FileCacheSeekableStream.java
/*
* Copyright (c) 2008, Harald Kuhr
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* * Neither the name of the copyright holder nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package com.twelvemonkeys.io;
import com.twelvemonkeys.lang.Validate;
import java.io.*;
/**
* A {@code SeekableInputStream} implementation that caches data in a temporary {@code File}.
* <p>
* Temporary files are created as specified in {@link File#createTempFile(String, String, java.io.File)}.
* </p>
*
* @see MemoryCacheSeekableStream
* @see FileSeekableStream
*
* @see File#createTempFile(String, String)
* @see RandomAccessFile
*
* @author <a href="mailto:harald.kuhr@gmail.com">Harald Kuhr</a>
* @version $Id: //depot/branches/personal/haraldk/twelvemonkeys/release-2/twelvemonkeys-core/src/main/java/com/twelvemonkeys/io/FileCacheSeekableStream.java#5 $
*/
public final class FileCacheSeekableStream extends AbstractCachedSeekableStream {
private byte[] buffer;
/**
* Creates a {@code FileCacheSeekableStream} reading from the given
* {@code InputStream}. Data will be cached in a temporary file.
*
* @param pStream the {@code InputStream} to read from
*
* @throws IOException if the temporary file cannot be created,
* or cannot be opened for random access.
*/
public FileCacheSeekableStream(final InputStream pStream) throws IOException {
this(pStream, "iocache", null);
}
/**
* Creates a {@code FileCacheSeekableStream} reading from the given
* {@code InputStream}. Data will be cached in a temporary file, with
* the given base name.
*
* @param pStream the {@code InputStream} to read from
* @param pTempBaseName optional base name for the temporary file
*
* @throws IOException if the temporary file cannot be created,
* or cannot be opened for random access.
*/
public FileCacheSeekableStream(final InputStream pStream, final String pTempBaseName) throws IOException {
this(pStream, pTempBaseName, null);
}
/**
* Creates a {@code FileCacheSeekableStream} reading from the given
* {@code InputStream}. Data will be cached in a temporary file, with
* the given base name, in the given directory
*
* @param pStream the {@code InputStream} to read from
* @param pTempBaseName optional base name for the temporary file
* @param pTempDir optional temp directory
*
* @throws IOException if the temporary file cannot be created,
* or cannot be opened for random access.
*/
public FileCacheSeekableStream(final InputStream pStream, final String pTempBaseName, final File pTempDir) throws IOException {
// NOTE: We do validation BEFORE we create temp file, to avoid orphan files
this(Validate.notNull(pStream, "stream"), createTempFile(pTempBaseName, pTempDir));
}
/*protected*/ static File createTempFile(String pTempBaseName, File pTempDir) throws IOException {
Validate.notNull(pTempBaseName, "tempBaseName");
File file = File.createTempFile(pTempBaseName, null, pTempDir);
file.deleteOnExit();
return file;
}
// TODO: Consider exposing this for external use
/*protected*/ FileCacheSeekableStream(final InputStream pStream, final File pFile) throws FileNotFoundException {
super(pStream, new FileCache(pFile));
// TODO: Allow for custom buffer sizes?
buffer = new byte[1024];
}
public final boolean isCachedMemory() {
return false;
}
public final boolean isCachedFile() {
return true;
}
@Override
protected void closeImpl() throws IOException {
// TODO: Close cache file
super.closeImpl();
buffer = null;
}
@Override
public int read() throws IOException {
checkOpen();
int read;
if (position == streamPosition) {
// Read ahead into buffer, for performance
read = readAhead(buffer, 0, buffer.length);
if (read >= 0) {
read = buffer[0] & 0xff;
}
//System.out.println("Read 1 byte from stream: " + Integer.toHexString(read & 0xff));
}
else {
// ..or read byte from the cache
syncPosition();
read = getCache().read();
//System.out.println("Read 1 byte from cache: " + Integer.toHexString(read & 0xff));
}
// TODO: This field is not REALLY considered accessible.. :-P
if (read != -1) {
position++;
}
return read;
}
@Override
public int read(byte[] pBytes, int pOffset, int pLength) throws IOException {
checkOpen();
int length;
if (position == streamPosition) {
// Read bytes from the stream
length = readAhead(pBytes, pOffset, pLength);
//System.out.println("Read " + length + " byte from stream");
}
else {
// ...or read bytes from the cache
syncPosition();
length = getCache().read(pBytes, pOffset, (int) Math.min(pLength, streamPosition - position));
//System.out.println("Read " + length + " byte from cache");
}
// TODO: This field is not REALLY considered accessible.. :-P
if (length > 0) {
position += length;
}
return length;
}
private int readAhead(final byte[] pBytes, final int pOffset, final int pLength) throws IOException {
int length;
length = stream.read(pBytes, pOffset, pLength);
if (length > 0) {
streamPosition += length;
getCache().write(pBytes, pOffset, length);
}
return length;
}
// TODO: We need to close the cache file!!! Otherwise we are leaking file descriptors
final static class FileCache extends StreamCache {
private RandomAccessFile cacheFile;
public FileCache(final File pFile) throws FileNotFoundException {
Validate.notNull(pFile, "file");
cacheFile = new RandomAccessFile(pFile, "rw");
}
public void write(final int pByte) throws IOException {
cacheFile.write(pByte);
}
@Override
public void write(final byte[] pBuffer, final int pOffset, final int pLength) throws IOException {
cacheFile.write(pBuffer, pOffset, pLength);
}
public int read() throws IOException {
return cacheFile.read();
}
@Override
public int read(final byte[] pBuffer, final int pOffset, final int pLength) throws IOException {
return cacheFile.read(pBuffer, pOffset, pLength);
}
public void seek(final long pPosition) throws IOException {
cacheFile.seek(pPosition);
}
public long getPosition() throws IOException {
return cacheFile.getFilePointer();
}
@Override
void close() throws IOException {
cacheFile.close();
}
}
}