Mercurial > hg > graal-compiler
annotate src/share/vm/runtime/jniHandles.cpp @ 2125:7246a374a9f2
6458402: 3 jvmti tests fail with CMS and +ExplicitGCInvokesConcurrent
Summary: Make JvmtiGCMark safe to run non-safepoint and instrument CMS
Reviewed-by: ysr, dcubed
| author | kamg |
|---|---|
| date | Mon, 10 Jan 2011 17:14:53 -0500 |
| parents | f95d63e2154a |
| children | 9afee0b9fc1d |
| rev | line source |
|---|---|
| 0 | 1 /* |
| 1972 | 2 * Copyright (c) 1998, 2010, 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 | |
| 1972 | 25 #include "precompiled.hpp" |
| 26 #include "classfile/systemDictionary.hpp" | |
| 27 #include "oops/oop.inline.hpp" | |
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28 #include "prims/jvmtiTagMap.hpp" |
| 1972 | 29 #include "runtime/jniHandles.hpp" |
| 30 #include "runtime/mutexLocker.hpp" | |
| 31 #ifdef TARGET_OS_FAMILY_linux | |
| 32 # include "thread_linux.inline.hpp" | |
| 33 #endif | |
| 34 #ifdef TARGET_OS_FAMILY_solaris | |
| 35 # include "thread_solaris.inline.hpp" | |
| 36 #endif | |
| 37 #ifdef TARGET_OS_FAMILY_windows | |
| 38 # include "thread_windows.inline.hpp" | |
| 39 #endif | |
| 0 | 40 |
| 41 | |
| 42 JNIHandleBlock* JNIHandles::_global_handles = NULL; | |
| 43 JNIHandleBlock* JNIHandles::_weak_global_handles = NULL; | |
| 44 oop JNIHandles::_deleted_handle = NULL; | |
| 45 | |
| 46 | |
| 47 jobject JNIHandles::make_local(oop obj) { | |
| 48 if (obj == NULL) { | |
| 49 return NULL; // ignore null handles | |
| 50 } else { | |
| 51 Thread* thread = Thread::current(); | |
| 52 assert(Universe::heap()->is_in_reserved(obj), "sanity check"); | |
| 53 return thread->active_handles()->allocate_handle(obj); | |
| 54 } | |
| 55 } | |
| 56 | |
| 57 | |
| 58 // optimized versions | |
| 59 | |
| 60 jobject JNIHandles::make_local(Thread* thread, oop obj) { | |
| 61 if (obj == NULL) { | |
| 62 return NULL; // ignore null handles | |
| 63 } else { | |
| 64 assert(Universe::heap()->is_in_reserved(obj), "sanity check"); | |
| 65 return thread->active_handles()->allocate_handle(obj); | |
| 66 } | |
| 67 } | |
| 68 | |
| 69 | |
| 70 jobject JNIHandles::make_local(JNIEnv* env, oop obj) { | |
| 71 if (obj == NULL) { | |
| 72 return NULL; // ignore null handles | |
| 73 } else { | |
| 74 JavaThread* thread = JavaThread::thread_from_jni_environment(env); | |
| 75 assert(Universe::heap()->is_in_reserved(obj), "sanity check"); | |
| 76 return thread->active_handles()->allocate_handle(obj); | |
| 77 } | |
| 78 } | |
| 79 | |
| 80 | |
| 81 jobject JNIHandles::make_global(Handle obj) { | |
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82 assert(!Universe::heap()->is_gc_active(), "can't extend the root set during GC"); |
| 0 | 83 jobject res = NULL; |
| 84 if (!obj.is_null()) { | |
| 85 // ignore null handles | |
| 86 MutexLocker ml(JNIGlobalHandle_lock); | |
| 87 assert(Universe::heap()->is_in_reserved(obj()), "sanity check"); | |
| 88 res = _global_handles->allocate_handle(obj()); | |
| 89 } else { | |
| 90 CHECK_UNHANDLED_OOPS_ONLY(Thread::current()->clear_unhandled_oops()); | |
| 91 } | |
| 92 | |
| 93 return res; | |
| 94 } | |
| 95 | |
| 96 | |
| 97 jobject JNIHandles::make_weak_global(Handle obj) { | |
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98 assert(!Universe::heap()->is_gc_active(), "can't extend the root set during GC"); |
| 0 | 99 jobject res = NULL; |
| 100 if (!obj.is_null()) { | |
| 101 // ignore null handles | |
| 102 MutexLocker ml(JNIGlobalHandle_lock); | |
| 103 assert(Universe::heap()->is_in_reserved(obj()), "sanity check"); | |
| 104 res = _weak_global_handles->allocate_handle(obj()); | |
| 105 } else { | |
| 106 CHECK_UNHANDLED_OOPS_ONLY(Thread::current()->clear_unhandled_oops()); | |
| 107 } | |
| 108 return res; | |
| 109 } | |
| 110 | |
| 111 jmethodID JNIHandles::make_jmethod_id(methodHandle mh) { | |
| 112 return (jmethodID) make_weak_global(mh); | |
| 113 } | |
| 114 | |
| 115 | |
| 116 | |
| 117 void JNIHandles::change_method_associated_with_jmethod_id(jmethodID jmid, methodHandle mh) { | |
| 118 MutexLocker ml(JNIGlobalHandle_lock); // Is this necessary? | |
| 119 Handle obj = (Handle)mh; | |
| 120 oop* jobj = (oop*)jmid; | |
| 121 *jobj = obj(); | |
| 122 } | |
| 123 | |
| 124 | |
| 125 void JNIHandles::destroy_global(jobject handle) { | |
| 126 if (handle != NULL) { | |
| 127 assert(is_global_handle(handle), "Invalid delete of global JNI handle"); | |
| 128 *((oop*)handle) = deleted_handle(); // Mark the handle as deleted, allocate will reuse it | |
| 129 } | |
| 130 } | |
| 131 | |
| 132 | |
| 133 void JNIHandles::destroy_weak_global(jobject handle) { | |
| 134 if (handle != NULL) { | |
| 135 assert(!CheckJNICalls || is_weak_global_handle(handle), "Invalid delete of weak global JNI handle"); | |
| 136 *((oop*)handle) = deleted_handle(); // Mark the handle as deleted, allocate will reuse it | |
| 137 } | |
| 138 } | |
| 139 | |
| 140 void JNIHandles::destroy_jmethod_id(jmethodID mid) { | |
| 141 destroy_weak_global((jobject)mid); | |
| 142 } | |
| 143 | |
| 144 | |
| 145 void JNIHandles::oops_do(OopClosure* f) { | |
| 146 f->do_oop(&_deleted_handle); | |
| 147 _global_handles->oops_do(f); | |
| 148 } | |
| 149 | |
| 150 | |
| 151 void JNIHandles::weak_oops_do(BoolObjectClosure* is_alive, OopClosure* f) { | |
| 152 _weak_global_handles->weak_oops_do(is_alive, f); | |
| 153 } | |
| 154 | |
| 155 | |
| 156 void JNIHandles::initialize() { | |
| 157 _global_handles = JNIHandleBlock::allocate_block(); | |
| 158 _weak_global_handles = JNIHandleBlock::allocate_block(); | |
| 159 EXCEPTION_MARK; | |
| 160 // We will never reach the CATCH below since Exceptions::_throw will cause | |
| 161 // the VM to exit if an exception is thrown during initialization | |
| 1142 | 162 klassOop k = SystemDictionary::Object_klass(); |
| 0 | 163 _deleted_handle = instanceKlass::cast(k)->allocate_permanent_instance(CATCH); |
| 164 } | |
| 165 | |
| 166 | |
| 167 bool JNIHandles::is_local_handle(Thread* thread, jobject handle) { | |
| 168 JNIHandleBlock* block = thread->active_handles(); | |
| 169 | |
| 170 // Look back past possible native calls to jni_PushLocalFrame. | |
| 171 while (block != NULL) { | |
| 172 if (block->chain_contains(handle)) { | |
| 173 return true; | |
| 174 } | |
| 175 block = block->pop_frame_link(); | |
| 176 } | |
| 177 return false; | |
| 178 } | |
| 179 | |
| 180 | |
| 181 // Determine if the handle is somewhere in the current thread's stack. | |
| 182 // We easily can't isolate any particular stack frame the handle might | |
| 183 // come from, so we'll check the whole stack. | |
| 184 | |
| 185 bool JNIHandles::is_frame_handle(JavaThread* thr, jobject obj) { | |
| 186 // If there is no java frame, then this must be top level code, such | |
| 187 // as the java command executable, in which case, this type of handle | |
| 188 // is not permitted. | |
| 189 return (thr->has_last_Java_frame() && | |
| 190 (void*)obj < (void*)thr->stack_base() && | |
| 191 (void*)obj >= (void*)thr->last_Java_sp()); | |
| 192 } | |
| 193 | |
| 194 | |
| 195 bool JNIHandles::is_global_handle(jobject handle) { | |
| 196 return _global_handles->chain_contains(handle); | |
| 197 } | |
| 198 | |
| 199 | |
| 200 bool JNIHandles::is_weak_global_handle(jobject handle) { | |
| 201 return _weak_global_handles->chain_contains(handle); | |
| 202 } | |
| 203 | |
| 204 long JNIHandles::global_handle_memory_usage() { | |
| 205 return _global_handles->memory_usage(); | |
| 206 } | |
| 207 | |
| 208 long JNIHandles::weak_global_handle_memory_usage() { | |
| 209 return _weak_global_handles->memory_usage(); | |
| 210 } | |
| 211 | |
| 212 | |
| 213 class AlwaysAliveClosure: public BoolObjectClosure { | |
| 214 public: | |
| 215 bool do_object_b(oop obj) { return true; } | |
| 216 void do_object(oop obj) { assert(false, "Don't call"); } | |
| 217 }; | |
| 218 | |
| 219 class CountHandleClosure: public OopClosure { | |
| 220 private: | |
| 221 int _count; | |
| 222 public: | |
| 223 CountHandleClosure(): _count(0) {} | |
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224 virtual void do_oop(oop* unused) { |
| 0 | 225 _count++; |
| 226 } | |
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227 virtual void do_oop(narrowOop* unused) { ShouldNotReachHere(); } |
| 0 | 228 int count() { return _count; } |
| 229 }; | |
| 230 | |
| 231 // We assume this is called at a safepoint: no lock is needed. | |
| 232 void JNIHandles::print_on(outputStream* st) { | |
| 233 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint"); | |
| 234 assert(_global_handles != NULL && _weak_global_handles != NULL, | |
| 235 "JNIHandles not initialized"); | |
| 236 | |
| 237 CountHandleClosure global_handle_count; | |
| 238 AlwaysAliveClosure always_alive; | |
| 239 oops_do(&global_handle_count); | |
| 240 weak_oops_do(&always_alive, &global_handle_count); | |
| 241 | |
| 242 st->print_cr("JNI global references: %d", global_handle_count.count()); | |
| 243 st->cr(); | |
| 244 st->flush(); | |
| 245 } | |
| 246 | |
| 247 class VerifyHandleClosure: public OopClosure { | |
| 248 public: | |
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249 virtual void do_oop(oop* root) { |
| 0 | 250 (*root)->verify(); |
| 251 } | |
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252 virtual void do_oop(narrowOop* root) { ShouldNotReachHere(); } |
| 0 | 253 }; |
| 254 | |
| 255 void JNIHandles::verify() { | |
| 256 VerifyHandleClosure verify_handle; | |
| 257 AlwaysAliveClosure always_alive; | |
| 258 | |
| 259 oops_do(&verify_handle); | |
| 260 weak_oops_do(&always_alive, &verify_handle); | |
| 261 } | |
| 262 | |
| 263 | |
| 264 | |
| 265 void jni_handles_init() { | |
| 266 JNIHandles::initialize(); | |
| 267 } | |
| 268 | |
| 269 | |
| 270 int JNIHandleBlock::_blocks_allocated = 0; | |
| 271 JNIHandleBlock* JNIHandleBlock::_block_free_list = NULL; | |
| 272 #ifndef PRODUCT | |
| 273 JNIHandleBlock* JNIHandleBlock::_block_list = NULL; | |
| 274 #endif | |
| 275 | |
| 276 | |
| 277 void JNIHandleBlock::zap() { | |
| 278 // Zap block values | |
| 279 _top = 0; | |
| 280 for (int index = 0; index < block_size_in_oops; index++) { | |
| 281 _handles[index] = badJNIHandle; | |
| 282 } | |
| 283 } | |
| 284 | |
| 285 JNIHandleBlock* JNIHandleBlock::allocate_block(Thread* thread) { | |
| 286 assert(thread == NULL || thread == Thread::current(), "sanity check"); | |
| 287 JNIHandleBlock* block; | |
| 288 // Check the thread-local free list for a block so we don't | |
| 289 // have to acquire a mutex. | |
| 290 if (thread != NULL && thread->free_handle_block() != NULL) { | |
| 291 block = thread->free_handle_block(); | |
| 292 thread->set_free_handle_block(block->_next); | |
| 293 } | |
| 294 else { | |
| 295 // locking with safepoint checking introduces a potential deadlock: | |
| 296 // - we would hold JNIHandleBlockFreeList_lock and then Threads_lock | |
| 297 // - another would hold Threads_lock (jni_AttachCurrentThread) and then | |
| 298 // JNIHandleBlockFreeList_lock (JNIHandleBlock::allocate_block) | |
| 299 MutexLockerEx ml(JNIHandleBlockFreeList_lock, | |
| 300 Mutex::_no_safepoint_check_flag); | |
| 301 if (_block_free_list == NULL) { | |
| 302 // Allocate new block | |
| 303 block = new JNIHandleBlock(); | |
| 304 _blocks_allocated++; | |
| 305 if (TraceJNIHandleAllocation) { | |
| 306 tty->print_cr("JNIHandleBlock " INTPTR_FORMAT " allocated (%d total blocks)", | |
| 307 block, _blocks_allocated); | |
| 308 } | |
| 309 if (ZapJNIHandleArea) block->zap(); | |
| 310 #ifndef PRODUCT | |
| 311 // Link new block to list of all allocated blocks | |
| 312 block->_block_list_link = _block_list; | |
| 313 _block_list = block; | |
| 314 #endif | |
| 315 } else { | |
| 316 // Get block from free list | |
| 317 block = _block_free_list; | |
| 318 _block_free_list = _block_free_list->_next; | |
| 319 } | |
| 320 } | |
| 321 block->_top = 0; | |
| 322 block->_next = NULL; | |
| 323 block->_pop_frame_link = NULL; | |
| 324 // _last, _free_list & _allocate_before_rebuild initialized in allocate_handle | |
| 325 debug_only(block->_last = NULL); | |
| 326 debug_only(block->_free_list = NULL); | |
| 327 debug_only(block->_allocate_before_rebuild = -1); | |
| 328 return block; | |
| 329 } | |
| 330 | |
| 331 | |
| 332 void JNIHandleBlock::release_block(JNIHandleBlock* block, Thread* thread) { | |
| 333 assert(thread == NULL || thread == Thread::current(), "sanity check"); | |
| 334 JNIHandleBlock* pop_frame_link = block->pop_frame_link(); | |
| 335 // Put returned block at the beginning of the thread-local free list. | |
| 336 // Note that if thread == NULL, we use it as an implicit argument that | |
| 337 // we _don't_ want the block to be kept on the free_handle_block. | |
| 338 // See for instance JavaThread::exit(). | |
| 339 if (thread != NULL ) { | |
| 340 if (ZapJNIHandleArea) block->zap(); | |
| 341 JNIHandleBlock* freelist = thread->free_handle_block(); | |
| 342 block->_pop_frame_link = NULL; | |
| 343 thread->set_free_handle_block(block); | |
| 344 | |
| 345 // Add original freelist to end of chain | |
| 346 if ( freelist != NULL ) { | |
| 347 while ( block->_next != NULL ) block = block->_next; | |
| 348 block->_next = freelist; | |
| 349 } | |
| 350 block = NULL; | |
| 351 } | |
| 352 if (block != NULL) { | |
| 353 // Return blocks to free list | |
| 354 // locking with safepoint checking introduces a potential deadlock: | |
| 355 // - we would hold JNIHandleBlockFreeList_lock and then Threads_lock | |
| 356 // - another would hold Threads_lock (jni_AttachCurrentThread) and then | |
| 357 // JNIHandleBlockFreeList_lock (JNIHandleBlock::allocate_block) | |
| 358 MutexLockerEx ml(JNIHandleBlockFreeList_lock, | |
| 359 Mutex::_no_safepoint_check_flag); | |
| 360 while (block != NULL) { | |
| 361 if (ZapJNIHandleArea) block->zap(); | |
| 362 JNIHandleBlock* next = block->_next; | |
| 363 block->_next = _block_free_list; | |
| 364 _block_free_list = block; | |
| 365 block = next; | |
| 366 } | |
| 367 } | |
| 368 if (pop_frame_link != NULL) { | |
| 369 // As a sanity check we release blocks pointed to by the pop_frame_link. | |
| 370 // This should never happen (only if PopLocalFrame is not called the | |
| 371 // correct number of times). | |
| 372 release_block(pop_frame_link, thread); | |
| 373 } | |
| 374 } | |
| 375 | |
| 376 | |
| 377 void JNIHandleBlock::oops_do(OopClosure* f) { | |
| 378 JNIHandleBlock* current_chain = this; | |
| 379 // Iterate over chain of blocks, followed by chains linked through the | |
| 380 // pop frame links. | |
| 381 while (current_chain != NULL) { | |
| 382 for (JNIHandleBlock* current = current_chain; current != NULL; | |
| 383 current = current->_next) { | |
| 384 assert(current == current_chain || current->pop_frame_link() == NULL, | |
| 385 "only blocks first in chain should have pop frame link set"); | |
| 386 for (int index = 0; index < current->_top; index++) { | |
| 387 oop* root = &(current->_handles)[index]; | |
| 388 oop value = *root; | |
| 389 // traverse heap pointers only, not deleted handles or free list | |
| 390 // pointers | |
| 391 if (value != NULL && Universe::heap()->is_in_reserved(value)) { | |
| 392 f->do_oop(root); | |
| 393 } | |
| 394 } | |
| 395 // the next handle block is valid only if current block is full | |
| 396 if (current->_top < block_size_in_oops) { | |
| 397 break; | |
| 398 } | |
| 399 } | |
| 400 current_chain = current_chain->pop_frame_link(); | |
| 401 } | |
| 402 } | |
| 403 | |
| 404 | |
| 405 void JNIHandleBlock::weak_oops_do(BoolObjectClosure* is_alive, | |
| 406 OopClosure* f) { | |
| 407 for (JNIHandleBlock* current = this; current != NULL; current = current->_next) { | |
| 408 assert(current->pop_frame_link() == NULL, | |
| 409 "blocks holding weak global JNI handles should not have pop frame link set"); | |
| 410 for (int index = 0; index < current->_top; index++) { | |
| 411 oop* root = &(current->_handles)[index]; | |
| 412 oop value = *root; | |
| 413 // traverse heap pointers only, not deleted handles or free list pointers | |
| 414 if (value != NULL && Universe::heap()->is_in_reserved(value)) { | |
| 415 if (is_alive->do_object_b(value)) { | |
| 416 // The weakly referenced object is alive, update pointer | |
| 417 f->do_oop(root); | |
| 418 } else { | |
| 419 // The weakly referenced object is not alive, clear the reference by storing NULL | |
| 420 if (TraceReferenceGC) { | |
| 421 tty->print_cr("Clearing JNI weak reference (" INTPTR_FORMAT ")", root); | |
| 422 } | |
| 423 *root = NULL; | |
| 424 } | |
| 425 } | |
| 426 } | |
| 427 // the next handle block is valid only if current block is full | |
| 428 if (current->_top < block_size_in_oops) { | |
| 429 break; | |
| 430 } | |
| 431 } | |
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432 |
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433 /* |
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434 * JvmtiTagMap may also contain weak oops. The iteration of it is placed |
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435 * here so that we don't need to add it to each of the collectors. |
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436 */ |
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437 JvmtiTagMap::weak_oops_do(is_alive, f); |
| 0 | 438 } |
| 439 | |
| 440 | |
| 441 jobject JNIHandleBlock::allocate_handle(oop obj) { | |
| 442 assert(Universe::heap()->is_in_reserved(obj), "sanity check"); | |
| 443 if (_top == 0) { | |
| 444 // This is the first allocation or the initial block got zapped when | |
| 445 // entering a native function. If we have any following blocks they are | |
| 446 // not valid anymore. | |
| 447 for (JNIHandleBlock* current = _next; current != NULL; | |
| 448 current = current->_next) { | |
| 449 assert(current->_last == NULL, "only first block should have _last set"); | |
| 450 assert(current->_free_list == NULL, | |
| 451 "only first block should have _free_list set"); | |
| 452 current->_top = 0; | |
| 453 if (ZapJNIHandleArea) current->zap(); | |
| 454 } | |
| 455 // Clear initial block | |
| 456 _free_list = NULL; | |
| 457 _allocate_before_rebuild = 0; | |
| 458 _last = this; | |
| 459 if (ZapJNIHandleArea) zap(); | |
| 460 } | |
| 461 | |
| 462 // Try last block | |
| 463 if (_last->_top < block_size_in_oops) { | |
| 464 oop* handle = &(_last->_handles)[_last->_top++]; | |
| 465 *handle = obj; | |
| 466 return (jobject) handle; | |
| 467 } | |
| 468 | |
| 469 // Try free list | |
| 470 if (_free_list != NULL) { | |
| 471 oop* handle = _free_list; | |
| 472 _free_list = (oop*) *_free_list; | |
| 473 *handle = obj; | |
| 474 return (jobject) handle; | |
| 475 } | |
| 476 // Check if unused block follow last | |
| 477 if (_last->_next != NULL) { | |
| 478 // update last and retry | |
| 479 _last = _last->_next; | |
| 480 return allocate_handle(obj); | |
| 481 } | |
| 482 | |
| 483 // No space available, we have to rebuild free list or expand | |
| 484 if (_allocate_before_rebuild == 0) { | |
| 485 rebuild_free_list(); // updates _allocate_before_rebuild counter | |
| 486 } else { | |
| 487 // Append new block | |
| 488 Thread* thread = Thread::current(); | |
| 489 Handle obj_handle(thread, obj); | |
| 490 // This can block, so we need to preserve obj accross call. | |
| 491 _last->_next = JNIHandleBlock::allocate_block(thread); | |
| 492 _last = _last->_next; | |
| 493 _allocate_before_rebuild--; | |
| 494 obj = obj_handle(); | |
| 495 } | |
| 496 return allocate_handle(obj); // retry | |
| 497 } | |
| 498 | |
| 499 | |
| 500 void JNIHandleBlock::rebuild_free_list() { | |
| 501 assert(_allocate_before_rebuild == 0 && _free_list == NULL, "just checking"); | |
| 502 int free = 0; | |
| 503 int blocks = 0; | |
| 504 for (JNIHandleBlock* current = this; current != NULL; current = current->_next) { | |
| 505 for (int index = 0; index < current->_top; index++) { | |
| 506 oop* handle = &(current->_handles)[index]; | |
| 507 if (*handle == JNIHandles::deleted_handle()) { | |
| 508 // this handle was cleared out by a delete call, reuse it | |
| 509 *handle = (oop) _free_list; | |
| 510 _free_list = handle; | |
| 511 free++; | |
| 512 } | |
| 513 } | |
| 514 // we should not rebuild free list if there are unused handles at the end | |
| 515 assert(current->_top == block_size_in_oops, "just checking"); | |
| 516 blocks++; | |
| 517 } | |
| 518 // Heuristic: if more than half of the handles are free we rebuild next time | |
| 519 // as well, otherwise we append a corresponding number of new blocks before | |
| 520 // attempting a free list rebuild again. | |
| 521 int total = blocks * block_size_in_oops; | |
| 522 int extra = total - 2*free; | |
| 523 if (extra > 0) { | |
| 524 // Not as many free handles as we would like - compute number of new blocks to append | |
| 525 _allocate_before_rebuild = (extra + block_size_in_oops - 1) / block_size_in_oops; | |
| 526 } | |
| 527 if (TraceJNIHandleAllocation) { | |
| 528 tty->print_cr("Rebuild free list JNIHandleBlock " INTPTR_FORMAT " blocks=%d used=%d free=%d add=%d", | |
| 529 this, blocks, total-free, free, _allocate_before_rebuild); | |
| 530 } | |
| 531 } | |
| 532 | |
| 533 | |
| 534 bool JNIHandleBlock::contains(jobject handle) const { | |
| 535 return ((jobject)&_handles[0] <= handle && handle<(jobject)&_handles[_top]); | |
| 536 } | |
| 537 | |
| 538 | |
| 539 bool JNIHandleBlock::chain_contains(jobject handle) const { | |
| 540 for (JNIHandleBlock* current = (JNIHandleBlock*) this; current != NULL; current = current->_next) { | |
| 541 if (current->contains(handle)) { | |
| 542 return true; | |
| 543 } | |
| 544 } | |
| 545 return false; | |
| 546 } | |
| 547 | |
| 548 | |
| 549 int JNIHandleBlock::length() const { | |
| 550 int result = 1; | |
| 551 for (JNIHandleBlock* current = _next; current != NULL; current = current->_next) { | |
| 552 result++; | |
| 553 } | |
| 554 return result; | |
| 555 } | |
| 556 | |
| 557 // This method is not thread-safe, i.e., must be called whule holding a lock on the | |
| 558 // structure. | |
| 559 long JNIHandleBlock::memory_usage() const { | |
| 560 return length() * sizeof(JNIHandleBlock); | |
| 561 } | |
| 562 | |
| 563 | |
| 564 #ifndef PRODUCT | |
| 565 | |
| 566 bool JNIHandleBlock::any_contains(jobject handle) { | |
| 567 for (JNIHandleBlock* current = _block_list; current != NULL; current = current->_block_list_link) { | |
| 568 if (current->contains(handle)) { | |
| 569 return true; | |
| 570 } | |
| 571 } | |
| 572 return false; | |
| 573 } | |
| 574 | |
| 575 void JNIHandleBlock::print_statistics() { | |
| 576 int used_blocks = 0; | |
| 577 int free_blocks = 0; | |
| 578 int used_handles = 0; | |
| 579 int free_handles = 0; | |
| 580 JNIHandleBlock* block = _block_list; | |
| 581 while (block != NULL) { | |
| 582 if (block->_top > 0) { | |
| 583 used_blocks++; | |
| 584 } else { | |
| 585 free_blocks++; | |
| 586 } | |
| 587 used_handles += block->_top; | |
| 588 free_handles += (block_size_in_oops - block->_top); | |
| 589 block = block->_block_list_link; | |
| 590 } | |
| 591 tty->print_cr("JNIHandleBlocks statistics"); | |
| 592 tty->print_cr("- blocks allocated: %d", used_blocks + free_blocks); | |
| 593 tty->print_cr("- blocks in use: %d", used_blocks); | |
| 594 tty->print_cr("- blocks free: %d", free_blocks); | |
| 595 tty->print_cr("- handles in use: %d", used_handles); | |
| 596 tty->print_cr("- handles free: %d", free_handles); | |
| 597 } | |
| 598 | |
| 599 #endif |