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