1 /* 2 * Copyright (c) 2014, 2020, 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.Arrays; 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<>(32); 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 * Adds service providers for the given service type. 98 */ 99 private void addProviders(String service, ServiceProvider ... providers) { 100 List<ServiceProvider> list = map.get(service); 101 if (list == null) { 102 list = new CopyOnWriteArrayList<>(providers); 103 List<ServiceProvider> prev = map.putIfAbsent(service, list); 104 if (prev != null) { 105 // someone else got there 106 prev.addAll(list); 107 } 108 } else { 109 if (providers.length == 1) { 110 list.add(providers[0]); 111 } else { 112 list.addAll(Arrays.asList(providers)); 113 } 114 } 115 } 116 117 /** 118 * Registers the providers in the given module in this services catalog. 119 */ 120 public void register(Module module) { 121 ModuleDescriptor descriptor = module.getDescriptor(); 122 for (Provides provides : descriptor.provides()) { 123 String service = provides.service(); 124 List<String> providerNames = provides.providers(); 125 int count = providerNames.size(); 126 ServiceProvider[] providers = new ServiceProvider[count]; 127 for (int i = 0; i < count; i++) { 128 providers[i] = new ServiceProvider(module, providerNames.get(i)); 129 } 130 addProviders(service, providers); 131 } 132 } 133 134 /** 135 * Adds 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 addProviders(service.getName(), new ServiceProvider(module, impl.getName())); 141 } 142 143 /** 144 * Returns the (possibly empty) list of service providers that implement 145 * the given service type. 146 */ 147 public List<ServiceProvider> findServices(String service) { 148 return map.getOrDefault(service, List.of()); 149 } 150 151 /** 152 * Returns the ServicesCatalog for the given class loader or {@code null} 153 * if there is none. 154 */ 155 public static ServicesCatalog getServicesCatalogOrNull(ClassLoader loader) { 156 return CLV.get(loader); 157 } 158 159 /** 160 * Returns the ServicesCatalog for the given class loader, creating it if 161 * needed. 162 */ 163 public static ServicesCatalog getServicesCatalog(ClassLoader loader) { 164 // CLV.computeIfAbsent(loader, (cl, clv) -> create()); 165 ServicesCatalog catalog = CLV.get(loader); 166 if (catalog == null) { 167 catalog = create(); 168 ServicesCatalog previous = CLV.putIfAbsent(loader, catalog); 169 if (previous != null) catalog = previous; 170 } 171 return catalog; 172 } 173 174 // the ServicesCatalog registered to a class loader 175 private static final ClassLoaderValue<ServicesCatalog> CLV = new ClassLoaderValue<>(); 176 }