1 /*
2 * Copyright (c) 2016, 2018, 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/recorder/checkpoint/jfrCheckpointWriter.hpp"
27 #include "jfr/recorder/checkpoint/constant/jfrThreadGroup.hpp"
28 #include "jfr/utilities/jfrResourceManager.hpp"
29 #include "runtime/handles.inline.hpp"
30 #include "runtime/jniHandles.inline.hpp"
31 #include "runtime/safepoint.hpp"
32 #include "runtime/semaphore.hpp"
33 // to get CONTENT_TYPE defines
34 #include "tracefiles/traceTypes.hpp"
35 #include "utilities/growableArray.hpp"
36
37 class ThreadGroupExclusiveAccess : public StackObj {
38 private:
39 static Semaphore _mutex_semaphore;
40 public:
41 ThreadGroupExclusiveAccess() { _mutex_semaphore.wait(); }
42 ~ThreadGroupExclusiveAccess() { _mutex_semaphore.signal(); }
43 };
44
45 Semaphore ThreadGroupExclusiveAccess::_mutex_semaphore(1);
46 JfrThreadGroup* JfrThreadGroup::_instance = NULL;
47
48 class JfrThreadGroupPointers : public ResourceObj {
49 private:
50 const Handle _thread_group_handle;
51 jweak _thread_group_weak_ref;
52 public:
53 JfrThreadGroupPointers(Handle thread_group_handle, jweak thread_group_weak_ref);
54 Handle thread_group_handle() const;
55 jweak thread_group_weak_ref() const;
56 oopDesc* const thread_group_oop() const;
57 jweak transfer_weak_global_handle_ownership();
58 void clear_weak_ref();
59 };
60
61 JfrThreadGroupPointers::JfrThreadGroupPointers(Handle thread_group_handle, jweak thread_group_weak_ref) :
62 _thread_group_handle(thread_group_handle),
63 _thread_group_weak_ref(thread_group_weak_ref) {}
64
65 Handle JfrThreadGroupPointers::thread_group_handle() const {
66 return _thread_group_handle;
67 }
68
69 jweak JfrThreadGroupPointers::thread_group_weak_ref() const {
70 return _thread_group_weak_ref;
71 }
72
73 oopDesc* const JfrThreadGroupPointers::thread_group_oop() const {
74 assert(_thread_group_weak_ref == NULL ||
75 JNIHandles::resolve_non_null(_thread_group_weak_ref) == _thread_group_handle(), "invariant");
76 return _thread_group_handle();
77 }
78
79 jweak JfrThreadGroupPointers::transfer_weak_global_handle_ownership() {
80 jweak temp = _thread_group_weak_ref;
81 _thread_group_weak_ref = NULL;
82 return temp;
83 }
84
85 void JfrThreadGroupPointers::clear_weak_ref() {
86 if (NULL != _thread_group_weak_ref) {
87 JNIHandles::destroy_weak_global(_thread_group_weak_ref);
88 }
89 }
90
91 class JfrThreadGroupsHelper : public ResourceObj {
92 private:
93 static const int invalid_iterator_pos = -1;
94 GrowableArray<JfrThreadGroupPointers*>* _thread_group_hierarchy;
95 int _current_iterator_pos;
96
97 int populate_thread_group_hierarchy(const JavaThread* jt, Thread* current);
98 JfrThreadGroupPointers& at(int index);
99
100 public:
101 JfrThreadGroupsHelper(const JavaThread* jt, Thread* current);
102 ~JfrThreadGroupsHelper();
103 JfrThreadGroupPointers& next();
104 bool is_valid() const;
105 bool has_next() const;
106 };
107
108 JfrThreadGroupsHelper::JfrThreadGroupsHelper(const JavaThread* jt, Thread* current) {
109 _thread_group_hierarchy = new GrowableArray<JfrThreadGroupPointers*>(10, false, mtTracing);
110 _current_iterator_pos = populate_thread_group_hierarchy(jt, current) - 1;
111 }
112
113 JfrThreadGroupsHelper::~JfrThreadGroupsHelper() {
114 assert(_current_iterator_pos == invalid_iterator_pos, "invariant");
115 for (int i = 0; i < _thread_group_hierarchy->length(); ++i) {
116 _thread_group_hierarchy->at(i)->clear_weak_ref();
117 }
118 }
119
120 JfrThreadGroupPointers& JfrThreadGroupsHelper::at(int index) {
121 assert(_thread_group_hierarchy != NULL, "invariant");
122 assert(index > invalid_iterator_pos && index < _thread_group_hierarchy->length(), "invariant");
123 return *(_thread_group_hierarchy->at(index));
124 }
125
126 bool JfrThreadGroupsHelper::has_next() const {
127 return _current_iterator_pos > invalid_iterator_pos;
128 }
129
130 bool JfrThreadGroupsHelper::is_valid() const {
131 return (_thread_group_hierarchy != NULL && _thread_group_hierarchy->length() > 0);
132 }
133
134 JfrThreadGroupPointers& JfrThreadGroupsHelper::next() {
135 assert(is_valid(), "invariant");
136 return at(_current_iterator_pos--);
137 }
138
139 /*
140 * If not at a safepoint, we create global weak references for
141 * all reachable threadgroups for this thread.
142 * If we are at a safepoint, the caller is the VMThread during
143 * JFR checkpointing. It can use naked oops, because nothing
144 * will move before the list of threadgroups is cleared and
145 * mutator threads restarted. The threadgroup list is cleared
146 * later by the VMThread as one of the final steps in JFR checkpointing
147 * (not here).
148 */
149 int JfrThreadGroupsHelper::populate_thread_group_hierarchy(const JavaThread* jt, Thread* current) {
150 assert(jt != NULL && jt->is_Java_thread(), "invariant");
151 assert(current != NULL, "invariant");
152 assert(_thread_group_hierarchy != NULL, "invariant");
153
154 // immediate thread group
155 Handle thread_group_handle(current, java_lang_Thread::threadGroup(jt->threadObj()));
156 if (thread_group_handle == NULL) {
157 return 0;
158 }
159
160 const bool use_weak_handles = !SafepointSynchronize::is_at_safepoint();
161 jweak thread_group_weak_ref = use_weak_handles ? JNIHandles::make_weak_global(thread_group_handle) : NULL;
162
163 JfrThreadGroupPointers* thread_group_pointers = new JfrThreadGroupPointers(thread_group_handle, thread_group_weak_ref);
164 _thread_group_hierarchy->append(thread_group_pointers);
165 // immediate parent thread group
166 oop parent_thread_group_obj = java_lang_ThreadGroup::parent(thread_group_handle());
167 Handle parent_thread_group_handle(current, parent_thread_group_obj);
168
169 // and check parents parents...
170 while (!(parent_thread_group_handle == NULL)) {
171 const jweak parent_group_weak_ref = use_weak_handles ? JNIHandles::make_weak_global(parent_thread_group_handle) : NULL;
172 thread_group_pointers = new JfrThreadGroupPointers(parent_thread_group_handle, parent_group_weak_ref);
173 _thread_group_hierarchy->append(thread_group_pointers);
174 parent_thread_group_obj = java_lang_ThreadGroup::parent(parent_thread_group_handle());
175 parent_thread_group_handle = Handle(current, parent_thread_group_obj);
176 }
177 return _thread_group_hierarchy->length();
178 }
179
180 static traceid next_id() {
181 static traceid _current_threadgroup_id = 0;
182 return ++_current_threadgroup_id;
183 }
184
185 class JfrThreadGroup::JfrThreadGroupEntry : public JfrCHeapObj {
186 friend class JfrThreadGroup;
187 private:
188 traceid _thread_group_id;
189 traceid _parent_group_id;
190 char* _thread_group_name; // utf8 format
191 // If an entry is created during a safepoint, the
192 // _thread_group_oop contains a direct oop to
193 // the java.lang.ThreadGroup object.
194 // If an entry is created on javathread exit time (not at safepoint),
195 // _thread_group_weak_ref contains a JNI weak global handle
196 // indirection to the java.lang.ThreadGroup object.
197 // Note: we cannot use a union here since CHECK_UNHANDLED_OOPS makes oop have
198 // a ctor which isn't allowed in a union by the SunStudio compiler
199 oop _thread_group_oop;
200 jweak _thread_group_weak_ref;
201
202 JfrThreadGroupEntry(const char* tgstr, JfrThreadGroupPointers& ptrs);
203 ~JfrThreadGroupEntry();
204
205 traceid thread_group_id() const { return _thread_group_id; }
206 void set_thread_group_id(traceid tgid) { _thread_group_id = tgid; }
207
208 const char* const thread_group_name() const { return _thread_group_name; }
209 void set_thread_group_name(const char* tgname);
210
211 traceid parent_group_id() const { return _parent_group_id; }
212 void set_parent_group_id(traceid pgid) { _parent_group_id = pgid; }
213
214 void set_thread_group(JfrThreadGroupPointers& ptrs);
215 bool is_equal(const JfrThreadGroupPointers& ptrs) const;
216 const oop thread_group() const;
217 };
218
219 JfrThreadGroup::JfrThreadGroupEntry::JfrThreadGroupEntry(const char* tgname, JfrThreadGroupPointers& ptrs) :
220 _thread_group_id(0),
221 _parent_group_id(0),
222 _thread_group_name(NULL),
223 _thread_group_oop(NULL),
224 _thread_group_weak_ref(NULL) {
225 set_thread_group_name(tgname);
226 set_thread_group(ptrs);
227 }
228
229 JfrThreadGroup::JfrThreadGroupEntry::~JfrThreadGroupEntry() {
230 if (_thread_group_name != NULL) {
231 JfrCHeapObj::free(_thread_group_name, strlen(_thread_group_name) + 1);
232 }
233 if (_thread_group_weak_ref != NULL) {
234 JNIHandles::destroy_weak_global(_thread_group_weak_ref);
235 }
236 }
237
238 void JfrThreadGroup::JfrThreadGroupEntry::set_thread_group_name(const char* tgname) {
239 assert(_thread_group_name == NULL, "invariant");
240 if (tgname != NULL) {
241 size_t len = strlen(tgname);
242 _thread_group_name = JfrCHeapObj::new_array<char>(len+1);
243 strncpy(_thread_group_name, tgname, len);
244 _thread_group_name[len] = '\0';
245 }
246 }
247
248 const oop JfrThreadGroup::JfrThreadGroupEntry::thread_group() const {
249 return _thread_group_weak_ref != NULL ? JNIHandles::resolve(_thread_group_weak_ref) : _thread_group_oop;
250 }
251
252 void JfrThreadGroup::JfrThreadGroupEntry::set_thread_group(JfrThreadGroupPointers& ptrs) {
253 _thread_group_weak_ref = ptrs.transfer_weak_global_handle_ownership();
254 if (_thread_group_weak_ref == NULL) {
255 _thread_group_oop = ptrs.thread_group_oop();
256 assert(_thread_group_oop != NULL, "invariant");
257 } else {
258 _thread_group_oop = NULL;
259 }
260 }
261
262 JfrThreadGroup::JfrThreadGroup() : _list(NULL) {
263 _list = new (ResourceObj::C_HEAP, mtTracing) GrowableArray<JfrThreadGroupEntry*>(30, true);
264 }
265
266 JfrThreadGroup::~JfrThreadGroup() {
267 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
268 if (_list != NULL) {
269 for (int i = 0; i < _list->length(); i++) {
270 JfrThreadGroupEntry* e = _list->at(i);
271 delete e;
272 }
273 delete _list;
274 }
275 }
276
277 JfrThreadGroup* JfrThreadGroup::instance() {
278 return _instance;
279 }
280
281 void JfrThreadGroup::set_instance(JfrThreadGroup* new_instance) {
282 _instance = new_instance;
283 }
284
285 traceid JfrThreadGroup::thread_group_id(const JavaThread* jt, Thread* current) {
286 ResourceMark rm(current);
287 HandleMark hm(current);
288 JfrThreadGroupsHelper helper(jt, current);
289 return helper.is_valid() ? thread_group_id_internal(helper) : 0;
290 }
291
292 traceid JfrThreadGroup::thread_group_id(JavaThread* const jt) {
293 assert(!JfrStream_lock->owned_by_self(), "holding stream lock but should not hold it here");
294 return thread_group_id(jt, jt);
295 }
296
297 traceid JfrThreadGroup::thread_group_id_internal(JfrThreadGroupsHelper& helper) {
298 ThreadGroupExclusiveAccess lock;
299 JfrThreadGroup* tg_instance = instance();
300 if (tg_instance == NULL) {
301 tg_instance = new JfrThreadGroup();
302 if (tg_instance == NULL) {
303 return 0;
304 }
305 set_instance(tg_instance);
306 }
307
308 JfrThreadGroupEntry* tge = NULL;
309 int parent_thread_group_id = 0;
310 while (helper.has_next()) {
311 JfrThreadGroupPointers& ptrs = helper.next();
312 tge = tg_instance->find_entry(ptrs);
313 if (NULL == tge) {
314 tge = tg_instance->new_entry(ptrs);
315 assert(tge != NULL, "invariant");
316 tge->set_parent_group_id(parent_thread_group_id);
317 }
318 parent_thread_group_id = tge->thread_group_id();
319 }
320 // the last entry in the hierarchy is the immediate thread group
321 return tge->thread_group_id();
322 }
323
324 bool JfrThreadGroup::JfrThreadGroupEntry::is_equal(const JfrThreadGroupPointers& ptrs) const {
325 return ptrs.thread_group_oop() == thread_group();
326 }
327
328 JfrThreadGroup::JfrThreadGroupEntry*
329 JfrThreadGroup::find_entry(const JfrThreadGroupPointers& ptrs) const {
330 for (int index = 0; index < _list->length(); ++index) {
331 JfrThreadGroupEntry* curtge = _list->at(index);
332 if (curtge->is_equal(ptrs)) {
333 return curtge;
334 }
335 }
336 return (JfrThreadGroupEntry*) NULL;
337 }
338
339 // Assumes you already searched for the existence
340 // of a corresponding entry in find_entry().
341 JfrThreadGroup::JfrThreadGroupEntry*
342 JfrThreadGroup::new_entry(JfrThreadGroupPointers& ptrs) {
343 JfrThreadGroupEntry* const tge = new JfrThreadGroupEntry(java_lang_ThreadGroup::name(ptrs.thread_group_oop()), ptrs);
344 add_entry(tge);
345 return tge;
346 }
347
348 int JfrThreadGroup::add_entry(JfrThreadGroupEntry* tge) {
349 assert(tge != NULL, "attempting to add a null entry!");
350 assert(0 == tge->thread_group_id(), "id must be unassigned!");
351 tge->set_thread_group_id(next_id());
352 return _list->append(tge);
353 }
354
355 void JfrThreadGroup::write_thread_group_entries(JfrCheckpointWriter& writer) const {
356 assert(_list != NULL && !_list->is_empty(), "should not need be here!");
357 const int number_of_tg_entries = _list->length();
358 writer.write_number_of_constants(number_of_tg_entries);
359 for (int index = 0; index < number_of_tg_entries; ++index) {
360 const JfrThreadGroupEntry* const curtge = _list->at(index);
361 writer.write_key(curtge->thread_group_id());
362 writer.write(curtge->parent_group_id());
363 writer.write(curtge->thread_group_name());
364 }
365 }
366
367 void JfrThreadGroup::write_selective_thread_group(JfrCheckpointWriter* writer, traceid thread_group_id) const {
368 assert(writer != NULL, "invariant");
369 assert(_list != NULL && !_list->is_empty(), "should not need be here!");
370 const int number_of_tg_entries = _list->length();
371
372 // save context
373 const JfrCheckpointContext ctx = writer->context();
374 writer->write_constant_type(CONSTANT_TYPE_THREADGROUP);
375 const jlong count_offset = writer->reserve(sizeof(u4)); // Don't know how many yet
376 int number_of_entries_written = 0;
377 for (int index = number_of_tg_entries - 1; index >= 0; --index) {
378 const JfrThreadGroupEntry* const curtge = _list->at(index);
379 if (thread_group_id == curtge->thread_group_id()) {
380 writer->write_key(curtge->thread_group_id());
381 writer->write(curtge->parent_group_id());
382 writer->write(curtge->thread_group_name());
383 ++number_of_entries_written;
384 thread_group_id = curtge->parent_group_id();
385 }
386 }
387 if (number_of_entries_written == 0) {
388 // nothing to write, restore context
389 writer->set_context(ctx);
390 return;
391 }
392 assert(number_of_entries_written > 0, "invariant");
393 writer->write_number_of_constants(number_of_entries_written, count_offset);
394 }
395
396 // Write out JfrThreadGroup instance and then delete it
397 void JfrThreadGroup::write(JfrCheckpointWriter& writer) {
398 ThreadGroupExclusiveAccess lock;
399 JfrThreadGroup* tg_instance = instance();
400 assert(tg_instance != NULL, "invariant");
401 ResourceManager<JfrThreadGroup> tg_handle(tg_instance);
402 set_instance(NULL);
403 tg_handle->write_thread_group_entries(writer);
404 }
405
406 // for writing a particular thread group
407 void JfrThreadGroup::write(JfrCheckpointWriter* writer, traceid thread_group_id) {
408 assert(writer != NULL, "invariant");
409 ThreadGroupExclusiveAccess lock;
410 JfrThreadGroup* const tg_instance = instance();
411 assert(tg_instance != NULL, "invariant");
412 tg_instance->write_selective_thread_group(writer, thread_group_id);
413 }