TablespaceVersionStore.java

package com.splout.db.hazelcast;

/*
 * #%L
 * Splout SQL Server
 * %%
 * Copyright (C) 2012 Datasalt Systems S.L.
 * %%
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 * #L%
 */

import com.google.common.io.Files;
import com.hazelcast.core.MapLoader;
import com.hazelcast.core.MapStore;
import com.splout.db.common.JSONSerDe;
import com.splout.db.common.JSONSerDe.JSONSerDeException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.codehaus.jackson.type.TypeReference;

import java.io.File;
import java.io.IOException;
import java.nio.charset.Charset;
import java.util.*;

/**
 * A Hazelcast MapLoader and MapStore that saves each map key/value in a file named "key" that contains "value" as a string (JSON).
 * Saves data for CoordinationStructures.VERSIONS_BEING_SERVED
 */
public class TablespaceVersionStore implements MapLoader<String, Map<String, Long>>, MapStore<String, Map<String, Long>> {

  private final static Log log = LogFactory.getLog(TablespaceVersionStore.class);

  private File folder;
  private final static Charset UTF8 = Charset.forName("UTF-8");

  public TablespaceVersionStore(String baseFolder) {
    File folder = new File(baseFolder);
    if (!folder.exists()) {
      folder.mkdirs();
    }
    this.folder = folder;
  }

  @Override
  public void delete(String key) {
    File file = getKeyFile(key);
    if (file.exists()) {
      file.delete();
    }
  }

  @Override
  public void deleteAll(Collection<String> keys) {
    for (String key : keys) {
      delete(key);
    }
  }

  @Override
  public void store(String key, Map<String, Long> value) {
    log.info("Store: " + key + " value: " + value);
    try {
      /**
       * Save value as UTF8 String in a File
       */
      Files.write(JSONSerDe.ser(value).getBytes(UTF8), getKeyFile(key));
    } catch (IOException e) {
      throw new RuntimeException(e);
    } catch (JSONSerDeException e) {
      throw new RuntimeException(e);
    }
  }

  @Override
  public void storeAll(Map<String, Map<String, Long>> keyValues) {
    for (Map.Entry<String, Map<String, Long>> keyValue : keyValues.entrySet()) {
      store(keyValue.getKey(), keyValue.getValue());
    }
  }

  @Override
  public Map<String, Long> load(String key) {
//		log.info("Load: " + key);
    try {
      /**
       * Load value from a String in a File
       */
      Map<String, Long> map = readValues(getKeyFile(key));
//			log.info("Load to return: " + map);
      return map;
    } catch (IOException e) {
      throw new RuntimeException(e);
    } catch (JSONSerDeException e) {
      throw new RuntimeException(e);
    }
  }

  @Override
  public Map<String, Map<String, Long>> loadAll(Collection<String> keys) {
//  	log.info("Load all: " + keys);
    Map<String, Map<String, Long>> toReturn = new HashMap<String, Map<String, Long>>();
    for (String key : keys) {
      Map<String, Long> result = load(key);
      toReturn.put(key, result);
    }
//  	log.info("Load all to return: " + toReturn);
    return toReturn;
  }

  @Override
  public Set<String> loadAllKeys() {
//		log.info("Load all keys:");
    File[] files = folder.listFiles();
    if (files == null) {
      return null;
    }
    Set<String> keys = new HashSet<String>();
    for (File file : files) {
      keys.add(file.getName());
    }
//  	log.info("Load all keys to return: " + keys);
    return keys;
  }

  // --------------------------------- //

  protected File getKeyFile(String key) {
    return new File(folder, key);
  }

  public final static TypeReference<Map<String, Long>> MAP_STRING_LONG_TYPE_REF = new TypeReference<Map<String, Long>>() {

  };

  protected Map<String, Long> readValues(File file) throws JSONSerDeException, IOException {
    if (file.exists()) {
      return JSONSerDe.deSer(Files.toString(file, UTF8), MAP_STRING_LONG_TYPE_REF);
    } else {
      return null;
    }
  }
}