1 /*
  2  * Copyright (c) 2011, 2021, Oracle and/or its affiliates. All rights reserved.
  3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  4  *
  5  * This code is free software; you can redistribute it and/or modify it
  6  * under the terms of the GNU General Public License version 2 only, as
  7  * published by the Free Software Foundation.
  8  *
  9  * This code is distributed in the hope that it will be useful, but WITHOUT
 10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 12  * version 2 for more details (a copy is included in the LICENSE file that
 13  * accompanied this code).
 14  *
 15  * You should have received a copy of the GNU General Public License version
 16  * 2 along with this work; if not, write to the Free Software Foundation,
 17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 18  *
 19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 20  * or visit www.oracle.com if you need additional information or have any
 21  * questions.
 22  *
 23  */
 24 
 25 #ifndef SHARE_JFR_RECORDER_CHECKPOINT_TYPES_TRACEID_JFRTRACEID_HPP
 26 #define SHARE_JFR_RECORDER_CHECKPOINT_TYPES_TRACEID_JFRTRACEID_HPP
 27 
 28 #include "jni.h"
 29 #include "jfr/utilities/jfrTypes.hpp"
 30 #include "memory/allocation.hpp"
 31 
 32 class ClassLoaderData;
 33 class Klass;
 34 class Method;
 35 class ModuleEntry;
 36 class PackageEntry;
 37 class Thread;
 38 
 39 /*
 40  * JfrTraceId is a means of tagging, e.g. marking, specific instances as being actively in-use.
 41  * The most common situation is a committed event that has a field that is referring to a specific instance.
 42  * Now there exist a relation between an event (field) and an artifact of some kind.
 43  * We track this relation during runtime using the JfrTraceId mechanism in order to reify it into the chunk
 44  * where the event is finally written.
 45  *
 46  * It is the event commit mechanism that tags instances as in-use. The tag routines return the untagged traceid
 47  * as a mapping key, and the commit mechanism writes the key into the event field.
 48  * Consequently, the mechanism is opaque and not something a user needs to know about.
 49  * Indeed, the API promotes using well-known JVM concepts directly in events, such as having a Klass* as an event field.
 50  *
 51  * Tagging allows for many-to-one mappings of constants, lazy evaluation / collection of tags during chunk rotation
 52  * and concurrency (by using an epoch relative tagging scheme).
 53  *
 54  * JfrTraceId(s) have been added to support tagging instances of classes such as:
 55  *
 56  *   Klass (includes Method)
 57  *   ClassLoaderData
 58  *   ModuleEntry
 59  *   PackageEntry
 60  *
 61  * These classes have been extended to include a _traceid field (64-bits).
 62  *
 63  * Each instance is uniquely identified by a type-relative monotonic counter that is unique over the VM lifecycle.
 64  * "Tagging an instance" essentially means to set contextually determined (by epoch) marker bits in the _traceid field.
 65  * The constants associated with a tagged instance is a set of which is determined by a constant type definition,
 66  * and these constants are then serialized in an upcoming checkpoint event for the relevant chunk.
 67  *
 68  * Note that a "tagging" is relative to a chunk. Having serialized the tagged instance, the tag bits are reset (for that epoch).
 69  * As mentioned previously, the returned traceid is always the untagged value.
 70  *
 71  * We also use the _traceid field in Klass to quickly identify (bit check) if a newly loaded klass is of type jdk.jfr.Event.
 72  * (see jfr/instrumentation/jfrEventClassTransformer.cpp)
 73  *
 74  *
 75  * _traceid bit layout and description planned to go here
 76  *
 77  *
 78  */
 79 
 80 class JfrTraceId : public AllStatic {
 81   friend class JfrRecorder;
 82  private:
 83   static bool initialize();
 84  public:
 85   static void assign(const Klass* klass);
 86   static void assign(const ModuleEntry* module);
 87   static void assign(const PackageEntry* package);
 88   static void assign(const ClassLoaderData* cld);
 89   static traceid assign_primitive_klass_id();
 90   static traceid assign_thread_id();
 91 
 92   // through load barrier
 93   static traceid load(const Klass* klass);
 94   static traceid load(jclass jc, bool raw = false);
 95   static traceid load(const Method* method);
 96   static traceid load(const Klass* klass, const Method* method);
 97   static traceid load(const ModuleEntry* module);
 98   static traceid load(const PackageEntry* package);
 99   static traceid load(const ClassLoaderData* cld);
100   static traceid load_leakp(const Klass* klass, const Method* method); // leak profiler
101 
102   // load barrier elision
103   static traceid load_raw(const Klass* klass);
104   static traceid load_raw(jclass jc);
105   static traceid load_raw(const Thread* thread);
106   static traceid load_raw(const Method* method);
107   static traceid load_raw(const ModuleEntry* module);
108   static traceid load_raw(const PackageEntry* package);
109   static traceid load_raw(const ClassLoaderData* cld);
110 
111   static void remove(const Klass* klass);
112   static void remove(const Method* method);
113   static void restore(const Klass* klass);
114 
115   // set of event classes made visible to java
116   static bool in_visible_set(const Klass* k);
117   static bool in_visible_set(const jclass jc);
118 
119   // jdk.jfr.Event
120   static bool is_jdk_jfr_event(const Klass* k);
121   static bool is_jdk_jfr_event(const jclass jc);
122   static void tag_as_jdk_jfr_event(const Klass* k);
123 
124   // jdk.jfr.Event subklasses
125   static bool is_jdk_jfr_event_sub(const Klass* k);
126   static bool is_jdk_jfr_event_sub(const jclass jc);
127   static void tag_as_jdk_jfr_event_sub(const Klass* k);
128   static void tag_as_jdk_jfr_event_sub(const jclass jc);
129 
130   static bool in_jdk_jfr_event_hierarchy(const Klass* k);
131   static bool in_jdk_jfr_event_hierarchy(const jclass jc);
132 
133   // klasses that host an event
134   static bool is_event_host(const Klass* k);
135   static bool is_event_host(const jclass jc);
136   static void tag_as_event_host(const Klass* k);
137   static void tag_as_event_host(const jclass jc);
138 };
139 
140 #endif // SHARE_JFR_RECORDER_CHECKPOINT_TYPES_TRACEID_JFRTRACEID_HPP
--- EOF ---