1/* 2 * Copyright (c) 2014, 2016, 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 26package jdk.internal.module; 27 28import java.lang.module.ModuleDescriptor; 29import java.lang.module.ModuleDescriptor.Provides; 30import java.util.ArrayList; 31import java.util.Collections; 32import java.util.List; 33import java.util.Map; 34import java.util.Objects; 35import java.util.concurrent.ConcurrentHashMap; 36import java.util.concurrent.CopyOnWriteArrayList; 37 38import jdk.internal.loader.ClassLoaderValue; 39 40/** 41 * A <em>services catalog</em>. Each {@code ClassLoader} and {@code Layer} has 42 * an optional {@code ServicesCatalog} for modules that provide services. 43 * 44 * @apiNote This class will be replaced once the ServiceLoader is further 45 * specified 46 */ 47public final class ServicesCatalog { 48 49 /** 50 * Represents a service provider in the services catalog. 51 */ 52 public final class ServiceProvider { 53 private final Module module; 54 private final String providerName; 55 56 public ServiceProvider(Module module, String providerName) { 57 this.module = module; 58 this.providerName = providerName; 59 } 60 61 public Module module() { 62 return module; 63 } 64 65 public String providerName() { 66 return providerName; 67 } 68 69 @Override 70 public int hashCode() { 71 return Objects.hash(module, providerName); 72 } 73 74 @Override 75 public boolean equals(Object ob) { 76 if (!(ob instanceof ServiceProvider)) 77 return false; 78 ServiceProvider that = (ServiceProvider)ob; 79 return Objects.equals(this.module, that.module) 80 && Objects.equals(this.providerName, that.providerName); 81 } 82 } 83 84 // service name -> list of providers 85 private final Map<String, List<ServiceProvider>> map = new ConcurrentHashMap<>(); 86 87 private ServicesCatalog() { } 88 89 /** 90 * Creates a ServicesCatalog that supports concurrent registration and 91 * and lookup 92 */ 93 public static ServicesCatalog create() { 94 return new ServicesCatalog(); 95 } 96 97 /** 98 * Returns the list of service provides for the given service type 99 * name, creating it if needed. 100 */ 101 private List<ServiceProvider> providers(String service) { 102 // avoid computeIfAbsent here 103 List<ServiceProvider> list = map.get(service); 104 if (list == null) { 105 list = new CopyOnWriteArrayList<>(); 106 List<ServiceProvider> prev = map.putIfAbsent(service, list); 107 if (prev != null) 108 list = prev; // someone else got there 109 } 110 return list; 111 } 112 113 /** 114 * Registers the providers in the given module in this services catalog. 115 */ 116 public void register(Module module) { 117 ModuleDescriptor descriptor = module.getDescriptor(); 118 for (Provides provides : descriptor.provides()) { 119 String service = provides.service(); 120 List<String> providerNames = provides.providers(); 121 int count = providerNames.size(); 122 if (count == 1) { 123 String pn = providerNames.get(0); 124 providers(service).add(new ServiceProvider(module, pn)); 125 } else { 126 List<ServiceProvider> list = new ArrayList<>(count); 127 for (String pn : providerNames) { 128 list.add(new ServiceProvider(module, pn)); 129 } 130 providers(service).addAll(list); 131 } 132 } 133 } 134 135 /** 136 * Add a provider in the given module to this services catalog 137 * 138 * @apiNote This method is for use by java.lang.instrument 139 */ 140 public void addProvider(Module module, Class<?> service, Class<?> impl) { 141 List<ServiceProvider> list = providers(service.getName()); 142 list.add(new ServiceProvider(module, impl.getName())); 143 } 144 145 /** 146 * Returns the (possibly empty) list of service providers that implement 147 * the given service type. 148 */ 149 public List<ServiceProvider> findServices(String service) { 150 return map.getOrDefault(service, Collections.emptyList()); 151 } 152 153 /** 154 * Returns the ServicesCatalog for the given class loader or {@code null} 155 * if there is none. 156 */ 157 public static ServicesCatalog getServicesCatalogOrNull(ClassLoader loader) { 158 return CLV.get(loader); 159 } 160 161 /** 162 * Returns the ServicesCatalog for the given class loader, creating it if 163 * needed. 164 */ 165 public static ServicesCatalog getServicesCatalog(ClassLoader loader) { 166 // CLV.computeIfAbsent(loader, (cl, clv) -> create()); 167 ServicesCatalog catalog = CLV.get(loader); 168 if (catalog == null) { 169 catalog = create(); 170 ServicesCatalog previous = CLV.putIfAbsent(loader, catalog); 171 if (previous != null) catalog = previous; 172 } 173 return catalog; 174 } 175 176 // the ServicesCatalog registered to a class loader 177 private static final ClassLoaderValue<ServicesCatalog> CLV = new ClassLoaderValue<>(); 178}