initial import

from http://www.informit.com/store/programming-with-posix-threads-9780201633924
2013-03-28 10:34:22 +08:00
commit a5ec64177d
55 changed files with 6183 additions and 0 deletions
--- a/semaphore_signal.c
+++ b/semaphore_signal.c
@@ -0,0 +1,116 @@
+/*
+ * semaphore_signal.c
+ *
+ * Demonstrate use of POSIX semaphores to wake a thread from
+ * within a signal catching function.
+ *
+ * Special notes: This program depends upon the _POSIX_TIMERS
+ * and _POSIX_SEMAPHORES features of POSIX 1003.1b-1993. It will
+ * not run (and may not compile) without them.
+ */
+#include <sys/types.h>
+#include <unistd.h>
+#include <pthread.h>
+#include <semaphore.h>
+#include <signal.h>
+#include <time.h>
+#include "errors.h"
+
+sem_t   semaphore;
+
+/*
+ * Signal catching function.
+ */
+void signal_catcher (int sig)
+{
+    if (sem_post (&semaphore) == -1)
+        errno_abort ("Post semaphore");
+}
+
+/*
+ * Thread start routine which waits on the semaphore.
+ */
+void *sem_waiter (void *arg)
+{
+    int number = (int)arg;
+    int counter;
+
+    /*
+     * Each thread waits 5 times.
+     */
+    for (counter = 1; counter <= 5; counter++) {
+        while (sem_wait (&semaphore) == -1) {
+            if (errno != EINTR)
+                errno_abort ("Wait on semaphore");
+        }
+        printf ("%d waking (%d)...\n", number, counter);
+    }
+    return NULL;
+}
+
+int main (int argc, char *argv[])
+{
+    int thread_count, status;
+    struct sigevent sig_event;
+    struct sigaction sig_action;
+    sigset_t sig_mask;
+    timer_t timer_id;
+    struct itimerspec timer_val;
+    pthread_t sem_waiters[5];
+
+#if !defined(_POSIX_SEMAPHORES) || !defined(_POSIX_TIMERS)
+# if !defined(_POSIX_SEMAPHORES)
+    printf ("This system does not support POSIX semaphores\n");
+# endif
+# if !defined(_POSIX_TIMERS)
+    printf ("This system does not support POSIX timers\n");
+# endif
+    return -1;
+#else
+    sem_init (&semaphore, 0, 0);
+
+    /*
+     * Create 5 threads to wait on a semaphore.
+     */
+    for (thread_count = 0; thread_count < 5; thread_count++) {
+        status = pthread_create (
+                &sem_waiters[thread_count], NULL,
+                sem_waiter, (void*)thread_count);
+        if (status != 0)
+            err_abort (status, "Create thread");
+    }
+
+    /*
+     * Set up a repeating timer using signal number SIGRTMIN,
+     * set to occur every 2 seconds.
+     */
+    sig_event.sigev_value.sival_int = 0;
+    sig_event.sigev_signo = SIGRTMIN;
+    sig_event.sigev_notify = SIGEV_SIGNAL;
+    if (timer_create (CLOCK_REALTIME, &sig_event, &timer_id) == -1)
+        errno_abort ("Create timer");
+    sigemptyset (&sig_mask);
+    sigaddset (&sig_mask, SIGRTMIN);
+    sig_action.sa_handler = signal_catcher;
+    sig_action.sa_mask = sig_mask;
+    sig_action.sa_flags = 0;
+    if (sigaction (SIGRTMIN, &sig_action, NULL) == -1)
+        errno_abort ("Set signal action");
+    timer_val.it_interval.tv_sec = 2;
+    timer_val.it_interval.tv_nsec = 0;
+    timer_val.it_value.tv_sec = 2;
+    timer_val.it_value.tv_nsec = 0;
+    if (timer_settime (timer_id, 0, &timer_val, NULL) == -1)
+        errno_abort ("Set timer");
+
+    /*
+     * Wait for all threads to complete.
+     */
+    for (thread_count = 0; thread_count < 5; thread_count++) {
+        status = pthread_join (sem_waiters[thread_count], NULL);
+        if (status != 0)
+            err_abort (status, "Join thread");
+    }
+    return 0;
+#endif
+}