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//==========================================================================

//

//        sync3.cxx

//

//        Sync test 3 -- tests priorities and priority inheritance

//

//==========================================================================

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//==========================================================================

//#####DESCRIPTIONBEGIN####

//

// Author(s):     dsm

// Contributors:    dsm

// Date:          1998-02-18

// Description: 

//     Creates mutexes and threads to set up starvation condition.

//     Checks simple priority inheritance cures this.

//     

//     The starvation condition is caused by the highest priority

//     thread, t0 waiting on a mutex which is never released because

//     it is held by t2.  t2 never releases it because t1 will be

//     running at a priority level higher than t2 (but lower than t0).

//     

//     With priority inheritance enabled, t2 will inherit its priority

//     from t0 when t0 tries to grab the mutex.

//     

// Options:

//     CYGIMP_THREAD_PRIORITY

//     CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL_INHERIT

//     CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL_SIMPLE

//####DESCRIPTIONEND####

#include <pkgconf/kernel.h>

#include <cyg/kernel/thread.hxx>

#include <cyg/kernel/thread.inl>

#include <cyg/kernel/sched.hxx>

#include <cyg/kernel/mutex.hxx>

#include <cyg/kernel/sema.hxx>

#include <cyg/infra/testcase.h>

#include <cyg/kernel/sched.inl>

#if defined(CYGIMP_THREAD_PRIORITY) && \

    !defined(CYGPKG_KERNEL_SMP_SUPPORT)

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

// Manufacture a simpler feature test macro for priority inheritance than

// the configuration gives us. We have priority inheritance if it is configured

// as the only protocol, or if it is the default protocol for dynamic protocol

// choice.

// FIXME: If we have dynamic protocol choice, we can also set priority inheritance

// as the protocol to be used on the mutexes we are interested in. At present we

// do not do this.

#ifdef CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL_INHERIT

# ifdef CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL_DYNAMIC

#  ifdef CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL_DEFAULT_INHERIT

#   define PRIORITY_INHERITANCE

#  else

#   undef PRIORITY_INHERITANCE

#  endif

# else

#  define PRIORITY_INHERITANCE

# endif

#else

# undef PRIORITY_INHERITANCE

#endif

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

#define NTHREADS 3

#include "testaux.hxx"

static Cyg_Mutex m0;

static Cyg_Binary_Semaphore s0, s1, s2;

static cyg_ucount8 m0d = 9;

static void check_priorities_normal()

{

    CHECK( 5 == thread[0]->get_priority());

    CHECK( 6 == thread[1]->get_priority());

    CHECK( 7 == thread[2]->get_priority());

}

static void check_priorities_inherited()

{

    CHECK( 5 == thread[0]->get_priority());

    CHECK( 6 == thread[1]->get_priority());

#ifdef PRIORITY_INHERITANCE

    CHECK( 5 == thread[2]->get_current_priority());

#endif

    CHECK( 7 == thread[2]->get_priority());

}

static void entry0( CYG_ADDRWORD data )

{

    s0.wait();                  // wait until t2 has gained m0.lock

    check_priorities_normal();

    m0.lock(); {

        check_priorities_normal();

        CHECK( 2 == m0d );

        m0d = 0;

    } m0.unlock();

    check_priorities_normal();

#ifdef PRIORITY_INHERITANCE

    CYG_TEST_PASS_FINISH("Sync 3 OK -- priority inheritance worked");

#else

    CYG_TEST_FAIL_FINISH("Sync 3: thread not starved");

#endif

    // NOT REACHED

}

static void entry1( CYG_ADDRWORD data )

{

    s1.wait();

    // The delay below will allow testing of the priority inheritance

    // mechanism when scheduler does not guarantee to schedule threads

    // in strict priority order.

    for ( volatile cyg_ucount32 i=0; i < 100000; i++ )

        ; // math is hard

#ifdef PRIORITY_INHERITANCE

    // thread0 should have stopped by this point

    CYG_TEST_FAIL_FINISH("Sync 3: priority inheritance mechanism failed");

#else

    // With strict priority scheduling and no priority inheritance

    // this is expected to happen.

    CYG_TEST_PASS_FINISH("Sync 3 OK");

#endif

    CYG_TEST_FAIL_FINISH("Not reached");

}

void entry2( CYG_ADDRWORD data )

{

    m0.lock(); {

        CHECK( 9 == m0d );

        check_priorities_normal();

        s0.post();              // Now I have lock on m0, wake t0 then t1 

        check_priorities_inherited();

        s1.post();

        check_priorities_inherited();

        m0d = 2;

    } m0.unlock();

    check_priorities_normal();

    m0.lock(); {

        check_priorities_normal();

        CHECK( 0 == m0d );

        m0d = 21;

        s2.wait();              // never posted

    } m0.unlock();

}

void sync3_main(void)

{

    CYG_TEST_INIT();

    new_thread( entry0, 0);

    new_thread( entry1, 1);

    new_thread( entry2, 2);

    thread[0]->set_priority(5);

    thread[1]->set_priority(6);

    thread[2]->set_priority(7);

    Cyg_Scheduler::start();

    CYG_TEST_FAIL_FINISH("Not reached");

}

externC void

cyg_start( void )

{

#ifdef CYGSEM_HAL_STOP_CONSTRUCTORS_ON_FLAG

    cyg_hal_invoke_constructors();

#endif

    sync3_main();

}

#else // defined(CYGIMP_THREAD_PRIORITY) etc

externC void

cyg_start( void )

{

    CYG_TEST_INIT();

    CYG_TEST_INFO("Sync3 test requires:\n"

                         "defined(CYGIMP_THREAD_PRIORITY) &&\n"

                         "!defined(CYGPKG_KERNEL_SMP_SUPPORT)\n");

    CYG_TEST_NA("Sync3 test requirements");

}

#endif // defined(CYGIMP_THREAD_PRIORITY) etc

// EOF sync3.cxx