src/share/vm/logging/log.hpp

*** 104,113 ****
--- 104,131 ----
                            size_t msg_len,
                            const char* fmt,
                            va_list args);
  };
  
+ //
+ // Log class that embeds both log tags and a log level.
+ //
+ // The class provides a way to write the tags and log level once,
+ // so that redundant specification of tags or levels can be avoided.
+ //
+ // Example usage:
+ //   LogTarget(Debug, gc) out;
+ //   if (out.is_enabled()) {
+ //     ...
+ //     out.print("Worker: %u", i);
+ //     out.print(" data: %d", x);
+ //     ...
+ //     print_stats(out.stream());
+ //   }
+ //
+ #define LogTarget(level, ...) LogTargetImpl<LogLevel::level, LOG_TAGS(__VA_ARGS__)>
+ 
  template <LogTagType T0, LogTagType T1 = LogTag::__NO_TAG, LogTagType T2 = LogTag::__NO_TAG, LogTagType T3 = LogTag::__NO_TAG,
            LogTagType T4 = LogTag::__NO_TAG, LogTagType GuardTag = LogTag::__NO_TAG>
  class LogImpl VALUE_OBJ_CLASS_SPEC {
   private:
    static const size_t LogBufferSize = 512;
*** 182,187 ****
--- 200,231 ----
    }
    LOG_LEVEL_LIST
  #undef LOG_LEVEL
  };
  
+ // Combines logging tags and a logging level.
+ template <LogLevelType level, LogTagType T0, LogTagType T1 = LogTag::__NO_TAG, LogTagType T2 = LogTag::__NO_TAG,
+           LogTagType T3 = LogTag::__NO_TAG, LogTagType T4 = LogTag::__NO_TAG, LogTagType GuardTag = LogTag::__NO_TAG>
+ class LogTargetImpl {
+ public:
+   // Empty constructor to avoid warnings on MSVC about unused variables
+   // when the log instance is only used for static functions.
+   LogTargetImpl() {
+   }
+ 
+   static bool is_enabled() {
+     return LogImpl<T0, T1, T2, T3, T4, GuardTag>::is_level(level);
+   }
+ 
+   static void print(const char* fmt, ...) ATTRIBUTE_PRINTF(1, 2) {
+     va_list args;
+     va_start(args, fmt);
+     LogImpl<T0, T1, T2, T3, T4, GuardTag>::vwrite(level, fmt, args);
+     va_end(args);
+   }
+ 
+   static outputStream* stream() {
+     return new logStream(&LogImpl<T0, T1, T2, T3, T4, GuardTag>::template write<level>);
+   }
+ };
+ 
  #endif // SHARE_VM_LOGGING_LOG_HPP