/*
* Copyright (c) 2000, 2012, 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
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*/
package javax.imageio.stream;
import java.io.File;
import java.io.InputStream;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.file.Files;
import com.sun.imageio.stream.StreamCloser;
import com.sun.imageio.stream.StreamFinalizer;
import sun.java2d.Disposer;
import sun.java2d.DisposerRecord;
/**
* An implementation of {@code ImageInputStream} that gets its
* input from a regular {@code InputStream}. A file is used to
* cache previously read data.
*
*/
public class FileCacheImageInputStream extends ImageInputStreamImpl {
private InputStream stream;
private File cacheFile;
private RandomAccessFile cache;
private static final int BUFFER_LENGTH = 1024;
private byte[] buf = new byte[BUFFER_LENGTH];
private long length = 0L;
private boolean foundEOF = false;
/** The referent to be registered with the Disposer. */
private final Object disposerReferent;
/** The DisposerRecord that closes the underlying cache. */
private final DisposerRecord disposerRecord;
/** The CloseAction that closes the stream in
* the StreamCloser's shutdown hook */
private final StreamCloser.CloseAction closeAction;
/**
* Constructs a {@code FileCacheImageInputStream} that will read
* from a given {@code InputStream}.
*
* <p> A temporary file is used as a cache. If
* {@code cacheDir} is non-{@code null} and is a
* directory, the file will be created there. If it is
* {@code null}, the system-dependent default temporary-file
* directory will be used (see the documentation for
* {@code File.createTempFile} for details).
*
* @param stream an {@code InputStream} to read from.
* @param cacheDir a {@code File} indicating where the
* cache file should be created, or {@code null} to use the
* system directory.
*
* @exception IllegalArgumentException if {@code stream} is
* {@code null}.
* @exception IllegalArgumentException if {@code cacheDir} is
* non-{@code null} but is not a directory.
* @throws IOException if a cache file cannot be created.
*/
public FileCacheImageInputStream(InputStream stream, File cacheDir)
throws IOException {
if (stream == null) {
throw new IllegalArgumentException("stream == null!");
}
if ((cacheDir != null) && !(cacheDir.isDirectory())) {
throw new IllegalArgumentException("Not a directory!");
}
this.stream = stream;
if (cacheDir == null)
this.cacheFile = Files.createTempFile("imageio", ".tmp").toFile();
else
this.cacheFile = Files.createTempFile(cacheDir.toPath(), "imageio", ".tmp")
.toFile();
this.cache = new RandomAccessFile(cacheFile, "rw");
this.closeAction = StreamCloser.createCloseAction(this);
StreamCloser.addToQueue(closeAction);
disposerRecord = new StreamDisposerRecord(cacheFile, cache);
if (getClass() == FileCacheImageInputStream.class) {
disposerReferent = new Object();
Disposer.addRecord(disposerReferent, disposerRecord);
} else {
disposerReferent = new StreamFinalizer(this);
}
}
/**
* 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 file.
*
* @throws IOException if an I/O error occurs while reading from the
* source file
*/
private long readUntil(long pos) throws IOException {
// We've already got enough data cached
if (pos < length) {
return pos;
}
// pos >= length but length isn't getting any bigger, so return it
if (foundEOF) {
return length;
}
long len = pos - length;
cache.seek(length);
while (len > 0) {
// Copy a buffer's worth of data from the source to the cache
// BUFFER_LENGTH will always fit into an int so this is safe
int nbytes =
stream.read(buf, 0, (int)Math.min(len, (long)BUFFER_LENGTH));
if (nbytes == -1) {
foundEOF = true;
return length;
}
cache.write(buf, 0, nbytes);
len -= nbytes;
length += nbytes;
}
return pos;
}
public int read() throws IOException {
checkClosed();
bitOffset = 0;
long next = streamPos + 1;
long pos = readUntil(next);
if (pos >= next) {
cache.seek(streamPos++);
return cache.read();
} else {
return -1;
}
}
public int read(byte[] b, int off, int len) throws IOException {
checkClosed();
if (b == null) {
throw new NullPointerException("b == null!");
}
// Fix 4430357 - if off + len < 0, overflow occurred
if (off < 0 || len < 0 || off + len > b.length || off + len < 0) {
throw new IndexOutOfBoundsException
("off < 0 || len < 0 || off+len > b.length || off+len < 0!");
}
bitOffset = 0;
if (len == 0) {
return 0;
}
long pos = readUntil(streamPos + len);
// len will always fit into an int so this is safe
len = (int)Math.min((long)len, pos - streamPos);
if (len > 0) {
cache.seek(streamPos);
cache.readFully(b, off, len);
streamPos += len;
return len;
} else {
return -1;
}
}
/**
* Returns {@code true} since this
* {@code ImageInputStream} caches data in order to allow
* seeking backwards.
*
* @return {@code true}.
*
* @see #isCachedMemory
* @see #isCachedFile
*/
public boolean isCached() {
return true;
}
/**
* Returns {@code true} since this
* {@code ImageInputStream} maintains a file cache.
*
* @return {@code true}.
*
* @see #isCached
* @see #isCachedMemory
*/
public boolean isCachedFile() {
return true;
}
/**
* Returns {@code false} since this
* {@code ImageInputStream} does not maintain a main memory
* cache.
*
* @return {@code false}.
*
* @see #isCached
* @see #isCachedFile
*/
public boolean isCachedMemory() {
return false;
}
/**
* Closes this {@code FileCacheImageInputStream}, closing
* and removing the cache file. The source {@code InputStream}
* is not closed.
*
* @throws IOException if an error occurs.
*/
public void close() throws IOException {
super.close();
disposerRecord.dispose(); // this will close/delete the cache file
stream = null;
cache = null;
cacheFile = null;
StreamCloser.removeFromQueue(closeAction);
}
/**
* {@inheritDoc}
*/
protected void finalize() throws Throwable {
// Empty finalizer: for performance reasons we instead use the
// Disposer mechanism for ensuring that the underlying
// RandomAccessFile is closed/deleted prior to garbage collection
}
private static class StreamDisposerRecord implements DisposerRecord {
private File cacheFile;
private RandomAccessFile cache;
public StreamDisposerRecord(File cacheFile, RandomAccessFile cache) {
this.cacheFile = cacheFile;
this.cache = cache;
}
public synchronized void dispose() {
if (cache != null) {
try {
cache.close();
} catch (IOException e) {
} finally {
cache = null;
}
}
if (cacheFile != null) {
cacheFile.delete();
cacheFile = null;
}
// Note: Explicit removal of the stream from the StreamCloser
// queue is not mandatory in this case, as it will be removed
// automatically by GC shortly after this method is called.
}
}
}