Add FLAGS_log_utc_time; when 'true' the time will be written in log in UTC, resolves #571

src/config.h.cmake.in

@@ -142,6 +142,9 @@
 /* define if localtime_r is available in time.h */
 #cmakedefine HAVE_LOCALTIME_R
 
+/* define if gmtime_r is available in time.h */
+#cmakedefine HAVE_GMTIME_R
+
 /* Define to the sub-directory in which libtool stores uninstalled libraries.
    */
 #cmakedefine LT_OBJDIR

src/glog/logging.h.in

@@ -380,6 +380,9 @@ DECLARE_int32(max_log_size);
 // Sets whether to avoid logging to the disk if the disk is full.
 DECLARE_bool(stop_logging_if_full_disk);
 
+// Use UTC time for logging
+DECLARE_bool(log_utc_time);
+
 #ifdef MUST_UNDEF_GFLAGS_DECLARE_MACROS
 #undef MUST_UNDEF_GFLAGS_DECLARE_MACROS
 #undef DECLARE_VARIABLE

src/logging.cc

@@ -187,6 +187,9 @@ GLOG_DEFINE_bool(stop_logging_if_full_disk, false,
 GLOG_DEFINE_string(log_backtrace_at, "",
                    "Emit a backtrace when logging at file:linenum.");
 
+GLOG_DEFINE_bool(log_utc_time, false,
+    "Use UTC time for logging.");
+
 // TODO(hamaji): consider windows
 #define PATH_SEPARATOR '/'
 
@@ -1129,7 +1132,10 @@ void LogFileObject::Write(bool force_flush,
     rollover_attempt_ = 0;
 
     struct ::tm tm_time;
-    localtime_r(&timestamp, &tm_time);
+    if (FLAGS_log_utc_time)
+        gmtime_r(&timestamp, &tm_time);
+    else
+        localtime_r(&timestamp, &tm_time);
 
     // The logfile's filename will have the date/time & pid in it
     ostringstream time_pid_stream;
@@ -1213,7 +1219,7 @@ void LogFileObject::Write(bool force_flush,
                        << ' '
                        << setw(2) << tm_time.tm_hour << ':'
                        << setw(2) << tm_time.tm_min << ':'
-                       << setw(2) << tm_time.tm_sec << '\n'
+                       << setw(2) << tm_time.tm_sec << (FLAGS_log_utc_time ? " UTC\n" : "\n")
                        << "Running on machine: "
                        << LogDestination::hostname() << '\n'
                        << "Log line format: [IWEF]yyyymmdd hh:mm:ss.uuuuuu "
@@ -1418,7 +1424,10 @@ void LogMessage::Init(const char* file,
   data_->outvec_ = NULL;
   WallTime now = WallTime_Now();
   data_->timestamp_ = static_cast<time_t>(now);
-  localtime_r(&data_->timestamp_, &data_->tm_time_);
+  if(FLAGS_log_utc_time)
+    gmtime_r(&data_->timestamp_, &data_->tm_time_);
+  else
+    localtime_r(&data_->timestamp_, &data_->tm_time_);
   data_->usecs_ = static_cast<int32>((now - data_->timestamp_) * 1000000);
 
   data_->num_chars_to_log_ = 0;

src/windows/glog/logging.h

@@ -381,6 +381,9 @@ DECLARE_int32(max_log_size);
 // Sets whether to avoid logging to the disk if the disk is full.
 DECLARE_bool(stop_logging_if_full_disk);
 
+// Use UTC time for logging.
+DECLARE_bool(log_utc_time);
+
 #ifdef MUST_UNDEF_GFLAGS_DECLARE_MACROS
 #undef MUST_UNDEF_GFLAGS_DECLARE_MACROS
 #undef DECLARE_VARIABLE

src/windows/port.cc

@@ -54,6 +54,12 @@ struct tm* localtime_r(const time_t* timep, struct tm* result) {
   return result;
 }
 #endif // not HAVE_LOCALTIME_R
+#ifndef HAVE_GMTIME_R
+struct tm* gmtime_r(const time_t* timep, struct tm* result) {
+    gmtime_s(result, timep);
+    return result;
+}
+#endif // not HAVE_GMTIME_R
 #ifndef HAVE_SNPRINTF
 int snprintf(char *str, size_t size, const char *format, ...) {
   va_list ap;

src/windows/port.h

@@ -159,6 +159,10 @@ enum { PTHREAD_ONCE_INIT = 0 };   // important that this be 0! for SpinLock
 extern GOOGLE_GLOG_DLL_DECL struct tm* localtime_r(const time_t* timep, struct tm* result);
 #endif // not HAVE_LOCALTIME_R
 
+#ifndef HAVE_GMTIME_R
+extern GOOGLE_GLOG_DLL_DECL struct tm* gmtime_r(const time_t* timep, struct tm* result);
+#endif // not HAVE_GMTIME_R
+
 inline char* strerror_r(int errnum, char* buf, size_t buflen) {
   strerror_s(buf, buflen, errnum);
   return buf;