/*

 * Copyright (c) 2001, 2018, 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.lang.annotation.Native;

/**

 * Manipulates a native array of structs corresponding to (fd, events) pairs.

 *

 * typedef struct pollfd {

 *    SOCKET fd;            // 4 bytes

 *    short events;         // 2 bytes

 * } pollfd_t;

 *

 * @author Konstantin Kladko

 * @author Mike McCloskey

 */

class PollArrayWrapper {

    private AllocatedNativeObject pollArray; // The fd array

    long pollArrayAddress; // pollArrayAddress

    @Native private static final short FD_OFFSET     = 0; // fd offset in pollfd

    @Native private static final short EVENT_OFFSET  = 4; // events offset in pollfd

    static short SIZE_POLLFD = 8; // sizeof pollfd struct

    private int size; // Size of the pollArray

    PollArrayWrapper(int newSize) {

        int allocationSize = newSize * SIZE_POLLFD;

        pollArray = new AllocatedNativeObject(allocationSize, true);

        pollArrayAddress = pollArray.address();

        this.size = newSize;

    }

    // Prepare another pollfd struct for use.

    void putEntry(int index, SelectionKeyImpl ski) {

        putDescriptor(index, ski.getFDVal());

        putEventOps(index, 0);

    }

    // Writes the pollfd entry from the source wrapper at the source index

    // over the entry in the target wrapper at the target index.

    void replaceEntry(PollArrayWrapper source, int sindex,

                                     PollArrayWrapper target, int tindex) {

        target.putDescriptor(tindex, source.getDescriptor(sindex));

        target.putEventOps(tindex, source.getEventOps(sindex));

    }

    // Grows the pollfd array to new size

    void grow(int newSize) {

        PollArrayWrapper temp = new PollArrayWrapper(newSize);

        for (int i = 0; i < size; i++)

            replaceEntry(this, i, temp, i);

        pollArray.free();

        pollArray = temp.pollArray;

        this.size = temp.size;

        pollArrayAddress = pollArray.address();

    }

    void free() {

        pollArray.free();

    }

    // Access methods for fd structures

    void putDescriptor(int i, int fd) {

        pollArray.putInt(SIZE_POLLFD * i + FD_OFFSET, fd);

    }

    void putEventOps(int i, int event) {

        pollArray.putShort(SIZE_POLLFD * i + EVENT_OFFSET, (short)event);

    }

    int getEventOps(int i) {

        return pollArray.getShort(SIZE_POLLFD * i + EVENT_OFFSET);

    }

    int getDescriptor(int i) {

       return pollArray.getInt(SIZE_POLLFD * i + FD_OFFSET);

    }

    // Adds Windows wakeup socket at a given index.

    void addWakeupSocket(int fdVal, int index) {

        putDescriptor(index, fdVal);

        putEventOps(index, Net.POLLIN);

    }

}