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	/*
	* Copyright (c) 2003, 2012, 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.management.snmp.util;

	import com.sun.jmx.snmp.SnmpOid;
	import com.sun.jmx.mbeanserver.Util;

	import java.io.Serializable;

	import java.util.Comparator;
	import java.util.Arrays;
	import java.util.Map;
	import java.util.TreeMap;
	import java.util.List;
	import java.util.Iterator;

	import java.lang.ref.WeakReference;


	/**
	* This abstract class implements a weak cache that holds table data, for
	* a table whose data is obtained from a list where a name can be obtained
	* for each item in the list.
	* <p>This object maintains a map between an entry name and its associated
	* SnmpOid index, so that a given entry is always associated to the same
	* index.</p>
	* <p><b>NOTE: This class is not synchronized, subclasses must implement
	* the appropriate synchronization whwn needed.</b></p>
	**/
	public abstract class SnmpNamedListTableCache extends SnmpListTableCache {

	/**
	* This map associate an entry name with the SnmpOid index that's
	* been allocated for it.
	**/
	protected TreeMap<String, SnmpOid> names = new TreeMap<>();

	/**
	* The last allocate index.
	**/
	protected long last = 0;

	/**
	* true if the index has wrapped.
	**/
	boolean wrapped = false;

	/**
	* Returns the key to use as name for the given <var>item</var>.
	* <br>This method is called by {@link #getIndex(Object,List,int,Object)}.
	* The given <var>item</var> is expected to be always associated with
	* the same name.
	* @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 a key name must be determined.
	**/
	protected abstract String getKey(Object context, List<?> rawDatas,
	int rank, Object item);

	/**
	* Find a new index for the entry corresponding to the
	* given <var>item</var>.
	* <br>This method is called by {@link #getIndex(Object,List,int,Object)}
	* when a new index needs to be allocated for an <var>item</var>. The
	* index returned must not be already in used.
	* @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 SnmpOid makeIndex(Object context, List<?> rawDatas,
	int rank, Object item) {

	// check we are in the limits of an unsigned32.
	if (++last > 0x00000000FFFFFFFFL) {
	// we just wrapped.
	log.debug("makeIndex", "Index wrapping...");
	last = 0;
	wrapped=true;
	}

	// If we never wrapped, we can safely return last as new index.
	if (!wrapped) return new SnmpOid(last);

	// We wrapped. We must look for an unused index.
	for (int i=1;i < 0x00000000FFFFFFFFL;i++) {
	if (++last > 0x00000000FFFFFFFFL) last = 1;
	final SnmpOid testOid = new SnmpOid(last);

	// Was this index already in use?
	if (names == null) return testOid;
	if (names.containsValue(testOid)) continue;

	// Have we just used it in a previous iteration?
	if (context == null) return testOid;
	if (((Map)context).containsValue(testOid)) continue;

	// Ok, not in use.
	return testOid;
	}
	// all indexes are in use! we're stuck.
	// // throw new IndexOutOfBoundsException("No index available.");
	// better to return null and log an error.
	return null;
	}

	/**
	* Call {@link #getKey(Object,List,int,Object)} in order to get
	* the item name. Then check whether an index was already allocated
	* for the entry by that name. If yes return it. Otherwise, call
	* {@link #makeIndex(Object,List,int,Object)} to compute a new
	* index for that entry.
	* Finally store the association between
	* the name and index in the context TreeMap.
	* @param context The context passed to
	* {@link #updateCachedDatas(Object,List)}.
	* It is expected to
	* be an instance of {@link TreeMap}.
	* @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 SnmpOid getIndex(Object context, List<?> rawDatas,
	int rank, Object item) {
	final String key = getKey(context,rawDatas,rank,item);
	final Object index = (names==null\|\|key==null)?null:names.get(key);
	final SnmpOid result =
	((index != null)?((SnmpOid)index):makeIndex(context,rawDatas,
	rank,item));
	if ((context != null) && (key != null) && (result != null)) {
	Map<Object, Object> map = Util.cast(context);
	map.put(key,result);
	}
	log.debug("getIndex","key="+key+", index="+result);
	return result;
	}

	/**
	* Allocate a new {@link TreeMap} to serve as context, then
	* call {@link SnmpListTableCache#updateCachedDatas(Object,List)}, and
	* finally replace the {@link #names} TreeMap by the new allocated
	* TreeMap.
	* @param rawDatas The table datas from which the cached data will be
	* computed.
	**/
	protected SnmpCachedData updateCachedDatas(Object context, List<?> rawDatas) {
	TreeMap<String,SnmpOid> ctxt = new TreeMap<>();
	final SnmpCachedData result =
	super.updateCachedDatas(context,rawDatas);
	names = ctxt;
	return result;
	}


	/**
	* Load a list of raw data from which to build the cached data.
	* This method is called when nothing is found in the request
	* contextual cache.
	* @param userData The request contextual cache allocated by
	* the {@link JvmContextFactory}.
	*
	**/
	protected abstract List<?> loadRawDatas(Map<Object,Object> userData);

	/**
	*The name under which the raw data is to be found/put in
	* the request contextual cache.
	**/
	protected abstract String getRawDatasKey();

	/**
	* Get a list of raw data from which to build the cached data.
	* Obtains a list of raw data by first looking it up in the
	* request contextual cache <var>userData</var> under the given
	* <var>key</var>. If nothing is found in the cache, calls
	* {@link #loadRawDatas(Map)} to obtain a new rawData list,
	* and cache the result in <var>userData</var> under <var>key</var>.
	* @param userData The request contextual cache allocated by
	* the {@link JvmContextFactory}.
	* @param key The name under which the raw data is to be found/put in
	* the request contextual cache.
	*
	**/
	protected List<?> getRawDatas(Map<Object, Object> userData, String key) {
	List<?> rawDatas = null;

	// Look for memory manager list in request contextual cache.
	if (userData != null)
	rawDatas = (List<?>)userData.get(key);

	if (rawDatas == null) {
	// No list in contextual cache, get it from API
	rawDatas = loadRawDatas(userData);


	// Put list in cache...
	if (rawDatas != null && userData != null)
	userData.put(key, rawDatas);
	}

	return rawDatas;
	}

	/**
	* Update cahed datas.
	* Obtains a {@link List} of raw datas by calling
	* {@link #getRawDatas(Map,String) getRawDatas((Map)context,getRawDatasKey())}.<br>
	* Then allocate a new {@link TreeMap} to serve as temporary map between
	* names and indexes, and call {@link #updateCachedDatas(Object,List)}
	* with that temporary map as context.<br>
	* Finally replaces the {@link #names} TreeMap by the temporary
	* TreeMap.
	* @param context The request contextual cache allocated by the
	* {@link JvmContextFactory}.
	**/
	protected SnmpCachedData updateCachedDatas(Object context) {

	final Map<Object, Object> userData =
	(context instanceof Map)?Util.<Map<Object, Object>>cast(context):null;

	// Look for memory manager list in request contextual cache.
	final List<?> rawDatas = getRawDatas(userData,getRawDatasKey());

	log.debug("updateCachedDatas","rawDatas.size()=" +
	((rawDatas==null)?"<no data>":""+rawDatas.size()));

	TreeMap<String,SnmpOid> ctxt = new TreeMap<>();
	final SnmpCachedData result =
	super.updateCachedDatas(ctxt,rawDatas);
	names = ctxt;
	return result;
	}

	static final MibLogger log = new MibLogger(SnmpNamedListTableCache.class);
	}

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