--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/logging/logMessageBuffer.hpp	Mon May 09 15:46:12 2016 +0200
@@ -0,0 +1,131 @@
+/*
+ * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code 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 code 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
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+#ifndef SHARE_VM_LOGGING_LOGMESSAGEBUFFER_HPP
+#define SHARE_VM_LOGGING_LOGMESSAGEBUFFER_HPP
+
+#include "logging/logDecorations.hpp"
+#include "logging/logLevel.hpp"
+#include "memory/allocation.hpp"
+
+class LogMessageBuffer : public StackObj {
+  friend class LogMessageTest;
+ protected:
+  struct LogLine VALUE_OBJ_CLASS_SPEC {
+    LogLevelType level;
+    size_t message_offset;
+  };
+  static const size_t InitialLineCapacity = 10;
+  static const size_t InitialMessageBufferCapacity = 1024;
+
+  size_t _message_buffer_size;
+  size_t _message_buffer_capacity;
+  char* _message_buffer;
+
+  size_t _line_count;
+  size_t _line_capacity;
+  LogLine* _lines;
+
+  bool _allocated;
+  LogLevelType _least_detailed_level;
+  size_t (*_prefix_fn)(char*, size_t);
+
+  void initialize_buffers();
+
+ private:
+  // Forbid copy assignment and copy constructor.
+  void operator=(const LogMessageBuffer& ref) {}
+  LogMessageBuffer(const LogMessageBuffer& ref) {}
+
+ public:
+  LogMessageBuffer();
+  ~LogMessageBuffer();
+
+  class Iterator {
+   private:
+    const LogMessageBuffer& _message;
+    size_t _current_line_index;
+    LogLevelType _level;
+    LogDecorations &_decorations;
+
+    void skip_messages_with_finer_level();
+
+   public:
+    Iterator(const LogMessageBuffer& message, LogLevelType level, LogDecorations& decorations)
+        : _message(message), _level(level), _decorations(decorations), _current_line_index(0) {
+      skip_messages_with_finer_level();
+    }
+
+    void operator++(int) {
+      _current_line_index++;
+      skip_messages_with_finer_level();
+    }
+
+    bool is_at_end() {
+      return _current_line_index == _message._line_count;
+    }
+
+    const char* message() const {
+      return _message._message_buffer + _message._lines[_current_line_index].message_offset;
+    }
+
+    const LogDecorations& decorations() {
+      _decorations.set_level(_message._lines[_current_line_index].level);
+      return _decorations;
+    }
+  };
+
+  void reset();
+
+  LogLevelType least_detailed_level() const {
+    return _least_detailed_level;
+  }
+
+  Iterator iterator(LogLevelType level, LogDecorations& decorations) const {
+    return Iterator(*this, level, decorations);
+  }
+
+  // Lines in LogMessageBuffers are not automatically prefixed based on tags
+  // like regular simple messages (see LogPrefix.hpp for more about prefixes).
+  // It is, however, possible to specify a prefix per LogMessageBuffer,
+  // using set_prefix(). Lines added to the LogMessageBuffer after a prefix
+  // function has been set will be prefixed automatically.
+  // Setting this to NULL will disable prefixing.
+  void set_prefix(size_t (*prefix_fn)(char*, size_t)) {
+    _prefix_fn = prefix_fn;
+  }
+
+  ATTRIBUTE_PRINTF(3, 4)
+  void write(LogLevelType level, const char* fmt, ...);
+
+  ATTRIBUTE_PRINTF(3, 0)
+  virtual void vwrite(LogLevelType level, const char* fmt, va_list args);
+
+#define LOG_LEVEL(level, name) \
+  LogMessageBuffer& v##name(const char* fmt, va_list args) ATTRIBUTE_PRINTF(2, 0); \
+  LogMessageBuffer& name(const char* fmt, ...) ATTRIBUTE_PRINTF(2, 3);
+  LOG_LEVEL_LIST
+#undef LOG_LEVEL
+};
+
+#endif // SHARE_VM_LOGGING_LOGMESSAGEBUFFER_HPP