001 /*
002 * Sonar, open source software quality management tool.
003 * Copyright (C) 2009 SonarSource SA
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 org.apache.commons.lang.StringUtils;
029 import org.codehaus.plexus.classworlds.ClassWorld;
030 import org.codehaus.plexus.classworlds.realm.ClassRealm;
031 import org.codehaus.plexus.classworlds.realm.DuplicateRealmException;
032 import org.codehaus.plexus.classworlds.realm.NoSuchRealmException;
033 import org.sonar.api.utils.Logs;
034 import org.sonar.api.utils.SonarException;
035
036 import com.google.common.collect.Lists;
037
038 /**
039 * Encapsulates manipulations with ClassLoaders, such as creation and establishing dependencies. Current implementation based on
040 * {@link ClassWorld}.
041 *
042 * <h3>IMPORTANT</h3>
043 * <p>
044 * If we have pluginA , then all classes and resources from package and subpackages of <b>org.sonar.plugins.pluginA.api</b> will be visible
045 * for all other plugins even if they located in dependent library.
046 * </p>
047 *
048 * <h4>Search order for {@link ClassRealm} :</h4>
049 * <ul>
050 * <li>parent class loader (passed via the constructor) if there is one</li>
051 * <li>imports</li>
052 * <li>realm's constituents</li>
053 * <li>parent realm</li>
054 * </ul>
055 *
056 * @since 2.4
057 */
058 public class ClassLoadersCollection {
059
060 private static final String[] PREFIXES_TO_EXPORT = { "org.sonar.plugins.", "com.sonar.plugins.", "com.sonarsource.plugins." };
061
062 private ClassWorld world = new ClassWorld();
063 private ClassLoader baseClassLoader;
064
065 public ClassLoadersCollection(ClassLoader baseClassLoader) {
066 this.baseClassLoader = baseClassLoader;
067 }
068
069 /**
070 * Generates URLClassLoader with specified delegation model.
071 *
072 * @param key plugin key
073 * @param urls libraries
074 * @param childFirst true, if child-first delegation model required instead of parent-first
075 * @return created ClassLoader, but actually this method shouldn't return anything, because dependencies must be established - see
076 * {@link #done()}.
077 */
078 public ClassLoader createClassLoader(String key, Collection<URL> urls, boolean childFirst) {
079 try {
080 List<URL> resources = Lists.newArrayList();
081 List<URL> others = Lists.newArrayList();
082 for (URL url : urls) {
083 if (isResource(url)) {
084 resources.add(url);
085 } else {
086 others.add(url);
087 }
088 }
089 ClassLoader parent;
090 if (resources.isEmpty()) {
091 parent = baseClassLoader;
092 } else {
093 parent = new ResourcesClassLoader(resources, baseClassLoader);
094 }
095 final ClassRealm realm;
096 if (childFirst) {
097 ClassRealm parentRealm = world.newRealm(key + "-parent", parent);
098 realm = parentRealm.createChildRealm(key);
099 } else {
100 realm = world.newRealm(key, parent);
101 }
102 for (URL url : others) {
103 realm.addURL(url);
104 }
105 return realm;
106 } catch (DuplicateRealmException e) {
107 throw new SonarException(e);
108 }
109 }
110
111 /**
112 * Establishes dependencies among ClassLoaders.
113 */
114 public void done() {
115 for (Object o : world.getRealms()) {
116 ClassRealm realm = (ClassRealm) o;
117 if ( !StringUtils.endsWith(realm.getId(), "-parent")) {
118 String[] packagesToExport = new String[PREFIXES_TO_EXPORT.length];
119 for (int i = 0; i < PREFIXES_TO_EXPORT.length; i++) {
120 // important to have dot at the end of package name only for classworlds 1.1
121 packagesToExport[i] = PREFIXES_TO_EXPORT[i] + realm.getId() + ".api";
122 }
123 export(realm, packagesToExport);
124 }
125 }
126 }
127
128 /**
129 * Exports specified packages from given ClassRealm to all others.
130 */
131 private void export(ClassRealm realm, String... packages) {
132 Logs.INFO.debug("Exporting " + Arrays.toString(packages) + " from " + realm.getId());
133 for (Object o : world.getRealms()) {
134 ClassRealm dep = (ClassRealm) o;
135 if ( !StringUtils.equals(dep.getId(), realm.getId())) {
136 try {
137 for (String packageName : packages) {
138 dep.importFrom(realm.getId(), packageName);
139 }
140 } catch (NoSuchRealmException e) {
141 // should never happen
142 throw new SonarException(e);
143 }
144 }
145 }
146 }
147
148 /**
149 * Note that this method should be called only after creation of all ClassLoaders - see {@link #done()}.
150 */
151 public ClassLoader get(String key) {
152 try {
153 return world.getRealm(key);
154 } catch (NoSuchRealmException e) {
155 return null;
156 }
157 }
158
159 private boolean isResource(URL url) {
160 String path = url.getPath();
161 return !StringUtils.endsWith(path, ".jar") && !StringUtils.endsWith(path, "/");
162 }
163
164 }