8047125: (ref) More phantom object references

Reviewed-by: mchung, dfuchs, ahgross, jmasa, brutisso, mgerdin

hotspot/src/share/vm/classfile/systemDictionary.cpp

@@ -1905,11 +1905,12 @@ void SystemDictionary::initialize_preloaded_classes(TRAPS) {
   InstanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER);
   InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
 
-  initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(PhantomReference_klass), scan, CHECK);
+  initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Cleaner_klass), scan, CHECK);
   InstanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT);
   InstanceKlass::cast(WK_KLASS(WeakReference_klass))->set_reference_type(REF_WEAK);
   InstanceKlass::cast(WK_KLASS(FinalReference_klass))->set_reference_type(REF_FINAL);
   InstanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM);
+  InstanceKlass::cast(WK_KLASS(Cleaner_klass))->set_reference_type(REF_CLEANER);
 
   // JSR 292 classes
   WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);

hotspot/src/share/vm/classfile/systemDictionary.hpp

@@ -128,6 +128,7 @@ class Ticks;
   do_klass(WeakReference_klass,                         java_lang_ref_WeakReference,               Pre                 ) \
   do_klass(FinalReference_klass,                        java_lang_ref_FinalReference,              Pre                 ) \
   do_klass(PhantomReference_klass,                      java_lang_ref_PhantomReference,            Pre                 ) \
+  do_klass(Cleaner_klass,                               sun_misc_Cleaner,                          Pre                 ) \
   do_klass(Finalizer_klass,                             java_lang_ref_Finalizer,                   Pre                 ) \
                                                                                                                          \
   do_klass(Thread_klass,                                java_lang_Thread,                          Pre                 ) \

hotspot/src/share/vm/classfile/vmSymbols.hpp

@@ -79,6 +79,7 @@
   template(java_lang_ref_WeakReference,               "java/lang/ref/WeakReference")              \
   template(java_lang_ref_FinalReference,              "java/lang/ref/FinalReference")             \
   template(java_lang_ref_PhantomReference,            "java/lang/ref/PhantomReference")           \
+  template(sun_misc_Cleaner,                          "sun/misc/Cleaner")                         \
   template(java_lang_ref_Finalizer,                   "java/lang/ref/Finalizer")                  \
   template(java_lang_reflect_AccessibleObject,        "java/lang/reflect/AccessibleObject")       \
   template(java_lang_reflect_Method,                  "java/lang/reflect/Method")                 \

hotspot/src/share/vm/memory/referenceProcessor.cpp

@@ -118,6 +118,7 @@ ReferenceProcessor::ReferenceProcessor(MemRegion span,
   _discoveredWeakRefs    = &_discoveredSoftRefs[_max_num_q];
   _discoveredFinalRefs   = &_discoveredWeakRefs[_max_num_q];
   _discoveredPhantomRefs = &_discoveredFinalRefs[_max_num_q];
+  _discoveredCleanerRefs = &_discoveredPhantomRefs[_max_num_q];
 
   // Initialize all entries to NULL
   for (uint i = 0; i < _max_num_q * number_of_subclasses_of_ref(); i++) {
@@ -246,6 +247,13 @@ ReferenceProcessorStats ReferenceProcessor::process_discovered_references(
     phantom_count =
       process_discovered_reflist(_discoveredPhantomRefs, NULL, false,
                                  is_alive, keep_alive, complete_gc, task_executor);
+
+    // Process cleaners, but include them in phantom statistics.  We expect
+    // Cleaner references to be temporary, and don't want to deal with
+    // possible incompatibilities arising from making it more visible.
+    phantom_count +=
+      process_discovered_reflist(_discoveredCleanerRefs, NULL, false,
+                                 is_alive, keep_alive, complete_gc, task_executor);
   }
 
   // Weak global JNI references. It would make more sense (semantically) to
@@ -885,6 +893,7 @@ void ReferenceProcessor::balance_all_queues() {
   balance_queues(_discoveredWeakRefs);
   balance_queues(_discoveredFinalRefs);
   balance_queues(_discoveredPhantomRefs);
+  balance_queues(_discoveredCleanerRefs);
 }
 
 size_t
@@ -998,6 +1007,9 @@ inline DiscoveredList* ReferenceProcessor::get_discovered_list(ReferenceType rt)
     case REF_PHANTOM:
       list = &_discoveredPhantomRefs[id];
       break;
+    case REF_CLEANER:
+      list = &_discoveredCleanerRefs[id];
+      break;
     case REF_NONE:
       // we should not reach here if we are an InstanceRefKlass
     default:
@@ -1263,6 +1275,17 @@ void ReferenceProcessor::preclean_discovered_references(
       preclean_discovered_reflist(_discoveredPhantomRefs[i], is_alive,
                                   keep_alive, complete_gc, yield);
     }
+
+    // Cleaner references.  Included in timing for phantom references.  We
+    // expect Cleaner references to be temporary, and don't want to deal with
+    // possible incompatibilities arising from making it more visible.
+    for (uint i = 0; i < _max_num_q; i++) {
+      if (yield->should_return()) {
+        return;
+      }
+      preclean_discovered_reflist(_discoveredCleanerRefs[i], is_alive,
+                                  keep_alive, complete_gc, yield);
+    }
   }
 }
 
@@ -1331,6 +1354,7 @@ const char* ReferenceProcessor::list_name(uint i) {
      case 1: return "WeakRef";
      case 2: return "FinalRef";
      case 3: return "PhantomRef";
+     case 4: return "CleanerRef";
    }
    ShouldNotReachHere();
    return NULL;

hotspot/src/share/vm/memory/referenceProcessor.hpp

@@ -264,9 +264,10 @@ class ReferenceProcessor : public CHeapObj<mtGC> {
   DiscoveredList* _discoveredWeakRefs;
   DiscoveredList* _discoveredFinalRefs;
   DiscoveredList* _discoveredPhantomRefs;
+  DiscoveredList* _discoveredCleanerRefs;
 
  public:
-  static int number_of_subclasses_of_ref() { return (REF_PHANTOM - REF_OTHER); }
+  static int number_of_subclasses_of_ref() { return (REF_CLEANER - REF_OTHER); }
 
   uint num_q()                             { return _num_q; }
   uint max_num_q()                         { return _max_num_q; }

hotspot/src/share/vm/memory/referenceType.hpp

@@ -35,7 +35,8 @@ enum ReferenceType {
   REF_SOFT,      // Subclass of java/lang/ref/SoftReference
   REF_WEAK,      // Subclass of java/lang/ref/WeakReference
   REF_FINAL,     // Subclass of java/lang/ref/FinalReference
-  REF_PHANTOM    // Subclass of java/lang/ref/PhantomReference
+  REF_PHANTOM,   // Subclass of java/lang/ref/PhantomReference
+  REF_CLEANER    // Subclass of sun/misc/Cleaner
 };
 
 #endif // SHARE_VM_MEMORY_REFRERENCETYPE_HPP

hotspot/src/share/vm/runtime/vmStructs.cpp

@@ -661,6 +661,7 @@ typedef TwoOopHashtable<Symbol*, mtClass>     SymbolTwoOopHashtable;
       static_field(SystemDictionary,            WK_KLASS(WeakReference_klass),                 Klass*)                               \
       static_field(SystemDictionary,            WK_KLASS(FinalReference_klass),                Klass*)                               \
       static_field(SystemDictionary,            WK_KLASS(PhantomReference_klass),              Klass*)                               \
+      static_field(SystemDictionary,            WK_KLASS(Cleaner_klass),                       Klass*)                               \
       static_field(SystemDictionary,            WK_KLASS(Finalizer_klass),                     Klass*)                               \
       static_field(SystemDictionary,            WK_KLASS(Thread_klass),                        Klass*)                               \
       static_field(SystemDictionary,            WK_KLASS(ThreadGroup_klass),                   Klass*)                               \