linuxthreads/Examples/ex18.c

   1 /*
   2  * Beat up the pthread_key_create and pthread_key_delete
   3  * functions.
   4  */
   5
   6 #if 0
   7 #define CHATTY
   8 #endif
   9
  10 #include <stdio.h>
  11 #include <errno.h>
  12 #include <stdlib.h>
  13 #include <pthread.h>
  14 #include <unistd.h>
  15
  16 const int beatup_iterations = 10000;
  17 const int num_threads = 30;
  18 const int max_keys = 500;
  19
  20 struct key_list {
  21   struct key_list *next;
  22   pthread_key_t key;
  23 };
  24
  25 struct key_list *key_list;
  26 pthread_mutex_t key_lock = PTHREAD_MUTEX_INITIALIZER;
  27
  28 /*
  29  * Create a new key and put it at the tail of a linked list.
  30  * If the linked list grows to a certain length, delete a key from the
  31  * head of * the list.
  32  */
  33
  34 static void
  35 beat_up(void)
  36 {
  37   struct key_list *new = malloc(sizeof *new);
  38   struct key_list **iter, *old_key = 0;
  39   int key_count = 0;
  40
  41   if (new == 0) {
  42     fprintf(stderr, "malloc failed\n");
  43     abort();
  44   }
  45
  46   new->next = 0;
  47
  48   if (pthread_key_create(&new->key, 0) != 0) {
  49     fprintf(stderr, "pthread_key_create failed\n");
  50     abort();
  51   }
  52
  53   if (pthread_getspecific(new->key) != 0) {
  54     fprintf(stderr, "new pthread_key_t resolves to non-null value\n");
  55     abort();
  56   }
  57
  58   pthread_setspecific(new->key, (void *) 1);
  59
  60 #ifdef CHATTY
  61   printf("created key\n");
  62 #endif
  63
  64   pthread_mutex_lock(&key_lock);
  65
  66   for (iter = &key_list; *iter != 0; iter = &(*iter)->next)
  67     key_count++;
  68
  69   *iter = new;
  70
  71   if (key_count > max_keys) {
  72     old_key = key_list;
  73     key_list = key_list->next;
  74   }
  75
  76   pthread_mutex_unlock(&key_lock);
  77
  78   if (old_key != 0) {
  79 #ifdef CHATTY
  80     printf("deleting key\n");
  81 #endif
  82     pthread_key_delete(old_key->key);
  83   }
  84 }
  85
  86 static void *
  87 thread(void *arg)
  88 {
  89   int i;
  90   for (i = 0; i < beatup_iterations; i++)
  91     beat_up();
  92   return 0;
  93 }
  94
  95 int
  96 main(void)
  97 {
  98   int i;
  99   pthread_attr_t detached_thread;
 100
 101   pthread_attr_init(&detached_thread);
 102   pthread_attr_setdetachstate(&detached_thread, PTHREAD_CREATE_DETACHED);
 103
 104   for (i = 0; i < num_threads; i++) {
 105     pthread_t thread_id;
 106     while (pthread_create(&thread_id, &detached_thread, thread, 0) == EAGAIN) {
 107       /* let some threads die, so system can breathe. :) */
 108       sleep(1);
 109     }
 110   }
 111
 112   pthread_exit(0);
 113 }