[SOLVED] CS代考计算机代写 /* Low-priority main thread L acquires lock A. Medium-priority

/* Low-priority main thread L acquires lock A.Medium-priority
thread M then acquires lock B then blocks on acquiring lock A.
High-priority thread H then blocks on acquiring lock B.Thus,
thread H donates its priority to M, which in turn donates it
to thread L.

Based on a test originally submitted for Stanford’s CS 140 in
winter 1999 by Matt Franklin ,
Greg Hutchins , Yu Ping Hu
.Modified by arens. */

#include
#include “tests/threads/tests.h”
#include “threads/init.h”
#include “threads/lock.h”
#include “threads/thread.h”

struct locks
{
struct lock *a;
struct lock *b;
};

static thread_func medium_thread_func;
static thread_func high_thread_func;

void
test_priority_donate_nest (void)
{
struct lock a, b;
struct locks locks;

/* This test does not work with the MLFQS. */
ASSERT (!thread_mlfqs);

/* Make sure our priority is the default. */
ASSERT (thread_get_priority () == PRI_DEFAULT);

lock_init (&a);
lock_init (&b);

lock_acquire (&a);

locks.a = &a
locks.b = &b
thread_create (“medium”, PRI_DEFAULT + 1, medium_thread_func, &locks);
thread_yield ();
msg (“Low thread should have priority %d.Actual priority: %d.”,
PRI_DEFAULT + 1, thread_get_priority ());

thread_create (“high”, PRI_DEFAULT + 2, high_thread_func, &b);
thread_yield ();
msg (“Low thread should have priority %d.Actual priority: %d.”,
PRI_DEFAULT + 2, thread_get_priority ());

lock_release (&a);
thread_yield ();
msg (“Medium thread should just have finished.”);
msg (“Low thread should have priority %d.Actual priority: %d.”,
PRI_DEFAULT, thread_get_priority ());
}

static void
medium_thread_func (void *locks_)
{
struct locks *locks = locks_;

lock_acquire (locks->b);
lock_acquire (locks->a);

msg (“Medium thread should have priority %d.Actual priority: %d.”,
PRI_DEFAULT + 2, thread_get_priority ());
msg (“Medium thread got the lock.”);

lock_release (locks->a);
thread_yield ();

lock_release (locks->b);
thread_yield ();

msg (“High thread should have just finished.”);
msg (“Middle thread finished.”);
}

static void
high_thread_func (void *lock_)
{
struct lock *lock = lock_;

lock_acquire (lock);
msg (“High thread got the lock.”);
lock_release (lock);
msg (“High thread finished.”);
}