text: /* Creates N threads, each of which sleeps a different, fixed
     duration, M times.  Records the wake-up order and verifies
     that it is valid. */
  
  #include <stdio.h>
  #include "tests/threads/tests.h"
  #include "threads/init.h"
  #include "threads/malloc.h"
  #include "threads/synch.h"
  #include "threads/thread.h"
  #include "devices/timer.h"
  
  static void test_sleep (int thread_cnt, int iterations);
  
  void
  test_alarm_single (void)
  {
    test_sleep (5, 1);
  }
  
  void
  test_alarm_multiple (void)
  {
    test_sleep (5, 7);
  }
  
  /* Information about the test. */
  struct sleep_test
    {
      int64_t start;              /* Current time at start of test. */
      int iterations;             /* Number of iterations per thread. */
  
      /* Output. */
      struct lock output_lock;    /* Lock protecting output buffer. */
      int *output_pos;            /* Current position in output buffer. */
    };
  
  /* Information about an individual thread in the test. */
  struct sleep_thread
    {
      struct sleep_test *test;     /* Info shared between all threads. */
      int id;                     /* Sleeper ID. */
      int duration;               /* Number of ticks to sleep. */
      int iterations;             /* Iterations counted so far. */
    };
  
  static void sleeper (void *);
  
  /* Runs THREAD_CNT threads thread sleep ITERATIONS times each. */
  static void
  test_sleep (int thread_cnt, int iterations)
  {
    struct sleep_test test;
    struct sleep_thread *threads;
    int *output, *op;
    int product;
    int i;
  
    /* This test does not work with the MLFQS. */
    ASSERT (!thread_mlfqs);
  
    msg ("Creating %d threads to sleep %d times each.", thread_cnt, iterations);
    msg ("Thread 0 sleeps 10 ticks each time,");
    msg ("thread 1 sleeps 20 ticks each time, and so on.");
    msg ("If successful, product of iteration count and");
    msg ("sleep duration will appear in nondescending order.");
  
    /* Allocate memory. */
    threads = malloc (sizeof *threads * thread_cnt);
    output = malloc (sizeof *output * iterations * thread_cnt * 2);
    if (threads == NULL || output == NULL)
      PANIC ("couldn't allocate memory for test");
  
    /* Initialize test. */
    test.start = timer_ticks () + 100;
    test.iterations = iterations;
    lock_init (&test.output_lock);
    test.output_pos = output;
  
    /* Start threads. */
    ASSERT (output != NULL);
    for (i = 0; i < thread_cnt; i++)
      {
        struct sleep_thread *t = threads + i;
        char name[16];
  
        t->test = &test;
        t->id = i;
        t->duration = (i + 1) * 10;
        t->iterations = 0;
  
        snprintf (name, sizeof name, "thread %d", i);
        thread_create (name, PRI_DEFAULT, sleeper, t);
      }
  
    /* Wait long enough for all the threads to finish. */
    timer_sleep (100 + thread_cnt * iterations * 10 + 100);
  
    /* Acquire the output lock in case some rogue thread is still
       running. */
    lock_acquire (&test.output_lock);
  
    /* Print completion order. */
    product = 0;
    for (op = output; op < test.output_pos; op++)
      {
        struct sleep_thread *t;
        int new_prod;
  
        ASSERT (*op >= 0 && *op < thread_cnt);
        t = threads + *op;
  
        new_prod = ++t->iterations * t->duration;
  
        msg ("thread %d: duration=%d, iteration=%d, product=%d",
             t->id, t->duration, t->iterations, new_prod);
  
        if (new_prod >= product)
          product = new_prod;
        else
          fail ("thread %d woke up out of order (%d > %d)!",
                t->id, product, new_prod);
      }
  
    /* Verify that we had the proper number of wakeups. */
    for (i = 0; i < thread_cnt; i++)
      if (threads[i].iterations != iterations)
        fail ("thread %d woke up %d times instead of %d",
              i, threads[i].iterations, iterations);
  
    lock_release (&test.output_lock);
    free (output);
    free (threads);
  }
  
  /* Sleeper thread. */
  static void
  sleeper (void *t_)
  {
    struct sleep_thread *t = t_;
    struct sleep_test *test = t->test;
    int i;
  
    for (i = 1; i <= test->iterations; i++)
      {
        int64_t sleep_until = test->start + i * t->duration;
        timer_sleep (sleep_until - timer_ticks ());
        lock_acquire (&test->output_lock);
        *test->output_pos++ = t->id;
        lock_release (&test->output_lock);
      }
  }
  