/*

 * Copyright (c) 2011, 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_TYPES_TRACEID_JFRTRACEID_HPP

#define SHARE_VM_JFR_CHECKPOINT_TYPES_TRACEID_JFRTRACEID_HPP

#include "jni.h"

#include "jfr/utilities/jfrTypes.hpp"

#include "memory/allocation.hpp"

class ClassLoaderData;

class Klass;

class Method;

class ModuleEntry;

class PackageEntry;

class Thread;

/*

 * JfrTraceId is a means of tagging, e.g. marking, specific instances as being actively in-use.

 * The most common situation is a committed event that has a field that is referring to a specific instance.

 * Now there exist a relation between an event (field) and an artifact of some kind.

 * We track this relation during runtime using the JfrTraceId mechanism in order to reify it into the chunk

 * where the event is finally written.

 *

 * It is the event commit mechanism that tags instances as in-use. The tag routines return the untagged traceid

 * as a mapping key, and the commit mechanism writes the key into the event field.

 * Consequently, the mechanism is opaque and not something a user needs to know about.

 * Indeed, the API promotes using well-known JVM concepts directly in events, such as having a Klass* as an event field.

 *

 * Tagging allows for many-to-one mappings of constants, lazy evaluation / collection of tags during chunk rotation

 * and concurrency (by using an epoch relative tagging scheme).

 *

 * JfrTraceId(s) have been added to support tagging instances of classes such as:

 *

 *   Klass (includes Method)

 *   ClassLoaderData

 *   ModuleEntry

 *   PackageEntry

 *

 * These classes have been extended to include a _traceid field (64-bits).

 *

 * Each instance is uniquely identified by a type-relative monotonic counter that is unique over the VM lifecycle.

 * "Tagging an instance" essentially means to set contextually determined (by epoch) marker bits in the _traceid field.

 * The constants associated with a tagged instance is a set of which is determined by a constant type definition,

 * and these constants are then serialized in an upcoming checkpoint event for the relevant chunk.

 *

 * Note that a "tagging" is relative to a chunk. Having serialized the tagged instance, the tag bits are reset (for that epoch).

 * As mentioned previously, the returned traceid is always the untagged value.

 *

 * We also use the _traceid field in Klass to quickly identify (bit check) if a newly loaded klass is of type jdk.jfr.Event.

 * (see jfr/instrumentation/jfrEventClassTransformer.cpp)

 *

 *

 * _traceid bit layout and description planned to go here

 *

 *

 */

class JfrTraceId : public AllStatic {

 public:

  static void assign(const Klass* klass);

  static void assign(const ModuleEntry* module);

  static void assign(const PackageEntry* package);

  static void assign(const ClassLoaderData* cld);

  static traceid assign_thread_id();

  static traceid get(const Klass* klass);

  static traceid get(jclass jc);

  static traceid get(const Thread* thread);

  // tag construct as used, returns pre-tagged traceid

  static traceid use(const Klass* klass, bool leakp = false);

  static traceid use(jclass jc, bool leakp = false);

  static traceid use(const Method* method, bool leakp = false);

  static traceid use(const ModuleEntry* module, bool leakp = false);

  static traceid use(const PackageEntry* package, bool leakp = false);

  static traceid use(const ClassLoaderData* cld, bool leakp = false);

  static void remove(const Klass* klass);

  static void restore(const Klass* klass);

  // set of event classes made visible to java

  static bool in_visible_set(const Klass* k);

  static bool in_visible_set(const jclass jc);

  // jdk.jfr.Event

  static bool is_jdk_jfr_event(const Klass* k);

  static bool is_jdk_jfr_event(const jclass jc);

  static void tag_as_jdk_jfr_event(const Klass* k);

  // jdk.jfr.Event subklasses

  static bool is_jdk_jfr_event_sub(const Klass* k);

  static bool is_jdk_jfr_event_sub(const jclass jc);

  static void tag_as_jdk_jfr_event_sub(const Klass* k);

  static void tag_as_jdk_jfr_event_sub(const jclass jc);

  static bool in_jdk_jfr_event_hierarchy(const Klass* k);

  static bool in_jdk_jfr_event_hierarchy(const jclass jc);

  // klasses that host an event

  static bool is_event_host(const Klass* k);

  static bool is_event_host(const jclass jc);

  static void tag_as_event_host(const Klass* k);

  static void tag_as_event_host(const jclass jc);

};

#endif // SHARE_VM_JFR_CHECKPOINT_TYPES_TRACEID_JFRTRACEID_HPP