io.cdap.cdap.internal.app.runtime.plugin.PluginClassLoaders Maven / Gradle / Ivy
/*
* Copyright © 2015 Cask Data, Inc.
*
* 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 io.cdap.cdap.internal.app.runtime.plugin;
import com.google.common.base.Function;
import com.google.common.base.Throwables;
import com.google.common.collect.HashMultimap;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Iterables;
import com.google.common.collect.Multimap;
import io.cdap.cdap.api.plugin.Plugin;
import io.cdap.cdap.common.lang.CombineClassLoader;
import io.cdap.cdap.common.lang.FilterClassLoader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.Set;
import javax.annotation.Nullable;
/**
* A utility class to help constructing ClassLoaders for plugins in program context.
*/
public final class PluginClassLoaders {
private static final Function CLASS_TO_RESOURCE_NAME = new Function() {
@Override
public String apply(String className) {
return className.replace('.', '/') + ".class";
}
};
/**
* Returns a {@link ClassLoader} that only allows loading of plugin classes and plugin exported classes.
* It should only be used in context when a single ClassLoader is needed to load all different kinds of user classes
* (e.g. in MapReduce/Spark).
*/
public static ClassLoader createFilteredPluginsClassLoader(Map plugins,
@Nullable PluginInstantiator pluginInstantiator) {
if (plugins.isEmpty() || pluginInstantiator == null) {
return new CombineClassLoader(null);
}
try {
// Gather all explicitly used plugin class names. It is needed for external plugin case.
Multimap artifactPluginClasses = getArtifactPluginClasses(plugins);
List pluginClassLoaders = new ArrayList<>();
for (Plugin plugin : plugins.values()) {
ClassLoader pluginClassLoader = pluginInstantiator.getPluginClassLoader(plugin);
if (pluginClassLoader instanceof PluginClassLoader) {
// A ClassLoader to allow loading of all plugin classes used by the program.
Collection pluginClasses = artifactPluginClasses.get(plugin);
if (!pluginClasses.isEmpty()) {
pluginClassLoaders.add(createClassFilteredClassLoader(pluginClasses, pluginClassLoader));
}
// A ClassLoader to allow all export package classes to be loadable.
pluginClassLoaders.add(((PluginClassLoader) pluginClassLoader).getExportPackagesClassLoader());
}
}
return new CombineClassLoader(null, pluginClassLoaders);
} catch (IOException e) {
throw Throwables.propagate(e);
}
}
/**
* Returns a {@link Multimap} from {@link Plugin} to set of classes used by the program.
*/
private static Multimap getArtifactPluginClasses(Map plugins) {
Multimap result = HashMultimap.create();
for (Map.Entry entry : plugins.entrySet()) {
result.put(entry.getValue(), entry.getValue().getPluginClass().getClassName());
}
return result;
}
private static ClassLoader createClassFilteredClassLoader(Iterable allowedClasses,
ClassLoader parentClassLoader) {
final Set allowedResources = ImmutableSet.copyOf(Iterables.transform(allowedClasses,
CLASS_TO_RESOURCE_NAME));
return new FilterClassLoader(parentClassLoader, new FilterClassLoader.Filter() {
@Override
public boolean acceptResource(String resource) {
return allowedResources.contains(resource);
}
@Override
public boolean acceptPackage(String packageName) {
return true;
}
});
}
private PluginClassLoaders() {
// no-op
}
}