--- /dev/null	2017-11-09 09:38:01.297999907 +0100
+++ new/src/hotspot/share/jfr/recorder/checkpoint/constant/jfrTagSetWriter.hpp	2018-04-09 15:00:42.473732059 +0200
@@ -0,0 +1,109 @@
+/*
+ * Copyright (c) 2017, 2018, 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_JFR_CHECKPOINT_CONSTANT_JFRTAGSETWRITER_HPP
+#define SHARE_VM_JFR_CHECKPOINT_CONSTANT_JFRTAGSETWRITER_HPP
+
+#include "jfr/recorder/checkpoint/jfrCheckpointWriter.hpp"
+#include "memory/allocation.hpp"
+// to get CONTENT_TYPE defines
+#include "tracefiles/traceTypes.hpp"
+
+template <typename WriterImpl, u4 CONSTANT_TYPE_ID>
+class JfrArtifactWriterHost : public StackObj {
+ private:
+  WriterImpl _impl;
+  JfrCheckpointWriter* _writer;
+  JfrCheckpointContext _ctx;
+  jlong _count_offset;
+  int _count;
+  bool _skip_header;
+ public:
+  JfrArtifactWriterHost(JfrCheckpointWriter* writer,
+                        JfrArtifactSet* artifacts,
+                        bool class_unload,
+                        bool skip_header = false) : _impl(writer, artifacts, class_unload),
+                                                    _writer(writer),
+                                                    _ctx(writer->context()),
+                                                    _count(0),
+                                                    _skip_header(skip_header) {
+    assert(_writer != NULL, "invariant");
+    if (!_skip_header) {
+      _writer->write_constant_type((JfrConstantTypeId)CONSTANT_TYPE_ID);
+      _count_offset = _writer->reserve(sizeof(u4)); // Don't know how many yet
+    }
+  }
+
+  ~JfrArtifactWriterHost() {
+    if (_count == 0) {
+      // nothing written, restore context for rewind
+      _writer->set_context(_ctx);
+      return;
+    }
+    assert(_count > 0, "invariant");
+    if (!_skip_header) {
+      _writer->write_number_of_constants(_count, _count_offset);
+    }
+  }
+
+  bool operator()(typename WriterImpl::Type const & value) {
+    this->_count += _impl(value);
+    return true;
+  }
+
+  int count() const   { return _count; }
+  void add(int count) { _count += count; }
+};
+
+typedef int(*artifact_write_operation)(JfrCheckpointWriter*, JfrArtifactSet*, const void*);
+
+template <typename T, artifact_write_operation op>
+class JfrArtifactWriterImplHost {
+ private:
+  JfrCheckpointWriter* _writer;
+  JfrArtifactSet* _artifacts;
+  bool _class_unload;
+ public:
+  typedef T Type;
+  JfrArtifactWriterImplHost(JfrCheckpointWriter* writer, JfrArtifactSet* artifacts, bool class_unload) :
+    _writer(writer), _artifacts(artifacts), _class_unload(class_unload) {}
+  int operator()(T const& value) {
+    return op(this->_writer, this->_artifacts, value);
+  }
+};
+
+template <typename T, typename Predicate, artifact_write_operation op>
+class JfrPredicatedArtifactWriterImplHost : public JfrArtifactWriterImplHost<T, op> {
+ private:
+  Predicate _predicate;
+  typedef JfrArtifactWriterImplHost<T, op> Parent;
+ public:
+  JfrPredicatedArtifactWriterImplHost(JfrCheckpointWriter* writer, JfrArtifactSet* artifacts, bool class_unload) :
+    Parent(writer, artifacts, class_unload), _predicate(class_unload) {}
+  int operator()(T const& value) {
+    return _predicate(value) ? Parent::operator()(value) : 0;
+  }
+};
+
+#endif // SHARE_VM_JFR_CHECKPOINT_CONSTANT_JFRTAGSETWRITER_HPP