1 /*
   2  * Copyright (c) 1997, 2006, Oracle and/or its affiliates. All rights reserved.
   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  *
  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 // An instanceRefKlass is a specialized instanceKlass for Java
  26 // classes that are subclasses of java/lang/ref/Reference.
  27 //
  28 // These classes are used to implement soft/weak/final/phantom
  29 // references and finalization, and need special treatment by the
  30 // garbage collector.
  31 //
  32 // During GC discovered reference objects are added (chained) to one
  33 // of the four lists below, depending on the type of reference.
  34 // The linked occurs through the next field in class java/lang/ref/Reference.
  35 //
  36 // Afterwards, the discovered references are processed in decreasing
  37 // order of reachability. Reference objects eligible for notification
  38 // are linked to the static pending_list in class java/lang/ref/Reference,
  39 // and the pending list lock object in the same class is notified.
  40 
  41 
  42 class instanceRefKlass: public instanceKlass {
  43  public:
  44   // Type testing
  45   bool oop_is_instanceRef() const             { return true; }
  46 
  47   // Casting from klassOop
  48   static instanceRefKlass* cast(klassOop k) {
  49     assert(k->klass_part()->oop_is_instanceRef(), "cast to instanceRefKlass");
  50     return (instanceRefKlass*) k->klass_part();
  51   }
  52 
  53   // allocation
  54   DEFINE_ALLOCATE_PERMANENT(instanceRefKlass);
  55 
  56   // Garbage collection
  57   int  oop_adjust_pointers(oop obj);
  58   void oop_follow_contents(oop obj);
  59 
  60   // Parallel Scavenge and Parallel Old
  61   PARALLEL_GC_DECLS
  62 
  63   int oop_oop_iterate(oop obj, OopClosure* blk) {
  64     return oop_oop_iterate_v(obj, blk);
  65   }
  66   int oop_oop_iterate_m(oop obj, OopClosure* blk, MemRegion mr) {
  67     return oop_oop_iterate_v_m(obj, blk, mr);
  68   }
  69 
  70 #define InstanceRefKlass_OOP_OOP_ITERATE_DECL(OopClosureType, nv_suffix)                \
  71   int oop_oop_iterate##nv_suffix(oop obj, OopClosureType* blk);                         \
  72   int oop_oop_iterate##nv_suffix##_m(oop obj, OopClosureType* blk, MemRegion mr);
  73 
  74   ALL_OOP_OOP_ITERATE_CLOSURES_1(InstanceRefKlass_OOP_OOP_ITERATE_DECL)
  75   ALL_OOP_OOP_ITERATE_CLOSURES_2(InstanceRefKlass_OOP_OOP_ITERATE_DECL)
  76 
  77 #ifndef SERIALGC
  78 #define InstanceRefKlass_OOP_OOP_ITERATE_BACKWARDS_DECL(OopClosureType, nv_suffix)      \
  79   int oop_oop_iterate_backwards##nv_suffix(oop obj, OopClosureType* blk);
  80 
  81   ALL_OOP_OOP_ITERATE_CLOSURES_1(InstanceRefKlass_OOP_OOP_ITERATE_BACKWARDS_DECL)
  82   ALL_OOP_OOP_ITERATE_CLOSURES_2(InstanceRefKlass_OOP_OOP_ITERATE_BACKWARDS_DECL)
  83 #endif // !SERIALGC
  84 
  85   static void release_and_notify_pending_list_lock(BasicLock *pending_list_basic_lock);
  86   static void acquire_pending_list_lock(BasicLock *pending_list_basic_lock);
  87 
  88   // Update non-static oop maps so 'referent', 'nextPending' and
  89   // 'discovered' will look like non-oops
  90   static void update_nonstatic_oop_maps(klassOop k);
  91 
  92  public:
  93   // Verification
  94   void oop_verify_on(oop obj, outputStream* st);
  95 };