org.wildfly.security.provider.util.ServiceLoaderSupplier Maven / Gradle / Ivy
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This artifact provides a single jar that contains all classes required to use remote EJB and JMS, including
all dependencies. It is intended for use by those not using maven, maven users should just import the EJB and
JMS BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up
with different versions on classes on the class path).
/*
* 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;
}
}