/*

 * Copyright (c) 2008, 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 sun.nio.ch;

import java.nio.channels.*;

import java.net.SocketAddress;

import java.net.SocketOption;

import java.net.StandardSocketOptions;

import java.net.InetSocketAddress;

import java.io.FileDescriptor;

import java.io.IOException;

import java.util.Set;

import java.util.HashSet;

import java.util.Collections;

import java.util.concurrent.Future;

import java.util.concurrent.locks.ReadWriteLock;

import java.util.concurrent.locks.ReentrantReadWriteLock;

import sun.net.NetHooks;

/**

 * Base implementation of AsynchronousServerSocketChannel.

 */

abstract class AsynchronousServerSocketChannelImpl

    extends AsynchronousServerSocketChannel

    implements Cancellable, Groupable

{

    protected final FileDescriptor fd;

    // the local address to which the channel's socket is bound

    protected volatile InetSocketAddress localAddress;

    // need this lock to set local address

    private final Object stateLock = new Object();

    // close support

    private ReadWriteLock closeLock = new ReentrantReadWriteLock();

    private volatile boolean closed;

    // set true when accept operation is cancelled

    private volatile boolean acceptKilled;

    // set true when exclusive binding is on and SO_REUSEADDR is emulated

    private boolean isReuseAddress;

    AsynchronousServerSocketChannelImpl(AsynchronousChannelGroupImpl group) {

        super(group.provider());

        this.fd = Net.serverSocket(true);

    }

    @Override

    public final boolean isOpen() {

        return !closed;

    }

    /**

     * Marks beginning of access to file descriptor/handle

     */

    final void begin() throws IOException {

        closeLock.readLock().lock();

        if (!isOpen())

            throw new ClosedChannelException();

    }

    /**

     * Marks end of access to file descriptor/handle

     */

    final void end() {

        closeLock.readLock().unlock();

    }

    /**

     * Invoked to close file descriptor/handle.

     */

    abstract void implClose() throws IOException;

    @Override

    public final void close() throws IOException {

        // synchronize with any threads using file descriptor/handle

        closeLock.writeLock().lock();

        try {

            if (closed)

                return;     // already closed

            closed = true;

        } finally {

            closeLock.writeLock().unlock();

        }

        implClose();

    }

    /**

     * Invoked by accept to accept connection

     */

    abstract Future<AsynchronousSocketChannel>

        implAccept(Object attachment,

                   CompletionHandler<AsynchronousSocketChannel,Object> handler);

    @Override

    public final Future<AsynchronousSocketChannel> accept() {

        return implAccept(null, null);

    }

    @Override

    @SuppressWarnings("unchecked")

    public final <A> void accept(A attachment,

                                 CompletionHandler<AsynchronousSocketChannel,? super A> handler)

    {

        if (handler == null)

            throw new NullPointerException("'handler' is null");

        implAccept(attachment, (CompletionHandler<AsynchronousSocketChannel,Object>)handler);

    }

    final boolean isAcceptKilled() {

        return acceptKilled;

    }

    @Override

    public final void onCancel(PendingFuture<?,?> task) {

        acceptKilled = true;

    }

    @Override

    public final AsynchronousServerSocketChannel bind(SocketAddress local, int backlog)

        throws IOException

    {

        InetSocketAddress isa = (local == null) ? new InetSocketAddress(0) :

            Net.checkAddress(local);

        SecurityManager sm = System.getSecurityManager();

        if (sm != null)

            sm.checkListen(isa.getPort());

        try {

            begin();

            synchronized (stateLock) {

                if (localAddress != null)

                    throw new AlreadyBoundException();

                NetHooks.beforeTcpBind(fd, isa.getAddress(), isa.getPort());

                Net.bind(fd, isa.getAddress(), isa.getPort());

                Net.listen(fd, backlog < 1 ? 50 : backlog);

                localAddress = Net.localAddress(fd);

            }

        } finally {

            end();

        }

        return this;

    }

    @Override

    public final SocketAddress getLocalAddress() throws IOException {

        if (!isOpen())

            throw new ClosedChannelException();

        return Net.getRevealedLocalAddress(localAddress);

    }

    @Override

    public final <T> AsynchronousServerSocketChannel setOption(SocketOption<T> name,

                                                               T value)

        throws IOException

    {

        if (name == null)

            throw new NullPointerException();

        if (!supportedOptions().contains(name))

            throw new UnsupportedOperationException("'" + name + "' not supported");

        try {

            begin();

            if (name == StandardSocketOptions.SO_REUSEADDR &&

                    Net.useExclusiveBind())

            {

                // SO_REUSEADDR emulated when using exclusive bind

                isReuseAddress = (Boolean)value;

            } else {

                Net.setSocketOption(fd, Net.UNSPEC, name, value);

            }

            return this;

        } finally {

            end();

        }

    }

    @Override

    @SuppressWarnings("unchecked")

    public final <T> T getOption(SocketOption<T> name) throws IOException {

        if (name == null)

            throw new NullPointerException();

        if (!supportedOptions().contains(name))

            throw new UnsupportedOperationException("'" + name + "' not supported");

        try {

            begin();

            if (name == StandardSocketOptions.SO_REUSEADDR &&

                    Net.useExclusiveBind())

            {

                // SO_REUSEADDR emulated when using exclusive bind

                return (T)Boolean.valueOf(isReuseAddress);

            }

            return (T) Net.getSocketOption(fd, Net.UNSPEC, name);

        } finally {

            end();

        }

    }

    private static class DefaultOptionsHolder {

        static final Set<SocketOption<?>> defaultOptions = defaultOptions();

        private static Set<SocketOption<?>> defaultOptions() {

            HashSet<SocketOption<?>> set = new HashSet<>(2);

            set.add(StandardSocketOptions.SO_RCVBUF);

            set.add(StandardSocketOptions.SO_REUSEADDR);

            if (Net.isReusePortAvailable()) {

                set.add(StandardSocketOptions.SO_REUSEPORT);

            }

            return Collections.unmodifiableSet(set);

        }

    }

    @Override

    public final Set<SocketOption<?>> supportedOptions() {

        return DefaultOptionsHolder.defaultOptions;

    }

    @Override

    public final String toString() {

        StringBuilder sb = new StringBuilder();

        sb.append(this.getClass().getName());

        sb.append('[');

        if (!isOpen())

            sb.append("closed");

        else {

            if (localAddress == null) {

                sb.append("unbound");

            } else {

                sb.append(Net.getRevealedLocalAddressAsString(localAddress));

            }

        }

        sb.append(']');

        return sb.toString();

    }

}