001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018 package org.apache.logging.log4j.core.config.plugins.processor;
019
020 import org.apache.logging.log4j.core.config.plugins.Plugin;
021 import org.apache.logging.log4j.core.config.plugins.PluginAliases;
022 import org.apache.logging.log4j.util.Strings;
023
024 import javax.annotation.processing.AbstractProcessor;
025 import javax.annotation.processing.RoundEnvironment;
026 import javax.annotation.processing.SupportedAnnotationTypes;
027 import javax.lang.model.SourceVersion;
028 import javax.lang.model.element.Element;
029 import javax.lang.model.element.ElementVisitor;
030 import javax.lang.model.element.TypeElement;
031 import javax.lang.model.util.Elements;
032 import javax.lang.model.util.SimpleElementVisitor6;
033 import javax.tools.Diagnostic.Kind;
034 import javax.tools.FileObject;
035 import javax.tools.StandardLocation;
036 import java.io.IOException;
037 import java.io.OutputStream;
038 import java.util.ArrayList;
039 import java.util.Collection;
040 import java.util.Collections;
041 import java.util.Map;
042 import java.util.Set;
043
044 /**
045 * Annotation processor for pre-scanning Log4j 2 plugins.
046 */
047 @SupportedAnnotationTypes("org.apache.logging.log4j.core.config.plugins.*")
048 public class PluginProcessor extends AbstractProcessor {
049
050 // TODO: this could be made more abstract to allow for compile-time and run-time plugin processing
051
052 /**
053 * The location of the plugin cache data file. This file is written to by this processor, and read from by
054 * {@link org.apache.logging.log4j.core.config.plugins.util.PluginManager}.
055 */
056 public static final String PLUGIN_CACHE_FILE = "META-INF/org/apache/logging/log4j/core/config/plugins/Log4j2Plugins.dat";
057
058 private final PluginCache pluginCache = new PluginCache();
059
060 @Override
061 public SourceVersion getSupportedSourceVersion() {
062 return SourceVersion.latest();
063 }
064
065 @Override
066 public boolean process(final Set<? extends TypeElement> annotations, final RoundEnvironment roundEnv) {
067 try {
068 final Set<? extends Element> elements = roundEnv.getElementsAnnotatedWith(Plugin.class);
069 if (elements.isEmpty()) {
070 return false;
071 }
072 collectPlugins(elements);
073 writeCacheFile(elements.toArray(new Element[elements.size()]));
074 return true;
075 } catch (final IOException e) {
076 error(e.getMessage());
077 return false;
078 }
079 }
080
081 private void error(final CharSequence message) {
082 processingEnv.getMessager().printMessage(Kind.ERROR, message);
083 }
084
085 private void collectPlugins(final Iterable<? extends Element> elements) {
086 final Elements elementUtils = processingEnv.getElementUtils();
087 final ElementVisitor<PluginEntry, Plugin> pluginVisitor =
088 new PluginElementVisitor(elementUtils);
089 final ElementVisitor<Collection<PluginEntry>, Plugin> pluginAliasesVisitor =
090 new PluginAliasesElementVisitor(elementUtils);
091 for (final Element element : elements) {
092 final Plugin plugin = element.getAnnotation(Plugin.class);
093 final PluginEntry entry = element.accept(pluginVisitor, plugin);
094 final Map<String, PluginEntry> category = pluginCache.getCategory(entry.getCategory());
095 category.put(entry.getKey(), entry);
096 final Collection<PluginEntry> entries = element.accept(pluginAliasesVisitor, plugin);
097 for (final PluginEntry pluginEntry : entries) {
098 category.put(pluginEntry.getKey(), pluginEntry);
099 }
100 }
101 }
102
103 private void writeCacheFile(final Element... elements) throws IOException {
104 final FileObject fo = processingEnv.getFiler().createResource(StandardLocation.CLASS_OUTPUT,
105 Strings.EMPTY, PLUGIN_CACHE_FILE, elements);
106 final OutputStream out = fo.openOutputStream();
107 try {
108 pluginCache.writeCache(out);
109 } finally {
110 out.close();
111 }
112 }
113
114 /**
115 * ElementVisitor to scan the Plugin annotation.
116 */
117 private static class PluginElementVisitor extends SimpleElementVisitor6<PluginEntry, Plugin> {
118
119 private final Elements elements;
120
121 private PluginElementVisitor(final Elements elements) {
122 this.elements = elements;
123 }
124
125 @Override
126 public PluginEntry visitType(final TypeElement e, final Plugin plugin) {
127 if (plugin == null) {
128 throw new NullPointerException("Plugin annotation is null.");
129 }
130 final PluginEntry entry = new PluginEntry();
131 entry.setKey(plugin.name().toLowerCase());
132 entry.setClassName(elements.getBinaryName(e).toString());
133 entry.setName(Plugin.EMPTY.equals(plugin.elementType()) ? plugin.name() : plugin.elementType());
134 entry.setPrintable(plugin.printObject());
135 entry.setDefer(plugin.deferChildren());
136 entry.setCategory(plugin.category());
137 return entry;
138 }
139 }
140
141 /**
142 * ElementVisitor to scan the PluginAliases annotation.
143 */
144 private static class PluginAliasesElementVisitor extends SimpleElementVisitor6<Collection<PluginEntry>, Plugin> {
145
146 private final Elements elements;
147
148 private PluginAliasesElementVisitor(final Elements elements) {
149 super(Collections.<PluginEntry>emptyList());
150 this.elements = elements;
151 }
152
153 @Override
154 public Collection<PluginEntry> visitType(final TypeElement e, final Plugin plugin) {
155 final PluginAliases aliases = e.getAnnotation(PluginAliases.class);
156 if (aliases == null) {
157 return DEFAULT_VALUE;
158 }
159 final Collection<PluginEntry> entries = new ArrayList<PluginEntry>(aliases.value().length);
160 for (final String alias : aliases.value()) {
161 final PluginEntry entry = new PluginEntry();
162 entry.setKey(alias.toLowerCase());
163 entry.setClassName(elements.getBinaryName(e).toString());
164 entry.setName(Plugin.EMPTY.equals(plugin.elementType()) ? alias : plugin.elementType());
165 entry.setPrintable(plugin.printObject());
166 entry.setDefer(plugin.deferChildren());
167 entry.setCategory(plugin.category());
168 entries.add(entry);
169 }
170 return entries;
171 }
172 }
173 }