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 java.io.IOException; 021 import java.io.OutputStream; 022 import java.util.ArrayList; 023 import java.util.Collection; 024 import java.util.Collections; 025 import java.util.Set; 026 import java.util.concurrent.ConcurrentMap; 027 028 import javax.annotation.processing.AbstractProcessor; 029 import javax.annotation.processing.RoundEnvironment; 030 import javax.annotation.processing.SupportedAnnotationTypes; 031 import javax.lang.model.SourceVersion; 032 import javax.lang.model.element.Element; 033 import javax.lang.model.element.ElementVisitor; 034 import javax.lang.model.element.TypeElement; 035 import javax.lang.model.util.Elements; 036 import javax.lang.model.util.SimpleElementVisitor6; 037 import javax.tools.Diagnostic.Kind; 038 import javax.tools.FileObject; 039 import javax.tools.StandardLocation; 040 041 import org.apache.logging.log4j.core.config.plugins.Plugin; 042 import org.apache.logging.log4j.core.config.plugins.PluginAliases; 043 import org.apache.logging.log4j.util.Strings; 044 045 /** 046 * Annotation processor for pre-scanning Log4j 2 plugins. 047 */ 048 @SupportedAnnotationTypes("org.apache.logging.log4j.core.config.plugins.*") 049 public class PluginProcessor extends AbstractProcessor { 050 051 // TODO: this could be made more abstract to allow for compile-time and run-time plugin processing 052 053 /** 054 * The location of the plugin cache data file. This file is written to by this processor, and read from by 055 * {@link org.apache.logging.log4j.core.config.plugins.util.PluginManager}. 056 */ 057 public static final String PLUGIN_CACHE_FILE = "META-INF/org/apache/logging/log4j/core/config/plugins/Log4j2Plugins.dat"; 058 059 private final PluginCache pluginCache = new PluginCache(); 060 061 @Override 062 public SourceVersion getSupportedSourceVersion() { 063 return SourceVersion.latest(); 064 } 065 066 @Override 067 public boolean process(final Set<? extends TypeElement> annotations, final RoundEnvironment roundEnv) { 068 try { 069 final Set<? extends Element> elements = roundEnv.getElementsAnnotatedWith(Plugin.class); 070 if (elements.isEmpty()) { 071 return false; 072 } 073 collectPlugins(elements); 074 writeCacheFile(elements.toArray(new Element[elements.size()])); 075 return true; 076 } catch (final IOException e) { 077 error(e.getMessage()); 078 return false; 079 } 080 } 081 082 private void error(final CharSequence message) { 083 processingEnv.getMessager().printMessage(Kind.ERROR, message); 084 } 085 086 private void collectPlugins(final Iterable<? extends Element> elements) { 087 final Elements elementUtils = processingEnv.getElementUtils(); 088 final ElementVisitor<PluginEntry, Plugin> pluginVisitor = 089 new PluginElementVisitor(elementUtils); 090 final ElementVisitor<Collection<PluginEntry>, Plugin> pluginAliasesVisitor = 091 new PluginAliasesElementVisitor(elementUtils); 092 for (final Element element : elements) { 093 final Plugin plugin = element.getAnnotation(Plugin.class); 094 final PluginEntry entry = element.accept(pluginVisitor, plugin); 095 final ConcurrentMap<String, PluginEntry> category = pluginCache.getCategory(entry.getCategory()); 096 category.put(entry.getKey(), entry); 097 final Collection<PluginEntry> entries = element.accept(pluginAliasesVisitor, plugin); 098 for (final PluginEntry pluginEntry : entries) { 099 category.put(pluginEntry.getKey(), pluginEntry); 100 } 101 } 102 } 103 104 private void writeCacheFile(final Element... elements) throws IOException { 105 final FileObject fo = processingEnv.getFiler().createResource(StandardLocation.CLASS_OUTPUT, 106 Strings.EMPTY, PLUGIN_CACHE_FILE, elements); 107 final OutputStream out = fo.openOutputStream(); 108 try { 109 pluginCache.writeCache(out); 110 } finally { 111 out.close(); 112 } 113 } 114 115 /** 116 * ElementVisitor to scan the Plugin annotation. 117 */ 118 private static class PluginElementVisitor extends SimpleElementVisitor6<PluginEntry, Plugin> { 119 120 private final Elements elements; 121 122 private PluginElementVisitor(final Elements elements) { 123 this.elements = elements; 124 } 125 126 @Override 127 public PluginEntry visitType(final TypeElement e, final Plugin plugin) { 128 if (plugin == null) { 129 throw new NullPointerException("Plugin annotation is null."); 130 } 131 final PluginEntry entry = new PluginEntry(); 132 entry.setKey(plugin.name().toLowerCase()); 133 entry.setClassName(elements.getBinaryName(e).toString()); 134 entry.setName(Plugin.EMPTY.equals(plugin.elementType()) ? plugin.name() : plugin.elementType()); 135 entry.setPrintable(plugin.printObject()); 136 entry.setDefer(plugin.deferChildren()); 137 entry.setCategory(plugin.category()); 138 return entry; 139 } 140 } 141 142 /** 143 * ElementVisitor to scan the PluginAliases annotation. 144 */ 145 private static class PluginAliasesElementVisitor extends SimpleElementVisitor6<Collection<PluginEntry>, Plugin> { 146 147 private final Elements elements; 148 149 private PluginAliasesElementVisitor(final Elements elements) { 150 super(Collections.<PluginEntry>emptyList()); 151 this.elements = elements; 152 } 153 154 @Override 155 public Collection<PluginEntry> visitType(final TypeElement e, final Plugin plugin) { 156 final PluginAliases aliases = e.getAnnotation(PluginAliases.class); 157 if (aliases == null) { 158 return DEFAULT_VALUE; 159 } 160 final Collection<PluginEntry> entries = new ArrayList<PluginEntry>(aliases.value().length); 161 for (final String alias : aliases.value()) { 162 final PluginEntry entry = new PluginEntry(); 163 entry.setKey(alias.toLowerCase()); 164 entry.setClassName(elements.getBinaryName(e).toString()); 165 entry.setName(Plugin.EMPTY.equals(plugin.elementType()) ? alias : plugin.elementType()); 166 entry.setPrintable(plugin.printObject()); 167 entry.setDefer(plugin.deferChildren()); 168 entry.setCategory(plugin.category()); 169 entries.add(entry); 170 } 171 return entries; 172 } 173 } 174 }