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 018package org.apache.logging.log4j.core.config.plugins.processor; 019 020import org.apache.logging.log4j.core.config.plugins.Plugin; 021import org.apache.logging.log4j.core.config.plugins.PluginAliases; 022import org.apache.logging.log4j.util.Strings; 023 024import javax.annotation.processing.AbstractProcessor; 025import javax.annotation.processing.RoundEnvironment; 026import javax.annotation.processing.SupportedAnnotationTypes; 027import javax.lang.model.SourceVersion; 028import javax.lang.model.element.Element; 029import javax.lang.model.element.ElementVisitor; 030import javax.lang.model.element.TypeElement; 031import javax.lang.model.util.Elements; 032import javax.lang.model.util.SimpleElementVisitor6; 033import javax.tools.Diagnostic.Kind; 034import javax.tools.FileObject; 035import javax.tools.StandardLocation; 036import java.io.IOException; 037import java.io.OutputStream; 038import java.util.ArrayList; 039import java.util.Collection; 040import java.util.Collections; 041import java.util.Map; 042import java.util.Set; 043 044/** 045 * Annotation processor for pre-scanning Log4j 2 plugins. 046 */ 047@SupportedAnnotationTypes("org.apache.logging.log4j.core.config.plugins.*") 048public 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}