/*

 * Copyright (c) 1999, 2004, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package sun.java2d.loops;

public final class RenderCache {

    final class Entry {

        private SurfaceType src;

        private CompositeType comp;

        private SurfaceType dst;

        private Object value;

        public Entry(SurfaceType src,

                     CompositeType comp,

                     SurfaceType dst,

                     Object value)

        {

            this.src = src;

            this.comp = comp;

            this.dst = dst;

            this.value = value;

        }

        public boolean matches(SurfaceType src,

                               CompositeType comp,

                               SurfaceType dst)

        {

            // bug 4725045: using equals() causes different SurfaceType

            // objects with the same strings to match in the cache, which is

            // not the behavior we want.  Constrain the match to succeed only

            // on object matches instead.

            return ((this.src == src) &&

                    (this.comp == comp) &&

                    (this.dst == dst));

        }

        public Object getValue() {

            return value;

        }

    }

    private Entry entries[];

    public RenderCache(int size) {

        entries = new Entry[size];

    }

    public synchronized Object get(SurfaceType src,

                      CompositeType comp,

                      SurfaceType dst)

    {

        int max = entries.length - 1;

        for (int i = max; i >= 0; i--) {

            Entry e = entries[i];

            if (e == null) {

                break;

            }

            if (e.matches(src, comp, dst)) {

                if (i < max - 4) {

                    System.arraycopy(entries, i+1, entries, i, max - i);

                    entries[max] = e;

                }

                return e.getValue();

            }

        }

        return null;

    }

    public synchronized void put(SurfaceType src,

                    CompositeType comp,

                    SurfaceType dst,

                    Object value)

    {

        Entry e = new Entry(src, comp, dst, value);

        int num = entries.length;

        System.arraycopy(entries, 1, entries, 0, num - 1);

        entries[num - 1] = e;

    }

}