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/*
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* Copyright (c) 2016, 2018, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*
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*/
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#ifndef SHARE_VM_JFR_METADATA_JFRSERIALIZER_HPP
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#define SHARE_VM_JFR_METADATA_JFRSERIALIZER_HPP
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#include "memory/allocation.hpp"
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#include "jfr/recorder/checkpoint/jfrCheckpointWriter.hpp"
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#include "jfrfiles/jfrTypes.hpp"
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/*
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* A "type" in Jfr is a binary relation defined by enumerating a set of <key, value> ordered pairs:
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*
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* { <1, myvalue>, <2, mysecondvalue>, ... }
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*
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* The key should be a type relative unique id. A value is an instance of the type.
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*
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* By defining and registering a type, keys can be written to event fields and the
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* framework will maintain the mapping to the corresponding value (if you register as below).
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*
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* Inherit JfrSerializer, create a CHeapObj instance and then use JfrSerializer::register_serializer(...) to register.
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* Once registered, the ownership of the serializer instance is transferred to Jfr.
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*
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* How to register:
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*
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* bool register_serializer(JfrTypeId id, bool require_safepoint, bool permit_cache, JfrSerializer* serializer)
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*
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* The type identifiers are machine generated into an enum located in jfrfiles/jfrTypes.hpp (included).
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*
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* enum JfrTypeId {
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* ...
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* TYPE_THREADGROUP,
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* TYPE_CLASSLOADER,
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* TYPE_METHOD,
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* TYPE_SYMBOL,
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* TYPE_THREADSTATE,
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* TYPE_INFLATECAUSE,
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* ...
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*
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* id this is the id of the type your are defining (see the enum above).
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* require_safepoint indicate if your type need to be evaluated and serialized under a safepoint.
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* permit_cache indicate if your type constants are stable to be cached.
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* (implies the callback is invoked only once and the contents will be cached. Set this to true for static information).
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* serializer the serializer instance.
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*
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* See below for guidance about how to implement serialize().
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*
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*/
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class JfrSerializer : public CHeapObj<mtTracing> {
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public:
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virtual ~JfrSerializer() {}
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static bool register_serializer(JfrTypeId id, bool require_safepoint, bool permit_cache, JfrSerializer* serializer);
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virtual void serialize(JfrCheckpointWriter& writer) = 0;
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};
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/*
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* Defining serialize(JfrCheckpointWriter& writer):
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*
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* Invoke writer.write_count(N) for the number of ordered pairs (cardinality) to be defined.
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*
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* You then write each individual ordered pair, <key, value> ...
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*
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* Here is a simple example, describing a type defining string constants:
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*
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* void MyType::serialize(JfrCheckpointWriter& writer) {
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* const int nof_causes = ObjectSynchronizer::inflate_cause_nof;
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* writer.write_count(nof_causes); // write number of ordered pairs (mappings) to follow
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* for (int i = 0; i < nof_causes; i++) {
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* writer.write_key(i); // write key
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* writer.write(ObjectSynchronizer::inflate_cause_name((ObjectSynchronizer::InflateCause)i)); // write value
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* }
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* }
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*
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* Note that values can be complex, and can also referer to other types.
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*
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* Please see jfr/recorder/checkpoint/types/jfrType.cpp for reference.
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*/
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#endif // SHARE_VM_JFR_METADATA_JFRSERIALIZER_HPP
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