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; 028import javax.annotation.processing.AbstractProcessor; 029import javax.annotation.processing.RoundEnvironment; 030import javax.annotation.processing.SupportedAnnotationTypes; 031import javax.lang.model.SourceVersion; 032import javax.lang.model.element.Element; 033import javax.lang.model.element.ElementVisitor; 034import javax.lang.model.element.TypeElement; 035import javax.lang.model.util.Elements; 036import javax.lang.model.util.SimpleElementVisitor7; 037import javax.tools.Diagnostic.Kind; 038import javax.tools.FileObject; 039import javax.tools.StandardLocation; 040 041import org.apache.logging.log4j.core.config.plugins.Plugin; 042import org.apache.logging.log4j.core.config.plugins.PluginAliases; 043import 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.*") 049public 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 = 058 "META-INF/org/apache/logging/log4j/core/config/plugins/Log4j2Plugins.dat"; 059 060 private final PluginCache pluginCache = new PluginCache(); 061 062 @Override 063 public SourceVersion getSupportedSourceVersion() { 064 return SourceVersion.latest(); 065 } 066 067 @Override 068 public boolean process(final Set<? extends TypeElement> annotations, final RoundEnvironment roundEnv) { 069 try { 070 final Set<? extends Element> elements = roundEnv.getElementsAnnotatedWith(Plugin.class); 071 if (elements.isEmpty()) { 072 return false; 073 } 074 collectPlugins(elements); 075 writeCacheFile(elements.toArray(new Element[elements.size()])); 076 return true; 077 } catch (final IOException e) { 078 error(e.getMessage()); 079 return false; 080 } 081 } 082 083 private void error(final CharSequence message) { 084 processingEnv.getMessager().printMessage(Kind.ERROR, message); 085 } 086 087 private void collectPlugins(final Iterable<? extends Element> elements) { 088 final Elements elementUtils = processingEnv.getElementUtils(); 089 final ElementVisitor<PluginEntry, Plugin> pluginVisitor = new PluginElementVisitor(elementUtils); 090 final ElementVisitor<Collection<PluginEntry>, Plugin> pluginAliasesVisitor = new PluginAliasesElementVisitor( 091 elementUtils); 092 for (final Element element : elements) { 093 final Plugin plugin = element.getAnnotation(Plugin.class); 094 if (plugin == null) { 095 continue; 096 } 097 final PluginEntry entry = element.accept(pluginVisitor, plugin); 098 final Map<String, PluginEntry> category = pluginCache.getCategory(entry.getCategory()); 099 category.put(entry.getKey(), entry); 100 final Collection<PluginEntry> entries = element.accept(pluginAliasesVisitor, plugin); 101 for (final PluginEntry pluginEntry : entries) { 102 category.put(pluginEntry.getKey(), pluginEntry); 103 } 104 } 105 } 106 107 private void writeCacheFile(final Element... elements) throws IOException { 108 final FileObject fo = processingEnv.getFiler().createResource(StandardLocation.CLASS_OUTPUT, Strings.EMPTY, 109 PLUGIN_CACHE_FILE, elements); 110 try (final OutputStream out = fo.openOutputStream()) { 111 pluginCache.writeCache(out); 112 } 113 } 114 115 /** 116 * ElementVisitor to scan the Plugin annotation. 117 */ 118 private static class PluginElementVisitor extends SimpleElementVisitor7<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 Objects.requireNonNull(plugin, "Plugin annotation is null."); 129 final PluginEntry entry = new PluginEntry(); 130 entry.setKey(plugin.name().toLowerCase()); 131 entry.setClassName(elements.getBinaryName(e).toString()); 132 entry.setName(Plugin.EMPTY.equals(plugin.elementType()) ? plugin.name() : plugin.elementType()); 133 entry.setPrintable(plugin.printObject()); 134 entry.setDefer(plugin.deferChildren()); 135 entry.setCategory(plugin.category()); 136 return entry; 137 } 138 } 139 140 /** 141 * ElementVisitor to scan the PluginAliases annotation. 142 */ 143 private static class PluginAliasesElementVisitor extends SimpleElementVisitor7<Collection<PluginEntry>, Plugin> { 144 145 private final Elements elements; 146 147 private PluginAliasesElementVisitor(final Elements elements) { 148 super(Collections.<PluginEntry> emptyList()); 149 this.elements = elements; 150 } 151 152 @Override 153 public Collection<PluginEntry> visitType(final TypeElement e, final Plugin plugin) { 154 final PluginAliases aliases = e.getAnnotation(PluginAliases.class); 155 if (aliases == null) { 156 return DEFAULT_VALUE; 157 } 158 final Collection<PluginEntry> entries = new ArrayList<>(aliases.value().length); 159 for (final String alias : aliases.value()) { 160 final PluginEntry entry = new PluginEntry(); 161 entry.setKey(alias.toLowerCase()); 162 entry.setClassName(elements.getBinaryName(e).toString()); 163 entry.setName(Plugin.EMPTY.equals(plugin.elementType()) ? alias : plugin.elementType()); 164 entry.setPrintable(plugin.printObject()); 165 entry.setDefer(plugin.deferChildren()); 166 entry.setCategory(plugin.category()); 167 entries.add(entry); 168 } 169 return entries; 170 } 171 } 172}