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Xodus is pure Java transactional schema-less embedded database

There is a newer version: 2.0.1

/**
 * Copyright 2010 - 2018 JetBrains s.r.o.
 *
 * 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 jetbrains.exodus.log;

import org.jetbrains.annotations.NotNull;

import java.util.Iterator;

/**
 * Stops at the end of log or on the file hole
 */
public final class LoggableIterator implements Iterator {

    @NotNull
    private final Log log;
    @NotNull
    private final DataIterator it;

    LoggableIterator(@NotNull final Log log, final long startAddress) {
        this.log = log;
        it = log.readIteratorFrom(startAddress);
    }

    public long getHighAddress() {
        return it.getHighAddress();
    }

    @Override
    public RandomAccessLoggable next() {
        if (!hasNext()) {
            return null;
        }
        final RandomAccessLoggable result = log.read(it);
        if (!NullLoggable.isNullLoggable(result)) {
            it.skip(result.getDataLength());
        }
        return result;
    }

    @Override
    public boolean hasNext() {
        return it.hasNext();
    }

    @Override
    public void remove() {
    }
}