/*
* 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.jackrabbit.core.persistence.util;
import java.util.HashMap;
import org.apache.jackrabbit.core.util.StringIndex;
/**
* Implements a {@link StringIndex} that is based on a hashmap. Subclasses
* can override the protected {@link #load()} and {@link #save()} methods
* to implement persistent storage of the string index.
* <p>
* This class is thread-safe.
*/
public class HashMapIndex implements StringIndex {
/**
* holds the string-to-index lookups.
*/
protected final HashMap<String, Integer> stringToIndex =
new HashMap<String, Integer>();
/**
* holds the index-to-string lookups.
*/
protected final HashMap<Integer, String> indexToString =
new HashMap<Integer, String>();
/**
* Loads the lookup table.
*/
protected void load() {
}
/**
* Saves the lookup table.
*/
protected void save() {
}
/**
* {@inheritDoc}
*
* This implementation reloads the table from the resource if a lookup fails
* and if the resource was modified since.
*/
public synchronized int stringToIndex(String nsUri) {
Integer idx = stringToIndex.get(nsUri);
if (idx == null) {
load();
idx = stringToIndex.get(nsUri);
}
if (idx == null) {
// Need to use only 24 bits, since that's what
// the BundleBinding class stores in bundles
idx = nsUri.hashCode() & 0x00ffffff;
while (indexToString.containsKey(idx)) {
idx = (idx + 1) & 0x00ffffff;
}
stringToIndex.put(nsUri, idx);
indexToString.put(idx, nsUri);
save();
}
return idx;
}
/**
* {@inheritDoc}
*
* This implementation reloads the table from the resource if a lookup fails
* and if the resource was modified since.
*/
public synchronized String indexToString(int i) {
Integer idx = Integer.valueOf(i);
String s = indexToString.get(idx);
if (s == null) {
load();
s = indexToString.get(idx);
}
return s;
}
}