Subversion Repositories mkgmap

/*
 * Copyright (C) 2006 Steve Ratcliffe
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2 as
 *  published by the Free Software Foundation.
 *
 *  This program 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 for more details.
 *
 *
 * Author: Steve Ratcliffe
 * Create date: 07-Dec-2006
 */
package uk.me.parabola.imgfmt.app;

import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;

import uk.me.parabola.imgfmt.MapFailedException;
import uk.me.parabola.imgfmt.fs.ImgChannel;
import uk.me.parabola.log.Logger;

/**
 * A straight forward implementation that just keeps all the data in a buffer
 * until the file needs to be written to disk.
 *
 * @author Steve Ratcliffe
 */
public class BufferedImgFileWriter implements ImgFileWriter {
        private static final Logger log = Logger.getLogger(BufferedImgFileWriter.class);

        private static final int KBYTE = 1024;
        private static final int INIT_SIZE = 16 * KBYTE;
        private static final int GROW_SIZE = 128 * KBYTE;
        private static final int GUARD_SIZE = KBYTE;

        private final ImgChannel chan;

        private ByteBuffer buf = ByteBuffer.allocate(INIT_SIZE);
        private int bufferSize = INIT_SIZE;

        // The size of the file.  Note that for this to be set properly, the
        // position must be set to a low value after the full file is written. This
        // always happens because we go back and write the header after all is
        // written.
        private int maxSize;

        // The maximum allowed file size.
        private long maxAllowedSize = 0xffffff;

        public BufferedImgFileWriter(ImgChannel chan) {
                this.chan = chan;
                buf.order(ByteOrder.LITTLE_ENDIAN);
        }

        /**
         * Called to write out any saved buffers.  The strategy may write
         * directly to the file in which case this would have nothing or
         * little to do.
         */
        public void sync() throws IOException {
                buf.limit(maxSize);
                buf.position(0);
                log.debug("syncing to pos", chan.position(), ", size", buf.limit());
                chan.write(buf);
        }

        /**
         * Get the position.  Needed because may not be reflected in the underlying
         * file if being buffered.
         *
         * @return The logical position within the file.
         */
        public int position() {
                return buf.position();
        }

        /**
         * Set the position of the file.
         *
         * @param pos The new position in the file.
         */
        public void position(long pos) {
                int cur = position();
                if (cur > maxSize)
                        maxSize = cur;
                buf.position((int) pos);
        }

        /**
         * Called when the stream is closed.  Any resources can be freed.
         */
        public void close() throws IOException {
                chan.close();
        }

        /**
         * Write out a single byte.
         *
         * @param b The byte to write.
         */
        public void put(byte b) {
                ensureSize(1);
                buf.put(b);
        }

        /**
         * Write out two bytes.  Done in the correct byte order.
         *
         * @param c The value to write.
         */
        public void putChar(char c) {
                ensureSize(2);
                buf.putChar(c);
        }

        /**
         * Write out a 3 byte value in the correct byte order etc.
         *
         * @param val The value to write.
         */
        public void put3(int val) {
                ensureSize(3);
                buf.put((byte) (val & 0xff));
                buf.putChar((char) (val >> 8));
        }

        /**
         * Write out 4 byte value.
         *
         * @param val The value to write.
         */
        public void putInt(int val) {
                ensureSize(4);
                buf.putInt(val);
        }

        /**
         * Write out an arbitrary length sequence of bytes.
         *
         * @param val The values to write.
         */
        public void put(byte[] val) {
                ensureSize(val.length);
                buf.put(val);
        }

        /**
         * Write out part of a byte array.
         *
         * @param src   The array to take bytes from.
         * @param start  The start position.
         * @param length The number of bytes to write.
         */
        public void put(byte[] src, int start, int length) {
                ensureSize(length);
                buf.put(src, start, length);
        }

        public void put(ByteBuffer src) {
                ensureSize(src.limit());
                buf.put(src);
        }

        /**
         * Get the size of the file as written.
         *
         * NOTE: that calling this is only valid at certain times.
         *
         * @return The size of the file, if it is available.
         */
        public long getSize() {
                return maxSize;
        }

        public ByteBuffer getBuffer() {
                return buf;
        }

        /**
         * Make sure there is enough room for the data we are about to write.
         *
         * @param length The amount of data.
         */
        private void ensureSize(int length) {
                int needed = buf.position() + length;
                if (needed > (bufferSize - GUARD_SIZE)) {
                        while(needed > (bufferSize - GUARD_SIZE))
                                bufferSize += GROW_SIZE;
                        if (bufferSize > maxAllowedSize) {
                                // Previous message was confusing people, although it is difficult to come
                                // up with something that is strictly true in all situations.
                                throw new MapFailedException(
                                                "There is not enough room in a single garmin map for all the input data." +
                                                                " The .osm file should be split into smaller pieces first.");
                        }
                        ByteBuffer newb = ByteBuffer.allocate(bufferSize);
                        newb.order(ByteOrder.LITTLE_ENDIAN);
                        buf.flip();
                        newb.put(buf);
                        buf = newb;
                }
        }

        public void setMaxSize(long maxSize) {
                this.maxAllowedSize = maxSize;
        }
}