com.twelvemonkeys.io.MemoryCacheSeekableStream 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 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 java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;
/**
* A {@code SeekableInputStream} implementation that caches data in memory.
*
* @see FileCacheSeekableStream
*
* @author Harald Kuhr
* @version $Id: //depot/branches/personal/haraldk/twelvemonkeys/release-2/twelvemonkeys-core/src/main/java/com/twelvemonkeys/io/MemoryCacheSeekableStream.java#3 $
*/
public final class MemoryCacheSeekableStream extends AbstractCachedSeekableStream {
/**
* Creates a {@code MemoryCacheSeekableStream}, reading from the given
* {@code InputStream}. Data will be cached in memory.
*
* @param pStream the {@code InputStream} to read from.
*/
public MemoryCacheSeekableStream(final InputStream pStream) {
super(pStream, new MemoryCache());
}
public final boolean isCachedMemory() {
return true;
}
public final boolean isCachedFile() {
return false;
}
final static class MemoryCache extends StreamCache {
final static int BLOCK_SIZE = 1 << 13;
private final List cache = new ArrayList<>();
private long length;
private long position;
private long start;
private byte[] getBlock() throws IOException {
final long currPos = position - start;
if (currPos < 0) {
throw new IOException("StreamCache flushed before read position");
}
long index = currPos / BLOCK_SIZE;
if (index >= Integer.MAX_VALUE) {
throw new IOException("Memory cache max size exceeded");
}
if (index >= cache.size()) {
try {
cache.add(new byte[BLOCK_SIZE]);
// System.out.println("Allocating new block, size: " + BLOCK_SIZE);
// System.out.println("New total size: " + cache.size() * BLOCK_SIZE + " (" + cache.size() + " blocks)");
}
catch (OutOfMemoryError e) {
throw new IOException("No more memory for cache: " + cache.size() * BLOCK_SIZE);
}
}
//System.out.println("index: " + index);
return cache.get((int) index);
}
public void write(final int pByte) throws IOException {
byte[] buffer = getBlock();
int idx = (int) (position % BLOCK_SIZE);
buffer[idx] = (byte) pByte;
position++;
if (position > length) {
length = position;
}
}
// TODO: OptimizeMe!!!
@Override
public void write(final byte[] pBuffer, final int pOffset, final int pLength) throws IOException {
byte[] buffer = getBlock();
for (int i = 0; i < pLength; i++) {
int index = (int) position % BLOCK_SIZE;
if (index == 0) {
buffer = getBlock();
}
buffer[index] = pBuffer[pOffset + i];
position++;
}
if (position > length) {
length = position;
}
}
public int read() throws IOException {
if (position >= length) {
return -1;
}
byte[] buffer = getBlock();
int idx = (int) (position % BLOCK_SIZE);
position++;
return buffer[idx] & 0xff;
}
// TODO: OptimizeMe!!!
@Override
public int read(final byte[] pBytes, final int pOffset, final int pLength) throws IOException {
if (position >= length) {
return -1;
}
byte[] buffer = getBlock();
int bufferPos = (int) (position % BLOCK_SIZE);
// Find maxIdx and simplify test in for-loop
int maxLen = (int) Math.min(Math.min(pLength, buffer.length - bufferPos), length - position);
int i;
//for (i = 0; i < pLength && i < buffer.length - idx && i < length - position; i++) {
for (i = 0; i < maxLen; i++) {
pBytes[pOffset + i] = buffer[bufferPos + i];
}
position += i;
return i;
}
public void seek(final long pPosition) throws IOException {
if (pPosition < start) {
throw new IOException("Seek before flush position");
}
position = pPosition;
}
@Override
public void flush(final long pPosition) {
int firstPos = (int) (pPosition / BLOCK_SIZE) - 1;
for (int i = 0; i < firstPos; i++) {
cache.remove(0);
}
start = pPosition;
}
@Override
void close() throws IOException {
cache.clear();
}
public long getPosition() {
return position;
}
}
}