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 /*

  * 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;

 // XXX 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

  *   XXX 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);

   // XXX 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);

   // XXX 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