--- /dev/null	2020-02-13 04:30:26.348000000 +0000
+++ new/src/hotspot/share/logging/asynclog.hpp	2020-02-24 07:47:47.217119620 +0000
@@ -0,0 +1,171 @@
+/*
+ * Copyright (c) 2020, 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_LOGGING_ASYNCLOG_HPP
+#define SHARE_LOGGING_ASYNCLOG_HPP
+#include "logging/logLevel.hpp"
+#include "logging/logPrefix.hpp"
+#include "logging/logTagSet.hpp"
+#include "logging/logTag.hpp"
+#include "logging/logAsyncFlusher.hpp"
+#include "logging/logMessageBuffer.hpp"
+
+#define asynclog_error(...)   (!asynclog_is_enabled(Error, __VA_ARGS__))   ? (void)0 : AsyncLogImpl<LOG_TAGS(__VA_ARGS__)>().write<LogLevel::Error>
+#define asynclog_warning(...) (!asynclog_is_enabled(Warning, __VA_ARGS__)) ? (void)0 : AsyncLogImpl<LOG_TAGS(__VA_ARGS__)>().write<LogLevel::Warning>
+#define asynclog_info(...)    (!asynclog_is_enabled(Info, __VA_ARGS__))    ? (void)0 : AsyncLogImpl<LOG_TAGS(__VA_ARGS__)>().write<LogLevel::Info>
+#define asynclog_debug(...)   (!asynclog_is_enabled(Debug, __VA_ARGS__))   ? (void)0 : AsyncLogImpl<LOG_TAGS(__VA_ARGS__)>().write<LogLevel::Debug>
+#define asynclog_trace(...)   (!asynclog_is_enabled(Trace, __VA_ARGS__))   ? (void)0 : AsyncLogImpl<LOG_TAGS(__VA_ARGS__)>().write<LogLevel::Trace>
+
+// Macros for logging that should be excluded in product builds.
+// Available for levels Info, Debug and Trace. Includes test macro that
+// evaluates to false in product builds.
+#ifndef PRODUCT
+#define asynclog_develop_info(...)  (!asynclog_is_enabled(Info, __VA_ARGS__))   ? (void)0 : AsyncLogImpl<LOG_TAGS(__VA_ARGS__)>().write<LogLevel::Info>
+#define asynclog_develop_debug(...) (!asynclog_is_enabled(Debug, __VA_ARGS__))  ? (void)0 : AsyncLogImpl<LOG_TAGS(__VA_ARGS__)>().write<LogLevel::Debug>
+#define asynclog_develop_trace(...) (!asynclog_is_enabled(Trace, __VA_ARGS__))  ? (void)0 : AsyncLogImpl<LOG_TAGS(__VA_ARGS__)>().write<LogLevel::Trace>
+#define asynclog_develop_is_enabled(level, ...)  asynclog_is_enabled(level, __VA_ARGS__)
+#else
+#define DUMMY_ARGUMENT_CONSUMER(...)
+#define asynclog_develop_info(...)  DUMMY_ARGUMENT_CONSUMER
+#define asynclog_develop_debug(...) DUMMY_ARGUMENT_CONSUMER
+#define asynclog_develop_trace(...) DUMMY_ARGUMENT_CONSUMER
+#define asynclog_develop_is_enabled(...)  false
+#endif
+
+// Convenience macro to test if the logging is enabled on the specified level for given tags.
+#define asynclog_is_enabled(level, ...) (AsyncLogImpl<LOG_TAGS(__VA_ARGS__)>::is_level(LogLevel::level))
+
+#define AsyncLog(...)  AsyncLogImpl<LOG_TAGS(__VA_ARGS__)>
+#define AsyncLogTarget(level, ...) AsyncLogTargetImpl<LogLevel::level, LOG_TAGS(__VA_ARGS__)>
+
+template <LogLevelType level, LogTagType T0, LogTagType T1, LogTagType T2, LogTagType T3, LogTagType T4, LogTagType GuardTag>
+class AsyncLogTargetImpl;
+
+class Arena;
+
+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 AsyncLogImpl {
+ private:
+  Arena* _arena;
+  LogMessageBuffer* _buf;
+  void create_async_buffer() {
+      Arena* arena = new (mtLogging)Arena(mtLogging, LogMessageBuffer::initial_buffer_size());
+      _buf = new (mtLogging)LogMessageBuffer(arena);
+      _buf->set_prefix(LogPrefix<T0, T1, T2, T3, T4>::prefix);
+  }
+
+ public:
+  // Make sure no more than the maximum number of tags have been given.
+  // The GuardTag allows this to be detected if/when it happens. If the GuardTag
+  // is not __NO_TAG, the number of tags given exceeds the maximum allowed.
+  STATIC_ASSERT(GuardTag == LogTag::__NO_TAG); // Number of logging tags exceeds maximum supported!
+
+  AsyncLogImpl() : _arena(NULL), _buf(NULL) {
+  }
+
+  ~AsyncLogImpl() {
+      if (_buf != NULL) {
+        LogAsyncFlusher* flusher = LogAsyncFlusher::instance();
+        flusher->enqueue(&LogTagSetMapping<T0, T1, T2, T3, T4>::tagset(), _buf);
+      }
+  }
+
+  static bool is_level(LogLevelType level) {
+    return LogTagSetMapping<T0, T1, T2, T3, T4>::tagset().is_level(level);
+  }
+
+  ATTRIBUTE_PRINTF(3, 4)
+  void write(LogLevelType level, const char* fmt, ...) {
+    va_list args;
+    va_start(args, fmt);
+    vwrite(level, fmt, args);
+    va_end(args);
+  }
+
+  // to be implemented or deleted.
+  void write(const LogMessageBuffer& msg);
+
+  template <LogLevelType Level>
+  ATTRIBUTE_PRINTF(2, 3)
+  void write(const char* fmt, ...) {
+    va_list args;
+    va_start(args, fmt);
+    vwrite(Level, fmt, args);
+    va_end(args);
+  }
+
+  ATTRIBUTE_PRINTF(3, 0)
+  void vwrite(LogLevelType level, const char* fmt, va_list args) {
+    if (!_buf) create_async_buffer();
+    _buf->vwrite(level, fmt, args);
+  }
+
+#define LOG_LEVEL(level, name) ATTRIBUTE_PRINTF(2, 0) \
+  AsyncLogImpl& v##name(const char* fmt, va_list args) { \
+    vwrite(LogLevel::level, fmt, args); \
+    return *this; \
+  } \
+  AsyncLogImpl& name(const char* fmt, ...) ATTRIBUTE_PRINTF(2, 3) { \
+    va_list args; \
+    va_start(args, fmt); \
+    vwrite(LogLevel::level, fmt, args); \
+    va_end(args); \
+    return *this; \
+  } \
+  static bool is_##name() { \
+    return is_level(LogLevel::level); \
+  } \
+  static AsyncLogTargetImpl<LogLevel::level, T0, T1, T2, T3, T4, GuardTag>* name() { \
+    return (AsyncLogTargetImpl<LogLevel::level, T0, T1, T2, T3, T4, GuardTag>*)NULL; \
+  }
+  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 AsyncLogTargetImpl {
+public:
+  // Empty constructor to avoid warnings on MSVC about unused variables
+  // when the log instance is only used for static functions.
+  AsyncLogTargetImpl() {
+  }
+
+  static bool is_enabled() {
+    return AsyncLogImpl<T0, T1, T2, T3, T4, GuardTag>::is_level(level);
+  }
+
+  static void print(const char* fmt, ...) ATTRIBUTE_PRINTF(1, 2) {
+    AsyncLogImpl<T0, T1, T2, T3, T4, GuardTag> impl;
+    va_list args;
+
+    va_start(args, fmt);
+    impl.vwrite(level, fmt, args);
+    va_end(args);
+  }
+
+};
+
+#endif // SHARE_LOGGING_ASYNCLOG_HPP