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-rw-r--r--linuxthreads/Examples/ex18.c112
1 files changed, 112 insertions, 0 deletions
diff --git a/linuxthreads/Examples/ex18.c b/linuxthreads/Examples/ex18.c
new file mode 100644
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+++ b/linuxthreads/Examples/ex18.c
@@ -0,0 +1,112 @@
+/*
+ * Beat up the pthread_key_create and pthread_key_delete
+ * functions.
+ */
+
+#if 0
+#define CHATTY
+#endif
+
+#include <stdio.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <pthread.h>
+
+const int beatup_iterations = 10000;
+const int num_threads = 30;
+const int max_keys = 500;
+
+struct key_list {
+ struct key_list *next;
+ pthread_key_t key;
+};
+
+struct key_list *key_list;
+pthread_mutex_t key_lock = PTHREAD_MUTEX_INITIALIZER;
+
+/*
+ * Create a new key and put it at the tail of a linked list.
+ * If the linked list grows to a certain length, delete a key from the
+ * head of * the list.
+ */
+
+static void
+beat_up(void)
+{
+ struct key_list *new = malloc(sizeof *new);
+ struct key_list **iter, *old_key = 0;
+ int key_count = 0;
+
+ if (new == 0) {
+ fprintf(stderr, "malloc failed\n");
+ abort();
+ }
+
+ new->next = 0;
+
+ if (pthread_key_create(&new->key, 0) != 0) {
+ fprintf(stderr, "pthread_key_create failed\n");
+ abort();
+ }
+
+ if (pthread_getspecific(new->key) != 0) {
+ fprintf(stderr, "new pthread_key_t resolves to non-null value\n");
+ abort();
+ }
+
+ pthread_setspecific(new->key, (void *) 1);
+
+#ifdef CHATTY
+ printf("created key\n");
+#endif
+
+ pthread_mutex_lock(&key_lock);
+
+ for (iter = &key_list; *iter != 0; iter = &(*iter)->next)
+ key_count++;
+
+ *iter = new;
+
+ if (key_count > max_keys) {
+ old_key = key_list;
+ key_list = key_list->next;
+ }
+
+ pthread_mutex_unlock(&key_lock);
+
+ if (old_key != 0) {
+#ifdef CHATTY
+ printf("deleting key\n");
+#endif
+ pthread_key_delete(old_key->key);
+ }
+}
+
+static void *
+thread(void *arg)
+{
+ int i;
+ for (i = 0; i < beatup_iterations; i++)
+ beat_up();
+ return 0;
+}
+
+int
+main(void)
+{
+ int i;
+ pthread_attr_t detached_thread;
+
+ pthread_attr_init(&detached_thread);
+ pthread_attr_setdetachstate(&detached_thread, PTHREAD_CREATE_DETACHED);
+
+ for (i = 0; i < num_threads; i++) {
+ pthread_t thread_id;
+ while (pthread_create(&thread_id, &detached_thread, thread, 0) == EAGAIN) {
+ /* let some threads die, so system can breathe. :) */
+ sleep(1);
+ }
+ }
+
+ pthread_exit(0);
+}