initial import

from
http://www.informit.com/store/programming-with-posix-threads-9780201633924

cancel.c

@@ -0,0 +1,66 @@
+/*
+ * cancel.c
+ *
+ * Demonstrate use of synchronous cancellation using
+ * pthread_testcancel.
+ *
+ * Special notes: On a Solaris 2.5 uniprocessor, this test will
+ * hang unless a second LWP is created by calling
+ * thr_setconcurrency() because threads are not timesliced.
+ */
+#include <pthread.h>
+#include "errors.h"
+
+static int counter;
+
+/*
+ * Loop until cancelled. The thread can be cancelled only
+ * when it calls pthread_testcancel, which it does each 1000
+ * iterations.
+ */
+void *thread_routine (void *arg)
+{
+    DPRINTF (("thread_routine starting\n"));
+    for (counter = 0; ; counter++)
+        if ((counter % 1000) == 0) {
+            DPRINTF (("calling testcancel\n"));
+            pthread_testcancel ();
+        }
+}
+
+int main (int argc, char *argv[])
+{
+    pthread_t thread_id;
+    void *result;
+    int status;
+
+#ifdef sun
+    /*
+     * On Solaris 2.5, threads are not timesliced. To ensure
+     * that our two threads can run concurrently, we need to
+     * increase the concurrency level to 2.
+     */
+    DPRINTF (("Setting concurrency level to 2\n"));
+    thr_setconcurrency (2);
+#endif
+    status = pthread_create (
+        &thread_id, NULL, thread_routine, NULL);
+    if (status != 0)
+        err_abort (status, "Create thread");
+    sleep (2);
+
+    DPRINTF (("calling cancel\n"));
+    status = pthread_cancel (thread_id);
+    if (status != 0)
+        err_abort (status, "Cancel thread");
+
+    DPRINTF (("calling join\n"));
+    status = pthread_join (thread_id, &result);
+    if (status != 0)
+        err_abort (status, "Join thread");
+    if (result == PTHREAD_CANCELED)
+        printf ("Thread cancelled at iteration %d\n", counter);
+    else
+        printf ("Thread was not cancelled\n");
+    return 0;
+}