/*

 * Copyright (c) 2011, 2013, 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.

 */

/*

 * KQueueArrayWrapper.java

 * Implementation of Selector using FreeBSD / Mac OS X kqueues

 * Derived from Sun's DevPollArrayWrapper

 */

package sun.nio.ch;

import java.io.IOException;

import java.util.Iterator;

import java.util.LinkedList;

/*

 * struct kevent {           // 32-bit    64-bit

 *     uintptr_t ident;      //   4         8

 *     short     filter;     //   2         2

 *     u_short   flags;      //   2         2

 *     u_int     fflags;     //   4         4

 *     intptr_t  data;       //   4         8

 *     void      *udata;     //   4         8

 * }                  // Total:  20        32

 *

 * The implementation works in 32-bit and 64-bit world. We do this by calling a

 * native function that actually sets the sizes and offsets of the fields based

 * on which mode we're in.

 */

class KQueueArrayWrapper {

    // kevent filters

    static short EVFILT_READ;

    static short EVFILT_WRITE;

    // kevent struct

    // These fields are now set by initStructSizes in the static initializer.

    static short SIZEOF_KEVENT;

    static short FD_OFFSET;

    static short FILTER_OFFSET;

    // kevent array size

    static final int NUM_KEVENTS = 128;

    // Are we in a 64-bit VM?

    static boolean is64bit = false;

    // The kevent array (used for outcoming events only)

    private AllocatedNativeObject keventArray = null;

    private long keventArrayAddress;

    // The kqueue fd

    private int kq = -1;

    // The fd of the interrupt line going out

    private int outgoingInterruptFD;

    // The fd of the interrupt line coming in

    private int incomingInterruptFD;

    static {

        IOUtil.load();

        initStructSizes();

    }

    KQueueArrayWrapper() {

        int allocationSize = SIZEOF_KEVENT * NUM_KEVENTS;

        keventArray = new AllocatedNativeObject(allocationSize, true);

        keventArrayAddress = keventArray.address();

        kq = init();

    }

    // Used to update file description registrations

    private static class Update {

        SelChImpl channel;

        int events;

        Update(SelChImpl channel, int events) {

            this.channel = channel;

            this.events = events;

        }

    }

    private LinkedList<Update> updateList = new LinkedList<Update>();

    void initInterrupt(int fd0, int fd1) {

        outgoingInterruptFD = fd1;

        incomingInterruptFD = fd0;

        register0(kq, fd0, 1, 0);

    }

    int getReventOps(int index) {

        int result = 0;

        int offset = SIZEOF_KEVENT*index + FILTER_OFFSET;

        short filter = keventArray.getShort(offset);

        // This is all that's necessary based on inspection of usage:

        //   SinkChannelImpl, SourceChannelImpl, DatagramChannelImpl,

        //   ServerSocketChannelImpl, SocketChannelImpl

        if (filter == EVFILT_READ) {

            result |= Net.POLLIN;

        } else if (filter == EVFILT_WRITE) {

            result |= Net.POLLOUT;

        }

        return result;

    }

    int getDescriptor(int index) {

        int offset = SIZEOF_KEVENT*index + FD_OFFSET;

        /* The ident field is 8 bytes in 64-bit world, however the API wants us

         * to return an int. Hence read the 8 bytes but return as an int.

         */

        if (is64bit) {

          long fd = keventArray.getLong(offset);

          assert fd <= Integer.MAX_VALUE;

          return (int) fd;

        } else {

          return keventArray.getInt(offset);

        }

    }

    void setInterest(SelChImpl channel, int events) {

        synchronized (updateList) {

            // update existing registration

            updateList.add(new Update(channel, events));

        }

    }

    void release(SelChImpl channel) {

        synchronized (updateList) {

            // flush any pending updates

            for (Iterator<Update> it = updateList.iterator(); it.hasNext();) {

                if (it.next().channel == channel) {

                    it.remove();

                }

            }

            // remove

            register0(kq, channel.getFDVal(), 0, 0);

        }

    }

    void updateRegistrations() {

        synchronized (updateList) {

            Update u = null;

            while ((u = updateList.poll()) != null) {

                SelChImpl ch = u.channel;

                if (!ch.isOpen())

                    continue;

                register0(kq, ch.getFDVal(), u.events & Net.POLLIN, u.events & Net.POLLOUT);

            }

        }

    }

    void close() throws IOException {

        if (keventArray != null) {

            keventArray.free();

            keventArray = null;

        }

        if (kq >= 0) {

            FileDispatcherImpl.closeIntFD(kq);

            kq = -1;

        }

    }

    int poll(long timeout) {

        updateRegistrations();

        int updated = kevent0(kq, keventArrayAddress, NUM_KEVENTS, timeout);

        return updated;

    }

    void interrupt() {

        interrupt(outgoingInterruptFD);

    }

    private native int init();

    private static native void initStructSizes();

    private native void register0(int kq, int fd, int read, int write);

    private native int kevent0(int kq, long keventAddress, int keventCount,

                               long timeout);

    private static native void interrupt(int fd);

}