db4ostorage.java

lucene2.2.0版本

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.lucene.gdata.storage.db4o;

import java.util.ArrayList;
import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.lucene.gdata.data.GDataAccount;
import org.apache.lucene.gdata.data.ServerBaseEntry;
import org.apache.lucene.gdata.data.ServerBaseFeed;
import org.apache.lucene.gdata.storage.ModificationConflictException;
import org.apache.lucene.gdata.storage.ResourceNotFoundException;
import org.apache.lucene.gdata.storage.Storage;
import org.apache.lucene.gdata.storage.StorageController;
import org.apache.lucene.gdata.storage.StorageException;

import com.db4o.ObjectContainer;
import com.db4o.ObjectSet;
import com.db4o.query.Query;
import com.google.gdata.data.BaseEntry;
import com.google.gdata.data.BaseFeed;
import com.google.gdata.data.DateTime;

/**
 * 
 * Storage implementation for the DB4o storage component
 * @author Simon Willnauer
 * 
 */
public class DB4oStorage implements Storage {
    private static final Log LOG = LogFactory.getLog(DB4oStorage.class);

    private static final int RENDER_ACTIVATION_DEPTH = 100;

    private final ObjectContainer container;

    private final StorageController controller;

    private final List<String> semaphore = new ArrayList<String>();

    
    protected DB4oStorage(final ObjectContainer container,
            StorageController controller) {
        this.container = container;
        this.controller = controller;
    }

    private void createSemaphore(String key)
            throws ModificationConflictException {
        this.semaphore.add(key);
        if (this.container.ext().setSemaphore(key, 0))
            return;
        throw new ModificationConflictException(
                "can not create semaphore for key -- " + key);
    }

    private void releaseAllSemaphore() {
        for (String key : this.semaphore) {
            this.container.ext().releaseSemaphore(key);
        }
        this.semaphore.clear();
    }

    private void releaseSemaphore(String key) {
        if (this.semaphore.contains(key)) {
            this.container.ext().releaseSemaphore(key);
            this.semaphore.remove(key);
        }
    }

    /**
     * @see org.apache.lucene.gdata.storage.Storage#storeEntry(org.apache.lucene.gdata.data.ServerBaseEntry)
     */
    public BaseEntry storeEntry(ServerBaseEntry entry) throws StorageException {
        if (entry == null)
            throw new StorageException("Can not store entry -- is null");

        if (entry.getFeedId() == null)
            throw new StorageException("can not store entry -- feed id is null");
        if (LOG.isDebugEnabled())
            LOG.debug("Storing entry for feed: " + entry.getFeedId());
        BaseFeed<BaseFeed, BaseEntry> feed = getFeedOnly(entry.getFeedId(),entry.getServiceType());
       refreshPersistentObject(feed);
        try {
            StringBuilder idBuilder = new StringBuilder(entry.getFeedId());
            idBuilder.append(this.controller.releaseId());
            entry.setId(idBuilder.toString());
        } catch (StorageException e) {
            LOG.error("Can not create uid for entry -- " + e.getMessage(), e);
            throw new StorageException("Can not create uid for entry -- "
                    + e.getMessage(), e);

        }
        setUpdated(entry, feed);
        DB4oEntry intEntry = new DB4oEntry();
        intEntry.setEntry(entry.getEntry());
        intEntry.setUpdateTime(entry.getUpdated().getValue());
        intEntry.setFeedId(feed.getId());
        intEntry.setVersion(entry.getVersion());

       
        try {
            this.container.set(feed);
            this.container.set(intEntry);
            this.container.commit();
        } catch (Exception e) {
            LOG
                    .error("Error occured on persisting changes -- rollback changes");
            this.container.rollback();
            throw new StorageException("Can not persist changes -- "
                    + e.getMessage(), e);
        }
        if (LOG.isInfoEnabled())
            LOG.info("Stored Entry for entryID: " + entry.getId()
                    + " -- feedID: " + entry.getFeedId());
        return entry.getEntry();
    }

    private void setUpdated(ServerBaseEntry entry, DB4oEntry intEntry) {
        if (entry.getUpdated().compareTo(intEntry.getEntry().getUpdated()) <= 0) {
            if (LOG.isDebugEnabled())
                LOG
                        .debug("Set new UpdateTime to entry new entry time is less or equal the time of the stored entry -- old Entry: "
                                + intEntry.getEntry().getUpdated()
                                + "; new Entry: " + entry.getUpdated());
            entry.setUpdated(new DateTime(System.currentTimeMillis(), entry
                    .getUpdated().getTzShift()));
        }

    }

    private void setUpdated(ServerBaseEntry entry,
            BaseFeed<BaseFeed, BaseEntry> feed) {
        if (entry.getUpdated() != null){
            long timeInMilli = entry.getUpdated().getValue();
            int tzShift = entry.getUpdated().getTzShift();
            feed.setUpdated(new DateTime(timeInMilli, tzShift));
        }
        else{
            int timezone = 0;
            if(feed.getUpdated() != null){
                 timezone = feed.getUpdated().getTzShift();
            }
            long timeInMilli = System.currentTimeMillis();
            entry.setUpdated(new DateTime(timeInMilli,timezone));
            feed.setUpdated(new DateTime(timeInMilli,timezone));
        }
    }

    /**
     * @see org.apache.lucene.gdata.storage.Storage#deleteEntry(org.apache.lucene.gdata.data.ServerBaseEntry)
     */
    public void deleteEntry(ServerBaseEntry entry) throws StorageException {
        if (entry == null)
            throw new StorageException("Can not delete entry -- is null");
        if (entry.getFeedId() == null)
            throw new StorageException(
                    "can not delete entry -- feed id is null");
        if (entry.getId() == null)
            throw new StorageException("Can not delete entry -- id is null");
        if (LOG.isDebugEnabled())
            LOG.debug("delete entry for feed: " + entry.getFeedId()
                    + " entry ID: " + entry.getId());
        DB4oEntry persistentEntry = getInternalEntry(entry.getId());
        // lock the entry to prevent concurrent access
        createSemaphore(entry.getId());
        refreshPersistentObject(persistentEntry);
        if(persistentEntry.getVersion() != entry.getVersion())
            throw new ModificationConflictException(
                    "Current version does not match given version  -- currentVersion: "+persistentEntry.getVersion()+"; given Version: "+entry.getVersion() );
        BaseFeed<BaseFeed, BaseEntry> feed = getFeedOnly(entry.getFeedId(),entry.getServiceType());
        refreshPersistentObject(feed);
        DateTime time = DateTime.now();
        if (persistentEntry.getEntry().getUpdated() != null)
            time.setTzShift(persistentEntry.getEntry().getUpdated().getTzShift());
        feed.setUpdated(time);
        try {
            //delete the entry
            this.container.delete(persistentEntry.getEntry());
            this.container.delete(persistentEntry);
            this.container.set(feed);
            this.container.commit();
            
        } catch (Exception e) {
            LOG
                    .error("Error occured on persisting changes -- rollback changes");
            this.container.rollback();
            throw new StorageException("Can not persist changes -- "
                    + e.getMessage(), e);
        } finally {
            releaseSemaphore(entry.getId());
        }
    }

    /**
     * @see org.apache.lucene.gdata.storage.Storage#updateEntry(org.apache.lucene.gdata.data.ServerBaseEntry)
     */
    public BaseEntry updateEntry(ServerBaseEntry entry) throws StorageException {
        if (entry == null)
            throw new StorageException("Can not update entry -- is null");
        if (entry.getFeedId() == null)
            throw new StorageException(
                    "can not delete entry -- feed id is null");
        if (entry.getId() == null)
            throw new StorageException("Can not delete entry -- id is null");

        DB4oEntry persistentEntry = getInternalEntry(entry.getId());
        // lock the entry to prevent concurrent access
        createSemaphore(entry.getId());
        refreshPersistentObject(persistentEntry);
        if(persistentEntry.getVersion() != entry.getVersion())
            throw new ModificationConflictException(
                    "Current version does not match given version  -- currentVersion: "+persistentEntry.getVersion()+"; given Version: "+entry.getVersion() );
        
        setUpdated(entry, persistentEntry);
        BaseFeed<BaseFeed, BaseEntry> feed = getFeedOnly(entry.getFeedId(),entry.getServiceType());
        refreshPersistentObject(feed);
        BaseEntry retVal = entry.getEntry(); 
        DB4oEntry newEntry = new DB4oEntry();
        newEntry.setEntry(retVal);
        newEntry.setUpdateTime(entry.getUpdated().getValue());
        newEntry.setFeedId(feed.getId());
        // increment Version
        newEntry.setVersion((entry.getVersion())+1);

        setUpdated(entry, feed);
        try {
            this.container.set(feed);
            this.container.set(newEntry);
            this.container.delete(persistentEntry.getEntry());
            this.container.delete(persistentEntry);
            this.container.commit();
        } catch (Exception e) {
            LOG
                    .error("Error occured on persisting changes -- rollback changes");
            this.container.rollback();
            throw new StorageException("Can not persist changes -- "
                    + e.getMessage(), e);
        } finally {
            releaseSemaphore(entry.getId());
        }
        return retVal;

    }
    


    /**
     * @see org.apache.lucene.gdata.storage.Storage#getFeed(org.apache.lucene.gdata.data.ServerBaseFeed)
     */
    @SuppressWarnings("unchecked")
    public BaseFeed getFeed(ServerBaseFeed feed) throws StorageException {
        if (feed.getId() == null)
            throw new StorageException("can not get feed -- feed id is null");