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src/jdk.internal.vm.ci/share/classes/jdk.vm.ci.hotspot/src/jdk/vm/ci/hotspot/HandleCleaner.java

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  48     private final boolean isJObject;
  49 
  50     private HandleCleaner(Object wrapper, long handle, boolean isJObject) {
  51         super(wrapper);
  52         this.handle = handle;
  53         this.isJObject = isJObject;
  54     }
  55 
  56     /**
  57      * Releases the resource associated with {@code this.handle}.
  58      */
  59     @Override
  60     void doCleanup() {
  61         if (isJObject) {
  62             // The sentinel value used to denote a free handle is
  63             // an object on the HotSpot heap so we call into the
  64             // VM to set the target of an object handle to this value.
  65             CompilerToVM.compilerToVM().deleteGlobalHandle(handle);
  66         } else {
  67             // Setting the target of a jmetadata handle to 0 enables
  68             // the handle to be reused. See MetadataHandleBlock in
  69             // jvmciRuntime.cpp for more info.
  70             long value = UNSAFE.getLong(null, handle);
  71             UNSAFE.compareAndSetLong(null, handle, value, 0);
  72         }
  73     }
  74 
  75     /**
  76      * Registers a cleaner for {@code handle}. The cleaner will release the handle some time after
  77      * {@code wrapper} is detected as unreachable by the garbage collector.
  78      */
  79     @SuppressWarnings("unused")
  80     static void create(Object wrapper, long handle) {
  81         assert wrapper instanceof IndirectHotSpotObjectConstantImpl || wrapper instanceof MetaspaceHandleObject;
  82         new HandleCleaner(wrapper, handle, wrapper instanceof IndirectHotSpotObjectConstantImpl);
  83     }
  84 }


  48     private final boolean isJObject;
  49 
  50     private HandleCleaner(Object wrapper, long handle, boolean isJObject) {
  51         super(wrapper);
  52         this.handle = handle;
  53         this.isJObject = isJObject;
  54     }
  55 
  56     /**
  57      * Releases the resource associated with {@code this.handle}.
  58      */
  59     @Override
  60     void doCleanup() {
  61         if (isJObject) {
  62             // The sentinel value used to denote a free handle is
  63             // an object on the HotSpot heap so we call into the
  64             // VM to set the target of an object handle to this value.
  65             CompilerToVM.compilerToVM().deleteGlobalHandle(handle);
  66         } else {
  67             // Setting the target of a jmetadata handle to 0 enables
  68             // the handle to be reused. See MetadataHandles in
  69             // metadataHandles.hpp for more info.
  70             long value = UNSAFE.getLong(null, handle);
  71             UNSAFE.compareAndSetLong(null, handle, value, 0);
  72         }
  73     }
  74 
  75     /**
  76      * Registers a cleaner for {@code handle}. The cleaner will release the handle some time after
  77      * {@code wrapper} is detected as unreachable by the garbage collector.
  78      */
  79     @SuppressWarnings("unused")
  80     static void create(Object wrapper, long handle) {
  81         assert wrapper instanceof IndirectHotSpotObjectConstantImpl || wrapper instanceof MetaspaceHandleObject;
  82         new HandleCleaner(wrapper, handle, wrapper instanceof IndirectHotSpotObjectConstantImpl);
  83     }
  84 }
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