1 /*
   2  * Copyright (c) 2001, 2012, 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 #include "precompiled.hpp"
  26 #include "classfile/classLoaderData.hpp"
  27 #include "memory/cardTableRS.hpp"
  28 #include "memory/genRemSet.hpp"
  29 
  30 // This kind of "BarrierSet" allows a "CollectedHeap" to detect and
  31 // enumerate ref fields that have been modified (since the last
  32 // enumeration.)
  33 
  34 uintx GenRemSet::max_alignment_constraint(Name nm) {
  35   switch (nm) {
  36   case GenRemSet::CardTable:
  37     return CardTableRS::ct_max_alignment_constraint();
  38   default:
  39     guarantee(false, "Unrecognized GenRemSet type.");
  40     return (0); // Make Windows compiler happy
  41   }
  42 }
  43 
  44 class HasAccumulatedModifiedOopsClosure : public KlassClosure {
  45   bool _found;
  46  public:
  47   HasAccumulatedModifiedOopsClosure() : _found(false) {}
  48   void do_klass(Klass* klass) {
  49     if (_found) {
  50       return;
  51     }
  52 
  53     if (klass->has_accumulated_modified_oops()) {
  54       _found = true;
  55     }
  56   }
  57   bool found() {
  58     return _found;
  59   }
  60 };
  61 
  62 bool KlassRemSet::mod_union_is_clear() {
  63   HasAccumulatedModifiedOopsClosure closure;
  64   ClassLoaderDataGraph::classes_do(&closure);
  65 
  66   return !closure.found();
  67 }
  68 
  69 
  70 class ClearKlassModUnionClosure : public KlassClosure {
  71  public:
  72   void do_klass(Klass* klass) {
  73     if (klass->has_accumulated_modified_oops()) {
  74       klass->clear_accumulated_modified_oops();
  75     }
  76   }
  77 };
  78 
  79 void KlassRemSet::clear_mod_union() {
  80   ClearKlassModUnionClosure closure;
  81   ClassLoaderDataGraph::classes_do(&closure);
  82 }