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.Objects; 043import java.util.Set; 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 = "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 Map<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, Strings.EMPTY, 106 PLUGIN_CACHE_FILE, elements); 107 try (final OutputStream out = fo.openOutputStream()) { 108 pluginCache.writeCache(out); 109 } 110 } 111 112 /** 113 * ElementVisitor to scan the Plugin annotation. 114 */ 115 private static class PluginElementVisitor extends SimpleElementVisitor6<PluginEntry, Plugin> { 116 117 private final Elements elements; 118 119 private PluginElementVisitor(final Elements elements) { 120 this.elements = elements; 121 } 122 123 @Override 124 public PluginEntry visitType(final TypeElement e, final Plugin plugin) { 125 Objects.requireNonNull(plugin, "Plugin annotation is null."); 126 final PluginEntry entry = new PluginEntry(); 127 entry.setKey(plugin.name().toLowerCase()); 128 entry.setClassName(elements.getBinaryName(e).toString()); 129 entry.setName(Plugin.EMPTY.equals(plugin.elementType()) ? plugin.name() : plugin.elementType()); 130 entry.setPrintable(plugin.printObject()); 131 entry.setDefer(plugin.deferChildren()); 132 entry.setCategory(plugin.category()); 133 return entry; 134 } 135 } 136 137 /** 138 * ElementVisitor to scan the PluginAliases annotation. 139 */ 140 private static class PluginAliasesElementVisitor extends SimpleElementVisitor6<Collection<PluginEntry>, Plugin> { 141 142 private final Elements elements; 143 144 private PluginAliasesElementVisitor(final Elements elements) { 145 super(Collections.<PluginEntry>emptyList()); 146 this.elements = elements; 147 } 148 149 @Override 150 public Collection<PluginEntry> visitType(final TypeElement e, final Plugin plugin) { 151 final PluginAliases aliases = e.getAnnotation(PluginAliases.class); 152 if (aliases == null) { 153 return DEFAULT_VALUE; 154 } 155 final Collection<PluginEntry> entries = new ArrayList<>(aliases.value().length); 156 for (final String alias : aliases.value()) { 157 final PluginEntry entry = new PluginEntry(); 158 entry.setKey(alias.toLowerCase()); 159 entry.setClassName(elements.getBinaryName(e).toString()); 160 entry.setName(Plugin.EMPTY.equals(plugin.elementType()) ? alias : plugin.elementType()); 161 entry.setPrintable(plugin.printObject()); 162 entry.setDefer(plugin.deferChildren()); 163 entry.setCategory(plugin.category()); 164 entries.add(entry); 165 } 166 return entries; 167 } 168 } 169}