org.elasticsearch.index.store.DirectoryUtils Maven / Gradle / Ivy
/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch 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.elasticsearch.index.store;
import org.apache.lucene.store.CompoundFileDirectory;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.FilterDirectory;
import org.elasticsearch.common.Nullable;
/**
* Utils for working with {@link Directory} classes.
*/
public final class DirectoryUtils {
private DirectoryUtils() {} // no instance
/**
* Try and extract a store directory out of a directory, tries to take into
* account the fact that a directory is a filter directory, and/or a compound dir.
*/
@Nullable
public static Store.StoreDirectory getStoreDirectory(Directory dir) {
Directory current = dir;
while (true) {
if (current instanceof Store.StoreDirectory) {
return (Store.StoreDirectory) current;
}
if (current instanceof FilterDirectory) {
current = ((FilterDirectory) current).getDelegate();
} else if (current instanceof CompoundFileDirectory) {
current = ((CompoundFileDirectory) current).getDirectory();
} else {
return null;
}
}
}
private static final Directory getLeafDirectory(FilterDirectory dir) {
Directory current = dir.getDelegate();
while ((current instanceof FilterDirectory)) {
current = ((FilterDirectory) current).getDelegate();
}
return current;
}
/**
* Tries to extract the leaf of the {@link Directory} if the directory is a {@link FilterDirectory} and cast
* it to the given target class or returns null if the leaf is not assignable to the target class.
* If the given {@link Directory} is a concrete directory it will treated as a leaf and the above applies.
*/
public static T getLeaf(Directory dir, Class targetClass) {
return getLeaf(dir, targetClass, null);
}
/**
* Tries to extract the leaf of the {@link Directory} if the directory is a {@link FilterDirectory} and cast
* it to the given target class or returns the given default value, if the leaf is not assignable to the target class.
* If the given {@link Directory} is a concrete directory it will treated as a leaf and the above applies.
*/
public static T getLeaf(Directory dir, Class targetClass, T defaultValue) {
Directory d = dir;
if (dir instanceof FilterDirectory) {
d = getLeafDirectory((FilterDirectory) dir);
}
if (targetClass.isAssignableFrom(d.getClass())) {
return targetClass.cast(d);
} else {
return defaultValue;
}
}
}