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/*
* 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.Directory;
import org.apache.lucene.store.FileSwitchDirectory;
import org.apache.lucene.store.FilterDirectory;
/**
* Utils for working with {@link Directory} classes.
*/
public final class DirectoryUtils {
private DirectoryUtils() {} // no instance
static final <T extends Directory> Directory getLeafDirectory(FilterDirectory dir, Class<T> targetClass) {
Directory current = dir.getDelegate();
while (true) {
if ((current instanceof FilterDirectory)) {
if (targetClass != null && targetClass.isAssignableFrom(current.getClass())) {
break;
}
current = ((FilterDirectory) current).getDelegate();
} else {
break;
}
}
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 <code>null</code> 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 extends Directory> T getLeaf(Directory dir, Class<T> 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 extends Directory> T getLeaf(Directory dir, Class<T> targetClass, T defaultValue) {
Directory d = dir;
if (dir instanceof FilterDirectory) {
d = getLeafDirectory((FilterDirectory) dir, targetClass);
}
if (d instanceof FileSwitchDirectory) {
T leaf = getLeaf(((FileSwitchDirectory) d).getPrimaryDir(), targetClass);
if (leaf == null) {
d = getLeaf(((FileSwitchDirectory) d).getSecondaryDir(), targetClass, defaultValue);
} else {
d = leaf;
}
}
if (d != null && targetClass.isAssignableFrom(d.getClass())) {
return targetClass.cast(d);
} else {
return defaultValue;
}
}
}
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