org.wildfly.security.OneTimeSecurityFactory Maven / Gradle / Ivy
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* JBoss, Home of Professional Open Source.
* Copyright 2014 Red Hat, Inc., and individual contributors
* as indicated by the @author tags.
*
* Licensed 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.wildfly.security;
import static org.wildfly.security.ElytronMessages.log;
import java.security.GeneralSecurityException;
/**
* A {@link SecurityFactory} implementation which calls delegated factory at first and
* returns created object for any other create call. Thread safe.
*
* @author David M. Lloyd
*/
public final class OneTimeSecurityFactory implements SecurityFactory {
private volatile SecurityFactory factory;
private volatile T obj;
/**
* Creates a new factory instance.
*
* @param factory a security factory to use to obtain object which should be returned by this factory every time
*/
public OneTimeSecurityFactory(final SecurityFactory factory) {
this.factory = factory;
}
public T create() throws GeneralSecurityException {
T val = obj;
if (val == null) {
if (Thread.holdsLock(this)) {
throw log.cannotInstantiateSelfReferentialFactory();
}
synchronized (this) {
val = obj;
if (val == null) {
val = obj = factory.create();
factory = null;
}
}
}
return val;
}
}