java-classic-code/java-commons-cache/LevelDB.java

package com.yiidata.flume.cache;

import com.yiidata.flume.cache.serde.Serializer;
import com.yiidata.flume.cache.serde.StringSerializer;
import com.yiidata.flume.support.FlumeConfig;
import lombok.NonNull;
import org.iq80.leveldb.DB;
import org.iq80.leveldb.Options;
import org.iq80.leveldb.impl.Iq80DBFactory;

import java.io.Closeable;
import java.io.File;
import java.io.IOException;

/**
 *
 * Level DB Cache 实现
 *
 * <pre>
 *
 * Created by zhenqin.
 * User: zhenqin
 * Date: 2021/7/20
 * Time: 14:46
 * Vendor: yiidata.com
 *
 * </pre>
 *
 * @author zhenqin
 */
public class LevelDB implements ICache<String>, Closeable {


    /**
     * level db
     */
    final DB db;



    /**
     * KEY 序列化
     */
    private final Serializer<String> KEY_SERDE = new StringSerializer();


    public LevelDB() {
        final File levelDbPath = new File(FlumeConfig.getAppHome(), "db");
        if(!levelDbPath.exists()) {
            levelDbPath.mkdirs();
        }

        try {
            final Options options = new Options();
            options.createIfMissing(true).errorIfExists(false);
            this.db = new Iq80DBFactory().open(levelDbPath, options);
        } catch (Exception e) {
            throw new IllegalStateException(e);
        }
    }

    @Override
    public void add(@NonNull String key, @NonNull String value) {
        db.put(KEY_SERDE.serialize(key), KEY_SERDE.serialize(value));
    }

    @Override
    public void add(String key, int exp, String value) {
        add(key, value);
    }

    @Override
    public String get(@NonNull String key) {
        return KEY_SERDE.deserialize(db.get(KEY_SERDE.serialize(key)));
    }

    @Override
    public String remove(@NonNull String key) {
        db.delete(KEY_SERDE.serialize(key));
        return null;
    }

    @Override
    public int removeByPrefix(String prefix) {
        return 0;
    }

    @Override
    public void clear() {

    }

    @Override
    public int size() {
        return 0;
    }

    @Override
    public void shutdown() {
        try {
            close();
        } catch (IOException ignore) {}
    }

    @Override
    public void close() throws IOException {
        db.close();
    }

    public static void main(String[] args) {
        final LevelDB levelDB = new LevelDB();
        /*
        for (int i = 0; i < 100000; i++) {
            levelDB.add("hello" + i, "world, " + i);
        }*/
        long start = System.currentTimeMillis();
        for (int i = 0; i < 100; i++) {
            final String va = levelDB.get("hello" + i);
            System.out.println(va);
        }
        System.out.println(System.currentTimeMillis() - start);
        /*
        start = System.currentTimeMillis();
        for (int i = 0; i < 100000; i++) {
            levelDB.get("hello" + i);
        }
        System.out.println(System.currentTimeMillis() - start);*/
        levelDB.shutdown();
    }
}