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-rw-r--r--linuxthreads/Examples/ex4.c115
1 files changed, 0 insertions, 115 deletions
diff --git a/linuxthreads/Examples/ex4.c b/linuxthreads/Examples/ex4.c
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index 5c8b929e22..0000000000
--- a/linuxthreads/Examples/ex4.c
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@@ -1,115 +0,0 @@
-/* Making a library function that uses static variables thread-safe.
-   Illustrates: thread-specific data, pthread_once(). */
-
-#include <stddef.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <pthread.h>
-
-/* This is a typical example of a library function that uses
-   static variables to accumulate results between calls.
-   Here, it just returns the concatenation of all string arguments
-   that were given to it. */
-
-#if 0
-
-char *
-str_accumulate (char *s)
-{
-  static char accu[1024] = { 0 };
-  strcat (accu, s);
-  return accu;
-}
-
-#endif
-
-/* Of course, this cannot be used in a multi-threaded program
-   because all threads store "accu" at the same location.
-   So, we'll use thread-specific data to have a different "accu"
-   for each thread. */
-
-/* Key identifying the thread-specific data */
-static pthread_key_t str_key;
-/* "Once" variable ensuring that the key for str_alloc will be allocated
-   exactly once. */
-static pthread_once_t str_alloc_key_once = PTHREAD_ONCE_INIT;
-
-/* Forward functions */
-static void str_alloc_key (void);
-static void str_alloc_destroy_accu (void *accu);
-
-/* Thread-safe version of str_accumulate */
-
-static char *
-str_accumulate (const char *s)
-{
-  char *accu;
-
-  /* Make sure the key is allocated */
-  pthread_once (&str_alloc_key_once, str_alloc_key);
-  /* Get the thread-specific data associated with the key */
-  accu = (char *) pthread_getspecific (str_key);
-  /* It's initially NULL, meaning that we must allocate the buffer first. */
-  if (accu == NULL)
-    {
-      accu = malloc (1024);
-      if (accu == NULL)
-	return NULL;
-      accu[0] = 0;
-      /* Store the buffer pointer in the thread-specific data. */
-      pthread_setspecific (str_key, (void *) accu);
-      printf ("Thread %lx: allocating buffer at %p\n", pthread_self (), accu);
-    }
-  /* Now we can use accu just as in the non thread-safe code. */
-  strcat (accu, s);
-  return accu;
-}
-
-/* Function to allocate the key for str_alloc thread-specific data. */
-
-static void
-str_alloc_key (void)
-{
-  pthread_key_create (&str_key, str_alloc_destroy_accu);
-  printf ("Thread %lx: allocated key %d\n", pthread_self (), str_key);
-}
-
-/* Function to free the buffer when the thread exits. */
-/* Called only when the thread-specific data is not NULL. */
-
-static void
-str_alloc_destroy_accu (void *accu)
-{
-  printf ("Thread %lx: freeing buffer at %p\n", pthread_self (), accu);
-  free (accu);
-}
-
-/* Test program */
-
-static void *
-process (void *arg)
-{
-  char *res;
-  res = str_accumulate ("Result of ");
-  res = str_accumulate ((char *) arg);
-  res = str_accumulate (" thread");
-  printf ("Thread %lx: \"%s\"\n", pthread_self (), res);
-  return NULL;
-}
-
-int
-main (int argc, char **argv)
-{
-  char *res;
-  pthread_t th1, th2;
-
-  res = str_accumulate ("Result of ");
-  pthread_create (&th1, NULL, process, (void *) "first");
-  pthread_create (&th2, NULL, process, (void *) "second");
-  res = str_accumulate ("initial thread");
-  printf ("Thread %lx: \"%s\"\n", pthread_self (), res);
-  pthread_join (th1, NULL);
-  pthread_join (th2, NULL);
-  return 0;
-}