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src/share/vm/runtime/jniHandles.cpp

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   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 
  25 #include "precompiled.hpp"
  26 #include "classfile/systemDictionary.hpp"

  27 #include "oops/oop.inline.hpp"
  28 #include "prims/jvmtiExport.hpp"
  29 #include "runtime/jniHandles.hpp"
  30 #include "runtime/mutexLocker.hpp"
  31 #include "runtime/thread.inline.hpp"
  32 
  33 JNIHandleBlock* JNIHandles::_global_handles       = NULL;
  34 JNIHandleBlock* JNIHandles::_weak_global_handles  = NULL;
  35 oop             JNIHandles::_deleted_handle       = NULL;
  36 
  37 
  38 jobject JNIHandles::make_local(oop obj) {
  39   if (obj == NULL) {
  40     return NULL;                // ignore null handles
  41   } else {
  42     Thread* thread = Thread::current();
  43     assert(Universe::heap()->is_in_reserved(obj), "sanity check");
  44     return thread->active_handles()->allocate_handle(obj);
  45   }
  46 }


 376     current_chain = current_chain->pop_frame_link();
 377   }
 378 }
 379 
 380 
 381 void JNIHandleBlock::weak_oops_do(BoolObjectClosure* is_alive,
 382                                   OopClosure* f) {
 383   for (JNIHandleBlock* current = this; current != NULL; current = current->_next) {
 384     assert(current->pop_frame_link() == NULL,
 385       "blocks holding weak global JNI handles should not 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 pointers
 390       if (value != NULL && Universe::heap()->is_in_reserved(value)) {
 391         if (is_alive->do_object_b(value)) {
 392           // The weakly referenced object is alive, update pointer
 393           f->do_oop(root);
 394         } else {
 395           // The weakly referenced object is not alive, clear the reference by storing NULL
 396           if (TraceReferenceGC) {
 397             tty->print_cr("Clearing JNI weak reference (" INTPTR_FORMAT ")", p2i(root));
 398           }
 399           *root = NULL;
 400         }
 401       }
 402     }
 403     // the next handle block is valid only if current block is full
 404     if (current->_top < block_size_in_oops) {
 405       break;
 406     }
 407   }
 408 
 409   /*
 410    * JVMTI data structures may also contain weak oops.  The iteration of them
 411    * is placed here so that we don't need to add it to each of the collectors.
 412    */
 413   JvmtiExport::weak_oops_do(is_alive, f);
 414 }
 415 
 416 
 417 jobject JNIHandleBlock::allocate_handle(oop obj) {
 418   assert(Universe::heap()->is_in_reserved(obj), "sanity check");




   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 
  25 #include "precompiled.hpp"
  26 #include "classfile/systemDictionary.hpp"
  27 #include "logging/log.hpp"
  28 #include "oops/oop.inline.hpp"
  29 #include "prims/jvmtiExport.hpp"
  30 #include "runtime/jniHandles.hpp"
  31 #include "runtime/mutexLocker.hpp"
  32 #include "runtime/thread.inline.hpp"
  33 
  34 JNIHandleBlock* JNIHandles::_global_handles       = NULL;
  35 JNIHandleBlock* JNIHandles::_weak_global_handles  = NULL;
  36 oop             JNIHandles::_deleted_handle       = NULL;
  37 
  38 
  39 jobject JNIHandles::make_local(oop obj) {
  40   if (obj == NULL) {
  41     return NULL;                // ignore null handles
  42   } else {
  43     Thread* thread = Thread::current();
  44     assert(Universe::heap()->is_in_reserved(obj), "sanity check");
  45     return thread->active_handles()->allocate_handle(obj);
  46   }
  47 }


 377     current_chain = current_chain->pop_frame_link();
 378   }
 379 }
 380 
 381 
 382 void JNIHandleBlock::weak_oops_do(BoolObjectClosure* is_alive,
 383                                   OopClosure* f) {
 384   for (JNIHandleBlock* current = this; current != NULL; current = current->_next) {
 385     assert(current->pop_frame_link() == NULL,
 386       "blocks holding weak global JNI handles should not have pop frame link set");
 387     for (int index = 0; index < current->_top; index++) {
 388       oop* root = &(current->_handles)[index];
 389       oop value = *root;
 390       // traverse heap pointers only, not deleted handles or free list pointers
 391       if (value != NULL && Universe::heap()->is_in_reserved(value)) {
 392         if (is_alive->do_object_b(value)) {
 393           // The weakly referenced object is alive, update pointer
 394           f->do_oop(root);
 395         } else {
 396           // The weakly referenced object is not alive, clear the reference by storing NULL
 397                   log_develop(gc, ref)("Clearing JNI weak reference (" INTPTR_FORMAT ")", p2i(root));


 398           *root = NULL;
 399         }
 400       }
 401     }
 402     // the next handle block is valid only if current block is full
 403     if (current->_top < block_size_in_oops) {
 404       break;
 405     }
 406   }
 407 
 408   /*
 409    * JVMTI data structures may also contain weak oops.  The iteration of them
 410    * is placed here so that we don't need to add it to each of the collectors.
 411    */
 412   JvmtiExport::weak_oops_do(is_alive, f);
 413 }
 414 
 415 
 416 jobject JNIHandleBlock::allocate_handle(oop obj) {
 417   assert(Universe::heap()->is_in_reserved(obj), "sanity check");


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