New testpoint mechanism to instrument binaries for testing

[lttng-tools.git] / src / common / testpoint / testpoint.h

diff --git a/src/common/testpoint/testpoint.h b/src/common/testpoint/testpoint.h
new file mode 100644 (file)
index 0000000..ba3af8a
--- /dev/null
+++ b/src/common/testpoint/testpoint.h
@@ -0,0 +1,72 @@
+/*
+ * Copyright (C) 2012 - Christian Babeux <christian.babeux@efficios.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License, version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 51
+ * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef NTESTPOINT
+
+#define testpoint(name)
+#define TESTPOINT_DECL(name)
+
+#else /* NTESTPOINT */
+
+#include <urcu.h> /* for caa_likely/unlikely */
+
+extern int lttng_testpoint_activated;
+
+void *lttng_testpoint_lookup(const char *name);
+
+/*
+ * Testpoint is only active if the global lttng_testpoint_activated flag is
+ * set.
+ */
+#define testpoint(name)                                        \
+       do {                                                    \
+               if (caa_unlikely(lttng_testpoint_activated)) {  \
+                       __testpoint_##name##_wrapper();         \
+               }                                               \
+       } while (0)
+
+/*
+ * One wrapper per testpoint is generated. This is to keep track of the symbol
+ * lookup status and the corresponding function pointer, if any.
+ */
+#define _TESTPOINT_DECL(_name)                                         \
+       static inline void __testpoint_##_name##_wrapper(void)          \
+       {                                                               \
+               static void (*tp)(void);                                \
+               static int found;                                       \
+               const char *tp_name = "__testpoint_" #_name;            \
+                                                                       \
+               if (tp) {                                               \
+                       tp();                                           \
+               } else {                                                \
+                       if (!found) {                                   \
+                               tp = lttng_testpoint_lookup(tp_name);   \
+                               if (tp) {                               \
+                                       found = 1;                      \
+                                       tp();                           \
+                               } else {                                \
+                                       found = -1;                     \
+                               }                                       \
+                       }                                               \
+               }                                                       \
+       }
+
+/* Testpoint declaration */
+#define TESTPOINT_DECL(name)   \
+       _TESTPOINT_DECL(name)
+
+#endif /* NTESTPOINT */