org.apache.hadoop.hdfs.hoss.db.PathStore.java Source code

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Here is the source code for org.apache.hadoop.hdfs.hoss.db.PathStore.java

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/**
 * 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.hadoop.hdfs.hoss.db;

import java.io.File;
import java.nio.ByteBuffer;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hdfs.hoss.db.FileBlockStore;
import org.apache.hadoop.hdfs.hoss.db.HosMetaData;
import org.apache.hadoop.hdfs.hoss.db.PathPosition;
import org.apache.hadoop.hdfs.hoss.db.FileBlockStore.WriteBuffer;
import org.apache.hadoop.hdfs.hoss.util.StringSerializer;

public class PathStore {

    private static final Log LOG = LogFactory.getLog(PathStore.class);

    private FileBlockStore fbs;

    private final static int PATHLENGTH = 32;

    private final static int PATHWIDTH = 10;

    //private final static int BLOCKSIZE = 4 * 1024; // 4KB

    //private final static int PATHCNT = BLOCKSIZE / PATHLENGTH;

    //private volatile int numBlock;

    public PathStore() {
        File pathFile = new File(new File(HosMetaData.HOSSDIR), HosMetaData.PATHFILE);
        fbs = new FileBlockStore(pathFile, PATHLENGTH, true);
        fbs.enableMmap();
        fbs.open();
    }

    private String getFixedPath(long id) {
        return fixedLengthString(id, PATHWIDTH);
    }

    public static String fixedLengthString(long num, int width) {
        return String.format("%0" + width + "d", num);
    }

    /**
     * 
     * @param pathId
     * @param objId:the index-th block in fileblockstore
     * @param offset
     * @return
     */
    public PathPosition put(long objId, long pathId, long offset) {
        String path = getFixedPath(pathId);
        //set the block index in the fileblockstore
        final WriteBuffer wbuf = fbs.set((int) objId);
        final ByteBuffer buf = wbuf.buf();
        StringSerializer.fromStringToBuffer(buf, path, PATHWIDTH);
        buf.putLong(offset);
        buf.flip();
        wbuf.save();
        PathPosition pp = new PathPosition(path, offset);
        return pp;
    }

    /**
     * put path and offset to file
     * @param objId
     * @param offset
     * @return
     */
    private PathPosition put(long objId, long offset) {
        return put(objId, objId, offset);//objID+pathID+offset
    }

    public PathPosition put(long objId) {
        return put(objId, 0);
    }

    /**
     * get path and offset given object id 
     * @param objId
     * @return
     */
    public PathPosition get(long objId) {
        final ByteBuffer buf = fbs.get((int) objId);
        if (buf == null) {
            LOG.error("Error trying read object " + objId);
        }
        String path = StringSerializer.fromBufferToString(buf, PATHWIDTH);
        long offset = buf.getLong();
        PathPosition pp = new PathPosition(path, offset);
        return pp;
    }

    public void sync() {
        fbs.sync();
    }

    public void close() {
        fbs.sync();
        fbs.close();
    }

}