ojluni/src/main/java/sun/management/snmp/util/SnmpNamedListTableCache.java - platform/libcore.git - Git at Google

 /*
  * Copyright (c) 2003, 2006, 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 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 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 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 ctxt = new TreeMap();
         final SnmpCachedData result =
             super.updateCachedDatas(ctxt,rawDatas);
         names = ctxt;
         return result;
     }

     static final MibLogger log = new MibLogger(SnmpNamedListTableCache.class);
 }
	/*
	* Copyright (c) 2003, 2006, 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 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 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 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 ctxt = new TreeMap();
	final SnmpCachedData result =
	super.updateCachedDatas(ctxt,rawDatas);
	names = ctxt;
	return result;
	}

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