FFScanner.java

/*
 * Copyright 2014 Alexey Plotnik
 *
 * 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.
 */

package org.stem.db.compaction;

import org.stem.db.Blob;
import org.stem.db.FatFile;

import java.io.IOException;
import java.util.Iterator;

public class FFScanner implements Iterator<Blob> {

    private FatFile ff;
    private Blob currentBlob;
    int nextOffset = FatFile.PAYLOAD_OFFSET;

    public FFScanner(FatFile ff) {
        this.ff = ff;

        // TODO: looks like it's mistake, we can iterate not-full files
        //if (!ff.isFull())
        //throw new RuntimeException("Non-FULL FatFiles can not be iterated with FFScanner");
    }

    @Override
    public boolean hasNext() {
        ff.readLock.lock();
        try {
            Blob blob = Blob.deserialize(ff, nextOffset);
            if (null != blob) {
                currentBlob = blob;
                nextOffset += Blob.Header.SIZE + blob.getHeader().length;
                return true;
            } else {
                return false;
            }
        } catch (IOException e) {
            throw new RuntimeException(e);
        } finally {
            ff.readLock.unlock();
        }
    }

    @Override
    public Blob next() {
        return currentBlob;
    }

    @Override
    public void remove() {
        throw new UnsupportedOperationException();
    }
}