org.apache.hudi.common.util.collection.DiskMap Maven / Gradle / Ivy
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* 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.hudi.common.util.collection;
import org.apache.hudi.common.util.FileIOUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.File;
import java.io.IOException;
import java.io.Serializable;
import java.util.Map;
import java.util.UUID;
import java.util.stream.Stream;
/**
* This interface provides the map interface for storing records in disk after they
* spill over from memory. Used by {@link ExternalSpillableMap}.
*
* @param The generic type of the keys
* @param The generic type of the values
*/
public abstract class DiskMap implements Map, Iterable {
private static final Logger LOG = LoggerFactory.getLogger(DiskMap.class);
private static final String SUBFOLDER_PREFIX = "hudi";
private final File diskMapPathFile;
private transient Thread shutdownThread = null;
// Base path for the write file
protected final String diskMapPath;
public DiskMap(String basePath, String prefix) throws IOException {
this.diskMapPath =
String.format("%s/%s-%s-%s", basePath, SUBFOLDER_PREFIX, prefix, UUID.randomUUID().toString());
diskMapPathFile = new File(diskMapPath);
FileIOUtils.deleteDirectory(diskMapPathFile);
FileIOUtils.mkdir(diskMapPathFile);
// Make sure the folder is deleted when JVM exits
diskMapPathFile.deleteOnExit();
addShutDownHook();
}
/**
* Register shutdown hook to force flush contents of the data written to FileOutputStream from OS page cache
* (typically 4 KB) to disk.
*/
private void addShutDownHook() {
shutdownThread = new Thread(this::cleanup);
Runtime.getRuntime().addShutdownHook(shutdownThread);
}
/**
* @returns a stream of the values stored in the disk.
*/
abstract Stream valueStream();
/**
* Number of bytes spilled to disk.
*/
abstract long sizeOfFileOnDiskInBytes();
/**
* Close and cleanup the Map.
*/
public void close() {
cleanup(false);
}
/**
* Cleanup all resources, files and folders
* triggered by shutdownhook.
*/
private void cleanup() {
cleanup(true);
}
/**
* Cleanup all resources, files and folders.
*/
private void cleanup(boolean isTriggeredFromShutdownHook) {
try {
FileIOUtils.deleteDirectory(diskMapPathFile);
} catch (IOException exception) {
LOG.warn("Error while deleting the disk map directory=" + diskMapPath, exception);
}
if (!isTriggeredFromShutdownHook && shutdownThread != null) {
Runtime.getRuntime().removeShutdownHook(shutdownThread);
}
}
}