com.cloudhopper.datastore.tokyo.TokyoDataStore Maven / Gradle / Ivy

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package com.cloudhopper.datastore.tokyo;

/*
 * #%L
 * ch-datastore
 * %%
 * Copyright (C) 2012 Cloudhopper by Twitter
 * %%
 * Licensed 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.
 * #L%
 */

import com.cloudhopper.commons.util.HexUtil;
import com.cloudhopper.commons.util.StringUtil;
import com.cloudhopper.datastore.*;
import java.io.File;
import java.util.Timer;
import java.util.TimerTask;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import tokyocabinet.BDB;

/**
 * Tokyo Cabinet backed implementation of a DataStore.
 * 
 * @author joelauer
 */
public class TokyoDataStore extends BaseDataStore implements AscendingIteratorSupport {
    private final static Logger logger = LoggerFactory.getLogger(TokyoDataStore.class);

    // path used to generate a full path to the database file
    private File path;
    // the underlying b-tree database
    private BDB bdb;

    // for performance, the database is not synchronized on every put() and take()
    // if -1, sync() is disabled
    // if 0, sync() is called on ever put() and take()
    // if > 0, the amount of ms between a sync() call is made, set to 5 seconds by default
    private long synchronizeInterval;
    private Timer synchronizeTimer;
    private TimerTask synchronizeTimerTask;

    public TokyoDataStore() {
        super("TC-BDB");
        // defaults
        synchronizeInterval = 5000;
    }

    /**
     * Returns the underlying B-Tree database.  If not opened, this will return
     * null.
     * @return Null if not open, otherwise the B-Tree database.
     */
    public BDB getDatabase() {
        return bdb;
    }

    /**
     * Gets the interval between sync() calls to underlying Tokyo cabinet db.
     * For performance, by default, the database is not synchronized on every
     * put() and take().  If -1, sync() is disabled. If 0, sync() is called on
     * every put() and take().  Throughput will be dramatically decreased, but
     * it'll guarantee the data makes it into the file.  If > 0, its the length
     * of ms between a sync() call is made, set to 5 seconds by default
     * @return The synchronization interval in milliseconds
     */
    public long getSynchronizeInterval() {
        return synchronizeInterval;
    }

    /**
     * 
     * @throws QueueStoreException Thrown if the data store is already open
     *      when this method is called.
     */
    public void setSynchronizeInterval(long value) {
        this.synchronizeInterval = value;
    }

    private File getDatabaseFile() {
        return new File(getDirectory(), getName() + ".bdb");
    }

    @Override
    public void doDelete() throws DataStoreFatalException {
        File databaseFile = getDatabaseFile();
        try {
            databaseFile.delete();
        } catch (Exception e) {
            throw new DataStoreFatalException("Unable to delete " + databaseFile.getPath(), e);
        }
    }

    @Override
    public void doOpen() throws DataStoreFatalException {
        // create a tokyo cabinet backed queue
        bdb = new BDB();

        // just leave comparison as LEXICAL, don't set it to anything else

	/*
	// comparator that does a byte at a time, up to the length of the shorter key
	bdb.setcomparator(new tokyocabinet.BDBCMP() {
		public int compare(byte[] a, byte[] b) {
		    int itlen = a.length;
		    if (itlen > b.length) itlen = b.length;
		    for (int i=0;i