Java tutorial
/* * Copyright 2010 Proofpoint, Inc. * * 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.airlift.discovery.store; import com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.dataformat.smile.SmileFactory; import com.google.common.base.Function; import com.google.common.base.Throwables; import com.google.common.collect.Iterables; import io.airlift.log.Logger; import org.iq80.leveldb.DB; import org.iq80.leveldb.Options; import org.iq80.leveldb.impl.Iq80DBFactory; import javax.inject.Inject; import java.io.IOException; import java.util.Arrays; import java.util.Map; import static com.google.common.base.Predicates.notNull; public class PersistentStore implements LocalStore { private static final Logger log = Logger.get(PersistentStore.class); private final DB db; private final ObjectMapper mapper = new ObjectMapper(new SmileFactory()); @Inject public PersistentStore(PersistentStoreConfig config) throws IOException { db = Iq80DBFactory.factory.open(config.getLocation(), new Options().createIfMissing(true)); } @Override public void put(Entry entry) { byte[] dbEntry; try { dbEntry = mapper.writeValueAsBytes(entry); } catch (IOException e) { throw Throwables.propagate(e); } db.put(entry.getKey(), dbEntry); } @Override public Entry get(byte[] key) { try { return mapper.readValue(db.get(key), Entry.class); } catch (IOException e) { throw Throwables.propagate(e); } } @Override public void delete(byte[] key, Version version) { db.delete(key); } @Override public Iterable<Entry> getAll() { return Iterables.filter(Iterables.transform(db, new Function<Map.Entry<byte[], byte[]>, Entry>() { @Override public Entry apply(Map.Entry<byte[], byte[]> dbEntry) { try { return mapper.readValue(dbEntry.getValue(), Entry.class); } catch (IOException e) { byte[] key = dbEntry.getKey(); log.error(e, "Corrupt entry " + Arrays.toString(key)); // delete the corrupt entry... if another node has a non-corrupt version it will be replicated db.delete(key); // null if filtered below return null; } } }), notNull()); } }