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 * particular file as subject to the "Classpath" exception as provided
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 * 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).
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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 List. 
NOTE: This class is not synchronized, subclasses must implement
         the appropriate synchronization whwn needed.


/**
 * 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 item.

This method is called by updateCachedDatas(Object, List). The given item is expected to be always associated with
the same index.

Params:
/**
     * 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 item.

This method is called by updateCachedDatas(Object, List). 
Params:
Returns:By default item is returned.
/**
     * 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.

Params:
  • context – A context object, valid during the duration of of the call to this method, and that will be passed to getIndex and getData. 
     This method is intended to be called by SnmpTableCache.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.
    
       This class does not use the context object: it is a simple
       hook for subclassed.
  • rawDatas – The table datas from which the cached data will be
       computed.
Returns:the computed cached data.
/**
     * 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<SnmpOid, Object>(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);
    }

}