1 /*
2 * Copyright (c) 2011, 2019, 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_VM_JFR_CHECKPOINT_CONSTANT_TRACEID_JFRTRACEID_HPP
26 #define SHARE_VM_JFR_CHECKPOINT_CONSTANT_TRACEID_JFRTRACEID_HPP
27
28 #include "jni.h"
29 #include "classfile/classLoaderData.hpp"
30 #include "jfr/utilities/jfrTypes.hpp"
31 #include "memory/allocation.hpp"
32 #include "oops/arrayKlass.hpp"
33 #include "oops/klass.hpp"
34 #include "oops/instanceKlass.hpp"
35 #include "oops/method.hpp"
36
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 public:
82 static void assign(const Klass* klass);
83 static void assign(const ClassLoaderData* cld);
84 static traceid assign_thread_id();
85
86 static traceid get(const Klass* klass);
87 static traceid get(jclass jc);
88 static traceid get(const Thread* thread);
89
90 // tag construct as used, returns pre-tagged traceid
91 static traceid use(const Klass* klass, bool leakp = false);
92 static traceid use(jclass jc, bool leakp = false);
93 static traceid use(const Method* method, bool leakp = false);
94 static traceid use(const ClassLoaderData* cld, bool leakp = false);
95
96 static void remove(const Klass* klass);
97 static void restore(const Klass* klass);
98
99 // set of event classes made visible to java
100 static bool in_visible_set(const Klass* k);
101 static bool in_visible_set(const jclass jc);
102
103 // jdk.jfr.Event
104 static bool is_jdk_jfr_event(const Klass* k);
105 static bool is_jdk_jfr_event(const jclass jc);
106 static void tag_as_jdk_jfr_event(const Klass* k);
107
108 // jdk.jfr.Event subklasses
109 static bool is_jdk_jfr_event_sub(const Klass* k);
110 static bool is_jdk_jfr_event_sub(const jclass jc);
111 static void tag_as_jdk_jfr_event_sub(const Klass* k);
112 static void tag_as_jdk_jfr_event_sub(const jclass jc);
113
114 static bool in_jdk_jfr_event_hierarchy(const Klass* k);
115 static bool in_jdk_jfr_event_hierarchy(const jclass jc);
116
117 // klasses that host an event
118 static bool is_event_host(const Klass* k);
119 static bool is_event_host(const jclass jc);
120 static void tag_as_event_host(const Klass* k);
121 static void tag_as_event_host(const jclass jc);
122 };
123
124 #endif // SHARE_VM_JFR_CHECKPOINT_CONSTANT_TRACEID_JFRTRACEID_HPP