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Database Engine for QWAZR
There is a newer version: 1.5.0
/*
 * Copyright 2015-2018 Emmanuel Keller / QWAZR
 * 
 * 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 com.qwazr.database.store;

import com.qwazr.utils.IOUtils;
import org.fusesource.lmdbjni.Database;
import org.fusesource.lmdbjni.EntryIterator;
import org.fusesource.lmdbjni.Env;
import org.fusesource.lmdbjni.Transaction;

import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.util.Map;

class KeyStoreLmdb implements KeyStore {

    private final Env env;
    private final Database db;
    private final File file;

    public KeyStoreLmdb(final File file) throws IOException {
        this.file = file;
        if (!file.exists())
            Files.createDirectory(file.toPath());
        this.env = new Env(file.getAbsolutePath());
        this.db = env.openDatabase();
    }

    @Override
    final public void close() {
        IOUtils.closeQuietly(db, env);
    }

    @Override
    public Impl getImplementation() {
        return Impl.lmdb;
    }

    @Override
    final public boolean exists() {
        return file.exists();
    }

    @Override
    final public void delete() {
        env.close();
    }

    @Override
    final public byte[] get(final byte[] key) {
        return db.get(key);
    }

    @Override
    final public void put(final byte[] key, final byte[] value) {
        db.put(key, value);
    }

    @Override
    final public void delete(final byte[] key) {
        db.delete(key);
    }

    @Override
    final public KeyIterator iterator(final byte[] key) {
        return new KeyIteratorImpl(key);
    }

    private class KeyIteratorImpl implements KeyIterator {

        private final Transaction tx;
        private final EntryIterator it;

        private KeyIteratorImpl(byte[] key) {
            tx = env.createReadTransaction();
            it = db.seek(tx, key);
        }

        @Override
        final public void close() {
            IOUtils.closeQuietly(it, tx);
        }

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

        @Override
        final public Map.Entry next() {
            return it.next();
        }
    }
}