/**
* Copyright (C) 2009-2013 Barchart, Inc. <http://www.barchart.com/>
*
* All rights reserved. Licensed under the OSI BSD License.
*
* http://www.opensource.org/licenses/bsd-license.php
*/
package com.barchart.udt.nio;
import static com.barchart.udt.SocketUDT.*;
import java.io.IOException;
import java.nio.IntBuffer;
import java.nio.channels.ClosedSelectorException;
import java.nio.channels.IllegalSelectorException;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.spi.AbstractSelectableChannel;
import java.nio.channels.spi.AbstractSelector;
import java.nio.channels.spi.SelectorProvider;
import java.util.Iterator;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.barchart.udt.EpollUDT;
import com.barchart.udt.ExceptionUDT;
import com.barchart.udt.SocketUDT;
import com.barchart.udt.TypeUDT;
import com.barchart.udt.util.HelpUDT;
/**
* selector
* <p>
* design guidelines:
* <p>
* 1) follow general contracts of jdk 6 nio; see <a href=
* "https://github.com/barchart/barchart-udt/tree/master/barchart-udt-reference-jdk6"
* >barchart-udt-reference-jdk6</a>
* <p>
* 2) adapt to how netty is doing select; see <a href=
* "https://github.com/netty/netty/blob/master/transport/src/main/java/io/netty/channel/socket/nio/NioEventLoop.java"
* >NioEventLoop</a>
* <p>
* note: you must use {@link SelectorProviderUDT#openSelector()} to obtain
* instance of this class; do not use JDK
* {@link java.nio.channels.Selector#open()}
*/
public class SelectorUDT extends AbstractSelector {
protected static final Logger log = LoggerFactory
.getLogger(SelectorUDT.class);
/**
* use this call to instantiate a selector for UDT
*/
protected static Selector open(final TypeUDT type) throws IOException {
final SelectorProviderUDT provider;
switch (type) {
case DATAGRAM:
provider = SelectorProviderUDT.DATAGRAM;
break;
case STREAM:
provider = SelectorProviderUDT.STREAM;
break;
default:
log.error("unsupported type={}", type);
throw new IOException("unsupported type");
}
return provider.openSelector();
}
private final EpollUDT epollUDT = new EpollUDT();
/**
*/
public final int maximimSelectorSize;
/**
* list of epoll sockets with read interest
*/
private final IntBuffer readBuffer;
/**
* [ socket-id : selection-key ]
*/
private final ConcurrentMap<Integer, SelectionKeyUDT> //
registeredKeyMap = new ConcurrentHashMap<Integer, SelectionKeyUDT>();
/**
* public view : immutable
*/
private final Set<? extends SelectionKey> //
registeredKeySet = HelpUDT.unmodifiableSet(registeredKeyMap.values());
/**
* tracks correlation read with write for the same key
*/
private volatile int resultIndex;
/**
* set of keys with data ready for an operation
*/
private final ConcurrentMap<SelectionKeyUDT, SelectionKeyUDT> //
selectedKeyMap = new ConcurrentHashMap<SelectionKeyUDT, SelectionKeyUDT>();
/**
* public view : removal allowed, but not addition
*/
private final Set<? extends SelectionKey> //
selectedKeySet = HelpUDT.ungrowableSet(selectedKeyMap.keySet());
/** select is exclusive */
private final Lock selectLock = new ReentrantLock();
/** reported epoll socket list sizes */
private final IntBuffer sizeBuffer;
/**
* Canceled keys.
*/
private final ConcurrentMap<SelectionKeyUDT, SelectionKeyUDT> //
terminatedKeyMap = new ConcurrentHashMap<SelectionKeyUDT, SelectionKeyUDT>();
/** guarded by {@link #doSelectLocked} */
private volatile int wakeupBaseCount;
private volatile int wakeupStepCount;
/** list of epoll sockets with write interest */
private final IntBuffer writeBuffer;
protected SelectorUDT( //
final SelectorProvider provider, //
final int maximumSelectorSize //
) throws ExceptionUDT {
super(provider);
this.maximimSelectorSize = maximumSelectorSize;
readBuffer = HelpUDT.newDirectIntBufer(maximumSelectorSize);
writeBuffer = HelpUDT.newDirectIntBufer(maximumSelectorSize);
sizeBuffer = HelpUDT.newDirectIntBufer(UDT_SIZE_COUNT);
}
/**
* Enqueue cancel request.
*/
protected void cancel(final SelectionKeyUDT keyUDT) {
terminatedKeyMap.putIfAbsent(keyUDT, keyUDT);
}
/**
* Process pending cancel requests.
*/
protected void doCancel() {
if (terminatedKeyMap.isEmpty()) {
return;
}
final Iterator<SelectionKeyUDT> iterator = terminatedKeyMap.values()
.iterator();
while (iterator.hasNext()) {
final SelectionKeyUDT keyUDT = iterator.next();
iterator.remove();
if (keyUDT.isValid()) {
keyUDT.makeValid(false);
registeredKeyMap.remove(keyUDT.socketId());
}
}
}
/**
* @param millisTimeout
* <0 : invinite; =0 : immediate; >0 : finite;
*/
protected int doEpollEnter(final long millisTimeout) throws IOException {
if (!isOpen()) {
log.error("slector is closed");
throw new ClosedSelectorException();
}
try {
selectLock.lock();
return doEpollExclusive(millisTimeout);
} finally {
selectLock.unlock();
}
}
/**
* @param millisTimeout
*
* <0 : invinite;
*
* =0 : immediate;
*
* >0 : finite;
* @return
*
* <0 : should not happen
*
* =0 : means nothing was selected/timeout
*
* >0 : number of selected keys
*/
protected int doEpollExclusive(final long millisTimeout) throws IOException {
try {
/** java.nio.Selector contract for wakeup() */
// begin();
/** pre select */
doCancel();
/** select proper */
doEpollSelect(millisTimeout);
/** post select */
doResults();
} finally {
/** java.nio.Selector contract for wakeup() */
// end();
}
return selectedKeyMap.size();
}
/**
* @param millisTimeout
*
* <0 : infinite
*
* =0 : immediate
*
* >0 : finite
*/
protected int doEpollSelect(long millisTimeout) throws ExceptionUDT {
wakeupMarkBase();
int readyCount = 0;
if (millisTimeout < 0) {
/** infinite: do select in slices; check for wakeup; */
do {
readyCount = doEpollSelectUDT(DEFAULT_MIN_SELECTOR_TIMEOUT);
if (readyCount > 0 || wakeupIsPending()) {
break;
}
} while (true);
} else if (millisTimeout > 0) {
/** finite: do select in slices; check for wakeup; count down */
do {
readyCount = doEpollSelectUDT(DEFAULT_MIN_SELECTOR_TIMEOUT);
if (readyCount > 0 || wakeupIsPending()) {
break;
}
millisTimeout -= DEFAULT_MIN_SELECTOR_TIMEOUT;
} while (millisTimeout > 0);
} else {
/** immediate */
readyCount = doEpollSelectUDT(0);
}
return readyCount;
}
protected int doEpollSelectUDT(final long timeout) throws ExceptionUDT {
return SocketUDT.selectEpoll(//
epollUDT.id(), //
readBuffer, //
writeBuffer, //
sizeBuffer, //
timeout //
);
}
protected void doResults() {
final int resultIndex = this.resultIndex++;
doResultsRead(resultIndex);
doResultsWrite(resultIndex);
}
protected void doResultsRead(final int resultIndex) {
final int readSize = sizeBuffer.get(UDT_READ_INDEX);
for (int index = 0; index < readSize; index++) {
final int socketId = readBuffer.get(index);
final SelectionKeyUDT keyUDT = registeredKeyMap.get(socketId);
/**
* Epoll will report closed socket once in both read and write sets.
* But selector consumer may cancel the key before close.
*/
if (keyUDT == null) {
logSocketId("missing from read ", socketId);
continue;
}
if (keyUDT.doRead(resultIndex)) {
selectedKeyMap.putIfAbsent(keyUDT, keyUDT);
}
}
}
protected void doResultsWrite(final int resultIndex) {
final int writeSize = sizeBuffer.get(UDT_WRITE_INDEX);
for (int index = 0; index < writeSize; index++) {
final int socketId = writeBuffer.get(index);
final SelectionKeyUDT keyUDT = registeredKeyMap.get(socketId);
/**
* Epoll will report closed socket once in both read and write sets.
* But selector consumer may cancel the key before close.
*/
if (keyUDT == null) {
logSocketId("missing from write", socketId);
continue;
}
if (keyUDT.doWrite(resultIndex)) {
selectedKeyMap.putIfAbsent(keyUDT, keyUDT);
}
}
}
protected EpollUDT epollUDT() {
return epollUDT;
}
@Override
protected void implCloseSelector() throws IOException {
wakeup();
try {
selectLock.lock();
for (final SelectionKeyUDT keyUDT : registeredKeyMap.values()) {
cancel(keyUDT);
}
} finally {
selectLock.unlock();
}
doCancel();
}
@SuppressWarnings("unchecked")
@Override
public Set<SelectionKey> keys() {
if (!isOpen()) {
throw new ClosedSelectorException();
}
return (Set<SelectionKey>) registeredKeySet;
}
protected void logSocketId(final String title, final int socketId) {
if (log.isDebugEnabled()) {
log.debug("{} {}", title, String.format("[id: 0x%08x]", socketId));
}
}
/**
*/
@Override
protected SelectionKey register( //
final AbstractSelectableChannel channel, //
final int interestOps, //
final Object attachment //
) {
if (registeredKeyMap.size() >= maximimSelectorSize) {
log.error("reached maximimSelectorSize");
throw new IllegalSelectorException();
}
if (!(channel instanceof ChannelUDT)) {
log.error("!(channel instanceof ChannelUDT)");
throw new IllegalSelectorException();
}
final ChannelUDT channelUDT = (ChannelUDT) channel;
final Integer socketId = channelUDT.socketUDT().id();
SelectionKeyUDT keyUDT = registeredKeyMap.get(socketId);
if (keyUDT == null) {
keyUDT = new SelectionKeyUDT(this, channelUDT, attachment);
registeredKeyMap.putIfAbsent(socketId, keyUDT);
keyUDT = registeredKeyMap.get(socketId);
}
keyUDT.interestOps(interestOps);
return keyUDT;
}
@Override
public int select() throws IOException {
return select(0);
}
@Override
public int select(final long timeout) throws IOException {
if (timeout < 0) {
throw new IllegalArgumentException("negative timeout");
} else if (timeout > 0) {
return doEpollEnter(timeout);
} else {
return doEpollEnter(SocketUDT.TIMEOUT_INFINITE);
}
}
@SuppressWarnings("unchecked")
@Override
public Set<SelectionKey> selectedKeys() {
if (!isOpen()) {
throw new ClosedSelectorException();
}
return (Set<SelectionKey>) selectedKeySet;
}
@Override
public int selectNow() throws IOException {
return doEpollEnter(SocketUDT.TIMEOUT_NONE);
}
@Override
public Selector wakeup() {
wakeupStepCount++;
return this;
}
protected boolean wakeupIsPending() {
return wakeupBaseCount != wakeupStepCount;
}
protected void wakeupMarkBase() {
wakeupBaseCount = wakeupStepCount;
}
}