Bug 548967 - 1 bit mutex lock: add tests

Add a test case for the new API. Always check the emulated futex(2) implementation, even on systems with futex support.
2025-08-01 23:13:40 +02:00 · 2010-01-28 18:41:19 -05:00
parent 669b0f2d6b
commit 40eae351b1
6 changed files with 152 additions and 0 deletions
--- a/gthread/tests/1bit-mutex.c
+++ b/gthread/tests/1bit-mutex.c
@@ -0,0 +1,127 @@
+/*
+ * Copyright © 2008 Ryan Lortie
+ * Copyright © 2010 Codethink Limited
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * See the included COPYING file for more information.
+ */
+
+/* LOCKS should be more than the number of contention
+ * counters in gthread.c in order to ensure we exercise
+ * the case where they overlap.
+ */
+#define LOCKS      48
+#define ITERATIONS 10000
+#define THREADS    100
+
+
+#if TEST_EMULATED_FUTEX
+  /* this is defined for the 1bit-mutex-emufutex test.
+   *
+   * we want to test the emulated futex even if futex(2) is available.
+   */
+
+  /* side-step some glib build stuff */
+  #define DISABLE_VISIBILITY
+  #define GLIB_COMPILATION
+
+  /* rebuild gbitlock.c without futex support,
+     defining our own version of the g_bit_*lock symbols
+   */
+  #define g_bit_lock            _emufutex_g_bit_lock
+  #define g_bit_trylock         _emufutex_g_bit_trylock
+  #define g_bit_unlock          _emufutex_g_bit_unlock
+  #define _g_futex_thread_init  _emufutex_g_futex_thread_init
+
+  #define G_BIT_LOCK_FORCE_FUTEX_EMULATION
+
+  #include <glib/gbitlock.c>
+#endif
+
+#include <glib.h>
+
+volatile GThread *owners[LOCKS];
+volatile gint     locks[LOCKS];
+volatile gint     bits[LOCKS];
+
+static void
+acquire (int nr)
+{
+  GThread *self;
+
+  self = g_thread_self ();
+
+  g_bit_lock (&locks[nr], bits[nr]);
+  g_assert (owners[nr] == NULL);   /* hopefully nobody else is here */
+  owners[nr] = self;
+
+  /* let some other threads try to ruin our day */
+  g_thread_yield ();
+  g_thread_yield ();
+  g_thread_yield ();
+
+  g_assert (owners[nr] == self);   /* hopefully this is still us... */
+  owners[nr] = NULL;               /* make way for the next guy */
+  g_bit_unlock (&locks[nr], bits[nr]);
+}
+
+static gpointer
+thread_func (gpointer data)
+{
+  gint i;
+
+  for (i = 0; i < ITERATIONS; i++)
+    acquire (g_random_int () % LOCKS);
+
+  return NULL;
+}
+
+static void
+testcase (void)
+{
+  GThread *threads[THREADS];
+  int i;
+
+  g_thread_init (NULL);
+
+#ifdef TEST_EMULATED_FUTEX
+  _g_futex_thread_init ();
+  #define SUFFIX "-emufutex"
+
+  /* ensure that we are using the emulated futex by checking
+   * (at compile-time) for the existance of 'g_futex_mutex'
+   */
+  g_assert (g_futex_mutex != NULL);
+#else
+  #define SUFFIX ""
+#endif
+
+  for (i = 0; i < LOCKS; i++)
+    bits[i] = g_random_int () % 32;
+
+  for (i = 0; i < THREADS; i++)
+    threads[i] = g_thread_create (thread_func, NULL, TRUE, NULL);
+
+  for (i = 0; i < THREADS; i++)
+    g_thread_join (threads[i]);
+
+  for (i = 0; i < LOCKS; i++)
+    {
+      g_assert (owners[i] == NULL);
+      g_assert (locks[i] == 0);
+    }
+}
+
+int
+main (int argc, char **argv)
+{
+  g_test_init (&argc, &argv, NULL);
+
+  g_test_add_func ("/glib/1bit-mutex" SUFFIX, testcase);
+
+  return g_test_run ();
+}