/*
* 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.security.principal;
import org.apache.commons.collections.map.LRUMap;
import java.security.Principal;
import java.util.Properties;
/**
* A base class of a principal provider implementing common tasks and a
* caching facility. Extending classes should only deal with the retrieval of
* {@link Principal}s from their source, the caching of the principials is done
* by this implementation.
* <p/>
* The {@link PrincipalProvider} mehtods that that involve searching like
* {@link PrincipalProvider#getGroupMembership(Principal)} are not cached.
*/
public abstract class AbstractPrincipalProvider implements PrincipalProvider {
/** Option name for the max size of the cache to use */
public static final String MAXSIZE_KEY = "cacheMaxSize";
/** Option name to enable negative cache entries (see JCR-2672) */
public static final String NEGATIVE_ENTRY_KEY = "cacheIncludesNegative";
/** flag indicating if the instance has not been {@link #close() closed} */
private boolean initialized;
/**
* flag indicating if the cache should include 'negative' entries.
* @see #NEGATIVE_ENTRY_KEY
*/
private boolean includeNegative;
/** the principal cache */
private LRUMap cache;
/**
* Create a new instance of <code>AbstractPrincipalProvider</code>.
* Initialization and cache are set up upon {@link #init(Properties)}
*/
protected AbstractPrincipalProvider() {
}
/**
* Check if the instance has been closed {@link #close()}.
*
* @throws IllegalStateException if this instance was closed.
*/
protected void checkInitialized() {
if (!initialized) {
throw new IllegalStateException("Not initialized.");
}
}
/**
* Clear the principal cache.
*/
protected synchronized void clearCache() {
cache.clear();
}
/**
* Add an entry to the principal cache.
*
* @param principal to be cached.
*/
protected synchronized void addToCache(Principal principal) {
cache.put(principal.getName(), principal);
}
/**
* Called if the cache does not contain the principal requested.<br>
* Implementations should return a {@link Principal} from their source,
* if it contains one for the given name or <code>null</code>.
*
* @param principalName Name of the principal to be returned.
* @return Principal or null, if non provided for the given name
* @see #getPrincipal(String)
*/
protected abstract Principal providePrincipal(String principalName);
//--------------------------------------------------< PrincipalProvider >---
/**
* {@inheritDoc}
*
* {@link #providePrincipal(String)} is called, if no matching entry
* is present in the cache.<br>
* NOTE: If the cache is enabled to contain negative entries (see
* {@link #NEGATIVE_ENTRY_KEY} configuration option), the cache will also
* store negative matches (as <code>null</code> values) in the principal cache.
*/
public synchronized Principal getPrincipal(String principalName) {
checkInitialized();
if (cache.containsKey(principalName)) {
return (Principal) cache.get(principalName);
} else {
Principal principal = providePrincipal(principalName);
if (principal != null || includeNegative) {
cache.put(principalName, principal);
}
return principal;
}
}
/**
* @see PrincipalProvider#init(java.util.Properties)
*/
public synchronized void init(Properties options) {
if (initialized) {
throw new IllegalStateException("already initialized");
}
int maxSize = Integer.parseInt(options.getProperty(MAXSIZE_KEY, "1000"));
cache = new LRUMap(maxSize);
includeNegative = Boolean.parseBoolean(options.getProperty(NEGATIVE_ENTRY_KEY, "false"));
initialized = true;
}
/**
* Clears the cache and calls the implementation to close their resources
* @see PrincipalProvider#close()
*/
public synchronized void close() {
checkInitialized();
cache.clear();
initialized = false;
}
}