/* This file is part of VoltDB.
* Copyright (C) 2008-2010 VoltDB Inc.
*
* This file contains original code and/or modifications of original code.
* Any modifications made by VoltDB Inc. are licensed under the following
* terms and conditions:
*
* VoltDB is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* VoltDB is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with VoltDB. If not, see <http://www.gnu.org/licenses/>.
*/
/* Copyright (C) 2008
* Evan Jones
* Massachusetts Institute of Technology
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
* IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
package org.voltdb.network;
import java.io.IOException;
import java.nio.channels.ReadableByteChannel;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicLong;
import java.util.ArrayDeque;
import org.voltdb.utils.DBBPool;
import org.voltdb.utils.DBBPool.BBContainer;
/**
Provides a non-blocking stream-like interface on top of the Java NIO ReadableByteChannel. It calls
the underlying read() method only when needed.
*/
public class NIOReadStream {
NIOReadStream() {
m_numReadStreams.incrementAndGet();
}
/** @returns the number of bytes available to be read. */
int dataAvailable() {
return m_totalAvailable;
}
int getInt() {
// TODO: Optimize?
byte[] intbytes = new byte[4];
getBytes(intbytes);
int output = 0;
for (int i = 0; i < intbytes.length; ++i) {
output <<= 8;
output |= (intbytes[i]) & 0xff;
}
return output;
}
void getBytes(byte[] output) {
if (m_totalAvailable < output.length) {
throw new IllegalStateException("Requested " + output.length + " bytes; only have "
+ m_totalAvailable + " bytes; call tryRead() first");
}
int bytesCopied = 0;
while (bytesCopied < output.length) {
BBContainer first = m_readBuffers.peekFirst();
if (first == null) {
// Steal the write buffer
m_writeBuffer.b.flip();
m_readBuffers.add(m_writeBuffer);
first = m_writeBuffer;
m_writeBuffer = null;
}
assert first.b.remaining() > 0;
// Copy bytes from first into output
int bytesRemaining = first.b.remaining();
int bytesToCopy = output.length - bytesCopied;
if (bytesToCopy > bytesRemaining) bytesToCopy = bytesRemaining;
first.b.get(output, bytesCopied, bytesToCopy);
bytesCopied += bytesToCopy;
m_totalAvailable -= bytesToCopy;
if (first.b.remaining() == 0) {
// read an entire block: move it to the empty buffers list
m_readBuffers.poll();
first.discard();
}
}
if (bytesCopied > 0) {
m_globalAvailable.addAndGet(0 - bytesCopied);
}
}
/**
* Read at most maxBytes from the network. Will read until the network would
* block, the stream is closed or the maximum bytes to read is reached.
* @param maxBytes
* @return -1 if closed otherwise total buffered bytes. In all cases,
* data may be buffered in the stream - even when the channel is closed.
*/
final int read(ReadableByteChannel channel, int maxBytes, final DBBPool pool) throws IOException {
int bytesRead = 0;
int lastRead = 1;
try {
while (bytesRead < maxBytes && lastRead > 0) {
if (m_writeBuffer == null) {
m_writeBuffer = pool.acquire(BUFFER_SIZE);
}
lastRead = channel.read(m_writeBuffer.b);
// EOF, no data read
if (lastRead < 0 && bytesRead == 0) {
if (m_writeBuffer.b.position() == 0) {
m_writeBuffer.discard();
m_writeBuffer = null;
}
return -1;
}
//Data read
if (lastRead > 0) {
bytesRead += lastRead;
if (!m_writeBuffer.b.hasRemaining()) {
m_writeBuffer.b.flip();
m_readBuffers.add(m_writeBuffer);
m_writeBuffer = null;
} else {
break;
}
}
}
} finally {
if (bytesRead > 0) {
m_globalAvailable.addAndGet(bytesRead);
m_bytesRead.addAndGet(bytesRead);
m_totalAvailable += bytesRead;
}
}
return bytesRead;
}
void shutdown() {
for (BBContainer c : m_readBuffers) {
c.discard();
}
if (m_writeBuffer != null) {
m_writeBuffer.discard();
}
m_readBuffers.clear();
m_writeBuffer = null;
m_numReadStreams.decrementAndGet();
}
static final int BUFFER_SIZE = 8192;
private final ArrayDeque<BBContainer> m_readBuffers = new ArrayDeque<BBContainer>();
private BBContainer m_writeBuffer = null;
private int m_totalAvailable = 0;
private AtomicInteger m_globalAvailable = new AtomicInteger(0);
private AtomicInteger m_numReadStreams = new AtomicInteger(0);
private AtomicLong m_bytesRead = new AtomicLong();
private long m_lastBytesRead = 0;
long getBytesRead(boolean interval) {
if (interval) {
final long bytesRead = m_bytesRead.get();
final long bytesReadThisTime = bytesRead - m_lastBytesRead;
m_lastBytesRead = bytesRead;
return bytesReadThisTime;
} else {
return m_bytesRead.get();
}
}
}