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.annotation.processing.SupportedSourceVersion; 032 import javax.lang.model.SourceVersion; 033 import javax.lang.model.element.Element; 034 import javax.lang.model.element.ElementVisitor; 035 import javax.lang.model.element.TypeElement; 036 import javax.lang.model.util.Elements; 037 import javax.lang.model.util.SimpleElementVisitor6; 038 import javax.tools.Diagnostic.Kind; 039 import javax.tools.FileObject; 040 import javax.tools.StandardLocation; 041 042 import org.apache.logging.log4j.core.config.plugins.Plugin; 043 import org.apache.logging.log4j.core.config.plugins.PluginAliases; 044 import 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.*") 050 @SupportedSourceVersion(SourceVersion.RELEASE_6) 051 public class PluginProcessor extends AbstractProcessor { 052 053 // TODO: this could be made more abstract to allow for compile-time and run-time plugin processing 054 055 /** 056 * The location of the plugin cache data file. This file is written to by this processor, and read from by 057 * {@link org.apache.logging.log4j.core.config.plugins.util.PluginManager}. 058 */ 059 public static final String PLUGIN_CACHE_FILE = "META-INF/org/apache/logging/log4j/core/config/plugins/Log4j2Plugins.dat"; 060 061 private final PluginCache pluginCache = new PluginCache(); 062 063 @Override 064 public boolean process(final Set<? extends TypeElement> annotations, final RoundEnvironment roundEnv) { 065 try { 066 final Set<? extends Element> elements = roundEnv.getElementsAnnotatedWith(Plugin.class); 067 if (elements.isEmpty()) { 068 return false; 069 } 070 collectPlugins(elements); 071 writeCacheFile(elements.toArray(new Element[elements.size()])); 072 return true; 073 } catch (final IOException e) { 074 error(e.getMessage()); 075 return false; 076 } 077 } 078 079 private void error(final CharSequence message) { 080 processingEnv.getMessager().printMessage(Kind.ERROR, message); 081 } 082 083 private void collectPlugins(final Iterable<? extends Element> elements) { 084 final Elements elementUtils = processingEnv.getElementUtils(); 085 final ElementVisitor<PluginEntry, Plugin> pluginVisitor = 086 new PluginElementVisitor(elementUtils); 087 final ElementVisitor<Collection<PluginEntry>, Plugin> pluginAliasesVisitor = 088 new PluginAliasesElementVisitor(elementUtils); 089 for (final Element element : elements) { 090 final Plugin plugin = element.getAnnotation(Plugin.class); 091 final PluginEntry entry = element.accept(pluginVisitor, plugin); 092 final ConcurrentMap<String, PluginEntry> category = pluginCache.getCategory(entry.getCategory()); 093 category.put(entry.getKey(), entry); 094 final Collection<PluginEntry> entries = element.accept(pluginAliasesVisitor, plugin); 095 for (final PluginEntry pluginEntry : entries) { 096 category.put(pluginEntry.getKey(), pluginEntry); 097 } 098 } 099 } 100 101 private void writeCacheFile(final Element... elements) throws IOException { 102 final FileObject fo = processingEnv.getFiler().createResource(StandardLocation.CLASS_OUTPUT, 103 Strings.EMPTY, PLUGIN_CACHE_FILE, elements); 104 final OutputStream out = fo.openOutputStream(); 105 try { 106 pluginCache.writeCache(out); 107 } finally { 108 out.close(); 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 if (plugin == null) { 126 throw new NullPointerException("Plugin annotation is null."); 127 } 128 final PluginEntry entry = new PluginEntry(); 129 entry.setKey(plugin.name().toLowerCase()); 130 entry.setClassName(elements.getBinaryName(e).toString()); 131 entry.setName(Plugin.EMPTY.equals(plugin.elementType()) ? plugin.name() : plugin.elementType()); 132 entry.setPrintable(plugin.printObject()); 133 entry.setDefer(plugin.deferChildren()); 134 entry.setCategory(plugin.category()); 135 return entry; 136 } 137 } 138 139 /** 140 * ElementVisitor to scan the PluginAliases annotation. 141 */ 142 private static class PluginAliasesElementVisitor extends SimpleElementVisitor6<Collection<PluginEntry>, Plugin> { 143 144 private final Elements elements; 145 146 private PluginAliasesElementVisitor(final Elements elements) { 147 super(Collections.<PluginEntry>emptyList()); 148 this.elements = elements; 149 } 150 151 @Override 152 public Collection<PluginEntry> visitType(final TypeElement e, final Plugin plugin) { 153 final PluginAliases aliases = e.getAnnotation(PluginAliases.class); 154 if (aliases == null) { 155 return DEFAULT_VALUE; 156 } 157 final Collection<PluginEntry> entries = new ArrayList<PluginEntry>(aliases.value().length); 158 for (final String alias : aliases.value()) { 159 final PluginEntry entry = new PluginEntry(); 160 entry.setKey(alias.toLowerCase()); 161 entry.setClassName(elements.getBinaryName(e).toString()); 162 entry.setName(Plugin.EMPTY.equals(plugin.elementType()) ? alias : plugin.elementType()); 163 entry.setPrintable(plugin.printObject()); 164 entry.setDefer(plugin.deferChildren()); 165 entry.setCategory(plugin.category()); 166 entries.add(entry); 167 } 168 return entries; 169 } 170 } 171 }