| /* | |
| * Copyright (c) 2007, 2024, 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 java.nio.channels.spi; | |
| import java.nio.channels.*; | |
| import java.io.IOException; | |
| import java.util.Iterator; | |
| import java.util.ServiceLoader; | |
| import java.util.ServiceConfigurationError; | |
| import java.util.concurrent.*; | |
| /** | |
| * Service-provider class for asynchronous channels. | |
| * | |
| * <p> An asynchronous channel provider is a concrete subclass of this class that | |
| * has a zero-argument constructor and implements the abstract methods specified | |
| * below. A given invocation of the Java virtual machine maintains a single | |
| * system-wide default provider instance, which is returned by the {@link | |
| * #provider() provider} method. The first invocation of that method will locate | |
| * the default provider as specified below. | |
| * | |
| * <p> All of the methods in this class are safe for use by multiple concurrent | |
| * threads. </p> | |
| * | |
| * @since 1.7 | |
| */ | |
| public abstract class AsynchronousChannelProvider { | |
| /** | |
| * Initializes a new instance of this class. | |
| */ | |
| protected AsynchronousChannelProvider() { | |
| } | |
| // lazy initialization of default provider | |
| private static class ProviderHolder { | |
| static final AsynchronousChannelProvider provider = load(); | |
| private static AsynchronousChannelProvider load() { | |
| AsynchronousChannelProvider p; | |
| p = loadProviderFromProperty(); | |
| if (p != null) | |
| return p; | |
| p = loadProviderAsService(); | |
| if (p != null) | |
| return p; | |
| return sun.nio.ch.DefaultAsynchronousChannelProvider.create(); | |
| } | |
| private static AsynchronousChannelProvider loadProviderFromProperty() { | |
| String cn = System.getProperty("java.nio.channels.spi.AsynchronousChannelProvider"); | |
| if (cn == null) | |
| return null; | |
| try { | |
| @SuppressWarnings("deprecation") | |
| Object tmp = Class.forName(cn, true, | |
| ClassLoader.getSystemClassLoader()).newInstance(); | |
| return (AsynchronousChannelProvider)tmp; | |
| } catch (ClassNotFoundException | | |
| InstantiationException | IllegalAccessException x) { | |
| throw new ServiceConfigurationError(null, x); | |
| } | |
| } | |
| private static AsynchronousChannelProvider loadProviderAsService() { | |
| ServiceLoader<AsynchronousChannelProvider> sl = | |
| ServiceLoader.load(AsynchronousChannelProvider.class, | |
| ClassLoader.getSystemClassLoader()); | |
| return sl.findFirst().orElse(null); | |
| } | |
| } | |
| /** | |
| * Returns the system-wide default asynchronous channel provider for this | |
| * invocation of the Java virtual machine. | |
| * | |
| * <p> The first invocation of this method locates the default provider | |
| * object as follows: </p> | |
| * | |
| * <ol> | |
| * | |
| * <li><p> If the system property | |
| * {@systemProperty java.nio.channels.spi.AsynchronousChannelProvider} is | |
| * defined then it is taken to be the fully-qualified name of a concrete | |
| * provider class. The class is loaded and instantiated; if this process | |
| * fails then an unspecified error is thrown. </p></li> | |
| * | |
| * <li><p> If a provider class has been installed in a jar file that is | |
| * visible to the system class loader, and that jar file contains a | |
| * provider-configuration file named | |
| * {@code java.nio.channels.spi.AsynchronousChannelProvider} in the resource | |
| * directory {@code META-INF/services}, then the first class name | |
| * specified in that file is taken. The class is loaded and | |
| * instantiated; if this process fails then an unspecified error is | |
| * thrown. </p></li> | |
| * | |
| * <li><p> Finally, if no provider has been specified by any of the above | |
| * means then the system-default provider class is instantiated and the | |
| * result is returned. </p></li> | |
| * | |
| * </ol> | |
| * | |
| * <p> Subsequent invocations of this method return the provider that was | |
| * returned by the first invocation. </p> | |
| * | |
| * @return The system-wide default AsynchronousChannel provider | |
| */ | |
| public static AsynchronousChannelProvider provider() { | |
| return ProviderHolder.provider; | |
| } | |
| /** | |
| * Constructs a new asynchronous channel group with a fixed thread pool. | |
| * | |
| * @param nThreads | |
| * The number of threads in the pool | |
| * @param threadFactory | |
| * The factory to use when creating new threads | |
| * | |
| * @return A new asynchronous channel group | |
| * | |
| * @throws IllegalArgumentException | |
| * If {@code nThreads <= 0} | |
| * @throws IOException | |
| * If an I/O error occurs | |
| * | |
| * @see AsynchronousChannelGroup#withFixedThreadPool | |
| */ | |
| public abstract AsynchronousChannelGroup | |
| openAsynchronousChannelGroup(int nThreads, ThreadFactory threadFactory) throws IOException; | |
| /** | |
| * Constructs a new asynchronous channel group with the given thread pool. | |
| * | |
| * @param executor | |
| * The thread pool | |
| * @param initialSize | |
| * A value {@code >=0} or a negative value for implementation | |
| * specific default | |
| * | |
| * @return A new asynchronous channel group | |
| * | |
| * @throws IOException | |
| * If an I/O error occurs | |
| * | |
| * @see AsynchronousChannelGroup#withCachedThreadPool | |
| */ | |
| public abstract AsynchronousChannelGroup | |
| openAsynchronousChannelGroup(ExecutorService executor, int initialSize) throws IOException; | |
| /** | |
| * Opens an asynchronous server-socket channel. | |
| * | |
| * @param group | |
| * The group to which the channel is bound, or {@code null} to | |
| * bind to the default group | |
| * | |
| * @return The new channel | |
| * | |
| * @throws IllegalChannelGroupException | |
| * If the provider that created the group differs from this provider | |
| * @throws ShutdownChannelGroupException | |
| * The group is shutdown | |
| * @throws IOException | |
| * If an I/O error occurs | |
| */ | |
| public abstract AsynchronousServerSocketChannel openAsynchronousServerSocketChannel | |
| (AsynchronousChannelGroup group) throws IOException; | |
| /** | |
| * Opens an asynchronous socket channel. | |
| * | |
| * @param group | |
| * The group to which the channel is bound, or {@code null} to | |
| * bind to the default group | |
| * | |
| * @return The new channel | |
| * | |
| * @throws IllegalChannelGroupException | |
| * If the provider that created the group differs from this provider | |
| * @throws ShutdownChannelGroupException | |
| * The group is shutdown | |
| * @throws IOException | |
| * If an I/O error occurs | |
| */ | |
| public abstract AsynchronousSocketChannel openAsynchronousSocketChannel | |
| (AsynchronousChannelGroup group) throws IOException; | |
| } |