io.dddspring.common.port.adapter.persistence.leveldb.LevelDBProvider Maven / Gradle / Ivy

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//   Copyright 2012,2013 Vaughn Vernon
//
//   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 io.dddspring.common.port.adapter.persistence.leveldb;

import io.dddspring.common.event.sourcing.EventStoreException;
import org.iq80.leveldb.DB;
import org.iq80.leveldb.DBFactory;
import org.iq80.leveldb.DBIterator;
import org.iq80.leveldb.Options;
import org.iq80.leveldb.impl.Iq80DBFactory;

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

public class LevelDBProvider {

    private static LevelDBProvider instance;

    private Map databases;

    public static synchronized LevelDBProvider instance() {
        if (instance == null) {
            instance = new LevelDBProvider();
        }

        return instance;
    }

    public void close(String aDirectoryPath) {
        synchronized (this.databases) {
            DB db = this.databases.get(aDirectoryPath);

            if (db != null) {
                this.databases.remove(aDirectoryPath);

                try {
                    db.close();
                } catch (IOException e) {
                    throw new IllegalStateException(
                            "Cannot completely close LevelDB database: "
                                + aDirectoryPath
                                + " because: "
                                + e.getMessage(),
                            e);
                }
            }
        }
    }

    public void closeAll() {
        List directoryPaths =
                new ArrayList(this.databases.keySet());

        for (String directoryPath : directoryPaths) {
            this.close(directoryPath);
        }
    }

    public DB databaseFrom(String aDirectoryPath) {
        DB db = null;

        synchronized (this.databases) {
            db = this.databases.get(aDirectoryPath);

            if (db == null) {
                db = this.openDatabase(aDirectoryPath);

                this.databases.put(aDirectoryPath, db);
            }
        }

        return db;
    }

    public void purge(DB aDatabase) {

        DBIterator iterator = aDatabase.iterator();

        try {
            iterator.seekToFirst();

            while (iterator.hasNext()) {
                Entry entry = iterator.next();

                aDatabase.delete(entry.getKey());
            }

        } catch (Throwable t) {
            throw new EventStoreException(
                    "Cannot purge LevelDB database: because: "
                        + t.getMessage(),
                    t);
        } finally {
            try {
                iterator.close();
            } catch (Throwable t) {
                // ignore
            }
        }
    }

    private LevelDBProvider() {
        super();

        this.databases = new HashMap();
    }

    private DB openDatabase(String aDirectoryPath) {

        try {
            DBFactory factory = new Iq80DBFactory();

            Options options = new Options();

            options.createIfMissing(true);

            DB db = factory.open(new File(aDirectoryPath), options);

            return db;

        } catch (Throwable t) {
            throw new IllegalStateException(
                    "Cannot open LevelDB database: "
                        + aDirectoryPath
                        + " because: "
                        + t.getMessage(),
                    t);
        }
    }
}