reorganize

src/ch05/once.c

@@ -0,0 +1,71 @@
+/*
+ * once.c
+ *
+ * Demonstrate the use of pthread_once() one-time
+ * initialization.
+ */
+#include <pthread.h>
+#include "errors.h"
+
+pthread_once_t once_block = PTHREAD_ONCE_INIT;
+pthread_mutex_t mutex;
+
+/*
+ * This is the one-time initialization routine. It will be
+ * called exactly once, no matter how many calls to pthread_once
+ * with the same control structure are made during the course of
+ * the program.
+ */
+void once_init_routine (void)
+{
+    int status;
+
+    status = pthread_mutex_init (&mutex, NULL);
+    if (status != 0)
+        err_abort (status, "Init Mutex");
+}
+
+/*
+ * Thread start routine that calls pthread_once.
+ */
+void *thread_routine (void *arg)
+{
+    int status;
+
+    status = pthread_once (&once_block, once_init_routine);
+    if (status != 0)
+        err_abort (status, "Once init");
+    status = pthread_mutex_lock (&mutex);
+    if (status != 0)
+        err_abort (status, "Lock mutex");
+    printf ("thread_routine has locked the mutex.\n");
+    status = pthread_mutex_unlock (&mutex);
+    if (status != 0)
+        err_abort (status, "Unlock mutex");
+    return NULL;
+}
+
+int main (int argc, char *argv[])
+{
+    pthread_t thread_id;
+    char *input, buffer[64];
+    int status;
+
+    status = pthread_create (&thread_id, NULL, thread_routine, NULL);
+    if (status != 0)
+        err_abort (status, "Create thread");
+    status = pthread_once (&once_block, once_init_routine);
+    if (status != 0)
+        err_abort (status, "Once init");
+    status = pthread_mutex_lock (&mutex);
+    if (status != 0)
+        err_abort (status, "Lock mutex");
+    printf ("Main has locked the mutex.\n");
+    status = pthread_mutex_unlock (&mutex);
+    if (status != 0)
+        err_abort (status, "Unlock mutex");
+    status = pthread_join (thread_id, NULL);
+    if (status != 0)
+        err_abort (status, "Join thread");
+    return 0;
+}