--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/java.desktop/share/classes/javax/imageio/stream/MemoryCache.java Sun Aug 17 15:54:13 2014 +0100
@@ -0,0 +1,364 @@
+/*
+ * 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</code> and
+ * <code>MemoryCacheImageOutputStream</code>.
+ * This class keeps an <code>ArrayList</code> 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</code>, 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</code>. 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</code> may be reused after a call
+ * to <code>reset()</code>.
+ */
+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</code> bytes are cached,
+ * or the end of the source is reached. The return value
+ * is equal to the smaller of <code>pos</code> and the
+ * length of the source.
+ */
+ 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</code>.
+ * 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 <code>disposeBefore()</code>}.
+ *
+ * @exception IndexOutOfBoundsException if any portion of
+ * the requested data is not in the cache (including if <code>pos</code>
+ * is in a block already disposed), or if either <code>pos</code> or
+ * <code>len</code> is < 0.
+ */
+ 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.
+ */
+ 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 withing 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</code> is <code>null</code>.
+ * @exception IndexOutOfBoundsException if <code>off</code>,
+ * <code>len</code>, or <code>pos</code> are negative,
+ * or if <code>off+len > b.length</code>.
+ */
+ 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</code> whose 8 least significant bits
+ * will be written.
+ * @param pos the cache position at which to begin writing.
+ *
+ * @exception IndexOutOfBoundsException if <code>pos</code> is negative.
+ */
+ 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</code>. Returns -1 if this position has
+ * not been cached or has been disposed.
+ */
+ 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</code> bytes from the cache, starting
+ * at cache position <code>pos</code>, into the array
+ * <code>b</code> at offset <code>off</code>.
+ *
+ * @exception NullPointerException if b is <code>null</code>
+ * @exception IndexOutOfBoundsException if <code>off</code>,
+ * <code>len</code> or <code>pos</code> are negative or if
+ * <code>off + len > b.length</code> or if any portion of the
+ * requested data is not in the cache (including if
+ * <code>pos</code> is in a block that has already been disposed).
+ */
+ 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</code>.
+ * The byte at <code>pos</code> remains available.
+ *
+ * @exception IndexOutOfBoundsException if <code>pos</code>
+ * 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;
+ }
+ }