/*

 * Copyright (c) 2011, 2015, 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

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 */

/*

 * 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.*;

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 a file descriptor to an entry containing the selection key

    private HashMap<Integer,MapEntry> fdMap;

    // 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;

    // used by updateSelectedKeys to handle cases where the same file

    // descriptor is polled by more than one filter

    private long updateCount;

    // Used to map file descriptors to a selection key and "update count"

    // (see updateSelectedKeys for usage).

    private static class MapEntry {

        SelectionKeyImpl ski;

        long updateCount;

        MapEntry(SelectionKeyImpl ski) {

            this.ski = ski;

        }

    }

    /**

     * 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;

        try {

            kqueueWrapper = new KQueueArrayWrapper();

            kqueueWrapper.initInterrupt(fd0, fd1);

            fdMap = new HashMap<>();

            totalChannels = 1;

        } catch (Throwable t) {

            try {

                FileDispatcherImpl.closeIntFD(fd0);

            } catch (IOException ioe0) {

                t.addSuppressed(ioe0);

            }

            try {

                FileDispatcherImpl.closeIntFD(fd1);

            } catch (IOException ioe1) {

                t.addSuppressed(ioe1);

            }

            throw t;

        }

    }

    protected int doSelect(long timeout)

        throws IOException

    {

        int entries = 0;

        if (closed)

            throw new ClosedSelectorException();

        processDeregisterQueue();

        try {

            begin();

            entries = kqueueWrapper.poll(timeout);

        } finally {

            end();

        }

        processDeregisterQueue();

        return updateSelectedKeys(entries);

    }

    /**

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

     * Add the ready keys to the selected key set.

     * 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;

        // A file descriptor may be registered with kqueue with more than one

        // filter and so there may be more than one event for a fd. The update

        // count in the MapEntry tracks when the fd was last updated and this

        // ensures that the ready ops are updated rather than replaced by a

        // second or subsequent event.

        updateCount++;

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

            int nextFD = kqueueWrapper.getDescriptor(i);

            if (nextFD == fd0) {

                interrupted = true;

            } else {

                MapEntry me = fdMap.get(Integer.valueOf(nextFD));

                // entry is null in the case of an interrupt

                if (me != null) {

                    int rOps = kqueueWrapper.getReventOps(i);

                    SelectionKeyImpl ski = me.ski;

                    if (selectedKeys.contains(ski)) {

                        // first time this file descriptor has been encountered on this

                        // update?

                        if (me.updateCount != updateCount) {

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

                                numKeysUpdated++;

                                me.updateCount = updateCount;

                            }

                        } else {

                            // ready ops have already been set on this update

                            ski.channel.translateAndUpdateReadyOps(rOps, ski);

                        }

                    } else {

                        ski.channel.translateAndSetReadyOps(rOps, ski);

                        if ((ski.nioReadyOps() & ski.nioInterestOps()) != 0) {

                            selectedKeys.add(ski);

                            numKeysUpdated++;

                            me.updateCount = updateCount;

                        }

                    }

                }

            }

        }

        if (interrupted) {

            // Clear the wakeup pipe

            synchronized (interruptLock) {

                IOUtil.drain(fd0);

                interruptTriggered = false;

            }

        }

        return numKeysUpdated;

    }

    protected void implClose() throws IOException {

        if (!closed) {

            closed = true;

            // prevent further wakeup

            synchronized (interruptLock) {

                interruptTriggered = true;

            }

            FileDispatcherImpl.closeIntFD(fd0);

            FileDispatcherImpl.closeIntFD(fd1);

            if (kqueueWrapper != null) {

                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) {

        if (closed)

            throw new ClosedSelectorException();

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

        fdMap.put(Integer.valueOf(fd), new MapEntry(ski));

        totalChannels++;

        keys.add(ski);

    }

    protected void implDereg(SelectionKeyImpl ski) throws IOException {

        int fd = ski.channel.getFDVal();

        fdMap.remove(Integer.valueOf(fd));

        kqueueWrapper.release(ski.channel);

        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) {

        if (closed)

            throw new ClosedSelectorException();

        kqueueWrapper.setInterest(ski.channel, ops);

    }

    public Selector wakeup() {

        synchronized (interruptLock) {

            if (!interruptTriggered) {

                kqueueWrapper.interrupt();

                interruptTriggered = true;

            }

        }

        return this;

    }

}