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/*
* 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.logging.log4j.util;
import java.lang.invoke.CallSite;
import java.lang.invoke.LambdaMetafactory;
import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles.Lookup;
import java.lang.invoke.MethodType;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.ServiceConfigurationError;
import java.util.ServiceLoader;
import java.util.Set;
import java.util.Spliterator;
import java.util.function.Consumer;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;
import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.status.StatusLogger;
/**
* This class should be considered internal.
*/
public final class ServiceLoaderUtil {
private static final int MAX_BROKEN_SERVICES = 8;
private ServiceLoaderUtil() {
}
/**
* Retrieves the available services from the caller's classloader.
*
* Broken services will be ignored.
*
* @param The service type.
* @param serviceType The class of the service.
* @param lookup The calling class data.
* @return A stream of service instances.
*/
public static Stream loadServices(final Class serviceType, final Lookup lookup) {
return loadServices(serviceType, lookup, false);
}
/**
* Retrieves the available services from the caller's classloader and possibly
* the thread context classloader.
*
* Broken services will be ignored.
*
* @param The service type.
* @param serviceType The class of the service.
* @param lookup The calling class data.
* @param useTccl If true the thread context classloader will also be used.
* @return A stream of service instances.
*/
public static Stream loadServices(final Class serviceType, final Lookup lookup, final boolean useTccl) {
return loadServices(serviceType, lookup, useTccl, true);
}
static Stream loadServices(final Class serviceType, final Lookup lookup, final boolean useTccl,
final boolean verbose) {
final ClassLoader classLoader = lookup.lookupClass().getClassLoader();
Stream services = loadClassloaderServices(serviceType, lookup, classLoader, verbose);
if (useTccl) {
final ClassLoader contextClassLoader = LoaderUtil.getThreadContextClassLoader();
if (contextClassLoader != classLoader) {
services = Stream.concat(services,
loadClassloaderServices(serviceType, lookup, contextClassLoader, verbose));
}
}
if (OsgiServiceLocator.isAvailable()) {
services = Stream.concat(services, OsgiServiceLocator.loadServices(serviceType, lookup, verbose));
}
final Set> classes = new HashSet<>();
// only the first occurrence of a class
return services.filter(service -> classes.add(service.getClass()));
}
static Stream loadClassloaderServices(final Class serviceType, final Lookup lookup,
final ClassLoader classLoader, final boolean verbose) {
return StreamSupport.stream(new ServiceLoaderSpliterator(serviceType, lookup, classLoader, verbose), false);
}
static Iterable callServiceLoader(final Lookup lookup, final Class serviceType, final ClassLoader classLoader,
final boolean verbose) {
try {
// Creates a lambda in the caller's domain that calls `ServiceLoader`
final MethodHandle loadHandle = lookup.findStatic(ServiceLoader.class, "load",
MethodType.methodType(ServiceLoader.class, Class.class, ClassLoader.class));
final CallSite callSite = LambdaMetafactory.metafactory(lookup,
"run",
MethodType.methodType(PrivilegedAction.class, Class.class, ClassLoader.class),
MethodType.methodType(Object.class),
loadHandle,
MethodType.methodType(ServiceLoader.class));
final PrivilegedAction> action = (PrivilegedAction>) callSite
.getTarget()//
.bindTo(serviceType)
.bindTo(classLoader)
.invoke();
final ServiceLoader serviceLoader;
if (System.getSecurityManager() == null) {
serviceLoader = action.run();
} else {
final MethodHandle privilegedHandle = lookup.findStatic(AccessController.class, "doPrivileged",
MethodType.methodType(Object.class, PrivilegedAction.class));
serviceLoader = (ServiceLoader) privilegedHandle.invoke(action);
}
return serviceLoader;
} catch (Throwable e) {
if (verbose) {
StatusLogger.getLogger().error("Unable to load services for service {}", serviceType, e);
}
}
return Collections.emptyList();
}
private static class ServiceLoaderSpliterator implements Spliterator {
private final Iterator serviceIterator;
private final Logger logger;
private final String serviceName;
public ServiceLoaderSpliterator(final Class serviceType, final Lookup lookup, final ClassLoader classLoader,
final boolean verbose) {
this.serviceIterator = callServiceLoader(lookup, serviceType, classLoader, verbose).iterator();
this.logger = verbose ? StatusLogger.getLogger() : null;
this.serviceName = serviceType.toString();
}
@Override
public boolean tryAdvance(final Consumer action) {
int i = MAX_BROKEN_SERVICES;
while (i-- > 0) {
try {
if (serviceIterator.hasNext()) {
action.accept(serviceIterator.next());
return true;
}
} catch (ServiceConfigurationError | LinkageError e) {
if (logger != null) {
logger.warn("Unable to load service class for service {}", serviceName, e);
}
} catch (Throwable e) {
if (logger != null) {
logger.warn("Unable to load service class for service {}", serviceName, e);
}
throw e;
}
}
return false;
}
@Override
public Spliterator trySplit() {
return null;
}
@Override
public long estimateSize() {
return Long.MAX_VALUE;
}
@Override
public int characteristics() {
return NONNULL | IMMUTABLE;
}
}
}
