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 package jdk.vm.ci.hotspot;
  24 
  25 import java.lang.ref.*;
  26 import java.util.*;
  27 
  28 import jdk.vm.ci.meta.*;







  29 
  30 /**
  31  * This class manages the set of metadata roots that must be scanned during garbage collection.
  32  * Because of class redefinition Method* and ConstantPool* can be freed if they don't appear to be
  33  * in use so they must be tracked when there are live references to them from Java.
  34  *
  35  * The general theory of operation is that all {@link MetaspaceWrapperObject}s are created by
  36  * calling into the VM which calls back out to actually create the wrapper instance. During the call
  37  * the VM keeps the metadata reference alive through the use of metadata handles. Once the call
  38  * completes the wrapper object is registered here and will be scanned during metadata scanning. The
  39  * weakness of the reference to the wrapper object allows them to be reclaimed when they are no
  40  * longer used.
  41  *
  42  */
  43 public class HotSpotJVMCIMetaAccessContext implements JVMCIMetaAccessContext {
  44 
  45     /**
  46      * The set of currently live contexts used for tracking of live metadata. Examined from the VM
  47      * during garbage collection.
  48      */

   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 package jdk.vm.ci.hotspot;
  24 
  25 import java.lang.ref.Reference;
  26 import java.lang.ref.ReferenceQueue;
  27 import java.lang.ref.WeakReference;
  28 import java.util.Arrays;
  29 import java.util.Iterator;
  30 import java.util.Map;
  31 import java.util.WeakHashMap;
  32 
  33 import jdk.vm.ci.meta.JVMCIMetaAccessContext;
  34 import jdk.vm.ci.meta.JavaKind;
  35 import jdk.vm.ci.meta.ResolvedJavaType;
  36 
  37 /**
  38  * This class manages the set of metadata roots that must be scanned during garbage collection.
  39  * Because of class redefinition Method* and ConstantPool* can be freed if they don't appear to be
  40  * in use so they must be tracked when there are live references to them from Java.
  41  *
  42  * The general theory of operation is that all {@link MetaspaceWrapperObject}s are created by
  43  * calling into the VM which calls back out to actually create the wrapper instance. During the call
  44  * the VM keeps the metadata reference alive through the use of metadata handles. Once the call
  45  * completes the wrapper object is registered here and will be scanned during metadata scanning. The
  46  * weakness of the reference to the wrapper object allows them to be reclaimed when they are no
  47  * longer used.
  48  *
  49  */
  50 public class HotSpotJVMCIMetaAccessContext implements JVMCIMetaAccessContext {
  51 
  52     /**
  53      * The set of currently live contexts used for tracking of live metadata. Examined from the VM
  54      * during garbage collection.
  55      */