/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.kafka.connect.storage;
import org.apache.kafka.connect.errors.ConnectException;
import org.apache.kafka.connect.runtime.WorkerConfig;
import org.apache.kafka.connect.runtime.standalone.StandaloneConfig;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.EOFException;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.nio.ByteBuffer;
import java.util.HashMap;
import java.util.Map;
/**
* Implementation of OffsetBackingStore that saves data locally to a file. To ensure this behaves
* similarly to a real backing store, operations are executed asynchronously on a background thread.
*/
public class FileOffsetBackingStore extends MemoryOffsetBackingStore {
private static final Logger log = LoggerFactory.getLogger(FileOffsetBackingStore.class);
private File file;
public FileOffsetBackingStore() {
}
@Override
public void configure(WorkerConfig config) {
super.configure(config);
file = new File(config.getString(StandaloneConfig.OFFSET_STORAGE_FILE_FILENAME_CONFIG));
}
@Override
public synchronized void start() {
super.start();
log.info("Starting FileOffsetBackingStore with file {}", file);
load();
}
@Override
public synchronized void stop() {
super.stop();
// Nothing to do since this doesn't maintain any outstanding connections/data
log.info("Stopped FileOffsetBackingStore");
}
@SuppressWarnings("unchecked")
private void load() {
try {
ObjectInputStream is = new ObjectInputStream(new FileInputStream(file));
Object obj = is.readObject();
if (!(obj instanceof HashMap))
throw new ConnectException("Expected HashMap but found " + obj.getClass());
Map<byte[], byte[]> raw = (Map<byte[], byte[]>) obj;
data = new HashMap<>();
for (Map.Entry<byte[], byte[]> mapEntry : raw.entrySet()) {
ByteBuffer key = (mapEntry.getKey() != null) ? ByteBuffer.wrap(mapEntry.getKey()) : null;
ByteBuffer value = (mapEntry.getValue() != null) ? ByteBuffer.wrap(mapEntry.getValue()) : null;
data.put(key, value);
}
is.close();
} catch (FileNotFoundException | EOFException e) {
// FileNotFoundException: Ignore, may be new.
// EOFException: Ignore, this means the file was missing or corrupt
} catch (IOException | ClassNotFoundException e) {
throw new ConnectException(e);
}
}
protected void save() {
try {
ObjectOutputStream os = new ObjectOutputStream(new FileOutputStream(file));
Map<byte[], byte[]> raw = new HashMap<>();
for (Map.Entry<ByteBuffer, ByteBuffer> mapEntry : data.entrySet()) {
byte[] key = (mapEntry.getKey() != null) ? mapEntry.getKey().array() : null;
byte[] value = (mapEntry.getValue() != null) ? mapEntry.getValue().array() : null;
raw.put(key, value);
}
os.writeObject(raw);
os.close();
} catch (IOException e) {
throw new ConnectException(e);
}
}
}