| /* |
| * Copyright (c) 2000, 2003, 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 javax.imageio.stream; |
| |
| import java.util.ArrayList; |
| import java.io.InputStream; |
| import java.io.OutputStream; |
| import java.io.IOException; |
| |
| /** |
| * Package-visible class consolidating common code for |
| * {@code MemoryCacheImageInputStream} and |
| * {@code MemoryCacheImageOutputStream}. |
| * This class keeps an {@code ArrayList} of 8K blocks, |
| * loaded sequentially. Blocks may only be disposed of |
| * from the index 0 forward. As blocks are freed, the |
| * corresponding entries in the array list are set to |
| * {@code null}, but no compacting is performed. |
| * This allows the index for each block to never change, |
| * and the length of the cache is always the same as the |
| * total amount of data ever cached. Cached data is |
| * therefore always contiguous from the point of last |
| * disposal to the current length. |
| * |
| * <p> The total number of blocks resident in the cache must not |
| * exceed {@code Integer.MAX_VALUE}. In practice, the limit of |
| * available memory will be exceeded long before this becomes an |
| * issue, since a full cache would contain 8192*2^31 = 16 terabytes of |
| * data. |
| * |
| * A {@code MemoryCache} may be reused after a call |
| * to {@code reset()}. |
| */ |
| class MemoryCache { |
| |
| private static final int BUFFER_LENGTH = 8192; |
| |
| private ArrayList<byte[]> cache = new ArrayList<>(); |
| |
| private long cacheStart = 0L; |
| |
| /** |
| * The largest position ever written to the cache. |
| */ |
| private long length = 0L; |
| |
| private byte[] getCacheBlock(long blockNum) throws IOException { |
| long blockOffset = blockNum - cacheStart; |
| if (blockOffset > Integer.MAX_VALUE) { |
| // This can only happen when the cache hits 16 terabytes of |
| // contiguous data... |
| throw new IOException("Cache addressing limit exceeded!"); |
| } |
| return cache.get((int)blockOffset); |
| } |
| |
| /** |
| * Ensures that at least {@code pos} bytes are cached, |
| * or the end of the source is reached. The return value |
| * is equal to the smaller of {@code pos} and the |
| * length of the source. |
| * |
| * @throws IOException if there is no more memory for cache |
| */ |
| public long loadFromStream(InputStream stream, long pos) |
| throws IOException { |
| // We've already got enough data cached |
| if (pos < length) { |
| return pos; |
| } |
| |
| int offset = (int)(length % BUFFER_LENGTH); |
| byte [] buf = null; |
| |
| long len = pos - length; |
| if (offset != 0) { |
| buf = getCacheBlock(length/BUFFER_LENGTH); |
| } |
| |
| while (len > 0) { |
| if (buf == null) { |
| try { |
| buf = new byte[BUFFER_LENGTH]; |
| } catch (OutOfMemoryError e) { |
| throw new IOException("No memory left for cache!"); |
| } |
| offset = 0; |
| } |
| |
| int left = BUFFER_LENGTH - offset; |
| int nbytes = (int)Math.min(len, (long)left); |
| nbytes = stream.read(buf, offset, nbytes); |
| if (nbytes == -1) { |
| return length; // EOF |
| } |
| |
| if (offset == 0) { |
| cache.add(buf); |
| } |
| |
| len -= nbytes; |
| length += nbytes; |
| offset += nbytes; |
| |
| if (offset >= BUFFER_LENGTH) { |
| // we've filled the current buffer, so a new one will be |
| // allocated next time around (and offset will be reset to 0) |
| buf = null; |
| } |
| } |
| |
| return pos; |
| } |
| |
| /** |
| * Writes out a portion of the cache to an {@code OutputStream}. |
| * This method preserves no state about the output stream, and does |
| * not dispose of any blocks containing bytes written. To dispose |
| * blocks, use {@link #disposeBefore disposeBefore()}. |
| * |
| * @exception IndexOutOfBoundsException if any portion of |
| * the requested data is not in the cache (including if {@code pos} |
| * is in a block already disposed), or if either {@code pos} or |
| * {@code len} is < 0. |
| * @throws IOException if there is an I/O exception while writing to the |
| * stream |
| */ |
| public void writeToStream(OutputStream stream, long pos, long len) |
| throws IOException { |
| if (pos + len > length) { |
| throw new IndexOutOfBoundsException("Argument out of cache"); |
| } |
| if ((pos < 0) || (len < 0)) { |
| throw new IndexOutOfBoundsException("Negative pos or len"); |
| } |
| if (len == 0) { |
| return; |
| } |
| |
| long bufIndex = pos/BUFFER_LENGTH; |
| if (bufIndex < cacheStart) { |
| throw new IndexOutOfBoundsException("pos already disposed"); |
| } |
| int offset = (int)(pos % BUFFER_LENGTH); |
| |
| byte[] buf = getCacheBlock(bufIndex++); |
| while (len > 0) { |
| if (buf == null) { |
| buf = getCacheBlock(bufIndex++); |
| offset = 0; |
| } |
| int nbytes = (int)Math.min(len, (long)(BUFFER_LENGTH - offset)); |
| stream.write(buf, offset, nbytes); |
| buf = null; |
| len -= nbytes; |
| } |
| } |
| |
| /** |
| * Ensure that there is space to write a byte at the given position. |
| * |
| * throws IOException if there is no more memory left for cache |
| */ |
| private void pad(long pos) throws IOException { |
| long currIndex = cacheStart + cache.size() - 1; |
| long lastIndex = pos/BUFFER_LENGTH; |
| long numNewBuffers = lastIndex - currIndex; |
| for (long i = 0; i < numNewBuffers; i++) { |
| try { |
| cache.add(new byte[BUFFER_LENGTH]); |
| } catch (OutOfMemoryError e) { |
| throw new IOException("No memory left for cache!"); |
| } |
| } |
| } |
| |
| /** |
| * Overwrites and/or appends the cache from a byte array. |
| * The length of the cache will be extended as needed to hold |
| * the incoming data. |
| * |
| * @param b an array of bytes containing data to be written. |
| * @param off the starting offset within the data array. |
| * @param len the number of bytes to be written. |
| * @param pos the cache position at which to begin writing. |
| * |
| * @exception NullPointerException if {@code b} is {@code null}. |
| * @exception IndexOutOfBoundsException if {@code off}, |
| * {@code len}, or {@code pos} are negative, |
| * or if {@code off+len > b.length}. |
| * @throws IOException if there is an I/O error while writing to the cache |
| */ |
| public void write(byte[] b, int off, int len, long pos) |
| throws IOException { |
| if (b == null) { |
| throw new NullPointerException("b == null!"); |
| } |
| // Fix 4430357 - if off + len < 0, overflow occurred |
| if ((off < 0) || (len < 0) || (pos < 0) || |
| (off + len > b.length) || (off + len < 0)) { |
| throw new IndexOutOfBoundsException(); |
| } |
| |
| // Ensure there is space for the incoming data |
| long lastPos = pos + len - 1; |
| if (lastPos >= length) { |
| pad(lastPos); |
| length = lastPos + 1; |
| } |
| |
| // Copy the data into the cache, block by block |
| int offset = (int)(pos % BUFFER_LENGTH); |
| while (len > 0) { |
| byte[] buf = getCacheBlock(pos/BUFFER_LENGTH); |
| int nbytes = Math.min(len, BUFFER_LENGTH - offset); |
| System.arraycopy(b, off, buf, offset, nbytes); |
| |
| pos += nbytes; |
| off += nbytes; |
| len -= nbytes; |
| offset = 0; // Always after the first time |
| } |
| } |
| |
| /** |
| * Overwrites or appends a single byte to the cache. |
| * The length of the cache will be extended as needed to hold |
| * the incoming data. |
| * |
| * @param b an {@code int} whose 8 least significant bits |
| * will be written. |
| * @param pos the cache position at which to begin writing. |
| * |
| * @exception IndexOutOfBoundsException if {@code pos} is negative. |
| * @throws IOException if there is an I/O error while writing to the cache |
| */ |
| public void write(int b, long pos) throws IOException { |
| if (pos < 0) { |
| throw new ArrayIndexOutOfBoundsException("pos < 0"); |
| } |
| |
| // Ensure there is space for the incoming data |
| if (pos >= length) { |
| pad(pos); |
| length = pos + 1; |
| } |
| |
| // Insert the data. |
| byte[] buf = getCacheBlock(pos/BUFFER_LENGTH); |
| int offset = (int)(pos % BUFFER_LENGTH); |
| buf[offset] = (byte)b; |
| } |
| |
| /** |
| * Returns the total length of data that has been cached, |
| * regardless of whether any early blocks have been disposed. |
| * This value will only ever increase. |
| */ |
| public long getLength() { |
| return length; |
| } |
| |
| /** |
| * Returns the single byte at the given position, as an |
| * {@code int}. Returns -1 if this position has |
| * not been cached or has been disposed. |
| * |
| * @throws IOException if an I/O error occurs while reading from the byte |
| * array |
| */ |
| public int read(long pos) throws IOException { |
| if (pos >= length) { |
| return -1; |
| } |
| |
| byte[] buf = getCacheBlock(pos/BUFFER_LENGTH); |
| if (buf == null) { |
| return -1; |
| } |
| |
| return buf[(int)(pos % BUFFER_LENGTH)] & 0xff; |
| } |
| |
| /** |
| * Copy {@code len} bytes from the cache, starting |
| * at cache position {@code pos}, into the array |
| * {@code b} at offset {@code off}. |
| * |
| * @exception NullPointerException if b is {@code null} |
| * @exception IndexOutOfBoundsException if {@code off}, |
| * {@code len} or {@code pos} are negative or if |
| * {@code off + len > b.length} or if any portion of the |
| * requested data is not in the cache (including if |
| * {@code pos} is in a block that has already been disposed). |
| * @throws IOException if an I/O exception occurs while reading from the |
| * byte array |
| */ |
| public void read(byte[] b, int off, int len, long pos) |
| throws IOException { |
| if (b == null) { |
| throw new NullPointerException("b == null!"); |
| } |
| // Fix 4430357 - if off + len < 0, overflow occurred |
| if ((off < 0) || (len < 0) || (pos < 0) || |
| (off + len > b.length) || (off + len < 0)) { |
| throw new IndexOutOfBoundsException(); |
| } |
| if (pos + len > length) { |
| throw new IndexOutOfBoundsException(); |
| } |
| |
| long index = pos/BUFFER_LENGTH; |
| int offset = (int)pos % BUFFER_LENGTH; |
| while (len > 0) { |
| int nbytes = Math.min(len, BUFFER_LENGTH - offset); |
| byte[] buf = getCacheBlock(index++); |
| System.arraycopy(buf, offset, b, off, nbytes); |
| |
| len -= nbytes; |
| off += nbytes; |
| offset = 0; // Always after the first time |
| } |
| } |
| |
| /** |
| * Free the blocks up to the position {@code pos}. |
| * The byte at {@code pos} remains available. |
| * |
| * @exception IndexOutOfBoundsException if {@code pos} |
| * is in a block that has already been disposed. |
| */ |
| public void disposeBefore(long pos) { |
| long index = pos/BUFFER_LENGTH; |
| if (index < cacheStart) { |
| throw new IndexOutOfBoundsException("pos already disposed"); |
| } |
| long numBlocks = Math.min(index - cacheStart, cache.size()); |
| for (long i = 0; i < numBlocks; i++) { |
| cache.remove(0); |
| } |
| this.cacheStart = index; |
| } |
| |
| /** |
| * Erase the entire cache contents and reset the length to 0. |
| * The cache object may subsequently be reused as though it had just |
| * been allocated. |
| */ |
| public void reset() { |
| cache.clear(); |
| cacheStart = 0; |
| length = 0L; |
| } |
| } |