/*

 * Copyright (c) 2011, 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.

 *

 * 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.

 */

/*

 * KQueueSelectorImpl.java

 * Implementation of Selector using FreeBSD / Mac OS X kqueues

 * Derived from Sun's DevPollSelectorImpl

 */

package sun.nio.ch;

import java.io.IOException;

import java.io.FileDescriptor;

import java.nio.channels.*;

import java.nio.channels.spi.*;

import java.util.*;

import sun.misc.*;

class KQueueSelectorImpl

    extends SelectorImpl

{

    // File descriptors used for interrupt

    protected int fd0;

    protected int fd1;

    // The kqueue manipulator

    KQueueArrayWrapper kqueueWrapper;

    // Count of registered descriptors (including interrupt)

    private int totalChannels;

    // Map from file descriptors to selection keys

    private HashMap<Integer,SelectionKeyImpl> fdToKey;

    // True if this Selector has been closed

    private boolean closed = false;

    // Lock for interrupt triggering and clearing

    private Object interruptLock = new Object();

    private boolean interruptTriggered = false;

    /**

     * Package private constructor called by factory method in

     * the abstract superclass Selector.

     */

    KQueueSelectorImpl(SelectorProvider sp) {

        super(sp);

        long fds = IOUtil.makePipe(false);

        fd0 = (int)(fds >>> 32);

        fd1 = (int)fds;

        kqueueWrapper = new KQueueArrayWrapper();

        kqueueWrapper.initInterrupt(fd0, fd1);

        fdToKey = new HashMap<>();

        totalChannels = 1;

    }

    protected int doSelect(long timeout)

        throws IOException

    {

        int entries = 0;

        if (closed)

            throw new ClosedSelectorException();

        processDeregisterQueue();

        if (timeout == 0  &&  totalChannels == 1)

            return 0;

        try {

            begin();

            entries = kqueueWrapper.poll(timeout);

        } finally {

            end();

        }

        processDeregisterQueue();

        return updateSelectedKeys(entries);

    }

    /**

     * Update the keys whose fd's have been selected by the devpoll

     * driver. Add the ready keys to the ready queue.

     * If the interrupt fd has been selected, drain it and clear the interrupt.

     */

    private int updateSelectedKeys(int entries)

        throws IOException

    {

        int numKeysUpdated = 0;

        boolean interrupted = false;

        for (int i = 0; i < entries; i++) {

            int nextFD = kqueueWrapper.getDescriptor(i);

            if (nextFD == fd0) {

                interrupted = true;

            } else {

                SelectionKeyImpl ski = fdToKey.get(new Integer(nextFD));

                // ski is null in the case of an interrupt

                if (ski != null) {

                    int rOps = kqueueWrapper.getReventOps(i);

                    if (selectedKeys.contains(ski)) {

                        if (ski.channel.translateAndSetReadyOps(rOps, ski)) {

                            numKeysUpdated++;

                        }

                    } else {

                        ski.channel.translateAndSetReadyOps(rOps, ski);

                        if ((ski.readyOps() & ski.interestOps()) != 0) {

                            selectedKeys.add(ski);

                            numKeysUpdated++;

                        }

                    }

                }

            }

        }

        if (interrupted) {

            // Clear the wakeup pipe

            synchronized (interruptLock) {

                IOUtil.drain(fd0);

                interruptTriggered = false;

            }

        }

        return numKeysUpdated;

    }

    protected void implClose() throws IOException {

        if (!closed) {

            closed = true;

            FileDispatcherImpl.closeIntFD(fd0);

            FileDispatcherImpl.closeIntFD(fd1);

            if (kqueueWrapper != null) {

                kqueueWrapper.release(fd0);

                kqueueWrapper.close();

                kqueueWrapper = null;

                selectedKeys = null;

                // Deregister channels

                Iterator<SelectionKey> i = keys.iterator();

                while (i.hasNext()) {

                    SelectionKeyImpl ski = (SelectionKeyImpl)i.next();

                    deregister(ski);

                    SelectableChannel selch = ski.channel();

                    if (!selch.isOpen() && !selch.isRegistered())

                        ((SelChImpl)selch).kill();

                    i.remove();

                }

                totalChannels = 0;

            }

            fd0 = -1;

            fd1 = -1;

        }

    }

    protected void implRegister(SelectionKeyImpl ski) {

        int fd = IOUtil.fdVal(ski.channel.getFD());

        fdToKey.put(new Integer(fd), ski);

        totalChannels++;

        keys.add(ski);

    }

    protected void implDereg(SelectionKeyImpl ski) throws IOException {

        int fd = ski.channel.getFDVal();

        fdToKey.remove(new Integer(fd));

        kqueueWrapper.release(fd);

        totalChannels--;

        keys.remove(ski);

        selectedKeys.remove(ski);

        deregister((AbstractSelectionKey)ski);

        SelectableChannel selch = ski.channel();

        if (!selch.isOpen() && !selch.isRegistered())

            ((SelChImpl)selch).kill();

    }

    public void putEventOps(SelectionKeyImpl ski, int ops) {

        int fd = IOUtil.fdVal(ski.channel.getFD());

        kqueueWrapper.setInterest(fd, ops);

    }

    public Selector wakeup() {

        synchronized (interruptLock) {

            if (!interruptTriggered) {

                kqueueWrapper.interrupt();

                interruptTriggered = true;

            }

        }

        return this;

    }

    static {

        Util.load();

    }

}