1 /*
2 * Copyright (c) 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 #include "precompiled.hpp"
26 #include "jfr/jfrEvents.hpp"
27 #include "jfr/leakprofiler/chains/edgeStore.hpp"
28 #include "jfr/leakprofiler/chains/pathToGcRootsOperation.hpp"
29 #include "jfr/leakprofiler/checkpoint/eventEmitter.hpp"
30 #include "jfr/leakprofiler/checkpoint/objectSampleCheckpoint.hpp"
31 #include "jfr/leakprofiler/sampling/objectSample.hpp"
32 #include "jfr/leakprofiler/sampling/objectSampler.hpp"
33 #include "memory/resourceArea.hpp"
34 #include "oops/markOop.hpp"
35 #include "oops/oop.inline.hpp"
36 #include "runtime/thread.inline.hpp"
37 #include "runtime/vmThread.hpp"
38
39 EventEmitter::EventEmitter(const JfrTicks& start_time, const JfrTicks& end_time) :
40 _start_time(start_time),
41 _end_time(end_time),
42 _thread(Thread::current()),
43 _jfr_thread_local(_thread->jfr_thread_local()),
44 _thread_id(_thread->jfr_thread_local()->thread_id()) {}
45
46 EventEmitter::~EventEmitter() {
47 // restore / reset thread local stack trace and thread id
48 _jfr_thread_local->set_thread_id(_thread_id);
49 _jfr_thread_local->clear_cached_stack_trace();
50 }
51
52 void EventEmitter::emit(ObjectSampler* sampler, int64_t cutoff_ticks, bool emit_all) {
53 assert(sampler != NULL, "invariant");
54
55 ResourceMark rm;
56 EdgeStore edge_store;
57 if (cutoff_ticks <= 0) {
58 // no reference chains
59 JfrTicks time_stamp = JfrTicks::now();
60 EventEmitter emitter(time_stamp, time_stamp);
61 emitter.write_events(sampler, &edge_store, emit_all);
62 return;
63 }
64 // events emitted with reference chains require a safepoint operation
65 PathToGcRootsOperation op(sampler, &edge_store, cutoff_ticks, emit_all);
66 VMThread::execute(&op);
67 }
68
69 size_t EventEmitter::write_events(ObjectSampler* object_sampler, EdgeStore* edge_store, bool emit_all) {
70 assert(_thread == Thread::current(), "invariant");
71 assert(_thread->jfr_thread_local() == _jfr_thread_local, "invariant");
72 assert(object_sampler != NULL, "invariant");
73 assert(edge_store != NULL, "invariant");
74
75 const jlong last_sweep = emit_all ? max_jlong : object_sampler->last_sweep().value();
76 size_t count = 0;
77
78 const ObjectSample* current = object_sampler->first();
79 while (current != NULL) {
80 ObjectSample* prev = current->prev();
81 if (current->is_alive_and_older_than(last_sweep)) {
82 write_event(current, edge_store);
83 ++count;
84 }
85 current = prev;
86 }
87
88 if (count > 0) {
89 // serialize associated checkpoints and potential chains
90 ObjectSampleCheckpoint::write(object_sampler, edge_store, emit_all, _thread);
91 }
92 return count;
93 }
94
95 static int array_size(const oop object) {
96 assert(object != NULL, "invariant");
97 if (object->is_array()) {
98 return arrayOop(object)->length();
99 }
100 return min_jint;
101 }
102
103 void EventEmitter::write_event(const ObjectSample* sample, EdgeStore* edge_store) {
104 assert(sample != NULL, "invariant");
105 assert(!sample->is_dead(), "invariant");
106 assert(edge_store != NULL, "invariant");
107 assert(_jfr_thread_local != NULL, "invariant");
108
109 const oop* object_addr = sample->object_addr();
110 traceid gc_root_id = 0;
111 const Edge* edge = NULL;
112 if (SafepointSynchronize::is_at_safepoint()) {
113 edge = (const Edge*)(*object_addr)->mark();
114 }
115 if (edge == NULL) {
116 // In order to dump out a representation of the event
117 // even though it was not reachable / too long to reach,
118 // we need to register a top level edge for this object.
119 edge = edge_store->put(object_addr);
120 } else {
121 gc_root_id = edge_store->gc_root_id(edge);
122 }
123
124 assert(edge != NULL, "invariant");
125 const traceid object_id = edge_store->get_id(edge);
126 assert(object_id != 0, "invariant");
127
128 EventOldObjectSample e(UNTIMED);
129 e.set_starttime(_start_time);
130 e.set_endtime(_end_time);
131 e.set_allocationTime(sample->allocation_time());
132 e.set_lastKnownHeapUsage(sample->heap_used_at_last_gc());
133 e.set_object(object_id);
134 e.set_arrayElements(array_size(edge->pointee()));
135 e.set_root(gc_root_id);
136
137 // Temporarily assigning both the stack trace id and thread id
138 // onto the thread local data structure of the emitter thread (for the duration
139 // of the commit() call). This trick provides a means to override
140 // the event generation mechanism by injecting externally provided id's.
141 // At this particular location, it allows us to emit an old object event
142 // supplying information from where the actual sampling occurred.
143 _jfr_thread_local->set_cached_stack_trace_id(sample->stack_trace_id());
144 assert(sample->has_thread(), "invariant");
145 _jfr_thread_local->set_thread_id(sample->thread_id());
146 e.commit();
147 }