001 /*
002 * Sonar, open source software quality management tool.
003 * Copyright (C) 2008-2011 SonarSource
004 * mailto:contact AT sonarsource DOT com
005 *
006 * Sonar is free software; you can redistribute it and/or
007 * modify it under the terms of the GNU Lesser General Public
008 * License as published by the Free Software Foundation; either
009 * version 3 of the License, or (at your option) any later version.
010 *
011 * Sonar is distributed in the hope that it will be useful,
012 * but WITHOUT ANY WARRANTY; without even the implied warranty of
013 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 * Lesser General Public License for more details.
015 *
016 * You should have received a copy of the GNU Lesser General Public
017 * License along with Sonar; if not, write to the Free Software
018 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02
019 */
020
021 package org.sonar.core.classloaders;
022
023 import java.net.URL;
024 import java.util.Arrays;
025 import java.util.Collection;
026 import java.util.List;
027
028 import com.google.common.collect.Lists;
029 import org.apache.commons.lang.StringUtils;
030 import org.codehaus.plexus.classworlds.ClassWorld;
031 import org.codehaus.plexus.classworlds.realm.ClassRealm;
032 import org.codehaus.plexus.classworlds.realm.DuplicateRealmException;
033 import org.codehaus.plexus.classworlds.realm.NoSuchRealmException;
034 import org.sonar.api.utils.Logs;
035 import org.sonar.api.utils.SonarException;
036
037 /**
038 * Encapsulates manipulations with ClassLoaders, such as creation and establishing dependencies. Current implementation based on
039 * {@link ClassWorld}.
040 *
041 * <h3>IMPORTANT</h3>
042 * <p>
043 * If we have pluginA , then all classes and resources from package and subpackages of <b>org.sonar.plugins.pluginA.api</b> will be visible
044 * for all other plugins even if they located in dependent library.
045 * </p>
046 *
047 * <h4>Search order for {@link ClassRealm} :</h4>
048 * <ul>
049 * <li>parent class loader (passed via the constructor) if there is one</li>
050 * <li>imports</li>
051 * <li>realm's constituents</li>
052 * <li>parent realm</li>
053 * </ul>
054 *
055 * @since 2.4
056 */
057 public class ClassLoadersCollection {
058
059 private static final String[] PREFIXES_TO_EXPORT = { "org.sonar.plugins.", "com.sonar.plugins.", "com.sonarsource.plugins." };
060
061 private ClassWorld world = new ClassWorld();
062 private ClassLoader baseClassLoader;
063
064 public ClassLoadersCollection(ClassLoader baseClassLoader) {
065 this.baseClassLoader = baseClassLoader;
066 }
067
068 /**
069 * Generates URLClassLoader with specified delegation model.
070 *
071 * @param key plugin key
072 * @param urls libraries
073 * @param childFirst true, if child-first delegation model required instead of parent-first
074 * @return created ClassLoader, but actually this method shouldn't return anything, because dependencies must be established - see
075 * {@link #done()}.
076 */
077 public ClassLoader createClassLoader(String key, Collection<URL> urls, boolean childFirst) {
078 try {
079 List<URL> resources = Lists.newArrayList();
080 List<URL> others = Lists.newArrayList();
081 for (URL url : urls) {
082 if (isResource(url)) {
083 resources.add(url);
084 } else {
085 others.add(url);
086 }
087 }
088 ClassLoader parent;
089 if (resources.isEmpty()) {
090 parent = baseClassLoader;
091 } else {
092 parent = new ResourcesClassLoader(resources, baseClassLoader);
093 }
094 final ClassRealm realm;
095 if (childFirst) {
096 ClassRealm parentRealm = world.newRealm(key + "-parent", parent);
097 realm = parentRealm.createChildRealm(key);
098 } else {
099 realm = world.newRealm(key, parent);
100 }
101 for (URL url : others) {
102 realm.addURL(url);
103 }
104 return realm;
105 } catch (DuplicateRealmException e) {
106 throw new SonarException(e);
107 }
108 }
109
110 public void extend(String baseKey, String key, Collection<URL> urls) {
111 try {
112 ClassRealm base = world.getRealm(baseKey);
113 base.createChildRealm(key); // we create new realm to be able to return it by key without conversion to baseKey
114 for (URL url : urls) {
115 base.addURL(url);
116 }
117 } catch (NoSuchRealmException e) {
118 throw new SonarException(e);
119 } catch (DuplicateRealmException e) {
120 throw new SonarException(e);
121 }
122 }
123
124 /**
125 * Establishes dependencies among ClassLoaders.
126 */
127 public void done() {
128 for (Object o : world.getRealms()) {
129 ClassRealm realm = (ClassRealm) o;
130 if (!StringUtils.endsWith(realm.getId(), "-parent")) {
131 String[] packagesToExport = new String[PREFIXES_TO_EXPORT.length];
132 for (int i = 0; i < PREFIXES_TO_EXPORT.length; i++) {
133 // important to have dot at the end of package name only for classworlds 1.1
134 packagesToExport[i] = PREFIXES_TO_EXPORT[i] + realm.getId() + ".api";
135 }
136 export(realm, packagesToExport);
137 }
138 }
139 }
140
141 /**
142 * Exports specified packages from given ClassRealm to all others.
143 */
144 private void export(ClassRealm realm, String... packages) {
145 Logs.INFO.debug("Exporting " + Arrays.toString(packages) + " from " + realm.getId());
146 for (Object o : world.getRealms()) {
147 ClassRealm dep = (ClassRealm) o;
148 if (!StringUtils.equals(dep.getId(), realm.getId())) {
149 try {
150 for (String packageName : packages) {
151 dep.importFrom(realm.getId(), packageName);
152 }
153 } catch (NoSuchRealmException e) {
154 // should never happen
155 throw new SonarException(e);
156 }
157 }
158 }
159 }
160
161 /**
162 * Note that this method should be called only after creation of all ClassLoaders - see {@link #done()}.
163 */
164 public ClassLoader get(String key) {
165 try {
166 return world.getRealm(key);
167 } catch (NoSuchRealmException e) {
168 return null;
169 }
170 }
171
172 private boolean isResource(URL url) {
173 String path = url.getPath();
174 return !StringUtils.endsWith(path, ".jar") && !StringUtils.endsWith(path, "/");
175 }
176
177 }