priority-change.c

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/** Verifies that lowering a thread's priority so that it is no
   longer the highest-priority thread in the system causes it to
   yield immediately. */
 
#include <stdio.h>
#include "tests/threads/tests.h"
#include "threads/init.h"
#include "threads/thread.h"
 
static thread_func changing_thread;
 
void
test_priority_change (void) 
{
  /* This test does not work with the MLFQS. */
  ASSERT (!thread_mlfqs);
 
  msg ("Creating a high-priority thread 2.");
  thread_create ("thread 2", PRI_DEFAULT + 1, changing_thread, NULL);
  msg ("Thread 2 should have just lowered its priority.");
  thread_set_priority (PRI_DEFAULT - 2);
  msg ("Thread 2 should have just exited.");
}
 
static void
changing_thread (void *aux UNUSED) 
{
  msg ("Thread 2 now lowering priority.");
  thread_set_priority (PRI_DEFAULT - 1);
  msg ("Thread 2 exiting.");
}