org.wildfly.security.provider.util.ServiceLoaderSupplier Maven / Gradle / Ivy
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* JBoss, Home of Professional Open Source.
* Copyright 2015 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.provider.util;
import org.wildfly.common.array.Arrays2;
import java.security.AccessControlContext;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.ServiceConfigurationError;
import java.util.ServiceLoader;
import java.util.function.Supplier;
/**
* A supplier which uses a service loader to find all instances of the given service, and return them as an array. The
* result is then cached.
*
* @author David M. Lloyd
*/
public class ServiceLoaderSupplier implements Supplier {
private final Class service;
final ClassLoader classLoader;
private int hashCode;
private volatile E[] result;
private final AccessControlContext acc;
public ServiceLoaderSupplier(final Class service, final ClassLoader classLoader) {
this.service = service;
this.classLoader = classLoader;
this.acc = AccessController.getContext() ;
}
public E[] get() {
if (result == null) {
synchronized (this) {
if (result == null) {
if (System.getSecurityManager() != null) {
result = AccessController.doPrivileged((PrivilegedAction) () -> loadServices(service, classLoader), acc);
} else {
result = loadServices(service, classLoader);
}
}
}
}
return result.clone();
}
E[] loadServices(final Class service, final ClassLoader classLoader) {
ArrayList list = new ArrayList<>();
ServiceLoader loader = ServiceLoader.load(service, classLoader);
Iterator iterator = loader.iterator();
for (;;) try {
if (! iterator.hasNext()) {
return list.toArray(Arrays2.createArray(service, list.size()));
}
list.add(iterator.next());
} catch (ServiceConfigurationError ignored) {
// explicitly ignored
}
}
public int hashCode() {
int hc = hashCode;
if (hc == 0) {
hc = service.hashCode() * 19 + (classLoader != null ? classLoader.hashCode() : 0);
if (hc == 0) hc = 1;
return hashCode = hc;
}
return hc;
}
public boolean equals(final Object obj) {
return obj instanceof ServiceLoaderSupplier && equals((ServiceLoaderSupplier) obj);
}
private boolean equals(final ServiceLoaderSupplier other) {
return other == this || other.service == service && other.classLoader == classLoader;
}
}