diff -r 115e09b7a004 -r 3acf8e5e2ca0 jdk/src/share/classes/java/nio/channels/spi/AsynchronousChannelProvider.java --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/jdk/src/share/classes/java/nio/channels/spi/AsynchronousChannelProvider.java Sun Feb 15 12:25:54 2009 +0000 @@ -0,0 +1,264 @@ +/* + * Copyright 2007-2009 Sun Microsystems, Inc. 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. Sun designates this + * particular file as subject to the "Classpath" exception as provided + * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, + * CA 95054 USA or visit www.sun.com if you need additional information or + * have any questions. + */ + +package java.nio.channels.spi; + +import java.nio.channels.*; +import java.net.ProtocolFamily; +import java.io.IOException; +import java.util.Iterator; +import java.util.ServiceLoader; +import java.util.ServiceConfigurationError; +import java.util.concurrent.*; +import java.security.AccessController; +import java.security.PrivilegedAction; + +/** + * Service-provider class for asynchronous channels. + * + *

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. + * + *

All of the methods in this class are safe for use by multiple concurrent + * threads.

+ * + * @since 1.7 + */ + +public abstract class AsynchronousChannelProvider { + private static Void checkPermission() { + SecurityManager sm = System.getSecurityManager(); + if (sm != null) + sm.checkPermission(new RuntimePermission("asynchronousChannelProvider")); + return null; + } + private AsynchronousChannelProvider(Void ignore) { } + + /** + * Initializes a new instance of this class. + * + * @throws SecurityException + * If a security manager has been installed and it denies + * {@link RuntimePermission}("asynchronousChannelProvider") + */ + protected AsynchronousChannelProvider() { + this(checkPermission()); + } + + // lazy initialization of default provider + private static class ProviderHolder { + static final AsynchronousChannelProvider provider = load(); + + private static AsynchronousChannelProvider load() { + return AccessController + .doPrivileged(new PrivilegedAction() { + public AsynchronousChannelProvider run() { + 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 { + Class c = Class.forName(cn, true, + ClassLoader.getSystemClassLoader()); + return (AsynchronousChannelProvider)c.newInstance(); + } catch (ClassNotFoundException x) { + throw new ServiceConfigurationError(null, x); + } catch (IllegalAccessException x) { + throw new ServiceConfigurationError(null, x); + } catch (InstantiationException x) { + throw new ServiceConfigurationError(null, x); + } catch (SecurityException x) { + throw new ServiceConfigurationError(null, x); + } + } + + private static AsynchronousChannelProvider loadProviderAsService() { + ServiceLoader sl = + ServiceLoader.load(AsynchronousChannelProvider.class, + ClassLoader.getSystemClassLoader()); + Iterator i = sl.iterator(); + for (;;) { + try { + return (i.hasNext()) ? i.next() : null; + } catch (ServiceConfigurationError sce) { + if (sce.getCause() instanceof SecurityException) { + // Ignore the security exception, try the next provider + continue; + } + throw sce; + } + } + } + } + + /** + * Returns the system-wide default asynchronous channel provider for this + * invocation of the Java virtual machine. + * + *

The first invocation of this method locates the default provider + * object as follows:

+ * + *
    + * + *

  1. If the system property + * 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.

    2. + * + *

  2. 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 + * java.nio.channels.spi.AsynchronousChannelProvider in the resource + * directory 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.

    3. + * + *

  3. 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.

    4. + * + *
+ * + *

Subsequent invocations of this method return the provider that was + * returned by the first invocation.

+ * + * @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 + * + * @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 + * + * @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; + + /** + * Opens an asynchronous datagram channel. + * + * @param family + * The protocol family, or {@code null} for the default protocol + * family + * @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 AsynchronousDatagramChannel openAsynchronousDatagramChannel + (ProtocolFamily family, AsynchronousChannelGroup group) throws IOException; +}