Mercurial > hg > truffle
annotate src/share/vm/prims/jvmtiRawMonitor.cpp @ 15177:66e3af78ea96
HSAIL: added safepoint support
Contributed-by: Eric Caspole <eric.caspole@amd.com>
author | Doug Simon <doug.simon@oracle.com> |
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date | Thu, 17 Apr 2014 00:44:32 +0200 |
parents | b9a9ed0f8eeb |
children | ce8f6bb717c9 |
rev | line source |
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1878 | 1 /* |
6842
b9a9ed0f8eeb
7197424: update copyright year to match last edit in jdk8 hotspot repository
mikael
parents:
6197
diff
changeset
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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" | |
28 #include "runtime/thread.hpp" | |
1878 | 29 |
6197 | 30 GrowableArray<JvmtiRawMonitor*> *JvmtiPendingMonitors::_monitors = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<JvmtiRawMonitor*>(1,true); |
1878 | 31 |
32 void JvmtiPendingMonitors::transition_raw_monitors() { | |
33 assert((Threads::number_of_threads()==1), | |
34 "Java thread has not created yet or more than one java thread \ | |
35 is running. Raw monitor transition will not work"); | |
36 JavaThread *current_java_thread = JavaThread::current(); | |
37 assert(current_java_thread->thread_state() == _thread_in_vm, "Must be in vm"); | |
38 { | |
39 ThreadBlockInVM __tbivm(current_java_thread); | |
40 for(int i=0; i< count(); i++) { | |
41 JvmtiRawMonitor *rmonitor = monitors()->at(i); | |
42 int r = rmonitor->raw_enter(current_java_thread); | |
43 assert(r == ObjectMonitor::OM_OK, "raw_enter should have worked"); | |
44 } | |
45 } | |
46 // pending monitors are converted to real monitor so delete them all. | |
47 dispose(); | |
48 } | |
49 | |
50 // | |
51 // class JvmtiRawMonitor | |
52 // | |
53 | |
54 JvmtiRawMonitor::JvmtiRawMonitor(const char *name) { | |
55 #ifdef ASSERT | |
6197 | 56 _name = strcpy(NEW_C_HEAP_ARRAY(char, strlen(name) + 1, mtInternal), name); |
1878 | 57 #else |
58 _name = NULL; | |
59 #endif | |
60 _magic = JVMTI_RM_MAGIC; | |
61 } | |
62 | |
63 JvmtiRawMonitor::~JvmtiRawMonitor() { | |
64 #ifdef ASSERT | |
65 FreeHeap(_name); | |
66 #endif | |
67 _magic = 0; | |
68 } | |
69 | |
70 | |
71 bool | |
72 JvmtiRawMonitor::is_valid() { | |
73 int value = 0; | |
74 | |
75 // This object might not be a JvmtiRawMonitor so we can't assume | |
76 // the _magic field is properly aligned. Get the value in a safe | |
77 // way and then check against JVMTI_RM_MAGIC. | |
78 | |
79 switch (sizeof(_magic)) { | |
80 case 2: | |
81 value = Bytes::get_native_u2((address)&_magic); | |
82 break; | |
83 | |
84 case 4: | |
85 value = Bytes::get_native_u4((address)&_magic); | |
86 break; | |
87 | |
88 case 8: | |
89 value = Bytes::get_native_u8((address)&_magic); | |
90 break; | |
91 | |
92 default: | |
93 guarantee(false, "_magic field is an unexpected size"); | |
94 } | |
95 | |
96 return value == JVMTI_RM_MAGIC; | |
97 } | |
98 | |
99 // ------------------------------------------------------------------------- | |
100 // The raw monitor subsystem is entirely distinct from normal | |
101 // java-synchronization or jni-synchronization. raw monitors are not | |
102 // associated with objects. They can be implemented in any manner | |
103 // that makes sense. The original implementors decided to piggy-back | |
104 // the raw-monitor implementation on the existing Java objectMonitor mechanism. | |
105 // This flaw needs to fixed. We should reimplement raw monitors as sui-generis. | |
106 // Specifically, we should not implement raw monitors via java monitors. | |
107 // Time permitting, we should disentangle and deconvolve the two implementations | |
108 // and move the resulting raw monitor implementation over to the JVMTI directories. | |
109 // Ideally, the raw monitor implementation would be built on top of | |
110 // park-unpark and nothing else. | |
111 // | |
112 // raw monitors are used mainly by JVMTI | |
113 // The raw monitor implementation borrows the ObjectMonitor structure, | |
114 // but the operators are degenerate and extremely simple. | |
115 // | |
116 // Mixed use of a single objectMonitor instance -- as both a raw monitor | |
117 // and a normal java monitor -- is not permissible. | |
118 // | |
119 // Note that we use the single RawMonitor_lock to protect queue operations for | |
120 // _all_ raw monitors. This is a scalability impediment, but since raw monitor usage | |
121 // is deprecated and rare, this is not of concern. The RawMonitor_lock can not | |
122 // be held indefinitely. The critical sections must be short and bounded. | |
123 // | |
124 // ------------------------------------------------------------------------- | |
125 | |
126 int JvmtiRawMonitor::SimpleEnter (Thread * Self) { | |
127 for (;;) { | |
128 if (Atomic::cmpxchg_ptr (Self, &_owner, NULL) == NULL) { | |
129 return OS_OK ; | |
130 } | |
131 | |
132 ObjectWaiter Node (Self) ; | |
133 Self->_ParkEvent->reset() ; // strictly optional | |
134 Node.TState = ObjectWaiter::TS_ENTER ; | |
135 | |
136 RawMonitor_lock->lock_without_safepoint_check() ; | |
137 Node._next = _EntryList ; | |
138 _EntryList = &Node ; | |
139 OrderAccess::fence() ; | |
140 if (_owner == NULL && Atomic::cmpxchg_ptr (Self, &_owner, NULL) == NULL) { | |
141 _EntryList = Node._next ; | |
142 RawMonitor_lock->unlock() ; | |
143 return OS_OK ; | |
144 } | |
145 RawMonitor_lock->unlock() ; | |
146 while (Node.TState == ObjectWaiter::TS_ENTER) { | |
147 Self->_ParkEvent->park() ; | |
148 } | |
149 } | |
150 } | |
151 | |
152 int JvmtiRawMonitor::SimpleExit (Thread * Self) { | |
153 guarantee (_owner == Self, "invariant") ; | |
154 OrderAccess::release_store_ptr (&_owner, NULL) ; | |
155 OrderAccess::fence() ; | |
156 if (_EntryList == NULL) return OS_OK ; | |
157 ObjectWaiter * w ; | |
158 | |
159 RawMonitor_lock->lock_without_safepoint_check() ; | |
160 w = _EntryList ; | |
161 if (w != NULL) { | |
162 _EntryList = w->_next ; | |
163 } | |
164 RawMonitor_lock->unlock() ; | |
165 if (w != NULL) { | |
166 guarantee (w ->TState == ObjectWaiter::TS_ENTER, "invariant") ; | |
167 ParkEvent * ev = w->_event ; | |
168 w->TState = ObjectWaiter::TS_RUN ; | |
169 OrderAccess::fence() ; | |
170 ev->unpark() ; | |
171 } | |
172 return OS_OK ; | |
173 } | |
174 | |
175 int JvmtiRawMonitor::SimpleWait (Thread * Self, jlong millis) { | |
176 guarantee (_owner == Self , "invariant") ; | |
177 guarantee (_recursions == 0, "invariant") ; | |
178 | |
179 ObjectWaiter Node (Self) ; | |
180 Node._notified = 0 ; | |
181 Node.TState = ObjectWaiter::TS_WAIT ; | |
182 | |
183 RawMonitor_lock->lock_without_safepoint_check() ; | |
184 Node._next = _WaitSet ; | |
185 _WaitSet = &Node ; | |
186 RawMonitor_lock->unlock() ; | |
187 | |
188 SimpleExit (Self) ; | |
189 guarantee (_owner != Self, "invariant") ; | |
190 | |
191 int ret = OS_OK ; | |
192 if (millis <= 0) { | |
193 Self->_ParkEvent->park(); | |
194 } else { | |
195 ret = Self->_ParkEvent->park(millis); | |
196 } | |
197 | |
198 // If thread still resides on the waitset then unlink it. | |
199 // Double-checked locking -- the usage is safe in this context | |
200 // as we TState is volatile and the lock-unlock operators are | |
201 // serializing (barrier-equivalent). | |
202 | |
203 if (Node.TState == ObjectWaiter::TS_WAIT) { | |
204 RawMonitor_lock->lock_without_safepoint_check() ; | |
205 if (Node.TState == ObjectWaiter::TS_WAIT) { | |
206 // Simple O(n) unlink, but performance isn't critical here. | |
207 ObjectWaiter * p ; | |
208 ObjectWaiter * q = NULL ; | |
209 for (p = _WaitSet ; p != &Node; p = p->_next) { | |
210 q = p ; | |
211 } | |
212 guarantee (p == &Node, "invariant") ; | |
213 if (q == NULL) { | |
214 guarantee (p == _WaitSet, "invariant") ; | |
215 _WaitSet = p->_next ; | |
216 } else { | |
217 guarantee (p == q->_next, "invariant") ; | |
218 q->_next = p->_next ; | |
219 } | |
220 Node.TState = ObjectWaiter::TS_RUN ; | |
221 } | |
222 RawMonitor_lock->unlock() ; | |
223 } | |
224 | |
225 guarantee (Node.TState == ObjectWaiter::TS_RUN, "invariant") ; | |
226 SimpleEnter (Self) ; | |
227 | |
228 guarantee (_owner == Self, "invariant") ; | |
229 guarantee (_recursions == 0, "invariant") ; | |
230 return ret ; | |
231 } | |
232 | |
233 int JvmtiRawMonitor::SimpleNotify (Thread * Self, bool All) { | |
234 guarantee (_owner == Self, "invariant") ; | |
235 if (_WaitSet == NULL) return OS_OK ; | |
236 | |
237 // We have two options: | |
238 // A. Transfer the threads from the WaitSet to the EntryList | |
239 // B. Remove the thread from the WaitSet and unpark() it. | |
240 // | |
241 // We use (B), which is crude and results in lots of futile | |
242 // context switching. In particular (B) induces lots of contention. | |
243 | |
244 ParkEvent * ev = NULL ; // consider using a small auto array ... | |
245 RawMonitor_lock->lock_without_safepoint_check() ; | |
246 for (;;) { | |
247 ObjectWaiter * w = _WaitSet ; | |
248 if (w == NULL) break ; | |
249 _WaitSet = w->_next ; | |
250 if (ev != NULL) { ev->unpark(); ev = NULL; } | |
251 ev = w->_event ; | |
252 OrderAccess::loadstore() ; | |
253 w->TState = ObjectWaiter::TS_RUN ; | |
254 OrderAccess::storeload(); | |
255 if (!All) break ; | |
256 } | |
257 RawMonitor_lock->unlock() ; | |
258 if (ev != NULL) ev->unpark(); | |
259 return OS_OK ; | |
260 } | |
261 | |
262 // Any JavaThread will enter here with state _thread_blocked | |
263 int JvmtiRawMonitor::raw_enter(TRAPS) { | |
264 TEVENT (raw_enter) ; | |
265 void * Contended ; | |
266 | |
267 // don't enter raw monitor if thread is being externally suspended, it will | |
268 // surprise the suspender if a "suspended" thread can still enter monitor | |
269 JavaThread * jt = (JavaThread *)THREAD; | |
270 if (THREAD->is_Java_thread()) { | |
271 jt->SR_lock()->lock_without_safepoint_check(); | |
272 while (jt->is_external_suspend()) { | |
273 jt->SR_lock()->unlock(); | |
274 jt->java_suspend_self(); | |
275 jt->SR_lock()->lock_without_safepoint_check(); | |
276 } | |
277 // guarded by SR_lock to avoid racing with new external suspend requests. | |
278 Contended = Atomic::cmpxchg_ptr (THREAD, &_owner, NULL) ; | |
279 jt->SR_lock()->unlock(); | |
280 } else { | |
281 Contended = Atomic::cmpxchg_ptr (THREAD, &_owner, NULL) ; | |
282 } | |
283 | |
284 if (Contended == THREAD) { | |
285 _recursions ++ ; | |
286 return OM_OK ; | |
287 } | |
288 | |
289 if (Contended == NULL) { | |
290 guarantee (_owner == THREAD, "invariant") ; | |
291 guarantee (_recursions == 0, "invariant") ; | |
292 return OM_OK ; | |
293 } | |
294 | |
295 THREAD->set_current_pending_monitor(this); | |
296 | |
297 if (!THREAD->is_Java_thread()) { | |
298 // No other non-Java threads besides VM thread would acquire | |
299 // a raw monitor. | |
300 assert(THREAD->is_VM_thread(), "must be VM thread"); | |
301 SimpleEnter (THREAD) ; | |
302 } else { | |
303 guarantee (jt->thread_state() == _thread_blocked, "invariant") ; | |
304 for (;;) { | |
305 jt->set_suspend_equivalent(); | |
306 // cleared by handle_special_suspend_equivalent_condition() or | |
307 // java_suspend_self() | |
308 SimpleEnter (THREAD) ; | |
309 | |
310 // were we externally suspended while we were waiting? | |
311 if (!jt->handle_special_suspend_equivalent_condition()) break ; | |
312 | |
313 // This thread was externally suspended | |
314 // | |
315 // This logic isn't needed for JVMTI raw monitors, | |
316 // but doesn't hurt just in case the suspend rules change. This | |
317 // logic is needed for the JvmtiRawMonitor.wait() reentry phase. | |
318 // We have reentered the contended monitor, but while we were | |
319 // waiting another thread suspended us. We don't want to reenter | |
320 // the monitor while suspended because that would surprise the | |
321 // thread that suspended us. | |
322 // | |
323 // Drop the lock - | |
324 SimpleExit (THREAD) ; | |
325 | |
326 jt->java_suspend_self(); | |
327 } | |
328 | |
329 assert(_owner == THREAD, "Fatal error with monitor owner!"); | |
330 assert(_recursions == 0, "Fatal error with monitor recursions!"); | |
331 } | |
332 | |
333 THREAD->set_current_pending_monitor(NULL); | |
334 guarantee (_recursions == 0, "invariant") ; | |
335 return OM_OK; | |
336 } | |
337 | |
338 // Used mainly for JVMTI raw monitor implementation | |
339 // Also used for JvmtiRawMonitor::wait(). | |
340 int JvmtiRawMonitor::raw_exit(TRAPS) { | |
341 TEVENT (raw_exit) ; | |
342 if (THREAD != _owner) { | |
343 return OM_ILLEGAL_MONITOR_STATE; | |
344 } | |
345 if (_recursions > 0) { | |
346 --_recursions ; | |
347 return OM_OK ; | |
348 } | |
349 | |
350 void * List = _EntryList ; | |
351 SimpleExit (THREAD) ; | |
352 | |
353 return OM_OK; | |
354 } | |
355 | |
356 // Used for JVMTI raw monitor implementation. | |
357 // All JavaThreads will enter here with state _thread_blocked | |
358 | |
359 int JvmtiRawMonitor::raw_wait(jlong millis, bool interruptible, TRAPS) { | |
360 TEVENT (raw_wait) ; | |
361 if (THREAD != _owner) { | |
362 return OM_ILLEGAL_MONITOR_STATE; | |
363 } | |
364 | |
365 // To avoid spurious wakeups we reset the parkevent -- This is strictly optional. | |
366 // The caller must be able to tolerate spurious returns from raw_wait(). | |
367 THREAD->_ParkEvent->reset() ; | |
368 OrderAccess::fence() ; | |
369 | |
370 // check interrupt event | |
371 if (interruptible && Thread::is_interrupted(THREAD, true)) { | |
372 return OM_INTERRUPTED; | |
373 } | |
374 | |
375 intptr_t save = _recursions ; | |
376 _recursions = 0 ; | |
377 _waiters ++ ; | |
378 if (THREAD->is_Java_thread()) { | |
379 guarantee (((JavaThread *) THREAD)->thread_state() == _thread_blocked, "invariant") ; | |
380 ((JavaThread *)THREAD)->set_suspend_equivalent(); | |
381 } | |
382 int rv = SimpleWait (THREAD, millis) ; | |
383 _recursions = save ; | |
384 _waiters -- ; | |
385 | |
386 guarantee (THREAD == _owner, "invariant") ; | |
387 if (THREAD->is_Java_thread()) { | |
388 JavaThread * jSelf = (JavaThread *) THREAD ; | |
389 for (;;) { | |
390 if (!jSelf->handle_special_suspend_equivalent_condition()) break ; | |
391 SimpleExit (THREAD) ; | |
392 jSelf->java_suspend_self(); | |
393 SimpleEnter (THREAD) ; | |
394 jSelf->set_suspend_equivalent() ; | |
395 } | |
396 } | |
397 guarantee (THREAD == _owner, "invariant") ; | |
398 | |
399 if (interruptible && Thread::is_interrupted(THREAD, true)) { | |
400 return OM_INTERRUPTED; | |
401 } | |
402 return OM_OK ; | |
403 } | |
404 | |
405 int JvmtiRawMonitor::raw_notify(TRAPS) { | |
406 TEVENT (raw_notify) ; | |
407 if (THREAD != _owner) { | |
408 return OM_ILLEGAL_MONITOR_STATE; | |
409 } | |
410 SimpleNotify (THREAD, false) ; | |
411 return OM_OK; | |
412 } | |
413 | |
414 int JvmtiRawMonitor::raw_notifyAll(TRAPS) { | |
415 TEVENT (raw_notifyAll) ; | |
416 if (THREAD != _owner) { | |
417 return OM_ILLEGAL_MONITOR_STATE; | |
418 } | |
419 SimpleNotify (THREAD, true) ; | |
420 return OM_OK; | |
421 } | |
422 |