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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);
}