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Cristal-ise is a description-driven software platform originally developed to track the construction of the CMS ECAL detector of the LHC at CERN. This is its core library, known as the kernel, which manages business objects called Items. Items are entirely configured from data, called descriptions, held in other Items. Every change of a state in an Item is a consequence of an execution of an activity in that Item's lifecycle, meaning that Cristal-ise applications are completely traceable, even in their design. It also supports extensive versioning of Item description data, giving the system a high level of flexibility.

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/**
 * This file is part of the CRISTAL-iSE kernel.
 * Copyright (c) 2001-2015 The CRISTAL Consortium. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation; either version 3 of the License, or (at
 * your option) any later version.
 *
 * This library is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; with out even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
 *
 * http://www.fsf.org/licensing/licenses/lgpl.html
 */
package org.cristalise.storage;

import java.util.ArrayList;
import java.util.ConcurrentModificationException;
import java.util.HashMap;
import java.util.Map;

import org.cristalise.kernel.common.PersistencyException;
import org.cristalise.kernel.entity.C2KLocalObject;
import org.cristalise.kernel.lookup.ItemPath;
import org.cristalise.kernel.persistency.ClusterStorage;
import org.cristalise.kernel.persistency.ClusterType;
import org.cristalise.kernel.process.auth.Authenticator;
import org.cristalise.kernel.querying.Query;
import org.cristalise.kernel.utils.Logger;


public class MemoryOnlyClusterStorage extends ClusterStorage {

    HashMap> memoryCache = new HashMap>();

    public void clear() {
        memoryCache.clear();
    }
    /**
     * 
     */
    public MemoryOnlyClusterStorage() {
        memoryCache = new HashMap>();
    }

    @Override
    public void open(Authenticator auth) throws PersistencyException {

    }

    @Override
    public void close() throws PersistencyException {
    }

    @Override
    public boolean checkQuerySupport(String language) {
        Logger.warning("MemoryOnlyClusterStorage DOES NOT Support any query");
        return false;
    }

    @Override
    public short queryClusterSupport(String clusterType) {
        return ClusterStorage.READWRITE;
    }

    @Override
    public String getName() {
        return "Memory Cache";
    }

    @Override
    public String getId() {
        return "Memory Cache";
    }

    @Override
    public String executeQuery(Query query) throws PersistencyException {
        throw new PersistencyException("UNIMPLEMENTED funnction");
    }

    @Override
    public C2KLocalObject get(ItemPath thisItem, String path)
            throws PersistencyException
    {
        Map sysKeyMemCache = memoryCache.get(thisItem);
    
        if (sysKeyMemCache != null) return sysKeyMemCache.get(path);

        return null;
    }

    @Override
    public void put(ItemPath thisItem, C2KLocalObject obj) throws PersistencyException {
        // create item cache if not present
        Map sysKeyMemCache;
        synchronized (memoryCache) {
            if (memoryCache.containsKey(thisItem))
                sysKeyMemCache = memoryCache.get(thisItem);
            else {
                sysKeyMemCache = new HashMap();
                memoryCache.put(thisItem, sysKeyMemCache);
            }
        }

        // store object in the cache
        String path = ClusterStorage.getPath(obj);
        synchronized(sysKeyMemCache) {
            sysKeyMemCache.put(path, obj);
        }

    }

    @Override
    public void delete(ItemPath thisItem, String path) throws PersistencyException {
        Map sysKeyMemCache = memoryCache.get(thisItem);
        if (sysKeyMemCache != null) {
            synchronized (sysKeyMemCache) {
                if (sysKeyMemCache.containsKey(path)) {
                    sysKeyMemCache.remove(path);
                    if (sysKeyMemCache.isEmpty()) {
                        synchronized (memoryCache) {
                            memoryCache.remove(thisItem);
                        }
                    }
                }
            }
        }
    }

    @Override
    public String[] getClusterContents(ItemPath thisItem, String path) throws PersistencyException {
        Map sysKeyMemCache = memoryCache.get(thisItem);
        ArrayList result = new ArrayList();
        if (sysKeyMemCache != null) {
            while (path.endsWith("/")) 
                path = path.substring(0,path.length()-1);
            path = path+"/";
            for (String thisPath : sysKeyMemCache.keySet()) {
                if (thisPath.startsWith(path)) {
                    String end = thisPath.substring(path.length());
                    int slash = end.indexOf('/');
                    String suffix = slash>-1?end.substring(0, slash):end;
                    if (!result.contains(suffix)) result.add(suffix);
                }
            }
        }
        return result.toArray(new String[result.size()]);
    }

    @Override
    public String[] getClusterContents(ItemPath itemPath, ClusterType type) throws PersistencyException {
        return getClusterContents(itemPath, type.getName());
    }

    public void dumpContents(ItemPath thisItem) {
        synchronized(memoryCache) {
            Logger.msg(0, "Cached Objects of Entity "+thisItem);
            Map sysKeyMemCache = memoryCache.get(thisItem);
            if (sysKeyMemCache == null) {
                Logger.msg(0, "No cache found");
                return;
            }
            try {
                synchronized(sysKeyMemCache) {
                    for (Object name : sysKeyMemCache.keySet()) {
                        String path = (String) name;
                        try {
                            Logger.msg(0, "    Path "+path+": "+sysKeyMemCache.get(path).getClass().getName());
                        } catch (NullPointerException e) {
                            Logger.msg(0, "    Path "+path+": reaped");
                        }
                    }
                }
            } catch (ConcurrentModificationException ex) {
                Logger.msg(0, "Cache modified - aborting");
            }
        }
        Logger.msg(0, "Total number of cached entities: "+memoryCache.size());
    }

    @Override
    public void postBoostrap() {
        //nothing to be done
    }

    @Override
    public void postStartServer() {
        //nothing to be done
    }

    @Override
    public void postConnect() {
        //nothing to be done
    }
}