com.sun.grizzly.comet.CometSelector Maven / Gradle / Ivy
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package com.sun.grizzly.comet;
import com.sun.grizzly.http.SelectorThread;
import com.sun.grizzly.util.LinkedTransferQueue;
import java.io.IOException;
import java.nio.ByteBuffer;
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.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.
*
* TODO: investigate if its possible to move this functionality to grizzly main
* selector inorder to lower the extra overhead this 2nd selector is.
*
* @author Jeanfrancois Arcand
* @author Gustav Trede
*/
public class CometSelector {
/**
* The {@link CometEngine} singleton
*/
protected final CometEngine cometEngine;
/**
* The {@link Selector}
*/
private Selector selector;
/**
* timestamp when last expireIdleKeys() performed its check
*/
private long lastIdleCheck;
/**
* Logger.
*/
private final Logger logger = SelectorThread.logger();
/**
*
*/
private final ByteBuffer dumybuffer = ByteBuffer.allocate(1);
/**
* The list of {@link SelectionKey} to register with the
* {@link Selector}
* TODO: replace with LinkedTransferQueue
*/
private final LinkedTransferQueue keysToRegister
= new LinkedTransferQueue();
/**
* 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();
doSelection();
}
}.start();
isStartedLatch.await();
}
/**
* the selection logic
*/
private void doSelection(){
while (true){
int selectorState = 0;
try{
try{
selectorState = selector.select(1000);
} catch (CancelledKeyException ex){
if (logger.isLoggable(Level.FINEST)){
logger.log(Level.FINEST,"CometSelector.open()",ex);
}
}
handleSelectedKeys();
expireIdleKeys();
registerNewKeys();
} catch (Throwable t){
handleException(t,null);
}finally{
if (selectorState <= 0){ //todo why is this needed ?
selector.selectedKeys().clear();
}
}
}
}
/**
* handle the selected keys
*/
private void handleSelectedKeys(){
for (SelectionKey cometKey:selector.selectedKeys()) {
try{
if (cometKey.isValid()) {
CometTask cometTask = (CometTask)cometKey.attachment();
boolean asyncExec = cometTask.isComethandlerisAsyncregistered();
if (asyncExec){
cometTask.setComethandlerisAsyncregistered(false);
if (cometKey.isReadable()){
cometKey.interestOps(cometKey.interestOps() & (~SelectionKey.OP_READ));
cometTask.upcoming_op = CometTask.OP_EVENT.READ;
}
if (cometKey.isWritable()){
cometKey.interestOps(cometKey.interestOps() & (~SelectionKey.OP_WRITE));
cometTask.upcoming_op = CometTask.OP_EVENT.WRITE;
}
}
if (cometTask.getSelectionKey().attachment() == null){
if (cometTask.cometHandlerNotResumed()){
if (asyncExec){
cometTask.execute();
}else{
checkIfclientClosedConnection(cometKey);
}
}
} else {
// logger.warning("cometselector comettask.mainkey has an attachment. ");
cancelKey(cometKey,false,true, true);
}
} else {
//logger.warning("cometselector select detected invalid cometKey.");
cancelKey(cometKey,false,true,true);
}
}catch(Throwable t){
handleException(t, cometKey);
}
}
// one shot clear is alot faster then removing each element one by one.
selector.selectedKeys().clear();
}
/**
*
* @param cometKey
*/
private void checkIfclientClosedConnection(SelectionKey cometKey) {
boolean connectionclosed = true;
try {
SocketChannel socketChannel = (SocketChannel)cometKey.channel();
dumybuffer.clear();
connectionclosed = socketChannel.read(dumybuffer) == -1;
} catch (Throwable ex) {
// null we dont want cancelkey to happen here, cause it does not cancel mainKey
handleException(ex, null);
}
finally{
if (connectionclosed)
cancelKey(cometKey, true, true, true);
}
}
/**
* perform the registration of new keys.
* The mainKey is the SelectionKey returned by the
* Selector used in the SelectorThread class.
*/
private void registerNewKeys(){
SelectionKey cometKey = null;
CometTask cometTask;
while ((cometTask = keysToRegister.poll()) != null ){
try{
SelectionKey mainKey = cometTask.getSelectionKey();
SocketChannel channel = (SocketChannel)mainKey.channel();
if (mainKey.isValid() && channel.isOpen()) {
cometKey = channel.register(selector,SelectionKey.OP_READ);
cometTask.setCometKey(cometKey);
cometKey.attach(cometTask);
cometTask.getCometContext().addActiveCometTask(cometTask);
cometTask.getCometContext().
addActiveHandler(cometTask.getCometHandler(), cometKey);
cometKey = null;
}
}catch(Throwable t){
handleException(t, cometKey);
}
}
}
/**
* Expires registered {@link SelectionKey}. If a
* {@link SelectionKey} is expired, the request will be resumed and the
* HTTP request will complete,
*/
private void expireIdleKeys(){
if (selector.keys().isEmpty()){
return;
}
final long current = System.currentTimeMillis();
if (current - lastIdleCheck < 1000){
return;
}
lastIdleCheck = current;
for (SelectionKey cometKey:selector.keys()){
try{
CometTask cometTask = (CometTask)cometKey.attachment();
if (cometTask == null)
continue;
if (cometTask.hasExpired(current)){
cancelKey(cometKey,false,true, true);
continue;
}
/**
* The connection has been resumed since the timeout is
* re-attached to the SelectionKey so cancel the Comet key.
*/
if (cometTask.getSelectionKey().attachment() instanceof Long){
cometKey.attach(null);
cometKey.cancel();
}
}catch(Throwable t){
handleException(t, cometKey);
}
}
}
/**
* handle exceptions for selection logic
* @param t
* @param key
*/
private void handleException(Throwable t, SelectionKey key){
try{
cancelKey(key,false,true, true);
} catch (Throwable t2){
logger.log(Level.SEVERE,"CometSelector",t2);
}
if (logger.isLoggable(Level.FINEST)){
logger.log(Level.FINEST,"CometSelector",t);
}
}
/**
* Cancel the {@link SelectionKey} associated with a suspended connection.
*/
protected boolean cancelKey(SelectionKey cometKey, boolean cancelMainKey,
boolean removeCometHandler, boolean notifyInterrupt){
if (cometKey == null){ //cometcontext.resume can give a null cometkey
return false;
}
boolean status = true;
CometTask cometTask = null;
// attach is only atomic since dolphin b06 , hence we must synchronize
// until we can require dolphin
// http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6436220
synchronized(cometKey){
cometTask = (CometTask) cometKey.attach(null);
if (cometTask != null){
//synchronizes internally on itself and canceledkeyset,
//we want hotspot to use lock coarsening.
cometKey.cancel();
}
}
status = cometTask != null;
if (status){
status = cometTask.getCometContext().interrupt(cometTask,
removeCometHandler, notifyInterrupt);
cometEngine.flushPostExecute(cometTask.getAsyncProcessorTask());
if (cancelMainKey){
cometTask.getSelectorThread().cancelKey(cometTask.getSelectionKey());
}
}
return status;
}
/**
* 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(CometTask cometTask){
if (cometTask.getSelectionKey().isValid() && selector != null){
cometTask.setExpireTime(System.currentTimeMillis());
keysToRegister.offer(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){
return channel.keyFor(selector);
}
}
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