com.twelvemonkeys.io.FileCacheSeekableStream Maven / Gradle / Ivy
/*
* 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 "TwelveMonkeys" 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 OWNER 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}.
*
* Temporary files are created as specified in {@link File#createTempFile(String, String, java.io.File)}.
*
* @see MemoryCacheSeekableStream
* @see FileSeekableStream
*
* @see File#createTempFile(String, String)
* @see RandomAccessFile
*
* @author Harald Kuhr
* @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 final InputStream mStream;
// private final RandomAccessFile mCache;
private byte[] mBuffer;
/** The stream positon in the backing stream (mStream) */
// private long mStreamPosition;
// TODO: getStreamPosition() should always be the same as
// mCache.getFilePointer()
// otherwise there's some inconsistency here... Enforce this?
/**
* 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?
mBuffer = new byte[1024];
}
public final boolean isCachedMemory() {
return false;
}
public final boolean isCachedFile() {
return true;
}
@Override
protected void closeImpl() throws IOException {
super.closeImpl();
mBuffer = null;
}
/*
public final boolean isCached() {
return true;
}
// InputStream overrides
@Override
public int available() throws IOException {
long avail = mStreamPosition - mPosition + mStream.available();
return avail > Integer.MAX_VALUE ? Integer.MAX_VALUE : (int) avail;
}
public void closeImpl() throws IOException {
mStream.close();
mCache.close();
// TODO: Delete cache file here?
// ThreadPool.invokeLater(new DeleteFileAction(mCacheFile));
}
*/
@Override
public int read() throws IOException {
checkOpen();
int read;
if (mPosition == mStreamPosition) {
// Read ahead into buffer, for performance
read = readAhead(mBuffer, 0, mBuffer.length);
if (read >= 0) {
read = mBuffer[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) {
mPosition++;
}
return read;
}
@Override
public int read(byte[] pBytes, int pOffset, int pLength) throws IOException {
checkOpen();
int length;
if (mPosition == mStreamPosition) {
// 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, mStreamPosition - mPosition));
//System.out.println("Read " + length + " byte from cache");
}
// TODO: This field is not REALLY considered accessible.. :-P
if (length > 0) {
mPosition += length;
}
return length;
}
private int readAhead(final byte[] pBytes, final int pOffset, final int pLength) throws IOException {
int length;
length = mStream.read(pBytes, pOffset, pLength);
if (length > 0) {
mStreamPosition += length;
getCache().write(pBytes, pOffset, length);
}
return length;
}
/*
private void syncPosition() throws IOException {
if (mCache.getFilePointer() != mPosition) {
mCache.seek(mPosition); // Assure EOF is correctly thrown
}
}
// Seekable overrides
protected void flushBeforeImpl(long pPosition) {
// TODO: Implement
// For now, it's probably okay to do nothing, this is just for
// performance (as long as people follow spec, not behaviour)
}
protected void seekImpl(long pPosition) throws IOException {
if (mStreamPosition < pPosition) {
// Make sure we append at end of cache
if (mCache.getFilePointer() != mStreamPosition) {
mCache.seek(mStreamPosition);
}
// Read diff from stream into cache
long left = pPosition - mStreamPosition;
int bufferLen = left > 1024 ? 1024 : (int) left;
byte[] buffer = new byte[bufferLen];
while (left > 0) {
int length = buffer.length < left ? buffer.length : (int) left;
int read = mStream.read(buffer, 0, length);
if (read > 0) {
mCache.write(buffer, 0, read);
mStreamPosition += read;
left -= read;
}
else if (read < 0) {
break;
}
}
}
else if (mStreamPosition >= pPosition) {
// Seek backwards into the cache
mCache.seek(pPosition);
}
// System.out.println("pPosition: " + pPosition);
// System.out.println("mStreamPosition: " + mStreamPosition);
// System.out.println("mCache.getFilePointer(): " + mCache.getFilePointer());
// NOTE: If mPosition == pPosition then we're good to go
}
*/
final static class FileCache extends StreamCache {
private RandomAccessFile mCacheFile;
public FileCache(final File pFile) throws FileNotFoundException {
Validate.notNull(pFile, "file");
mCacheFile = new RandomAccessFile(pFile, "rw");
}
public void write(final int pByte) throws IOException {
mCacheFile.write(pByte);
}
@Override
public void write(final byte[] pBuffer, final int pOffset, final int pLength) throws IOException {
mCacheFile.write(pBuffer, pOffset, pLength);
}
public int read() throws IOException {
return mCacheFile.read();
}
@Override
public int read(final byte[] pBuffer, final int pOffset, final int pLength) throws IOException {
return mCacheFile.read(pBuffer, pOffset, pLength);
}
public void seek(final long pPosition) throws IOException {
mCacheFile.seek(pPosition);
}
public long getPosition() throws IOException {
return mCacheFile.getFilePointer();
}
}
}
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