1 files changed, 96 insertions, 0 deletions
diff --git a/helgrind/tests/tc21_pthonce.c b/helgrind/tests/tc21_pthonce.c
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+++ b/helgrind/tests/tc21_pthonce.c
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+
+/* This really exists to check that Thrcheck behaves plausibly
+   with pthread_once calls.  Which it appears to.
+
+   The original source of this program is as shown below, although it
+   has been modified somewhat.  See
+   http://www.oreilly.com/pub/a/oreilly/ask_tim/2001/codepolicy.html
+   for OReilly's policy on using bits of their code examples.
+*/
+
+
+/********************************************************
+ * An example source module to accompany...
+ *
+ * "Using POSIX Threads: Programming with Pthreads"
+ *     by Brad Nichols, Dick Buttlar, Jackie Farrell
+ *     O'Reilly & Associates, Inc.
+ *
+ ********************************************************
+ * once_exam.c
+ *
+ * An example of using the pthreads_once() call to execute an
+ * initialization procedure.
+ *
+ * A program spawns multiple threads and each one tries to
+ * execute the routine welcome() using the once call. Only
+ * the first thread into the once routine will actually
+ * execute welcome().
+ *
+ * The program's main thread synchronizes its exit with the
+ * exit of the threads using the pthread_join() operation.
+ *
+*/
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <assert.h>
+
+#include <pthread.h>
+
+/* With more than 2 threads, the precise error reports vary between
+   platforms, in terms of the number of races detected.  Make life
+   simple and just have 2 threads and so just 1 race. */
+#define  NUM_THREADS 2
+
+static pthread_once_t welcome_once_block = PTHREAD_ONCE_INIT;
+
+static int unprotected1 = 0;
+static int unprotected2 = 0;
+
+/* This is a hack: delay threads except the first enough so as to
+   ensure threads[0] gets to the pthread_once call first.  This is so
+   as to ensure that this test produces results which aren't
+   scheduling sensitive.  (sigh) */
+void maybe_stall ( int myid )
+{
+   assert(myid >= 0 && myid < NUM_THREADS);
+   if (myid > 0)
+      sleep(1);
+}
+
+void welcome(void) {
+   printf("welcome: Welcome\n");
+   unprotected1++; /* this is harmless */
+}
+
+void* child ( void* argV ) { 
+   int r; 
+   maybe_stall( *(int*)argV );
+   r= pthread_once(&welcome_once_block, welcome); assert(!r);
+   printf("child: Hi, I'm thread %d\n", *(int*)argV);
+   unprotected2++; /* whereas this is a race */
+   return NULL;
+}
+
+int main ( void ) {
+   int       *id_arg, i, r;
+   pthread_t threads[NUM_THREADS];
+
+   id_arg = (int *)malloc(NUM_THREADS*sizeof(int));
+
+   for (i = 0; i < NUM_THREADS; i++) {
+      id_arg[i] = i;
+      r= pthread_create(&threads[i], NULL, child, &id_arg[i]);
+      assert(!r);
+   }
+
+   for (i = 0; i < NUM_THREADS; i++) {
+      pthread_join(threads[i], NULL);
+      /* printf("main: joined to thread %d\n", i); */
+   }
+   printf("main: Goodbye\n");
+   return 0;
+}