/* * 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; } }