forked from voldemort/voldemort
/
ByteBufferBackedOutputStream.java
123 lines (103 loc) · 3.69 KB
/
ByteBufferBackedOutputStream.java
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/*
* Copyright 2009 Mustard Grain, Inc
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package voldemort.common.nio;
import java.io.IOException;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import org.apache.commons.lang.mutable.MutableLong;
import voldemort.annotations.concurrency.NotThreadsafe;
import voldemort.utils.ByteUtils;
/**
* ByteBufferBackedOutputStream serves two purposes:
* <ol>
* <li>It allows a ByteBuffer to be the source of data for OutputStream-based
* callers
* <li>It expands the underlying buffer to accommodate incoming data
* </ol>
* This class is used to interface with callers using "classic" java.io.* APIs.
* This OutputStream provides the means to grow the buffer on demand as more
* data is written by those callers. For code that manages the
* ByteBufferBackedOutputStream, there are accessor methods for the underlying
* buffer as the object reference passed into the constructor is changed upon
* expansion. Additionally, some callers might wish to "un-expand" the buffer
* back to a more reasonable size after use.
*
*/
@NotThreadsafe
public class ByteBufferBackedOutputStream extends OutputStream {
private ByteBuffer buffer;
private boolean wasExpanded;
/**
* Reference to a size tracking object, that tracks the size of the buffer
* in bytes
*/
private MutableLong sizeTracker;
public ByteBufferBackedOutputStream(ByteBuffer buffer) {
this.buffer = buffer;
wasExpanded = false;
this.sizeTracker = null;
}
public ByteBufferBackedOutputStream(ByteBuffer buffer, MutableLong sizeTracker) {
this.buffer = buffer;
wasExpanded = false;
this.sizeTracker = sizeTracker;
if(buffer != null)
this.sizeTracker.add(buffer.capacity());
}
public ByteBuffer getBuffer() {
return buffer;
}
public void setBuffer(ByteBuffer newBuffer) {
// update the size tracker with the new buffer size
if((sizeTracker != null && this.buffer != null && newBuffer != null)) {
sizeTracker.add(newBuffer.capacity());
sizeTracker.subtract(this.buffer.capacity());
}
this.buffer = newBuffer;
wasExpanded = false;
}
@Override
public void write(int b) throws IOException {
expandIfNeeded(1);
buffer.put((byte) b);
}
@Override
public void write(byte[] bytes, int off, int len) throws IOException {
expandIfNeeded(len);
buffer.put(bytes, off, len);
}
private void expandIfNeeded(int len) {
int need = len - buffer.remaining();
if(need <= 0)
return;
int newCapacity = (buffer.capacity() + need) * 2;
// update the size tracker with the new buffer size
if(sizeTracker != null) {
sizeTracker.add(newCapacity);
sizeTracker.subtract(this.buffer.capacity());
}
buffer = ByteUtils.expand(buffer, newCapacity);
wasExpanded = true;
}
public boolean wasExpanded() {
return wasExpanded;
}
public void close() {
if(sizeTracker != null && this.buffer != null) {
sizeTracker.subtract(this.buffer.capacity());
}
}
}