/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.hadoop.hbase.io;
import java.io.IOException;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.List;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hbase.classification.InterfaceAudience;
import org.apache.hadoop.hbase.util.ByteBufferUtils;
/**
* An OutputStream which writes data into ByteBuffers. It will try to get ByteBuffer, as and when
* needed, from the passed pool. When pool is not giving a ByteBuffer it will create one on heap.
* Make sure to call {@link #releaseResources()} method once the Stream usage is over and
* data is transferred to the wanted destination.
* Not thread safe!
*/
@InterfaceAudience.Private
public class ByteBufferListOutputStream extends ByteBufferOutputStream {
private static final Log LOG = LogFactory.getLog(ByteBufferListOutputStream.class);
private ByteBufferPool pool;
// Keep track of the BBs where bytes written to. We will first try to get a BB from the pool. If
// it is not available will make a new one our own and keep writing to that. We keep track of all
// the BBs that we got from pool, separately so that on closeAndPutbackBuffers, we can make sure
// to return back all of them to pool
protected List<ByteBuffer> allBufs = new ArrayList<>();
protected List<ByteBuffer> bufsFromPool = new ArrayList<>();
private boolean lastBufFlipped = false;// Indicate whether the curBuf/lastBuf is flipped already
public ByteBufferListOutputStream(ByteBufferPool pool) {
this.pool = pool;
allocateNewBuffer();
}
private void allocateNewBuffer() {
if (this.curBuf != null) {
this.curBuf.flip();// On the current buf set limit = pos and pos = 0.
}
// Get an initial BB to work with from the pool
this.curBuf = this.pool.getBuffer();
if (this.curBuf == null) {
// No free BB at this moment. Make a new one. The pool returns off heap BBs. Don't make off
// heap BB on demand. It is difficult to account for all such and so proper sizing of Max
// direct heap size. See HBASE-15525 also for more details.
// Make BB with same size of pool's buffer size.
this.curBuf = ByteBuffer.allocate(this.pool.getBufferSize());
} else {
this.bufsFromPool.add(this.curBuf);
}
this.allBufs.add(this.curBuf);
}
@Override
public int size() {
int s = 0;
for (int i = 0; i < this.allBufs.size() - 1; i++) {
s += this.allBufs.get(i).remaining();
}
// On the last BB, it might not be flipped yet if getByteBuffers is not yet called
if (this.lastBufFlipped) {
s += this.curBuf.remaining();
} else {
s += this.curBuf.position();
}
return s;
}
@Override
public ByteBuffer getByteBuffer() {
throw new UnsupportedOperationException("This stream is not backed by a single ByteBuffer");
}
@Override
protected void checkSizeAndGrow(int extra) {
long capacityNeeded = curBuf.position() + (long) extra;
if (capacityNeeded > curBuf.limit()) {
allocateNewBuffer();
}
}
@Override
public void writeTo(OutputStream out) throws IOException {
// No usage of this API in code. Just making it as an Unsupported operation as of now
throw new UnsupportedOperationException();
}
/**
* Release the resources it uses (The ByteBuffers) which are obtained from pool. Call this only
* when all the data is fully used. And it must be called at the end of usage else we will leak
* ByteBuffers from pool.
*/
public void releaseResources() {
try {
close();
} catch (IOException e) {
LOG.debug(e);
}
// Return back all the BBs to pool
if (this.bufsFromPool != null) {
for (int i = 0; i < this.bufsFromPool.size(); i++) {
this.pool.putbackBuffer(this.bufsFromPool.get(i));
}
this.bufsFromPool = null;
}
this.allBufs = null;
this.curBuf = null;
}
@Override
public byte[] toByteArray(int offset, int length) {
// No usage of this API in code. Just making it as an Unsupported operation as of now
throw new UnsupportedOperationException();
}
/**
* We can be assured that the buffers returned by this method are all flipped
* @return list of bytebuffers
*/
public List<ByteBuffer> getByteBuffers() {
if (!this.lastBufFlipped) {
this.lastBufFlipped = true;
// All the other BBs are already flipped while moving to the new BB.
curBuf.flip();
}
return this.allBufs;
}
@Override
public void write(byte[] b, int off, int len) throws IOException {
int toWrite = 0;
while (len > 0) {
toWrite = Math.min(len, this.curBuf.remaining());
ByteBufferUtils.copyFromArrayToBuffer(this.curBuf, b, off, toWrite);
off += toWrite;
len -= toWrite;
if (len > 0) {
allocateNewBuffer();// The curBuf is over. Let us move to the next one
}
}
}
@Override
public void write(ByteBuffer b, int off, int len) throws IOException {
int toWrite = 0;
while (len > 0) {
toWrite = Math.min(len, this.curBuf.remaining());
ByteBufferUtils.copyFromBufferToBuffer(b, this.curBuf, off, toWrite);
off += toWrite;
len -= toWrite;
if (len > 0) {
allocateNewBuffer();// The curBuf is over. Let us move to the next one
}
}
}
}