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   assert(nm == GenRemSet::CardTable, "Unrecognized GenRemSet type.");
  36   return CardTableRS::ct_max_alignment_constraint();
  37 }
  38 
  39 class HasAccumulatedModifiedOopsClosure : public KlassClosure {
  40   bool _found;
  41  public:
  42   HasAccumulatedModifiedOopsClosure() : _found(false) {}
  43   void do_klass(Klass* klass) {
  44     if (_found) {
  45       return;
  46     }
  47 
  48     if (klass->has_accumulated_modified_oops()) {
  49       _found = true;
  50     }
  51   }
  52   bool found() {
  53     return _found;
  54   }
  55 };
  56 
  57 bool KlassRemSet::mod_union_is_clear() {
  58   HasAccumulatedModifiedOopsClosure closure;
  59   ClassLoaderDataGraph::classes_do(&closure);
  60 
  61   return !closure.found();
  62 }
  63 
  64 
  65 class ClearKlassModUnionClosure : public KlassClosure {
  66  public:
  67   void do_klass(Klass* klass) {
  68     if (klass->has_accumulated_modified_oops()) {
  69       klass->clear_accumulated_modified_oops();
  70     }
  71   }
  72 };
  73 
  74 void KlassRemSet::clear_mod_union() {
  75   ClearKlassModUnionClosure closure;
  76   ClassLoaderDataGraph::classes_do(&closure);
  77 }