Mercurial > hg > truffle
annotate src/share/vm/runtime/jniHandles.cpp @ 1777:179464550c7d
6983930: CMS: Various small cleanups ca September 2010
Summary: Fixed comment/documentation typos; converted some guarantee()s to assert()s.
Reviewed-by: jmasa
author | ysr |
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date | Fri, 10 Sep 2010 17:07:55 -0700 |
parents | 38e8278318ca |
children | f95d63e2154a |
rev | line source |
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0 | 1 /* |
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2 * Copyright (c) 1998, 2008, Oracle and/or its affiliates. All rights reserved. |
0 | 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 * | |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
0 | 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) { | |
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69 assert(!Universe::heap()->is_gc_active(), "can't extend the root set during GC"); |
0 | 70 jobject res = NULL; |
71 if (!obj.is_null()) { | |
72 // ignore null handles | |
73 MutexLocker ml(JNIGlobalHandle_lock); | |
74 assert(Universe::heap()->is_in_reserved(obj()), "sanity check"); | |
75 res = _global_handles->allocate_handle(obj()); | |
76 } else { | |
77 CHECK_UNHANDLED_OOPS_ONLY(Thread::current()->clear_unhandled_oops()); | |
78 } | |
79 | |
80 return res; | |
81 } | |
82 | |
83 | |
84 jobject JNIHandles::make_weak_global(Handle obj) { | |
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85 assert(!Universe::heap()->is_gc_active(), "can't extend the root set during GC"); |
0 | 86 jobject res = NULL; |
87 if (!obj.is_null()) { | |
88 // ignore null handles | |
89 MutexLocker ml(JNIGlobalHandle_lock); | |
90 assert(Universe::heap()->is_in_reserved(obj()), "sanity check"); | |
91 res = _weak_global_handles->allocate_handle(obj()); | |
92 } else { | |
93 CHECK_UNHANDLED_OOPS_ONLY(Thread::current()->clear_unhandled_oops()); | |
94 } | |
95 return res; | |
96 } | |
97 | |
98 jmethodID JNIHandles::make_jmethod_id(methodHandle mh) { | |
99 return (jmethodID) make_weak_global(mh); | |
100 } | |
101 | |
102 | |
103 | |
104 void JNIHandles::change_method_associated_with_jmethod_id(jmethodID jmid, methodHandle mh) { | |
105 MutexLocker ml(JNIGlobalHandle_lock); // Is this necessary? | |
106 Handle obj = (Handle)mh; | |
107 oop* jobj = (oop*)jmid; | |
108 *jobj = obj(); | |
109 } | |
110 | |
111 | |
112 void JNIHandles::destroy_global(jobject handle) { | |
113 if (handle != NULL) { | |
114 assert(is_global_handle(handle), "Invalid delete of global JNI handle"); | |
115 *((oop*)handle) = deleted_handle(); // Mark the handle as deleted, allocate will reuse it | |
116 } | |
117 } | |
118 | |
119 | |
120 void JNIHandles::destroy_weak_global(jobject handle) { | |
121 if (handle != NULL) { | |
122 assert(!CheckJNICalls || is_weak_global_handle(handle), "Invalid delete of weak global JNI handle"); | |
123 *((oop*)handle) = deleted_handle(); // Mark the handle as deleted, allocate will reuse it | |
124 } | |
125 } | |
126 | |
127 void JNIHandles::destroy_jmethod_id(jmethodID mid) { | |
128 destroy_weak_global((jobject)mid); | |
129 } | |
130 | |
131 | |
132 void JNIHandles::oops_do(OopClosure* f) { | |
133 f->do_oop(&_deleted_handle); | |
134 _global_handles->oops_do(f); | |
135 } | |
136 | |
137 | |
138 void JNIHandles::weak_oops_do(BoolObjectClosure* is_alive, OopClosure* f) { | |
139 _weak_global_handles->weak_oops_do(is_alive, f); | |
140 } | |
141 | |
142 | |
143 void JNIHandles::initialize() { | |
144 _global_handles = JNIHandleBlock::allocate_block(); | |
145 _weak_global_handles = JNIHandleBlock::allocate_block(); | |
146 EXCEPTION_MARK; | |
147 // We will never reach the CATCH below since Exceptions::_throw will cause | |
148 // the VM to exit if an exception is thrown during initialization | |
1142 | 149 klassOop k = SystemDictionary::Object_klass(); |
0 | 150 _deleted_handle = instanceKlass::cast(k)->allocate_permanent_instance(CATCH); |
151 } | |
152 | |
153 | |
154 bool JNIHandles::is_local_handle(Thread* thread, jobject handle) { | |
155 JNIHandleBlock* block = thread->active_handles(); | |
156 | |
157 // Look back past possible native calls to jni_PushLocalFrame. | |
158 while (block != NULL) { | |
159 if (block->chain_contains(handle)) { | |
160 return true; | |
161 } | |
162 block = block->pop_frame_link(); | |
163 } | |
164 return false; | |
165 } | |
166 | |
167 | |
168 // Determine if the handle is somewhere in the current thread's stack. | |
169 // We easily can't isolate any particular stack frame the handle might | |
170 // come from, so we'll check the whole stack. | |
171 | |
172 bool JNIHandles::is_frame_handle(JavaThread* thr, jobject obj) { | |
173 // If there is no java frame, then this must be top level code, such | |
174 // as the java command executable, in which case, this type of handle | |
175 // is not permitted. | |
176 return (thr->has_last_Java_frame() && | |
177 (void*)obj < (void*)thr->stack_base() && | |
178 (void*)obj >= (void*)thr->last_Java_sp()); | |
179 } | |
180 | |
181 | |
182 bool JNIHandles::is_global_handle(jobject handle) { | |
183 return _global_handles->chain_contains(handle); | |
184 } | |
185 | |
186 | |
187 bool JNIHandles::is_weak_global_handle(jobject handle) { | |
188 return _weak_global_handles->chain_contains(handle); | |
189 } | |
190 | |
191 long JNIHandles::global_handle_memory_usage() { | |
192 return _global_handles->memory_usage(); | |
193 } | |
194 | |
195 long JNIHandles::weak_global_handle_memory_usage() { | |
196 return _weak_global_handles->memory_usage(); | |
197 } | |
198 | |
199 | |
200 class AlwaysAliveClosure: public BoolObjectClosure { | |
201 public: | |
202 bool do_object_b(oop obj) { return true; } | |
203 void do_object(oop obj) { assert(false, "Don't call"); } | |
204 }; | |
205 | |
206 class CountHandleClosure: public OopClosure { | |
207 private: | |
208 int _count; | |
209 public: | |
210 CountHandleClosure(): _count(0) {} | |
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211 virtual void do_oop(oop* unused) { |
0 | 212 _count++; |
213 } | |
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214 virtual void do_oop(narrowOop* unused) { ShouldNotReachHere(); } |
0 | 215 int count() { return _count; } |
216 }; | |
217 | |
218 // We assume this is called at a safepoint: no lock is needed. | |
219 void JNIHandles::print_on(outputStream* st) { | |
220 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint"); | |
221 assert(_global_handles != NULL && _weak_global_handles != NULL, | |
222 "JNIHandles not initialized"); | |
223 | |
224 CountHandleClosure global_handle_count; | |
225 AlwaysAliveClosure always_alive; | |
226 oops_do(&global_handle_count); | |
227 weak_oops_do(&always_alive, &global_handle_count); | |
228 | |
229 st->print_cr("JNI global references: %d", global_handle_count.count()); | |
230 st->cr(); | |
231 st->flush(); | |
232 } | |
233 | |
234 class VerifyHandleClosure: public OopClosure { | |
235 public: | |
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236 virtual void do_oop(oop* root) { |
0 | 237 (*root)->verify(); |
238 } | |
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239 virtual void do_oop(narrowOop* root) { ShouldNotReachHere(); } |
0 | 240 }; |
241 | |
242 void JNIHandles::verify() { | |
243 VerifyHandleClosure verify_handle; | |
244 AlwaysAliveClosure always_alive; | |
245 | |
246 oops_do(&verify_handle); | |
247 weak_oops_do(&always_alive, &verify_handle); | |
248 } | |
249 | |
250 | |
251 | |
252 void jni_handles_init() { | |
253 JNIHandles::initialize(); | |
254 } | |
255 | |
256 | |
257 int JNIHandleBlock::_blocks_allocated = 0; | |
258 JNIHandleBlock* JNIHandleBlock::_block_free_list = NULL; | |
259 #ifndef PRODUCT | |
260 JNIHandleBlock* JNIHandleBlock::_block_list = NULL; | |
261 #endif | |
262 | |
263 | |
264 void JNIHandleBlock::zap() { | |
265 // Zap block values | |
266 _top = 0; | |
267 for (int index = 0; index < block_size_in_oops; index++) { | |
268 _handles[index] = badJNIHandle; | |
269 } | |
270 } | |
271 | |
272 JNIHandleBlock* JNIHandleBlock::allocate_block(Thread* thread) { | |
273 assert(thread == NULL || thread == Thread::current(), "sanity check"); | |
274 JNIHandleBlock* block; | |
275 // Check the thread-local free list for a block so we don't | |
276 // have to acquire a mutex. | |
277 if (thread != NULL && thread->free_handle_block() != NULL) { | |
278 block = thread->free_handle_block(); | |
279 thread->set_free_handle_block(block->_next); | |
280 } | |
281 else { | |
282 // locking with safepoint checking introduces a potential deadlock: | |
283 // - we would hold JNIHandleBlockFreeList_lock and then Threads_lock | |
284 // - another would hold Threads_lock (jni_AttachCurrentThread) and then | |
285 // JNIHandleBlockFreeList_lock (JNIHandleBlock::allocate_block) | |
286 MutexLockerEx ml(JNIHandleBlockFreeList_lock, | |
287 Mutex::_no_safepoint_check_flag); | |
288 if (_block_free_list == NULL) { | |
289 // Allocate new block | |
290 block = new JNIHandleBlock(); | |
291 _blocks_allocated++; | |
292 if (TraceJNIHandleAllocation) { | |
293 tty->print_cr("JNIHandleBlock " INTPTR_FORMAT " allocated (%d total blocks)", | |
294 block, _blocks_allocated); | |
295 } | |
296 if (ZapJNIHandleArea) block->zap(); | |
297 #ifndef PRODUCT | |
298 // Link new block to list of all allocated blocks | |
299 block->_block_list_link = _block_list; | |
300 _block_list = block; | |
301 #endif | |
302 } else { | |
303 // Get block from free list | |
304 block = _block_free_list; | |
305 _block_free_list = _block_free_list->_next; | |
306 } | |
307 } | |
308 block->_top = 0; | |
309 block->_next = NULL; | |
310 block->_pop_frame_link = NULL; | |
311 // _last, _free_list & _allocate_before_rebuild initialized in allocate_handle | |
312 debug_only(block->_last = NULL); | |
313 debug_only(block->_free_list = NULL); | |
314 debug_only(block->_allocate_before_rebuild = -1); | |
315 return block; | |
316 } | |
317 | |
318 | |
319 void JNIHandleBlock::release_block(JNIHandleBlock* block, Thread* thread) { | |
320 assert(thread == NULL || thread == Thread::current(), "sanity check"); | |
321 JNIHandleBlock* pop_frame_link = block->pop_frame_link(); | |
322 // Put returned block at the beginning of the thread-local free list. | |
323 // Note that if thread == NULL, we use it as an implicit argument that | |
324 // we _don't_ want the block to be kept on the free_handle_block. | |
325 // See for instance JavaThread::exit(). | |
326 if (thread != NULL ) { | |
327 if (ZapJNIHandleArea) block->zap(); | |
328 JNIHandleBlock* freelist = thread->free_handle_block(); | |
329 block->_pop_frame_link = NULL; | |
330 thread->set_free_handle_block(block); | |
331 | |
332 // Add original freelist to end of chain | |
333 if ( freelist != NULL ) { | |
334 while ( block->_next != NULL ) block = block->_next; | |
335 block->_next = freelist; | |
336 } | |
337 block = NULL; | |
338 } | |
339 if (block != NULL) { | |
340 // Return blocks to free list | |
341 // locking with safepoint checking introduces a potential deadlock: | |
342 // - we would hold JNIHandleBlockFreeList_lock and then Threads_lock | |
343 // - another would hold Threads_lock (jni_AttachCurrentThread) and then | |
344 // JNIHandleBlockFreeList_lock (JNIHandleBlock::allocate_block) | |
345 MutexLockerEx ml(JNIHandleBlockFreeList_lock, | |
346 Mutex::_no_safepoint_check_flag); | |
347 while (block != NULL) { | |
348 if (ZapJNIHandleArea) block->zap(); | |
349 JNIHandleBlock* next = block->_next; | |
350 block->_next = _block_free_list; | |
351 _block_free_list = block; | |
352 block = next; | |
353 } | |
354 } | |
355 if (pop_frame_link != NULL) { | |
356 // As a sanity check we release blocks pointed to by the pop_frame_link. | |
357 // This should never happen (only if PopLocalFrame is not called the | |
358 // correct number of times). | |
359 release_block(pop_frame_link, thread); | |
360 } | |
361 } | |
362 | |
363 | |
364 void JNIHandleBlock::oops_do(OopClosure* f) { | |
365 JNIHandleBlock* current_chain = this; | |
366 // Iterate over chain of blocks, followed by chains linked through the | |
367 // pop frame links. | |
368 while (current_chain != NULL) { | |
369 for (JNIHandleBlock* current = current_chain; current != NULL; | |
370 current = current->_next) { | |
371 assert(current == current_chain || current->pop_frame_link() == NULL, | |
372 "only blocks first in chain should have pop frame link set"); | |
373 for (int index = 0; index < current->_top; index++) { | |
374 oop* root = &(current->_handles)[index]; | |
375 oop value = *root; | |
376 // traverse heap pointers only, not deleted handles or free list | |
377 // pointers | |
378 if (value != NULL && Universe::heap()->is_in_reserved(value)) { | |
379 f->do_oop(root); | |
380 } | |
381 } | |
382 // the next handle block is valid only if current block is full | |
383 if (current->_top < block_size_in_oops) { | |
384 break; | |
385 } | |
386 } | |
387 current_chain = current_chain->pop_frame_link(); | |
388 } | |
389 } | |
390 | |
391 | |
392 void JNIHandleBlock::weak_oops_do(BoolObjectClosure* is_alive, | |
393 OopClosure* f) { | |
394 for (JNIHandleBlock* current = this; current != NULL; current = current->_next) { | |
395 assert(current->pop_frame_link() == NULL, | |
396 "blocks holding weak global JNI handles should not have pop frame link set"); | |
397 for (int index = 0; index < current->_top; index++) { | |
398 oop* root = &(current->_handles)[index]; | |
399 oop value = *root; | |
400 // traverse heap pointers only, not deleted handles or free list pointers | |
401 if (value != NULL && Universe::heap()->is_in_reserved(value)) { | |
402 if (is_alive->do_object_b(value)) { | |
403 // The weakly referenced object is alive, update pointer | |
404 f->do_oop(root); | |
405 } else { | |
406 // The weakly referenced object is not alive, clear the reference by storing NULL | |
407 if (TraceReferenceGC) { | |
408 tty->print_cr("Clearing JNI weak reference (" INTPTR_FORMAT ")", root); | |
409 } | |
410 *root = NULL; | |
411 } | |
412 } | |
413 } | |
414 // the next handle block is valid only if current block is full | |
415 if (current->_top < block_size_in_oops) { | |
416 break; | |
417 } | |
418 } | |
419 } | |
420 | |
421 | |
422 jobject JNIHandleBlock::allocate_handle(oop obj) { | |
423 assert(Universe::heap()->is_in_reserved(obj), "sanity check"); | |
424 if (_top == 0) { | |
425 // This is the first allocation or the initial block got zapped when | |
426 // entering a native function. If we have any following blocks they are | |
427 // not valid anymore. | |
428 for (JNIHandleBlock* current = _next; current != NULL; | |
429 current = current->_next) { | |
430 assert(current->_last == NULL, "only first block should have _last set"); | |
431 assert(current->_free_list == NULL, | |
432 "only first block should have _free_list set"); | |
433 current->_top = 0; | |
434 if (ZapJNIHandleArea) current->zap(); | |
435 } | |
436 // Clear initial block | |
437 _free_list = NULL; | |
438 _allocate_before_rebuild = 0; | |
439 _last = this; | |
440 if (ZapJNIHandleArea) zap(); | |
441 } | |
442 | |
443 // Try last block | |
444 if (_last->_top < block_size_in_oops) { | |
445 oop* handle = &(_last->_handles)[_last->_top++]; | |
446 *handle = obj; | |
447 return (jobject) handle; | |
448 } | |
449 | |
450 // Try free list | |
451 if (_free_list != NULL) { | |
452 oop* handle = _free_list; | |
453 _free_list = (oop*) *_free_list; | |
454 *handle = obj; | |
455 return (jobject) handle; | |
456 } | |
457 // Check if unused block follow last | |
458 if (_last->_next != NULL) { | |
459 // update last and retry | |
460 _last = _last->_next; | |
461 return allocate_handle(obj); | |
462 } | |
463 | |
464 // No space available, we have to rebuild free list or expand | |
465 if (_allocate_before_rebuild == 0) { | |
466 rebuild_free_list(); // updates _allocate_before_rebuild counter | |
467 } else { | |
468 // Append new block | |
469 Thread* thread = Thread::current(); | |
470 Handle obj_handle(thread, obj); | |
471 // This can block, so we need to preserve obj accross call. | |
472 _last->_next = JNIHandleBlock::allocate_block(thread); | |
473 _last = _last->_next; | |
474 _allocate_before_rebuild--; | |
475 obj = obj_handle(); | |
476 } | |
477 return allocate_handle(obj); // retry | |
478 } | |
479 | |
480 | |
481 void JNIHandleBlock::rebuild_free_list() { | |
482 assert(_allocate_before_rebuild == 0 && _free_list == NULL, "just checking"); | |
483 int free = 0; | |
484 int blocks = 0; | |
485 for (JNIHandleBlock* current = this; current != NULL; current = current->_next) { | |
486 for (int index = 0; index < current->_top; index++) { | |
487 oop* handle = &(current->_handles)[index]; | |
488 if (*handle == JNIHandles::deleted_handle()) { | |
489 // this handle was cleared out by a delete call, reuse it | |
490 *handle = (oop) _free_list; | |
491 _free_list = handle; | |
492 free++; | |
493 } | |
494 } | |
495 // we should not rebuild free list if there are unused handles at the end | |
496 assert(current->_top == block_size_in_oops, "just checking"); | |
497 blocks++; | |
498 } | |
499 // Heuristic: if more than half of the handles are free we rebuild next time | |
500 // as well, otherwise we append a corresponding number of new blocks before | |
501 // attempting a free list rebuild again. | |
502 int total = blocks * block_size_in_oops; | |
503 int extra = total - 2*free; | |
504 if (extra > 0) { | |
505 // Not as many free handles as we would like - compute number of new blocks to append | |
506 _allocate_before_rebuild = (extra + block_size_in_oops - 1) / block_size_in_oops; | |
507 } | |
508 if (TraceJNIHandleAllocation) { | |
509 tty->print_cr("Rebuild free list JNIHandleBlock " INTPTR_FORMAT " blocks=%d used=%d free=%d add=%d", | |
510 this, blocks, total-free, free, _allocate_before_rebuild); | |
511 } | |
512 } | |
513 | |
514 | |
515 bool JNIHandleBlock::contains(jobject handle) const { | |
516 return ((jobject)&_handles[0] <= handle && handle<(jobject)&_handles[_top]); | |
517 } | |
518 | |
519 | |
520 bool JNIHandleBlock::chain_contains(jobject handle) const { | |
521 for (JNIHandleBlock* current = (JNIHandleBlock*) this; current != NULL; current = current->_next) { | |
522 if (current->contains(handle)) { | |
523 return true; | |
524 } | |
525 } | |
526 return false; | |
527 } | |
528 | |
529 | |
530 int JNIHandleBlock::length() const { | |
531 int result = 1; | |
532 for (JNIHandleBlock* current = _next; current != NULL; current = current->_next) { | |
533 result++; | |
534 } | |
535 return result; | |
536 } | |
537 | |
538 // This method is not thread-safe, i.e., must be called whule holding a lock on the | |
539 // structure. | |
540 long JNIHandleBlock::memory_usage() const { | |
541 return length() * sizeof(JNIHandleBlock); | |
542 } | |
543 | |
544 | |
545 #ifndef PRODUCT | |
546 | |
547 bool JNIHandleBlock::any_contains(jobject handle) { | |
548 for (JNIHandleBlock* current = _block_list; current != NULL; current = current->_block_list_link) { | |
549 if (current->contains(handle)) { | |
550 return true; | |
551 } | |
552 } | |
553 return false; | |
554 } | |
555 | |
556 void JNIHandleBlock::print_statistics() { | |
557 int used_blocks = 0; | |
558 int free_blocks = 0; | |
559 int used_handles = 0; | |
560 int free_handles = 0; | |
561 JNIHandleBlock* block = _block_list; | |
562 while (block != NULL) { | |
563 if (block->_top > 0) { | |
564 used_blocks++; | |
565 } else { | |
566 free_blocks++; | |
567 } | |
568 used_handles += block->_top; | |
569 free_handles += (block_size_in_oops - block->_top); | |
570 block = block->_block_list_link; | |
571 } | |
572 tty->print_cr("JNIHandleBlocks statistics"); | |
573 tty->print_cr("- blocks allocated: %d", used_blocks + free_blocks); | |
574 tty->print_cr("- blocks in use: %d", used_blocks); | |
575 tty->print_cr("- blocks free: %d", free_blocks); | |
576 tty->print_cr("- handles in use: %d", used_handles); | |
577 tty->print_cr("- handles free: %d", free_handles); | |
578 } | |
579 | |
580 #endif |