1 /*

     2  * Copyright (c) 2001, 2015, 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 "gc/shared/cardTableRS.hpp"

    28 #include "gc/shared/genRemSet.hpp"

    29 #include "oops/klass.hpp"

    30 

    31 // This kind of "BarrierSet" allows a "CollectedHeap" to detect and

    32 // enumerate ref fields that have been modified (since the last

    33 // enumeration.)

    34 

    35 uintx GenRemSet::max_alignment_constraint() {

    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 }