/*
 * Copyright (c) 2014, 2016, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package jdk.internal.module;

import java.lang.module.ModuleDescriptor;
import java.lang.module.ModuleDescriptor.Provides;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.CopyOnWriteArrayList;

import jdk.internal.loader.ClassLoaderValue;

A services catalog. Each ClassLoader and Layer has an optional ServicesCatalog for modules that provide services.
API Note:This class will be replaced once the ServiceLoader is further specified
/** * A <em>services catalog</em>. Each {@code ClassLoader} and {@code Layer} has * an optional {@code ServicesCatalog} for modules that provide services. * * @apiNote This class will be replaced once the ServiceLoader is further * specified */
public final class ServicesCatalog {
Represents a service provider in the services catalog.
/** * Represents a service provider in the services catalog. */
public final class ServiceProvider { private final Module module; private final String providerName; public ServiceProvider(Module module, String providerName) { this.module = module; this.providerName = providerName; } public Module module() { return module; } public String providerName() { return providerName; } @Override public int hashCode() { return Objects.hash(module, providerName); } @Override public boolean equals(Object ob) { if (!(ob instanceof ServiceProvider)) return false; ServiceProvider that = (ServiceProvider)ob; return Objects.equals(this.module, that.module) && Objects.equals(this.providerName, that.providerName); } } // service name -> list of providers private final Map<String, List<ServiceProvider>> map = new ConcurrentHashMap<>(); private ServicesCatalog() { }
Creates a ServicesCatalog that supports concurrent registration and and lookup
/** * Creates a ServicesCatalog that supports concurrent registration and * and lookup */
public static ServicesCatalog create() { return new ServicesCatalog(); }
Returns the list of service provides for the given service type name, creating it if needed.
/** * Returns the list of service provides for the given service type * name, creating it if needed. */
private List<ServiceProvider> providers(String service) { // avoid computeIfAbsent here List<ServiceProvider> list = map.get(service); if (list == null) { list = new CopyOnWriteArrayList<>(); List<ServiceProvider> prev = map.putIfAbsent(service, list); if (prev != null) list = prev; // someone else got there } return list; }
Registers the providers in the given module in this services catalog.
/** * Registers the providers in the given module in this services catalog. */
public void register(Module module) { ModuleDescriptor descriptor = module.getDescriptor(); for (Provides provides : descriptor.provides()) { String service = provides.service(); List<String> providerNames = provides.providers(); int count = providerNames.size(); if (count == 1) { String pn = providerNames.get(0); providers(service).add(new ServiceProvider(module, pn)); } else { List<ServiceProvider> list = new ArrayList<>(count); for (String pn : providerNames) { list.add(new ServiceProvider(module, pn)); } providers(service).addAll(list); } } }
Add a provider in the given module to this services catalog
API Note:This method is for use by java.lang.instrument
/** * Add a provider in the given module to this services catalog * * @apiNote This method is for use by java.lang.instrument */
public void addProvider(Module module, Class<?> service, Class<?> impl) { List<ServiceProvider> list = providers(service.getName()); list.add(new ServiceProvider(module, impl.getName())); }
Returns the (possibly empty) list of service providers that implement the given service type.
/** * Returns the (possibly empty) list of service providers that implement * the given service type. */
public List<ServiceProvider> findServices(String service) { return map.getOrDefault(service, Collections.emptyList()); }
Returns the ServicesCatalog for the given class loader or null if there is none.
/** * Returns the ServicesCatalog for the given class loader or {@code null} * if there is none. */
public static ServicesCatalog getServicesCatalogOrNull(ClassLoader loader) { return CLV.get(loader); }
Returns the ServicesCatalog for the given class loader, creating it if needed.
/** * Returns the ServicesCatalog for the given class loader, creating it if * needed. */
public static ServicesCatalog getServicesCatalog(ClassLoader loader) { // CLV.computeIfAbsent(loader, (cl, clv) -> create()); ServicesCatalog catalog = CLV.get(loader); if (catalog == null) { catalog = create(); ServicesCatalog previous = CLV.putIfAbsent(loader, catalog); if (previous != null) catalog = previous; } return catalog; } // the ServicesCatalog registered to a class loader private static final ClassLoaderValue<ServicesCatalog> CLV = new ClassLoaderValue<>(); }