/*
* 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.core.config.plugins.processor;
import java.io.IOException;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Set;
import java.util.concurrent.ConcurrentMap;
import javax.annotation.processing.AbstractProcessor;
import javax.annotation.processing.RoundEnvironment;
import javax.annotation.processing.SupportedAnnotationTypes;
import javax.annotation.processing.SupportedSourceVersion;
import javax.lang.model.SourceVersion;
import javax.lang.model.element.Element;
import javax.lang.model.element.ElementVisitor;
import javax.lang.model.element.TypeElement;
import javax.lang.model.util.Elements;
import javax.lang.model.util.SimpleElementVisitor6;
import javax.tools.Diagnostic.Kind;
import javax.tools.FileObject;
import javax.tools.StandardLocation;
import org.apache.logging.log4j.core.config.plugins.Plugin;
import org.apache.logging.log4j.core.config.plugins.PluginAliases;
import org.apache.logging.log4j.util.Strings;
/**
* Annotation processor for pre-scanning Log4j 2 plugins.
*/
@SupportedAnnotationTypes("org.apache.logging.log4j.core.config.plugins.*")
@SupportedSourceVersion(SourceVersion.RELEASE_6)
public class PluginProcessor extends AbstractProcessor {
// TODO: this could be made more abstract to allow for compile-time and run-time plugin processing
/**
* The location of the plugin cache data file. This file is written to by this processor, and read from by
* {@link org.apache.logging.log4j.core.config.plugins.util.PluginManager}.
*/
public static final String PLUGIN_CACHE_FILE = "META-INF/org/apache/logging/log4j/core/config/plugins/Log4j2Plugins.dat";
private final PluginCache pluginCache = new PluginCache();
@Override
public boolean process(final Set<? extends TypeElement> annotations, final RoundEnvironment roundEnv) {
try {
final Set<? extends Element> elements = roundEnv.getElementsAnnotatedWith(Plugin.class);
if (elements.isEmpty()) {
return false;
}
collectPlugins(elements);
writeCacheFile(elements.toArray(new Element[elements.size()]));
return true;
} catch (final IOException e) {
error(e.getMessage());
return false;
}
}
private void error(final CharSequence message) {
processingEnv.getMessager().printMessage(Kind.ERROR, message);
}
private void collectPlugins(final Iterable<? extends Element> elements) {
final Elements elementUtils = processingEnv.getElementUtils();
final ElementVisitor<PluginEntry, Plugin> pluginVisitor =
new PluginElementVisitor(elementUtils);
final ElementVisitor<Collection<PluginEntry>, Plugin> pluginAliasesVisitor =
new PluginAliasesElementVisitor(elementUtils);
for (final Element element : elements) {
final Plugin plugin = element.getAnnotation(Plugin.class);
final PluginEntry entry = element.accept(pluginVisitor, plugin);
final ConcurrentMap<String, PluginEntry> category = pluginCache.getCategory(entry.getCategory());
category.put(entry.getKey(), entry);
final Collection<PluginEntry> entries = element.accept(pluginAliasesVisitor, plugin);
for (final PluginEntry pluginEntry : entries) {
category.put(pluginEntry.getKey(), pluginEntry);
}
}
}
private void writeCacheFile(final Element... elements) throws IOException {
final FileObject fo = processingEnv.getFiler().createResource(StandardLocation.CLASS_OUTPUT,
Strings.EMPTY, PLUGIN_CACHE_FILE, elements);
final OutputStream out = fo.openOutputStream();
try {
pluginCache.writeCache(out);
} finally {
out.close();
}
}
/**
* ElementVisitor to scan the Plugin annotation.
*/
private static class PluginElementVisitor extends SimpleElementVisitor6<PluginEntry, Plugin> {
private final Elements elements;
private PluginElementVisitor(final Elements elements) {
this.elements = elements;
}
@Override
public PluginEntry visitType(final TypeElement e, final Plugin plugin) {
if (plugin == null) {
throw new NullPointerException("Plugin annotation is null.");
}
final PluginEntry entry = new PluginEntry();
entry.setKey(plugin.name().toLowerCase());
entry.setClassName(elements.getBinaryName(e).toString());
entry.setName(Plugin.EMPTY.equals(plugin.elementType()) ? plugin.name() : plugin.elementType());
entry.setPrintable(plugin.printObject());
entry.setDefer(plugin.deferChildren());
entry.setCategory(plugin.category());
return entry;
}
}
/**
* ElementVisitor to scan the PluginAliases annotation.
*/
private static class PluginAliasesElementVisitor extends SimpleElementVisitor6<Collection<PluginEntry>, Plugin> {
private final Elements elements;
private PluginAliasesElementVisitor(final Elements elements) {
super(Collections.<PluginEntry>emptyList());
this.elements = elements;
}
@Override
public Collection<PluginEntry> visitType(final TypeElement e, final Plugin plugin) {
final PluginAliases aliases = e.getAnnotation(PluginAliases.class);
if (aliases == null) {
return DEFAULT_VALUE;
}
final Collection<PluginEntry> entries = new ArrayList<PluginEntry>(aliases.value().length);
for (final String alias : aliases.value()) {
final PluginEntry entry = new PluginEntry();
entry.setKey(alias.toLowerCase());
entry.setClassName(elements.getBinaryName(e).toString());
entry.setName(Plugin.EMPTY.equals(plugin.elementType()) ? alias : plugin.elementType());
entry.setPrintable(plugin.printObject());
entry.setDefer(plugin.deferChildren());
entry.setCategory(plugin.category());
entries.add(entry);
}
return entries;
}
}
}