/*

 * Copyright (c) 2000, 2010, 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.ByteBuffer;

import sun.misc.*;

/**

 * Manipulates a native array of iovec structs on Solaris:

 *

 * typedef struct iovec {

 *    caddr_t  iov_base;

      int      iov_len;

 * } iovec_t;

 *

 * @author Mike McCloskey

 * @since 1.4

 */

class IOVecWrapper {

    // Miscellaneous constants

    private static final int BASE_OFFSET = 0;

    private static final int LEN_OFFSET;

    private static final int SIZE_IOVEC;

    // The iovec array

    private final AllocatedNativeObject vecArray;

    // Number of elements in iovec array

    private final int size;

    // Buffers and position/remaining corresponding to elements in iovec array

    private final ByteBuffer[] buf;

    private final int[] position;

    private final int[] remaining;

    // Shadow buffers for cases when original buffer is substituted

    private final ByteBuffer[] shadow;

    // Base address of this array

    final long address;

    // Address size in bytes

    static int addressSize;

    private static class Deallocator implements Runnable {

        private final AllocatedNativeObject obj;

        Deallocator(AllocatedNativeObject obj) {

            this.obj = obj;

        }

        public void run() {

            obj.free();

        }

    }

    // per thread IOVecWrapper

    private static final ThreadLocal<IOVecWrapper> cached =

        new ThreadLocal<IOVecWrapper>();

    private IOVecWrapper(int size) {

        this.size      = size;

        this.buf       = new ByteBuffer[size];

        this.position  = new int[size];

        this.remaining = new int[size];

        this.shadow    = new ByteBuffer[size];

        this.vecArray  = new AllocatedNativeObject(size * SIZE_IOVEC, false);

        this.address   = vecArray.address();

    }

    static IOVecWrapper get(int size) {

        IOVecWrapper wrapper = cached.get();

        if (wrapper != null && wrapper.size < size) {

            // not big enough; eagerly release memory

            wrapper.vecArray.free();

            wrapper = null;

        }

        if (wrapper == null) {

            wrapper = new IOVecWrapper(size);

            Cleaner.create(wrapper, new Deallocator(wrapper.vecArray));

            cached.set(wrapper);

        }

        return wrapper;

    }

    void setBuffer(int i, ByteBuffer buf, int pos, int rem) {

        this.buf[i] = buf;

        this.position[i] = pos;

        this.remaining[i] = rem;

    }

    void setShadow(int i, ByteBuffer buf) {

        shadow[i] = buf;

    }

    ByteBuffer getBuffer(int i) {

        return buf[i];

    }

    int getPosition(int i) {

        return position[i];

    }

    int getRemaining(int i) {

        return remaining[i];

    }

    ByteBuffer getShadow(int i) {

        return shadow[i];

    }

    void clearRefs(int i) {

        buf[i] = null;

        shadow[i] = null;

    }

    void putBase(int i, long base) {

        int offset = SIZE_IOVEC * i + BASE_OFFSET;

        if (addressSize == 4)

            vecArray.putInt(offset, (int)base);

        else

            vecArray.putLong(offset, base);

    }

    void putLen(int i, long len) {

        int offset = SIZE_IOVEC * i + LEN_OFFSET;

        if (addressSize == 4)

            vecArray.putInt(offset, (int)len);

        else

            vecArray.putLong(offset, len);

    }

    static {

        addressSize = Util.unsafe().addressSize();

        LEN_OFFSET = addressSize;

        SIZE_IOVEC = (short) (addressSize * 2);

    }

}