Mercurial > hg > graal-compiler
comparison src/share/vm/runtime/jniHandles.cpp @ 0:a61af66fc99e jdk7-b24
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author | duke |
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date | Sat, 01 Dec 2007 00:00:00 +0000 |
parents | |
children | ba764ed4b6f2 |
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1 /* | |
2 * Copyright 1998-2007 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, | |
20 * CA 95054 USA or visit www.sun.com if you need additional information or | |
21 * have any questions. | |
22 * | |
23 */ | |
24 | |
25 # include "incls/_precompiled.incl" | |
26 # include "incls/_jniHandles.cpp.incl" | |
27 | |
28 | |
29 JNIHandleBlock* JNIHandles::_global_handles = NULL; | |
30 JNIHandleBlock* JNIHandles::_weak_global_handles = NULL; | |
31 oop JNIHandles::_deleted_handle = NULL; | |
32 | |
33 | |
34 jobject JNIHandles::make_local(oop obj) { | |
35 if (obj == NULL) { | |
36 return NULL; // ignore null handles | |
37 } else { | |
38 Thread* thread = Thread::current(); | |
39 assert(Universe::heap()->is_in_reserved(obj), "sanity check"); | |
40 return thread->active_handles()->allocate_handle(obj); | |
41 } | |
42 } | |
43 | |
44 | |
45 // optimized versions | |
46 | |
47 jobject JNIHandles::make_local(Thread* thread, oop obj) { | |
48 if (obj == NULL) { | |
49 return NULL; // ignore null handles | |
50 } else { | |
51 assert(Universe::heap()->is_in_reserved(obj), "sanity check"); | |
52 return thread->active_handles()->allocate_handle(obj); | |
53 } | |
54 } | |
55 | |
56 | |
57 jobject JNIHandles::make_local(JNIEnv* env, oop obj) { | |
58 if (obj == NULL) { | |
59 return NULL; // ignore null handles | |
60 } else { | |
61 JavaThread* thread = JavaThread::thread_from_jni_environment(env); | |
62 assert(Universe::heap()->is_in_reserved(obj), "sanity check"); | |
63 return thread->active_handles()->allocate_handle(obj); | |
64 } | |
65 } | |
66 | |
67 | |
68 jobject JNIHandles::make_global(Handle obj) { | |
69 jobject res = NULL; | |
70 if (!obj.is_null()) { | |
71 // ignore null handles | |
72 MutexLocker ml(JNIGlobalHandle_lock); | |
73 assert(Universe::heap()->is_in_reserved(obj()), "sanity check"); | |
74 res = _global_handles->allocate_handle(obj()); | |
75 } else { | |
76 CHECK_UNHANDLED_OOPS_ONLY(Thread::current()->clear_unhandled_oops()); | |
77 } | |
78 | |
79 return res; | |
80 } | |
81 | |
82 | |
83 jobject JNIHandles::make_weak_global(Handle obj) { | |
84 jobject res = NULL; | |
85 if (!obj.is_null()) { | |
86 // ignore null handles | |
87 MutexLocker ml(JNIGlobalHandle_lock); | |
88 assert(Universe::heap()->is_in_reserved(obj()), "sanity check"); | |
89 res = _weak_global_handles->allocate_handle(obj()); | |
90 } else { | |
91 CHECK_UNHANDLED_OOPS_ONLY(Thread::current()->clear_unhandled_oops()); | |
92 } | |
93 return res; | |
94 } | |
95 | |
96 jmethodID JNIHandles::make_jmethod_id(methodHandle mh) { | |
97 return (jmethodID) make_weak_global(mh); | |
98 } | |
99 | |
100 | |
101 | |
102 void JNIHandles::change_method_associated_with_jmethod_id(jmethodID jmid, methodHandle mh) { | |
103 MutexLocker ml(JNIGlobalHandle_lock); // Is this necessary? | |
104 Handle obj = (Handle)mh; | |
105 oop* jobj = (oop*)jmid; | |
106 *jobj = obj(); | |
107 } | |
108 | |
109 | |
110 void JNIHandles::destroy_global(jobject handle) { | |
111 if (handle != NULL) { | |
112 assert(is_global_handle(handle), "Invalid delete of global JNI handle"); | |
113 *((oop*)handle) = deleted_handle(); // Mark the handle as deleted, allocate will reuse it | |
114 } | |
115 } | |
116 | |
117 | |
118 void JNIHandles::destroy_weak_global(jobject handle) { | |
119 if (handle != NULL) { | |
120 assert(!CheckJNICalls || is_weak_global_handle(handle), "Invalid delete of weak global JNI handle"); | |
121 *((oop*)handle) = deleted_handle(); // Mark the handle as deleted, allocate will reuse it | |
122 } | |
123 } | |
124 | |
125 void JNIHandles::destroy_jmethod_id(jmethodID mid) { | |
126 destroy_weak_global((jobject)mid); | |
127 } | |
128 | |
129 | |
130 void JNIHandles::oops_do(OopClosure* f) { | |
131 f->do_oop(&_deleted_handle); | |
132 _global_handles->oops_do(f); | |
133 } | |
134 | |
135 | |
136 void JNIHandles::weak_oops_do(BoolObjectClosure* is_alive, OopClosure* f) { | |
137 _weak_global_handles->weak_oops_do(is_alive, f); | |
138 } | |
139 | |
140 | |
141 void JNIHandles::initialize() { | |
142 _global_handles = JNIHandleBlock::allocate_block(); | |
143 _weak_global_handles = JNIHandleBlock::allocate_block(); | |
144 EXCEPTION_MARK; | |
145 // We will never reach the CATCH below since Exceptions::_throw will cause | |
146 // the VM to exit if an exception is thrown during initialization | |
147 klassOop k = SystemDictionary::object_klass(); | |
148 _deleted_handle = instanceKlass::cast(k)->allocate_permanent_instance(CATCH); | |
149 } | |
150 | |
151 | |
152 bool JNIHandles::is_local_handle(Thread* thread, jobject handle) { | |
153 JNIHandleBlock* block = thread->active_handles(); | |
154 | |
155 // Look back past possible native calls to jni_PushLocalFrame. | |
156 while (block != NULL) { | |
157 if (block->chain_contains(handle)) { | |
158 return true; | |
159 } | |
160 block = block->pop_frame_link(); | |
161 } | |
162 return false; | |
163 } | |
164 | |
165 | |
166 // Determine if the handle is somewhere in the current thread's stack. | |
167 // We easily can't isolate any particular stack frame the handle might | |
168 // come from, so we'll check the whole stack. | |
169 | |
170 bool JNIHandles::is_frame_handle(JavaThread* thr, jobject obj) { | |
171 // If there is no java frame, then this must be top level code, such | |
172 // as the java command executable, in which case, this type of handle | |
173 // is not permitted. | |
174 return (thr->has_last_Java_frame() && | |
175 (void*)obj < (void*)thr->stack_base() && | |
176 (void*)obj >= (void*)thr->last_Java_sp()); | |
177 } | |
178 | |
179 | |
180 bool JNIHandles::is_global_handle(jobject handle) { | |
181 return _global_handles->chain_contains(handle); | |
182 } | |
183 | |
184 | |
185 bool JNIHandles::is_weak_global_handle(jobject handle) { | |
186 return _weak_global_handles->chain_contains(handle); | |
187 } | |
188 | |
189 long JNIHandles::global_handle_memory_usage() { | |
190 return _global_handles->memory_usage(); | |
191 } | |
192 | |
193 long JNIHandles::weak_global_handle_memory_usage() { | |
194 return _weak_global_handles->memory_usage(); | |
195 } | |
196 | |
197 | |
198 class AlwaysAliveClosure: public BoolObjectClosure { | |
199 public: | |
200 bool do_object_b(oop obj) { return true; } | |
201 void do_object(oop obj) { assert(false, "Don't call"); } | |
202 }; | |
203 | |
204 class CountHandleClosure: public OopClosure { | |
205 private: | |
206 int _count; | |
207 public: | |
208 CountHandleClosure(): _count(0) {} | |
209 void do_oop(oop* unused) { | |
210 _count++; | |
211 } | |
212 int count() { return _count; } | |
213 }; | |
214 | |
215 // We assume this is called at a safepoint: no lock is needed. | |
216 void JNIHandles::print_on(outputStream* st) { | |
217 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint"); | |
218 assert(_global_handles != NULL && _weak_global_handles != NULL, | |
219 "JNIHandles not initialized"); | |
220 | |
221 CountHandleClosure global_handle_count; | |
222 AlwaysAliveClosure always_alive; | |
223 oops_do(&global_handle_count); | |
224 weak_oops_do(&always_alive, &global_handle_count); | |
225 | |
226 st->print_cr("JNI global references: %d", global_handle_count.count()); | |
227 st->cr(); | |
228 st->flush(); | |
229 } | |
230 | |
231 class VerifyHandleClosure: public OopClosure { | |
232 public: | |
233 void do_oop(oop* root) { | |
234 (*root)->verify(); | |
235 } | |
236 }; | |
237 | |
238 void JNIHandles::verify() { | |
239 VerifyHandleClosure verify_handle; | |
240 AlwaysAliveClosure always_alive; | |
241 | |
242 oops_do(&verify_handle); | |
243 weak_oops_do(&always_alive, &verify_handle); | |
244 } | |
245 | |
246 | |
247 | |
248 void jni_handles_init() { | |
249 JNIHandles::initialize(); | |
250 } | |
251 | |
252 | |
253 int JNIHandleBlock::_blocks_allocated = 0; | |
254 JNIHandleBlock* JNIHandleBlock::_block_free_list = NULL; | |
255 #ifndef PRODUCT | |
256 JNIHandleBlock* JNIHandleBlock::_block_list = NULL; | |
257 #endif | |
258 | |
259 | |
260 void JNIHandleBlock::zap() { | |
261 // Zap block values | |
262 _top = 0; | |
263 for (int index = 0; index < block_size_in_oops; index++) { | |
264 _handles[index] = badJNIHandle; | |
265 } | |
266 } | |
267 | |
268 JNIHandleBlock* JNIHandleBlock::allocate_block(Thread* thread) { | |
269 assert(thread == NULL || thread == Thread::current(), "sanity check"); | |
270 JNIHandleBlock* block; | |
271 // Check the thread-local free list for a block so we don't | |
272 // have to acquire a mutex. | |
273 if (thread != NULL && thread->free_handle_block() != NULL) { | |
274 block = thread->free_handle_block(); | |
275 thread->set_free_handle_block(block->_next); | |
276 } | |
277 else { | |
278 // locking with safepoint checking introduces a potential deadlock: | |
279 // - we would hold JNIHandleBlockFreeList_lock and then Threads_lock | |
280 // - another would hold Threads_lock (jni_AttachCurrentThread) and then | |
281 // JNIHandleBlockFreeList_lock (JNIHandleBlock::allocate_block) | |
282 MutexLockerEx ml(JNIHandleBlockFreeList_lock, | |
283 Mutex::_no_safepoint_check_flag); | |
284 if (_block_free_list == NULL) { | |
285 // Allocate new block | |
286 block = new JNIHandleBlock(); | |
287 _blocks_allocated++; | |
288 if (TraceJNIHandleAllocation) { | |
289 tty->print_cr("JNIHandleBlock " INTPTR_FORMAT " allocated (%d total blocks)", | |
290 block, _blocks_allocated); | |
291 } | |
292 if (ZapJNIHandleArea) block->zap(); | |
293 #ifndef PRODUCT | |
294 // Link new block to list of all allocated blocks | |
295 block->_block_list_link = _block_list; | |
296 _block_list = block; | |
297 #endif | |
298 } else { | |
299 // Get block from free list | |
300 block = _block_free_list; | |
301 _block_free_list = _block_free_list->_next; | |
302 } | |
303 } | |
304 block->_top = 0; | |
305 block->_next = NULL; | |
306 block->_pop_frame_link = NULL; | |
307 // _last, _free_list & _allocate_before_rebuild initialized in allocate_handle | |
308 debug_only(block->_last = NULL); | |
309 debug_only(block->_free_list = NULL); | |
310 debug_only(block->_allocate_before_rebuild = -1); | |
311 return block; | |
312 } | |
313 | |
314 | |
315 void JNIHandleBlock::release_block(JNIHandleBlock* block, Thread* thread) { | |
316 assert(thread == NULL || thread == Thread::current(), "sanity check"); | |
317 JNIHandleBlock* pop_frame_link = block->pop_frame_link(); | |
318 // Put returned block at the beginning of the thread-local free list. | |
319 // Note that if thread == NULL, we use it as an implicit argument that | |
320 // we _don't_ want the block to be kept on the free_handle_block. | |
321 // See for instance JavaThread::exit(). | |
322 if (thread != NULL ) { | |
323 if (ZapJNIHandleArea) block->zap(); | |
324 JNIHandleBlock* freelist = thread->free_handle_block(); | |
325 block->_pop_frame_link = NULL; | |
326 thread->set_free_handle_block(block); | |
327 | |
328 // Add original freelist to end of chain | |
329 if ( freelist != NULL ) { | |
330 while ( block->_next != NULL ) block = block->_next; | |
331 block->_next = freelist; | |
332 } | |
333 block = NULL; | |
334 } | |
335 if (block != NULL) { | |
336 // Return blocks to free list | |
337 // locking with safepoint checking introduces a potential deadlock: | |
338 // - we would hold JNIHandleBlockFreeList_lock and then Threads_lock | |
339 // - another would hold Threads_lock (jni_AttachCurrentThread) and then | |
340 // JNIHandleBlockFreeList_lock (JNIHandleBlock::allocate_block) | |
341 MutexLockerEx ml(JNIHandleBlockFreeList_lock, | |
342 Mutex::_no_safepoint_check_flag); | |
343 while (block != NULL) { | |
344 if (ZapJNIHandleArea) block->zap(); | |
345 JNIHandleBlock* next = block->_next; | |
346 block->_next = _block_free_list; | |
347 _block_free_list = block; | |
348 block = next; | |
349 } | |
350 } | |
351 if (pop_frame_link != NULL) { | |
352 // As a sanity check we release blocks pointed to by the pop_frame_link. | |
353 // This should never happen (only if PopLocalFrame is not called the | |
354 // correct number of times). | |
355 release_block(pop_frame_link, thread); | |
356 } | |
357 } | |
358 | |
359 | |
360 void JNIHandleBlock::oops_do(OopClosure* f) { | |
361 JNIHandleBlock* current_chain = this; | |
362 // Iterate over chain of blocks, followed by chains linked through the | |
363 // pop frame links. | |
364 while (current_chain != NULL) { | |
365 for (JNIHandleBlock* current = current_chain; current != NULL; | |
366 current = current->_next) { | |
367 assert(current == current_chain || current->pop_frame_link() == NULL, | |
368 "only blocks first in chain should have pop frame link set"); | |
369 for (int index = 0; index < current->_top; index++) { | |
370 oop* root = &(current->_handles)[index]; | |
371 oop value = *root; | |
372 // traverse heap pointers only, not deleted handles or free list | |
373 // pointers | |
374 if (value != NULL && Universe::heap()->is_in_reserved(value)) { | |
375 f->do_oop(root); | |
376 } | |
377 } | |
378 // the next handle block is valid only if current block is full | |
379 if (current->_top < block_size_in_oops) { | |
380 break; | |
381 } | |
382 } | |
383 current_chain = current_chain->pop_frame_link(); | |
384 } | |
385 } | |
386 | |
387 | |
388 void JNIHandleBlock::weak_oops_do(BoolObjectClosure* is_alive, | |
389 OopClosure* f) { | |
390 for (JNIHandleBlock* current = this; current != NULL; current = current->_next) { | |
391 assert(current->pop_frame_link() == NULL, | |
392 "blocks holding weak global JNI handles should not have pop frame link set"); | |
393 for (int index = 0; index < current->_top; index++) { | |
394 oop* root = &(current->_handles)[index]; | |
395 oop value = *root; | |
396 // traverse heap pointers only, not deleted handles or free list pointers | |
397 if (value != NULL && Universe::heap()->is_in_reserved(value)) { | |
398 if (is_alive->do_object_b(value)) { | |
399 // The weakly referenced object is alive, update pointer | |
400 f->do_oop(root); | |
401 } else { | |
402 // The weakly referenced object is not alive, clear the reference by storing NULL | |
403 if (TraceReferenceGC) { | |
404 tty->print_cr("Clearing JNI weak reference (" INTPTR_FORMAT ")", root); | |
405 } | |
406 *root = NULL; | |
407 } | |
408 } | |
409 } | |
410 // the next handle block is valid only if current block is full | |
411 if (current->_top < block_size_in_oops) { | |
412 break; | |
413 } | |
414 } | |
415 } | |
416 | |
417 | |
418 jobject JNIHandleBlock::allocate_handle(oop obj) { | |
419 assert(Universe::heap()->is_in_reserved(obj), "sanity check"); | |
420 if (_top == 0) { | |
421 // This is the first allocation or the initial block got zapped when | |
422 // entering a native function. If we have any following blocks they are | |
423 // not valid anymore. | |
424 for (JNIHandleBlock* current = _next; current != NULL; | |
425 current = current->_next) { | |
426 assert(current->_last == NULL, "only first block should have _last set"); | |
427 assert(current->_free_list == NULL, | |
428 "only first block should have _free_list set"); | |
429 current->_top = 0; | |
430 if (ZapJNIHandleArea) current->zap(); | |
431 } | |
432 // Clear initial block | |
433 _free_list = NULL; | |
434 _allocate_before_rebuild = 0; | |
435 _last = this; | |
436 if (ZapJNIHandleArea) zap(); | |
437 } | |
438 | |
439 // Try last block | |
440 if (_last->_top < block_size_in_oops) { | |
441 oop* handle = &(_last->_handles)[_last->_top++]; | |
442 *handle = obj; | |
443 return (jobject) handle; | |
444 } | |
445 | |
446 // Try free list | |
447 if (_free_list != NULL) { | |
448 oop* handle = _free_list; | |
449 _free_list = (oop*) *_free_list; | |
450 *handle = obj; | |
451 return (jobject) handle; | |
452 } | |
453 // Check if unused block follow last | |
454 if (_last->_next != NULL) { | |
455 // update last and retry | |
456 _last = _last->_next; | |
457 return allocate_handle(obj); | |
458 } | |
459 | |
460 // No space available, we have to rebuild free list or expand | |
461 if (_allocate_before_rebuild == 0) { | |
462 rebuild_free_list(); // updates _allocate_before_rebuild counter | |
463 } else { | |
464 // Append new block | |
465 Thread* thread = Thread::current(); | |
466 Handle obj_handle(thread, obj); | |
467 // This can block, so we need to preserve obj accross call. | |
468 _last->_next = JNIHandleBlock::allocate_block(thread); | |
469 _last = _last->_next; | |
470 _allocate_before_rebuild--; | |
471 obj = obj_handle(); | |
472 } | |
473 return allocate_handle(obj); // retry | |
474 } | |
475 | |
476 | |
477 void JNIHandleBlock::rebuild_free_list() { | |
478 assert(_allocate_before_rebuild == 0 && _free_list == NULL, "just checking"); | |
479 int free = 0; | |
480 int blocks = 0; | |
481 for (JNIHandleBlock* current = this; current != NULL; current = current->_next) { | |
482 for (int index = 0; index < current->_top; index++) { | |
483 oop* handle = &(current->_handles)[index]; | |
484 if (*handle == JNIHandles::deleted_handle()) { | |
485 // this handle was cleared out by a delete call, reuse it | |
486 *handle = (oop) _free_list; | |
487 _free_list = handle; | |
488 free++; | |
489 } | |
490 } | |
491 // we should not rebuild free list if there are unused handles at the end | |
492 assert(current->_top == block_size_in_oops, "just checking"); | |
493 blocks++; | |
494 } | |
495 // Heuristic: if more than half of the handles are free we rebuild next time | |
496 // as well, otherwise we append a corresponding number of new blocks before | |
497 // attempting a free list rebuild again. | |
498 int total = blocks * block_size_in_oops; | |
499 int extra = total - 2*free; | |
500 if (extra > 0) { | |
501 // Not as many free handles as we would like - compute number of new blocks to append | |
502 _allocate_before_rebuild = (extra + block_size_in_oops - 1) / block_size_in_oops; | |
503 } | |
504 if (TraceJNIHandleAllocation) { | |
505 tty->print_cr("Rebuild free list JNIHandleBlock " INTPTR_FORMAT " blocks=%d used=%d free=%d add=%d", | |
506 this, blocks, total-free, free, _allocate_before_rebuild); | |
507 } | |
508 } | |
509 | |
510 | |
511 bool JNIHandleBlock::contains(jobject handle) const { | |
512 return ((jobject)&_handles[0] <= handle && handle<(jobject)&_handles[_top]); | |
513 } | |
514 | |
515 | |
516 bool JNIHandleBlock::chain_contains(jobject handle) const { | |
517 for (JNIHandleBlock* current = (JNIHandleBlock*) this; current != NULL; current = current->_next) { | |
518 if (current->contains(handle)) { | |
519 return true; | |
520 } | |
521 } | |
522 return false; | |
523 } | |
524 | |
525 | |
526 int JNIHandleBlock::length() const { | |
527 int result = 1; | |
528 for (JNIHandleBlock* current = _next; current != NULL; current = current->_next) { | |
529 result++; | |
530 } | |
531 return result; | |
532 } | |
533 | |
534 // This method is not thread-safe, i.e., must be called whule holding a lock on the | |
535 // structure. | |
536 long JNIHandleBlock::memory_usage() const { | |
537 return length() * sizeof(JNIHandleBlock); | |
538 } | |
539 | |
540 | |
541 #ifndef PRODUCT | |
542 | |
543 bool JNIHandleBlock::any_contains(jobject handle) { | |
544 for (JNIHandleBlock* current = _block_list; current != NULL; current = current->_block_list_link) { | |
545 if (current->contains(handle)) { | |
546 return true; | |
547 } | |
548 } | |
549 return false; | |
550 } | |
551 | |
552 void JNIHandleBlock::print_statistics() { | |
553 int used_blocks = 0; | |
554 int free_blocks = 0; | |
555 int used_handles = 0; | |
556 int free_handles = 0; | |
557 JNIHandleBlock* block = _block_list; | |
558 while (block != NULL) { | |
559 if (block->_top > 0) { | |
560 used_blocks++; | |
561 } else { | |
562 free_blocks++; | |
563 } | |
564 used_handles += block->_top; | |
565 free_handles += (block_size_in_oops - block->_top); | |
566 block = block->_block_list_link; | |
567 } | |
568 tty->print_cr("JNIHandleBlocks statistics"); | |
569 tty->print_cr("- blocks allocated: %d", used_blocks + free_blocks); | |
570 tty->print_cr("- blocks in use: %d", used_blocks); | |
571 tty->print_cr("- blocks free: %d", free_blocks); | |
572 tty->print_cr("- handles in use: %d", used_handles); | |
573 tty->print_cr("- handles free: %d", free_handles); | |
574 } | |
575 | |
576 #endif |