test
// Ensures that no barging can occur between :
//   - the frontend of the signal_block and the signaled thread
//   - the signaled  threadand the backend of the signal_block
//---------------------------------------------------------


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

#ifdef LONG_TEST
static const unsigned long N = 150_000ul;
#else
static const unsigned long N = 5_000ul;
#endif

#ifndef PREEMPTION_RATE
#define PREEMPTION_RATE 10`ms
#endif

Duration default_preemption() {
        return PREEMPTION_RATE;
}

enum state_t { WAITED, SIGNAL, BARGE };

monitor global_data_t {
        thread_desc * last_thread;
        thread_desc * last_signaller;
};

void ?{} ( global_data_t & this ) {
        this.last_thread = NULL;
        this.last_signaller = NULL;
}

void ^?{} ( global_data_t & this ) {}

global_data_t globalA, globalB;

condition cond;

volatile bool done;

//------------------------------------------------------------------------------
void wait_op( global_data_t & mutex a, global_data_t & mutex b, unsigned i ) {
    wait( cond, (uintptr_t)active_thread() );

        yield( random( 10 ) );

        if(a.last_thread != a.last_signaller || b.last_thread != b.last_signaller ) {
                sout | "ERROR Barging detected, expected" | a.last_signaller | b.last_signaller | "got" | a.last_thread | b.last_thread | endl;
                abort();
        }

        a.last_thread = b.last_thread = active_thread();

        yield( random( 10 ) );
}

thread Waiter {};
void main( Waiter & this ) {
        for( int i = 0; i < N; i++ ) {
                wait_op( globalA, globalB, i );
        }
}

//------------------------------------------------------------------------------
void signal_op( global_data_t & mutex a, global_data_t & mutex b ) {
        yield( random( 10 ) );

        [a.last_thread, b.last_thread, a.last_signaller, b.last_signaller] = active_thread();

        if( !is_empty( cond ) ) {

                thread_desc * next = front( cond );

                if( ! signal_block( cond ) ) {
                        sout | "ERROR expected to be able to signal" | endl;
                        abort();
                }

                yield( random( 10 ) );

                if(a.last_thread != next || b.last_thread != next) {
                        sout | "ERROR Barging detected, expected" | next | "got" | a.last_thread | b.last_thread | endl;
                        abort();
                }
        }

}

thread Signaller {};
void main( Signaller & this ) {
        while( !done ) {
                signal_op( globalA, globalB );
        }
}

//------------------------------------------------------------------------------
void barge_op( global_data_t & mutex a ) {
        a.last_thread = active_thread();
}

thread Barger {};
void main( Barger & this ) {
        for( unsigned i = 0; !done; i++ ) {
                //Choose some monitor to barge into with some irregular pattern
                bool choose_a = (i % 13) > (i % 17);
                if ( choose_a ) barge_op( globalA );
                else barge_op( globalB );
        }
}

//------------------------------------------------------------------------------

int main(int argc, char* argv[]) {
        srandom( time( NULL ) );
        done = false;
        processor p;
        {
                Signaller s[4];
                Barger b[13];
                sout | "Starting waiters" | endl;
                {
                        Waiter w[3];
                }
                sout | "Waiters done" | endl;
                done = true;
        }
}