Mercurial > hg > truffle
annotate src/share/vm/prims/jvmtiRawMonitor.cpp @ 20261:27188ae8bbbb
8035648: Don't use Handle in java_lang_String::print
Reviewed-by: coleenp, pliden
author | stefank |
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date | Thu, 27 Feb 2014 10:34:55 +0100 |
parents | ce8f6bb717c9 |
children |
rev | line source |
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1878 | 1 /* |
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mikael
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2 * Copyright (c) 2003, 2012, Oracle and/or its affiliates. All rights reserved. |
1878 | 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 | |
1972 | 25 #include "precompiled.hpp" |
26 #include "prims/jvmtiRawMonitor.hpp" | |
27 #include "runtime/interfaceSupport.hpp" | |
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28 #include "runtime/orderAccess.inline.hpp" |
ce8f6bb717c9
8042195: Introduce umbrella header orderAccess.inline.hpp.
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29 #include "runtime/thread.inline.hpp" |
1878 | 30 |
6197 | 31 GrowableArray<JvmtiRawMonitor*> *JvmtiPendingMonitors::_monitors = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<JvmtiRawMonitor*>(1,true); |
1878 | 32 |
33 void JvmtiPendingMonitors::transition_raw_monitors() { | |
34 assert((Threads::number_of_threads()==1), | |
35 "Java thread has not created yet or more than one java thread \ | |
36 is running. Raw monitor transition will not work"); | |
37 JavaThread *current_java_thread = JavaThread::current(); | |
38 assert(current_java_thread->thread_state() == _thread_in_vm, "Must be in vm"); | |
39 { | |
40 ThreadBlockInVM __tbivm(current_java_thread); | |
41 for(int i=0; i< count(); i++) { | |
42 JvmtiRawMonitor *rmonitor = monitors()->at(i); | |
43 int r = rmonitor->raw_enter(current_java_thread); | |
44 assert(r == ObjectMonitor::OM_OK, "raw_enter should have worked"); | |
45 } | |
46 } | |
47 // pending monitors are converted to real monitor so delete them all. | |
48 dispose(); | |
49 } | |
50 | |
51 // | |
52 // class JvmtiRawMonitor | |
53 // | |
54 | |
55 JvmtiRawMonitor::JvmtiRawMonitor(const char *name) { | |
56 #ifdef ASSERT | |
6197 | 57 _name = strcpy(NEW_C_HEAP_ARRAY(char, strlen(name) + 1, mtInternal), name); |
1878 | 58 #else |
59 _name = NULL; | |
60 #endif | |
61 _magic = JVMTI_RM_MAGIC; | |
62 } | |
63 | |
64 JvmtiRawMonitor::~JvmtiRawMonitor() { | |
65 #ifdef ASSERT | |
66 FreeHeap(_name); | |
67 #endif | |
68 _magic = 0; | |
69 } | |
70 | |
71 | |
72 bool | |
73 JvmtiRawMonitor::is_valid() { | |
74 int value = 0; | |
75 | |
76 // This object might not be a JvmtiRawMonitor so we can't assume | |
77 // the _magic field is properly aligned. Get the value in a safe | |
78 // way and then check against JVMTI_RM_MAGIC. | |
79 | |
80 switch (sizeof(_magic)) { | |
81 case 2: | |
82 value = Bytes::get_native_u2((address)&_magic); | |
83 break; | |
84 | |
85 case 4: | |
86 value = Bytes::get_native_u4((address)&_magic); | |
87 break; | |
88 | |
89 case 8: | |
90 value = Bytes::get_native_u8((address)&_magic); | |
91 break; | |
92 | |
93 default: | |
94 guarantee(false, "_magic field is an unexpected size"); | |
95 } | |
96 | |
97 return value == JVMTI_RM_MAGIC; | |
98 } | |
99 | |
100 // ------------------------------------------------------------------------- | |
101 // The raw monitor subsystem is entirely distinct from normal | |
102 // java-synchronization or jni-synchronization. raw monitors are not | |
103 // associated with objects. They can be implemented in any manner | |
104 // that makes sense. The original implementors decided to piggy-back | |
105 // the raw-monitor implementation on the existing Java objectMonitor mechanism. | |
106 // This flaw needs to fixed. We should reimplement raw monitors as sui-generis. | |
107 // Specifically, we should not implement raw monitors via java monitors. | |
108 // Time permitting, we should disentangle and deconvolve the two implementations | |
109 // and move the resulting raw monitor implementation over to the JVMTI directories. | |
110 // Ideally, the raw monitor implementation would be built on top of | |
111 // park-unpark and nothing else. | |
112 // | |
113 // raw monitors are used mainly by JVMTI | |
114 // The raw monitor implementation borrows the ObjectMonitor structure, | |
115 // but the operators are degenerate and extremely simple. | |
116 // | |
117 // Mixed use of a single objectMonitor instance -- as both a raw monitor | |
118 // and a normal java monitor -- is not permissible. | |
119 // | |
120 // Note that we use the single RawMonitor_lock to protect queue operations for | |
121 // _all_ raw monitors. This is a scalability impediment, but since raw monitor usage | |
122 // is deprecated and rare, this is not of concern. The RawMonitor_lock can not | |
123 // be held indefinitely. The critical sections must be short and bounded. | |
124 // | |
125 // ------------------------------------------------------------------------- | |
126 | |
127 int JvmtiRawMonitor::SimpleEnter (Thread * Self) { | |
128 for (;;) { | |
129 if (Atomic::cmpxchg_ptr (Self, &_owner, NULL) == NULL) { | |
130 return OS_OK ; | |
131 } | |
132 | |
133 ObjectWaiter Node (Self) ; | |
134 Self->_ParkEvent->reset() ; // strictly optional | |
135 Node.TState = ObjectWaiter::TS_ENTER ; | |
136 | |
137 RawMonitor_lock->lock_without_safepoint_check() ; | |
138 Node._next = _EntryList ; | |
139 _EntryList = &Node ; | |
140 OrderAccess::fence() ; | |
141 if (_owner == NULL && Atomic::cmpxchg_ptr (Self, &_owner, NULL) == NULL) { | |
142 _EntryList = Node._next ; | |
143 RawMonitor_lock->unlock() ; | |
144 return OS_OK ; | |
145 } | |
146 RawMonitor_lock->unlock() ; | |
147 while (Node.TState == ObjectWaiter::TS_ENTER) { | |
148 Self->_ParkEvent->park() ; | |
149 } | |
150 } | |
151 } | |
152 | |
153 int JvmtiRawMonitor::SimpleExit (Thread * Self) { | |
154 guarantee (_owner == Self, "invariant") ; | |
155 OrderAccess::release_store_ptr (&_owner, NULL) ; | |
156 OrderAccess::fence() ; | |
157 if (_EntryList == NULL) return OS_OK ; | |
158 ObjectWaiter * w ; | |
159 | |
160 RawMonitor_lock->lock_without_safepoint_check() ; | |
161 w = _EntryList ; | |
162 if (w != NULL) { | |
163 _EntryList = w->_next ; | |
164 } | |
165 RawMonitor_lock->unlock() ; | |
166 if (w != NULL) { | |
167 guarantee (w ->TState == ObjectWaiter::TS_ENTER, "invariant") ; | |
168 ParkEvent * ev = w->_event ; | |
169 w->TState = ObjectWaiter::TS_RUN ; | |
170 OrderAccess::fence() ; | |
171 ev->unpark() ; | |
172 } | |
173 return OS_OK ; | |
174 } | |
175 | |
176 int JvmtiRawMonitor::SimpleWait (Thread * Self, jlong millis) { | |
177 guarantee (_owner == Self , "invariant") ; | |
178 guarantee (_recursions == 0, "invariant") ; | |
179 | |
180 ObjectWaiter Node (Self) ; | |
181 Node._notified = 0 ; | |
182 Node.TState = ObjectWaiter::TS_WAIT ; | |
183 | |
184 RawMonitor_lock->lock_without_safepoint_check() ; | |
185 Node._next = _WaitSet ; | |
186 _WaitSet = &Node ; | |
187 RawMonitor_lock->unlock() ; | |
188 | |
189 SimpleExit (Self) ; | |
190 guarantee (_owner != Self, "invariant") ; | |
191 | |
192 int ret = OS_OK ; | |
193 if (millis <= 0) { | |
194 Self->_ParkEvent->park(); | |
195 } else { | |
196 ret = Self->_ParkEvent->park(millis); | |
197 } | |
198 | |
199 // If thread still resides on the waitset then unlink it. | |
200 // Double-checked locking -- the usage is safe in this context | |
201 // as we TState is volatile and the lock-unlock operators are | |
202 // serializing (barrier-equivalent). | |
203 | |
204 if (Node.TState == ObjectWaiter::TS_WAIT) { | |
205 RawMonitor_lock->lock_without_safepoint_check() ; | |
206 if (Node.TState == ObjectWaiter::TS_WAIT) { | |
207 // Simple O(n) unlink, but performance isn't critical here. | |
208 ObjectWaiter * p ; | |
209 ObjectWaiter * q = NULL ; | |
210 for (p = _WaitSet ; p != &Node; p = p->_next) { | |
211 q = p ; | |
212 } | |
213 guarantee (p == &Node, "invariant") ; | |
214 if (q == NULL) { | |
215 guarantee (p == _WaitSet, "invariant") ; | |
216 _WaitSet = p->_next ; | |
217 } else { | |
218 guarantee (p == q->_next, "invariant") ; | |
219 q->_next = p->_next ; | |
220 } | |
221 Node.TState = ObjectWaiter::TS_RUN ; | |
222 } | |
223 RawMonitor_lock->unlock() ; | |
224 } | |
225 | |
226 guarantee (Node.TState == ObjectWaiter::TS_RUN, "invariant") ; | |
227 SimpleEnter (Self) ; | |
228 | |
229 guarantee (_owner == Self, "invariant") ; | |
230 guarantee (_recursions == 0, "invariant") ; | |
231 return ret ; | |
232 } | |
233 | |
234 int JvmtiRawMonitor::SimpleNotify (Thread * Self, bool All) { | |
235 guarantee (_owner == Self, "invariant") ; | |
236 if (_WaitSet == NULL) return OS_OK ; | |
237 | |
238 // We have two options: | |
239 // A. Transfer the threads from the WaitSet to the EntryList | |
240 // B. Remove the thread from the WaitSet and unpark() it. | |
241 // | |
242 // We use (B), which is crude and results in lots of futile | |
243 // context switching. In particular (B) induces lots of contention. | |
244 | |
245 ParkEvent * ev = NULL ; // consider using a small auto array ... | |
246 RawMonitor_lock->lock_without_safepoint_check() ; | |
247 for (;;) { | |
248 ObjectWaiter * w = _WaitSet ; | |
249 if (w == NULL) break ; | |
250 _WaitSet = w->_next ; | |
251 if (ev != NULL) { ev->unpark(); ev = NULL; } | |
252 ev = w->_event ; | |
253 OrderAccess::loadstore() ; | |
254 w->TState = ObjectWaiter::TS_RUN ; | |
255 OrderAccess::storeload(); | |
256 if (!All) break ; | |
257 } | |
258 RawMonitor_lock->unlock() ; | |
259 if (ev != NULL) ev->unpark(); | |
260 return OS_OK ; | |
261 } | |
262 | |
263 // Any JavaThread will enter here with state _thread_blocked | |
264 int JvmtiRawMonitor::raw_enter(TRAPS) { | |
265 TEVENT (raw_enter) ; | |
266 void * Contended ; | |
267 | |
268 // don't enter raw monitor if thread is being externally suspended, it will | |
269 // surprise the suspender if a "suspended" thread can still enter monitor | |
270 JavaThread * jt = (JavaThread *)THREAD; | |
271 if (THREAD->is_Java_thread()) { | |
272 jt->SR_lock()->lock_without_safepoint_check(); | |
273 while (jt->is_external_suspend()) { | |
274 jt->SR_lock()->unlock(); | |
275 jt->java_suspend_self(); | |
276 jt->SR_lock()->lock_without_safepoint_check(); | |
277 } | |
278 // guarded by SR_lock to avoid racing with new external suspend requests. | |
279 Contended = Atomic::cmpxchg_ptr (THREAD, &_owner, NULL) ; | |
280 jt->SR_lock()->unlock(); | |
281 } else { | |
282 Contended = Atomic::cmpxchg_ptr (THREAD, &_owner, NULL) ; | |
283 } | |
284 | |
285 if (Contended == THREAD) { | |
286 _recursions ++ ; | |
287 return OM_OK ; | |
288 } | |
289 | |
290 if (Contended == NULL) { | |
291 guarantee (_owner == THREAD, "invariant") ; | |
292 guarantee (_recursions == 0, "invariant") ; | |
293 return OM_OK ; | |
294 } | |
295 | |
296 THREAD->set_current_pending_monitor(this); | |
297 | |
298 if (!THREAD->is_Java_thread()) { | |
299 // No other non-Java threads besides VM thread would acquire | |
300 // a raw monitor. | |
301 assert(THREAD->is_VM_thread(), "must be VM thread"); | |
302 SimpleEnter (THREAD) ; | |
303 } else { | |
304 guarantee (jt->thread_state() == _thread_blocked, "invariant") ; | |
305 for (;;) { | |
306 jt->set_suspend_equivalent(); | |
307 // cleared by handle_special_suspend_equivalent_condition() or | |
308 // java_suspend_self() | |
309 SimpleEnter (THREAD) ; | |
310 | |
311 // were we externally suspended while we were waiting? | |
312 if (!jt->handle_special_suspend_equivalent_condition()) break ; | |
313 | |
314 // This thread was externally suspended | |
315 // | |
316 // This logic isn't needed for JVMTI raw monitors, | |
317 // but doesn't hurt just in case the suspend rules change. This | |
318 // logic is needed for the JvmtiRawMonitor.wait() reentry phase. | |
319 // We have reentered the contended monitor, but while we were | |
320 // waiting another thread suspended us. We don't want to reenter | |
321 // the monitor while suspended because that would surprise the | |
322 // thread that suspended us. | |
323 // | |
324 // Drop the lock - | |
325 SimpleExit (THREAD) ; | |
326 | |
327 jt->java_suspend_self(); | |
328 } | |
329 | |
330 assert(_owner == THREAD, "Fatal error with monitor owner!"); | |
331 assert(_recursions == 0, "Fatal error with monitor recursions!"); | |
332 } | |
333 | |
334 THREAD->set_current_pending_monitor(NULL); | |
335 guarantee (_recursions == 0, "invariant") ; | |
336 return OM_OK; | |
337 } | |
338 | |
339 // Used mainly for JVMTI raw monitor implementation | |
340 // Also used for JvmtiRawMonitor::wait(). | |
341 int JvmtiRawMonitor::raw_exit(TRAPS) { | |
342 TEVENT (raw_exit) ; | |
343 if (THREAD != _owner) { | |
344 return OM_ILLEGAL_MONITOR_STATE; | |
345 } | |
346 if (_recursions > 0) { | |
347 --_recursions ; | |
348 return OM_OK ; | |
349 } | |
350 | |
351 void * List = _EntryList ; | |
352 SimpleExit (THREAD) ; | |
353 | |
354 return OM_OK; | |
355 } | |
356 | |
357 // Used for JVMTI raw monitor implementation. | |
358 // All JavaThreads will enter here with state _thread_blocked | |
359 | |
360 int JvmtiRawMonitor::raw_wait(jlong millis, bool interruptible, TRAPS) { | |
361 TEVENT (raw_wait) ; | |
362 if (THREAD != _owner) { | |
363 return OM_ILLEGAL_MONITOR_STATE; | |
364 } | |
365 | |
366 // To avoid spurious wakeups we reset the parkevent -- This is strictly optional. | |
367 // The caller must be able to tolerate spurious returns from raw_wait(). | |
368 THREAD->_ParkEvent->reset() ; | |
369 OrderAccess::fence() ; | |
370 | |
371 // check interrupt event | |
372 if (interruptible && Thread::is_interrupted(THREAD, true)) { | |
373 return OM_INTERRUPTED; | |
374 } | |
375 | |
376 intptr_t save = _recursions ; | |
377 _recursions = 0 ; | |
378 _waiters ++ ; | |
379 if (THREAD->is_Java_thread()) { | |
380 guarantee (((JavaThread *) THREAD)->thread_state() == _thread_blocked, "invariant") ; | |
381 ((JavaThread *)THREAD)->set_suspend_equivalent(); | |
382 } | |
383 int rv = SimpleWait (THREAD, millis) ; | |
384 _recursions = save ; | |
385 _waiters -- ; | |
386 | |
387 guarantee (THREAD == _owner, "invariant") ; | |
388 if (THREAD->is_Java_thread()) { | |
389 JavaThread * jSelf = (JavaThread *) THREAD ; | |
390 for (;;) { | |
391 if (!jSelf->handle_special_suspend_equivalent_condition()) break ; | |
392 SimpleExit (THREAD) ; | |
393 jSelf->java_suspend_self(); | |
394 SimpleEnter (THREAD) ; | |
395 jSelf->set_suspend_equivalent() ; | |
396 } | |
397 } | |
398 guarantee (THREAD == _owner, "invariant") ; | |
399 | |
400 if (interruptible && Thread::is_interrupted(THREAD, true)) { | |
401 return OM_INTERRUPTED; | |
402 } | |
403 return OM_OK ; | |
404 } | |
405 | |
406 int JvmtiRawMonitor::raw_notify(TRAPS) { | |
407 TEVENT (raw_notify) ; | |
408 if (THREAD != _owner) { | |
409 return OM_ILLEGAL_MONITOR_STATE; | |
410 } | |
411 SimpleNotify (THREAD, false) ; | |
412 return OM_OK; | |
413 } | |
414 | |
415 int JvmtiRawMonitor::raw_notifyAll(TRAPS) { | |
416 TEVENT (raw_notifyAll) ; | |
417 if (THREAD != _owner) { | |
418 return OM_ILLEGAL_MONITOR_STATE; | |
419 } | |
420 SimpleNotify (THREAD, true) ; | |
421 return OM_OK; | |
422 } | |
423 |