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

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 * 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,

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package sun.management.snmp.util;

import com.sun.jmx.snmp.SnmpOid;

import java.io.Serializable;

import java.util.Comparator;

import java.util.Arrays;

import java.util.TreeMap;

import java.util.List;

import java.util.Iterator;

import java.lang.ref.WeakReference;

/**

 * This abstract class implements a weak cache for a table whose data

 * is obtained from a {@link  List}.

 *

 * <p><b>NOTE: This class is not synchronized, subclasses must implement

 *          the appropriate synchronization whwn needed.</b></p>

 **/

public abstract class SnmpListTableCache extends SnmpTableCache {

    /**

     * The index of the entry corresponding to the given <var>item</var>.

     * <br>This method is called by {@link #updateCachedDatas(Object,List)}.

     * The given <var>item</var> is expected to be always associated with

     * the same index.

     * @param context The context passed to

     *        {@link #updateCachedDatas(Object,List)}.

     * @param rawDatas Raw table datas passed to

     *        {@link #updateCachedDatas(Object,List)}.

     * @param rank Rank of the given <var>item</var> in the

     *        <var>rawDatas</var> list iterator.

     * @param item The raw data object for which an index must be determined.

     **/

    protected abstract SnmpOid getIndex(Object context, List<?> rawDatas,

                                        int rank, Object item);

    /**

     * The data for the entry corresponding to the given <var>item</var>.

     * <br>This method is called by {@link #updateCachedDatas(Object,List)}.

     * @param context The context passed to

     *        {@link #updateCachedDatas(Object,List)}.

     * @param rawDatas Raw table datas passed to

     *        {@link #updateCachedDatas(Object,List)}.

     * @param rank Rank of the given <var>item</var> in the

     *        <var>rawDatas</var> list iterator.

     * @param item The raw data object from which the entry data must be

     *        extracted.

     * @return By default <var>item</var> is returned.

     **/

    protected Object getData(Object context, List<?> rawDatas,

                             int rank, Object item) {

        return item;

    }

    /**

     * Recompute cached data.

     * @param context A context object, valid during the duration of

     *        of the call to this method, and that will be passed to

     *        {@link #getIndex} and {@link #getData}. <br>

     *        This method is intended to be called by

     *        {@link #updateCachedDatas(Object)}. It is assumed that

     *        the context is be allocated by  before this method is called,

     *        and released just after this method has returned.<br>

     *        This class does not use the context object: it is a simple

     *        hook for subclassed.

     * @param rawDatas The table datas from which the cached data will be

     *        computed.

     * @return the computed cached data.

     **/

    protected SnmpCachedData updateCachedDatas(Object context, List<?> rawDatas) {

        final int size = ((rawDatas == null)?0:rawDatas.size());

        if (size == 0) return  null;

        final long time = System.currentTimeMillis();

        final Iterator<?> it  = rawDatas.iterator();

        final TreeMap<SnmpOid, Object> map =

                new TreeMap<>(SnmpCachedData.oidComparator);

        for (int rank=0; it.hasNext() ; rank++) {

            final Object  item  = it.next();

            final SnmpOid index = getIndex(context, rawDatas, rank, item);

            final Object  data  = getData(context, rawDatas, rank, item);

            if (index == null) continue;

            map.put(index,data);

        }

        return new SnmpCachedData(time,map);

    }

}