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package com.sun.enterprise.web.connector.grizzly.comet;
import com.sun.enterprise.web.connector.grizzly.SelectorThread;
import com.sun.enterprise.web.connector.grizzly.NioProvider;
import java.io.IOException;
import java.nio.channels.CancelledKeyException;
import java.nio.channels.SelectableChannel;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.Map.Entry;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.CountDownLatch;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* NIO {@link Selector} allowing {@link CometHandler} to receive
* non-blocking requests bytes during request polling.
*
* @author Jeanfrancois Arcand
*/
public class CometSelector {
// Workaround for Issue 555
private long lastSpinTimestamp;
private int emptySpinCounter;
/**
* The threshold for detecting selector.select spin on linux,
* used for enabling workaround to prevent server from hanging.
*/
private final static int spinRateTreshold = 2000;
/**
* Enable workaround Linux spinning Selector
*/
static final boolean isLinux =
System.getProperty("os.name").equalsIgnoreCase("linux") &&
!System.getProperty("java.version").startsWith("1.7");
/**
* The {@link CometEngine} singleton
*/
protected CometEngine cometEngine;
/**
* The {@link Selector}
*/
private Selector selector;
/**
* Logger.
*/
private Logger logger = SelectorThread.logger();
/**
* The list of {@link SelectionKey} to register with the
* {@link Selector}
*/
private ConcurrentHashMap<SelectionKey,CometTask> keysToRegister
= new ConcurrentHashMap<SelectionKey,CometTask>();
/**
* New {@link CometSelector}
* @param cometEngine The {@link CometEngine} singleton
*/
public CometSelector(CometEngine cometEngine) {
this.cometEngine = cometEngine;
}
/**
* Start the {@link Selector} running on its
* Thread.
*/
public void start() throws InterruptedException{
final CountDownLatch isStartedLatch = new CountDownLatch(1);
new Thread("CometSelector"){
{
setDaemon(true);
}
@Override
public void run(){
try{
selector = Selector.open();
} catch(IOException ex){
// Most probably a fd leak.
logger.log(Level.SEVERE,"CometSelector.open()",ex);
return;
}
isStartedLatch.countDown();
while (true){
SelectionKey key = null;
Set readyKeys;
Iterator<SelectionKey> iterator;
int selectorState = 0;
try{
selectorState = 0;
try{
selectorState = selector.select(1000);
} catch (CancelledKeyException ex){
if (logger.isLoggable(Level.FINEST)){
logger.log(Level.FINEST,"CometSelector.open()",ex);
}
}
readyKeys = selector.selectedKeys();
// JDK issue.
if (readyKeys.size() != 0 && isLinux) {
resetSpinCounter();
} else if (isLinux){
long sr = getSpinRate();
if (sr > spinRateTreshold) {
workaroundSelectorSpin();
}
}
iterator = readyKeys.iterator();
CometTask cometTask;
while (iterator.hasNext()) {
key = iterator.next();
iterator.remove();
try {
if (key.isValid()) {
cometTask = (CometTask) key.attachment();
if (key.isReadable()) {
key.interestOps(key.interestOps() &
(~SelectionKey.OP_READ));
cometTask.upcoming_op =
CometTask.OP_EVENT.READ;
}
if (key.isWritable()) {
key.interestOps(key.interestOps() &
(~SelectionKey.OP_WRITE));
cometTask.upcoming_op =
CometTask.OP_EVENT.WRITE;
}
if (cometTask != null &&
cometTask.getSelectionKey() != null &&
cometTask.getSelectionKey().attachment() == null) {
cometTask.execute();
} else {
key.cancel();
}
} else {
cancelKey(key);
}
} catch (Exception e) {
try {
cancelKey(key);
} catch (Exception ee) {
logger.log(Level.SEVERE, "CometSelector", ee);
}
}
}
Iterator<Entry<SelectionKey, CometTask>> entries =
keysToRegister.entrySet().iterator();
/**
* The mainKey is the SelectionKey returned by the
* Selector used in the SelectorThread class.
*/
SelectionKey mainKey;
SocketChannel channel;
while (entries.hasNext()) {
final Entry<SelectionKey, CometTask> entry = entries.next();
entries.remove();
mainKey = entry.getKey();
cometTask = entry.getValue();
try {
channel = (SocketChannel) mainKey.channel();
if (mainKey.isValid() && channel.isOpen()) {
key = channel.register(selector,
SelectionKey.OP_READ);
cometTask.setCometKey(key);
key.attach(cometTask);
} else {
cancelCometTask(cometTask);
}
} catch (Exception e) {
cancelCometTask(cometTask);
}
}
expireIdleKeys();
if (selectorState <= 0){
selector.selectedKeys().clear();
}
} catch (Throwable t){
if (key != null){
try{
cancelKey(key);
} catch (Throwable t2){
logger.log(Level.SEVERE,"CometSelector",t2);
}
}
if (selectorState <= 0){
selector.selectedKeys().clear();
}
if (logger.isLoggable(Level.FINEST)){
logger.log(Level.FINEST,"CometSelector",t);
}
}
}
}
}.start();
isStartedLatch.await();
}
/**
* Expires registered {@link SelectionKey}. If a
* {@link SelectionKey} is expired, the request will be resumed and the
* HTTP request will complete,
*/
protected void expireIdleKeys(){
Set<SelectionKey> readyKeys = selector.keys();
if (readyKeys.isEmpty()){
return;
}
long current = System.currentTimeMillis();
Iterator<SelectionKey> iterator = readyKeys.iterator();
SelectionKey key;
while (iterator.hasNext()) {
key = iterator.next();
try {
final CometTask cometTask = (CometTask) key.attachment();
if (cometTask == null) {
continue;
}
if (cometTask.getExpirationDelay() == -1) {
continue;
}
final long expire = cometTask.getExpireTime();
if (current - expire >= cometTask.getExpirationDelay()) {
cancelKey(key);
}
/**
* The connection has been resumed since the timeout is
* re-attached to the SelectionKey so cancel the Comet key.
*/
if (cometTask.getSelectionKey() != null &&
cometTask.getSelectionKey().attachment() instanceof Long) {
key.cancel();
cometEngine.interrupt(key);
}
} catch (Exception e) {
cancelKey(key);
}
}
}
/**
* Cancel a {@link SelectionKey}, and delegate the request
* polling interruption to the {@link CometEngine}
* @param key the expired {@link SelectionKey}
*/
protected synchronized void cancelKey(SelectionKey key){
if (key == null) return;
try{
CometTask cometTask = (CometTask)key.attachment();
if (cometTask != null){
cancelCometTask(cometTask);
} else {
cometEngine.interrupt(key);
}
} catch (Throwable t) {
logger.log(Level.SEVERE,"CometSelector",t);
} finally {
key.attach(null);
}
key.cancel();
}
protected synchronized void cancelCometTask(CometTask cometTask){
if (cometTask == null) return;
try{
SelectorThread st = cometTask.getSelectorThread();
SelectionKey mainKey = cometTask.getSelectionKey();
if (cometTask.getCometContext() != null) {
cometTask.getCometContext().interrupt(cometTask);
}
cometEngine.interrupt(cometTask);
st.cancelKey(mainKey);
} catch (Throwable t) {
logger.log(Level.SEVERE,"CometSelector",t);
}
}
/**
* Register the {@link SelectionKey} to the {@link Selector}. We
* cannot register the {@link SelectionKey} directy on the
* {@link Selector} because there is a deadlock in the VM (see bug XXX).
*/
public void registerKey(SelectionKey key, CometTask cometTask){
if (key == null || cometTask == null || !key.isValid() || selector == null) return;
cometTask.setExpireTime(System.currentTimeMillis());
keysToRegister.put(key, cometTask);
selector.wakeup();
}
/**
* Wakes up the {@link Selector}
*/
public void wakeup(){
selector.wakeup();
}
/**
* Return the SelectionKey associated with this channel.
*/
public SelectionKey cometKeyFor(SelectableChannel channel){
NioProvider nioP = NioProvider.getProvider();
if (nioP == null) {
return channel.keyFor(selector);
} else {
return nioP.keyFor(channel, selector);
}
}
public void resetSpinCounter(){
emptySpinCounter = 0;
}
public int getSpinRate(){
if (emptySpinCounter++ == 0){
lastSpinTimestamp = System.nanoTime();
} else if (emptySpinCounter == 1000) {
long deltatime = System.nanoTime() - lastSpinTimestamp;
int contspinspersec = (int) (1000 * 1000000000L / deltatime);
emptySpinCounter = 0;
return contspinspersec;
}
return 0;
}
private void workaroundSelectorSpin() throws IOException {
Selector newSelector = Selector.open();
Set<SelectionKey> keys = selector.keys();
for (SelectionKey key : keys) {
try {
key.channel().register(newSelector, key.interestOps(), key.attachment());
} catch (Exception e) {
}
}
try {
selector.close();
} catch (Exception e) {
}
selector = newSelector;
}
}