1 /*
2 * Copyright (c) 2014, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package jdk.internal.module;
27
28 import java.lang.module.ModuleDescriptor;
29 import java.lang.module.ModuleDescriptor.Provides;
30 import java.util.ArrayList;
31 import java.util.List;
32 import java.util.Map;
33 import java.util.Objects;
34 import java.util.concurrent.ConcurrentHashMap;
35 import java.util.concurrent.CopyOnWriteArrayList;
36
37 import jdk.internal.loader.ClassLoaderValue;
38
39 /**
40 * A <em>services catalog</em>. Each {@code ClassLoader} and {@code Layer} has
41 * an optional {@code ServicesCatalog} for modules that provide services.
42 *
43 * @apiNote This class will be replaced once the ServiceLoader is further
44 * specified
45 */
46 public final class ServicesCatalog {
47
48 /**
49 * Represents a service provider in the services catalog.
50 */
51 public final class ServiceProvider {
52 private final Module module;
53 private final String providerName;
54
55 public ServiceProvider(Module module, String providerName) {
56 this.module = module;
57 this.providerName = providerName;
58 }
59
60 public Module module() {
61 return module;
62 }
63
64 public String providerName() {
65 return providerName;
66 }
67
68 @Override
69 public int hashCode() {
70 return Objects.hash(module, providerName);
71 }
72
73 @Override
74 public boolean equals(Object ob) {
75 if (!(ob instanceof ServiceProvider))
76 return false;
77 ServiceProvider that = (ServiceProvider)ob;
78 return Objects.equals(this.module, that.module)
79 && Objects.equals(this.providerName, that.providerName);
80 }
81 }
82
83 // service name -> list of providers
84 private final Map<String, List<ServiceProvider>> map = new ConcurrentHashMap<>();
85
86 private ServicesCatalog() { }
87
88 /**
89 * Creates a ServicesCatalog that supports concurrent registration
90 * and lookup
91 */
92 public static ServicesCatalog create() {
93 return new ServicesCatalog();
94 }
95
96 /**
97 * Returns the list of service provides for the given service type
98 * name, creating it if needed.
99 */
100 private List<ServiceProvider> providers(String service) {
101 // avoid computeIfAbsent here
102 List<ServiceProvider> list = map.get(service);
103 if (list == null) {
104 list = new CopyOnWriteArrayList<>();
105 List<ServiceProvider> prev = map.putIfAbsent(service, list);
106 if (prev != null)
107 list = prev; // someone else got there
108 }
109 return list;
110 }
111
112 /**
113 * Registers the providers in the given module in this services catalog.
114 */
115 public void register(Module module) {
116 ModuleDescriptor descriptor = module.getDescriptor();
117 for (Provides provides : descriptor.provides()) {
118 String service = provides.service();
119 List<String> providerNames = provides.providers();
120 int count = providerNames.size();
121 if (count == 1) {
122 String pn = providerNames.get(0);
123 providers(service).add(new ServiceProvider(module, pn));
124 } else {
125 List<ServiceProvider> list = new ArrayList<>(count);
126 for (String pn : providerNames) {
127 list.add(new ServiceProvider(module, pn));
128 }
129 providers(service).addAll(list);
130 }
131 }
132 }
133
134 /**
135 * Add a provider in the given module to this services catalog
136 *
137 * @apiNote This method is for use by java.lang.instrument
138 */
139 public void addProvider(Module module, Class<?> service, Class<?> impl) {
140 List<ServiceProvider> list = providers(service.getName());
141 list.add(new ServiceProvider(module, impl.getName()));
142 }
143
144 /**
145 * Returns the (possibly empty) list of service providers that implement
146 * the given service type.
147 */
148 public List<ServiceProvider> findServices(String service) {
149 return map.getOrDefault(service, List.of());
150 }
151
152 /**
153 * Returns the ServicesCatalog for the given class loader or {@code null}
154 * if there is none.
155 */
156 public static ServicesCatalog getServicesCatalogOrNull(ClassLoader loader) {
157 return CLV.get(loader);
158 }
159
160 /**
161 * Returns the ServicesCatalog for the given class loader, creating it if
162 * needed.
163 */
164 public static ServicesCatalog getServicesCatalog(ClassLoader loader) {
165 // CLV.computeIfAbsent(loader, (cl, clv) -> create());
166 ServicesCatalog catalog = CLV.get(loader);
167 if (catalog == null) {
168 catalog = create();
169 ServicesCatalog previous = CLV.putIfAbsent(loader, catalog);
170 if (previous != null) catalog = previous;
171 }
172 return catalog;
173 }
174
175 // the ServicesCatalog registered to a class loader
176 private static final ClassLoaderValue<ServicesCatalog> CLV = new ClassLoaderValue<>();
177 }