src/common/testpoint/testpoint.h

   1 /*
   2  * Copyright (C) 2012 - Christian Babeux <christian.babeux@efficios.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License, version 2 only, as
   6  * published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  11  * more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along with
  14  * this program; if not, write to the Free Software Foundation, Inc., 51
  15  * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  16  */
  17
  18 #ifdef NTESTPOINT
  19
  20 #define testpoint(name)
  21 #define TESTPOINT_DECL(name)
  22
  23 #else /* NTESTPOINT */
  24
  25 #include <urcu.h> /* for caa_likely/unlikely */
  26
  27 extern int lttng_testpoint_activated;
  28
  29 void *lttng_testpoint_lookup(const char *name);
  30
  31 /*
  32  * Testpoint is only active if the global lttng_testpoint_activated flag is
  33  * set.
  34  */
  35 #define testpoint(name)                                 \
  36         do {                                                    \
  37                 if (caa_unlikely(lttng_testpoint_activated)) {  \
  38                         __testpoint_##name##_wrapper();         \
  39                 }                                               \
  40         } while (0)
  41
  42 /*
  43  * One wrapper per testpoint is generated. This is to keep track of the symbol
  44  * lookup status and the corresponding function pointer, if any.
  45  */
  46 #define _TESTPOINT_DECL(_name)                                          \
  47         static inline void __testpoint_##_name##_wrapper(void)          \
  48         {                                                               \
  49                 static void (*tp)(void);                                \
  50                 static int found;                                       \
  51                 const char *tp_name = "__testpoint_" #_name;            \
  52                                                                         \
  53                 if (tp) {                                               \
  54                         tp();                                           \
  55                 } else {                                                \
  56                         if (!found) {                                   \
  57                                 tp = lttng_testpoint_lookup(tp_name);   \
  58                                 if (tp) {                               \
  59                                         found = 1;                      \
  60                                         tp();                           \
  61                                 } else {                                \
  62                                         found = -1;                     \
  63                                 }                                       \
  64                         }                                               \
  65                 }                                                       \
  66         }
  67
  68 /* Testpoint declaration */
  69 #define TESTPOINT_DECL(name)    \
  70         _TESTPOINT_DECL(name)
  71
  72 #endif /* NTESTPOINT */