src/glog/logging.h.in: fix race conditions in LOG_EVERY_N

Fixes issue #439 by protecting critical sections with mutexes.

src/glog/logging.h.in

@@ -895,39 +895,60 @@ PLOG_IF(FATAL, GOOGLE_PREDICT_BRANCH_NOT_TAKEN((invocation) == -1))    \
 
 #define LOG_OCCURRENCES LOG_EVERY_N_VARNAME(occurrences_, __LINE__)
 #define LOG_OCCURRENCES_MOD_N LOG_EVERY_N_VARNAME(occurrences_mod_n_, __LINE__)
+#define LOG_OCCURRENCES_MUTEX LOG_EVERY_N_VARNAME(occurrences_mutex_, __LINE__)
+#define SHOULD_LOG_MESSAGE LOG_EVERY_N_VARNAME(should_log_message_, __LINE__)
 
 #define SOME_KIND_OF_LOG_EVERY_N(severity, n, what_to_do) \
   static int LOG_OCCURRENCES = 0, LOG_OCCURRENCES_MOD_N = 0; \
+  static Mutex LOG_OCCURRENCES_MUTEX; \
+  bool SHOULD_LOG_MESSAGE = false; \
+  LOG_OCCURRENCES_MUTEX.Lock(); \
   ++LOG_OCCURRENCES; \
   if (++LOG_OCCURRENCES_MOD_N > n) LOG_OCCURRENCES_MOD_N -= n; \
-  if (LOG_OCCURRENCES_MOD_N == 1) \
+  SHOULD_LOG_MESSAGE = LOG_OCCURRENCES_MOD_N == 1; \
+  LOG_OCCURRENCES_MUTEX.Unlock(); \
+  if (SHOULD_LOG_MESSAGE) \
     @ac_google_namespace@::LogMessage( \
         __FILE__, __LINE__, @ac_google_namespace@::GLOG_ ## severity, LOG_OCCURRENCES, \
         &what_to_do).stream()
 
 #define SOME_KIND_OF_LOG_IF_EVERY_N(severity, condition, n, what_to_do) \
   static int LOG_OCCURRENCES = 0, LOG_OCCURRENCES_MOD_N = 0; \
+  static Mutex LOG_OCCURRENCES_MUTEX; \
+  bool SHOULD_LOG_MESSAGE = false; \
+  LOG_OCCURRENCES_MUTEX.Lock(); \
   ++LOG_OCCURRENCES; \
-  if (condition && \
-      ((LOG_OCCURRENCES_MOD_N=(LOG_OCCURRENCES_MOD_N + 1) % n) == (1 % n))) \
+  SHOULD_LOG_MESSAGE = condition && \
+      ((LOG_OCCURRENCES_MOD_N=(LOG_OCCURRENCES_MOD_N + 1) % n) == (1 % n)); \
+  LOG_OCCURRENCES_MUTEX.Unlock(); \
+  if (SHOULD_LOG_MESSAGE) \
     @ac_google_namespace@::LogMessage( \
         __FILE__, __LINE__, @ac_google_namespace@::GLOG_ ## severity, LOG_OCCURRENCES, \
                  &what_to_do).stream()
 
 #define SOME_KIND_OF_PLOG_EVERY_N(severity, n, what_to_do) \
   static int LOG_OCCURRENCES = 0, LOG_OCCURRENCES_MOD_N = 0; \
+  static Mutex LOG_OCCURRENCES_MUTEX; \
+  bool SHOULD_LOG_MESSAGE = false; \
+  LOG_OCCURRENCES_MUTEX.Lock(); \
   ++LOG_OCCURRENCES; \
   if (++LOG_OCCURRENCES_MOD_N > n) LOG_OCCURRENCES_MOD_N -= n; \
-  if (LOG_OCCURRENCES_MOD_N == 1) \
+  SHOULD_LOG_MESSAGE = LOG_OCCURRENCES_MOD_N == 1; \
+  LOG_OCCURRENCES_MUTEX.Unlock(); \
+  if (SHOULD_LOG_MESSAGE) \
     @ac_google_namespace@::ErrnoLogMessage( \
         __FILE__, __LINE__, @ac_google_namespace@::GLOG_ ## severity, LOG_OCCURRENCES, \
         &what_to_do).stream()
 
 #define SOME_KIND_OF_LOG_FIRST_N(severity, n, what_to_do) \
   static int LOG_OCCURRENCES = 0; \
-  if (LOG_OCCURRENCES <= n) \
-    ++LOG_OCCURRENCES; \
-  if (LOG_OCCURRENCES <= n) \
+  static Mutex LOG_OCCURRENCES_MUTEX; \
+  bool SHOULD_LOG_MESSAGE = false; \
+  LOG_OCCURRENCES_MUTEX.Lock(); \
+  if (LOG_OCCURRENCES <= n) ++LOG_OCCURRENCES; \
+  SHOULD_LOG_MESSAGE = LOG_OCCURRENCES <= n; \
+  LOG_OCCURRENCES_MUTEX.Unlock(); \
+  if (SHOULD_LOG_MESSAGE) \
     @ac_google_namespace@::LogMessage( \
         __FILE__, __LINE__, @ac_google_namespace@::GLOG_ ## severity, LOG_OCCURRENCES, \
         &what_to_do).stream()