/*
* 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.mina.core.polling;
import java.net.SocketAddress;
import java.nio.channels.ClosedSelectorException;
import java.nio.channels.SelectionKey;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Queue;
import java.util.Set;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.Executor;
import java.util.concurrent.Semaphore;
import org.apache.mina.core.RuntimeIoException;
import org.apache.mina.core.buffer.IoBuffer;
import org.apache.mina.core.service.AbstractIoAcceptor;
import org.apache.mina.core.service.IoAcceptor;
import org.apache.mina.core.service.IoProcessor;
import org.apache.mina.core.session.AbstractIoSession;
import org.apache.mina.core.session.ExpiringSessionRecycler;
import org.apache.mina.core.session.IoSession;
import org.apache.mina.core.session.IoSessionConfig;
import org.apache.mina.core.session.IoSessionRecycler;
import org.apache.mina.core.write.WriteRequest;
import org.apache.mina.core.write.WriteRequestQueue;
import org.apache.mina.util.ExceptionMonitor;
/**
* {@link IoAcceptor} for datagram transport (UDP/IP).
*
* @author <a href="http://mina.apache.org">Apache MINA Project</a>
* @org.apache.xbean.XBean
*
* @param <S> the type of the {@link IoSession} this processor can handle
*/
public abstract class AbstractPollingConnectionlessIoAcceptor<S extends AbstractIoSession, H> extends
AbstractIoAcceptor implements IoProcessor<S> {
private static final IoSessionRecycler DEFAULT_RECYCLER = new ExpiringSessionRecycler();
/**
* A timeout used for the select, as we need to get out to deal with idle
* sessions
*/
private static final long SELECT_TIMEOUT = 1000L;
/** A lock used to protect the selector to be waked up before it's created */
private final Semaphore lock = new Semaphore(1);
private final Queue<AcceptorOperationFuture> registerQueue = new ConcurrentLinkedQueue<AcceptorOperationFuture>();
private final Queue<AcceptorOperationFuture> cancelQueue = new ConcurrentLinkedQueue<AcceptorOperationFuture>();
private final Queue<S> flushingSessions = new ConcurrentLinkedQueue<S>();
private final Map<SocketAddress, H> boundHandles = Collections.synchronizedMap(new HashMap<SocketAddress, H>());
private IoSessionRecycler sessionRecycler = DEFAULT_RECYCLER;
private final ServiceOperationFuture disposalFuture = new ServiceOperationFuture();
private volatile boolean selectable;
/** The thread responsible of accepting incoming requests */
private Acceptor acceptor;
private long lastIdleCheckTime;
/**
* Creates a new instance.
*/
protected AbstractPollingConnectionlessIoAcceptor(IoSessionConfig sessionConfig) {
this(sessionConfig, null);
}
/**
* Creates a new instance.
*/
protected AbstractPollingConnectionlessIoAcceptor(IoSessionConfig sessionConfig, Executor executor) {
super(sessionConfig, executor);
try {
init();
selectable = true;
} catch (RuntimeException e) {
throw e;
} catch (Exception e) {
throw new RuntimeIoException("Failed to initialize.", e);
} finally {
if (!selectable) {
try {
destroy();
} catch (Exception e) {
ExceptionMonitor.getInstance().exceptionCaught(e);
}
}
}
}
protected abstract void init() throws Exception;
protected abstract void destroy() throws Exception;
protected abstract int select() throws Exception;
protected abstract int select(long timeout) throws Exception;
protected abstract void wakeup();
protected abstract Set<SelectionKey> selectedHandles();
protected abstract H open(SocketAddress localAddress) throws Exception;
protected abstract void close(H handle) throws Exception;
protected abstract SocketAddress localAddress(H handle) throws Exception;
protected abstract boolean isReadable(H handle);
protected abstract boolean isWritable(H handle);
protected abstract SocketAddress receive(H handle, IoBuffer buffer) throws Exception;
protected abstract int send(S session, IoBuffer buffer, SocketAddress remoteAddress) throws Exception;
protected abstract S newSession(IoProcessor<S> processor, H handle, SocketAddress remoteAddress) throws Exception;
protected abstract void setInterestedInWrite(S session, boolean interested) throws Exception;
/**
* {@inheritDoc}
*/
@Override
protected void dispose0() throws Exception {
unbind();
startupAcceptor();
wakeup();
}
/**
* {@inheritDoc}
*/
@Override
protected final Set<SocketAddress> bindInternal(List<? extends SocketAddress> localAddresses) throws Exception {
// Create a bind request as a Future operation. When the selector
// have handled the registration, it will signal this future.
AcceptorOperationFuture request = new AcceptorOperationFuture(localAddresses);
// adds the Registration request to the queue for the Workers
// to handle
registerQueue.add(request);
// creates the Acceptor instance and has the local
// executor kick it off.
startupAcceptor();
// As we just started the acceptor, we have to unblock the select()
// in order to process the bind request we just have added to the
// registerQueue.
try {
lock.acquire();
// Wait a bit to give a chance to the Acceptor thread to do the select()
Thread.sleep(10);
wakeup();
} finally {
lock.release();
}
// Now, we wait until this request is completed.
request.awaitUninterruptibly();
if (request.getException() != null) {
throw request.getException();
}
// Update the local addresses.
// setLocalAddresses() shouldn't be called from the worker thread
// because of deadlock.
Set<SocketAddress> newLocalAddresses = new HashSet<SocketAddress>();
for (H handle : boundHandles.values()) {
newLocalAddresses.add(localAddress(handle));
}
return newLocalAddresses;
}
/**
* {@inheritDoc}
*/
@Override
protected final void unbind0(List<? extends SocketAddress> localAddresses) throws Exception {
AcceptorOperationFuture request = new AcceptorOperationFuture(localAddresses);
cancelQueue.add(request);
startupAcceptor();
wakeup();
request.awaitUninterruptibly();
if (request.getException() != null) {
throw request.getException();
}
}
/**
* {@inheritDoc}
*/
public final IoSession newSession(SocketAddress remoteAddress, SocketAddress localAddress) {
if (isDisposing()) {
throw new IllegalStateException("Already disposed.");
}
if (remoteAddress == null) {
throw new IllegalArgumentException("remoteAddress");
}
synchronized (bindLock) {
if (!isActive()) {
throw new IllegalStateException("Can't create a session from a unbound service.");
}
try {
return newSessionWithoutLock(remoteAddress, localAddress);
} catch (RuntimeException e) {
throw e;
} catch (Error e) {
throw e;
} catch (Exception e) {
throw new RuntimeIoException("Failed to create a session.", e);
}
}
}
private IoSession newSessionWithoutLock(SocketAddress remoteAddress, SocketAddress localAddress) throws Exception {
H handle = boundHandles.get(localAddress);
if (handle == null) {
throw new IllegalArgumentException("Unknown local address: " + localAddress);
}
IoSession session;
synchronized (sessionRecycler) {
session = sessionRecycler.recycle(remoteAddress);
if (session != null) {
return session;
}
// If a new session needs to be created.
S newSession = newSession(this, handle, remoteAddress);
getSessionRecycler().put(newSession);
session = newSession;
}
initSession(session, null, null);
try {
this.getFilterChainBuilder().buildFilterChain(session.getFilterChain());
getListeners().fireSessionCreated(session);
} catch (Throwable t) {
ExceptionMonitor.getInstance().exceptionCaught(t);
}
return session;
}
public final IoSessionRecycler getSessionRecycler() {
return sessionRecycler;
}
public final void setSessionRecycler(IoSessionRecycler sessionRecycler) {
synchronized (bindLock) {
if (isActive()) {
throw new IllegalStateException("sessionRecycler can't be set while the acceptor is bound.");
}
if (sessionRecycler == null) {
sessionRecycler = DEFAULT_RECYCLER;
}
this.sessionRecycler = sessionRecycler;
}
}
/**
* {@inheritDoc}
*/
public void add(S session) {
// Nothing to do for UDP
}
/**
* {@inheritDoc}
*/
public void flush(S session) {
if (scheduleFlush(session)) {
wakeup();
}
}
/**
* {@inheritDoc}
*/
public void write(S session, WriteRequest writeRequest) {
// We will try to write the message directly
long currentTime = System.currentTimeMillis();
final WriteRequestQueue writeRequestQueue = session.getWriteRequestQueue();
final int maxWrittenBytes = session.getConfig().getMaxReadBufferSize()
+ (session.getConfig().getMaxReadBufferSize() >>> 1);
int writtenBytes = 0;
try {
for (;;) {
if (writeRequest == null) {
writeRequest = writeRequestQueue.poll(session);
if (writeRequest == null) {
setInterestedInWrite(session, false);
break;
}
session.setCurrentWriteRequest(writeRequest);
}
IoBuffer buf = (IoBuffer) writeRequest.getMessage();
if (buf.remaining() == 0) {
// Clear and fire event
session.setCurrentWriteRequest(null);
buf.reset();
session.getFilterChain().fireMessageSent(writeRequest);
continue;
}
SocketAddress destination = writeRequest.getDestination();
if (destination == null) {
destination = session.getRemoteAddress();
}
int localWrittenBytes = send(session, buf, destination);
if ((localWrittenBytes == 0) || (writtenBytes >= maxWrittenBytes)) {
// Kernel buffer is full or wrote too much
setInterestedInWrite(session, true);
session.getWriteRequestQueue().offer(session, writeRequest);
scheduleFlush(session);
} else {
setInterestedInWrite(session, false);
// Clear and fire event
session.setCurrentWriteRequest(null);
writtenBytes += localWrittenBytes;
buf.reset();
session.getFilterChain().fireMessageSent(writeRequest);
break;
}
}
} catch (Exception e) {
session.getFilterChain().fireExceptionCaught(e);
} finally {
session.increaseWrittenBytes(writtenBytes, currentTime);
}
}
/**
* {@inheritDoc}
*/
public void remove(S session) {
getSessionRecycler().remove(session);
getListeners().fireSessionDestroyed(session);
}
/**
* {@inheritDoc}
*/
public void updateTrafficControl(S session) {
throw new UnsupportedOperationException();
}
/**
* Starts the inner Acceptor thread.
*/
private void startupAcceptor() throws InterruptedException {
if (!selectable) {
registerQueue.clear();
cancelQueue.clear();
flushingSessions.clear();
}
lock.acquire();
if (acceptor == null) {
acceptor = new Acceptor();
executeWorker(acceptor);
} else {
lock.release();
}
}
private boolean scheduleFlush(S session) {
// Set the schedule for flush flag if the session
// has not already be added to the flushingSessions
// queue
if (session.setScheduledForFlush(true)) {
flushingSessions.add(session);
return true;
} else {
return false;
}
}
/**
* This private class is used to accept incoming connection from
* clients. It's an infinite loop, which can be stopped when all
* the registered handles have been removed (unbound).
*/
private class Acceptor implements Runnable {
public void run() {
int nHandles = 0;
lastIdleCheckTime = System.currentTimeMillis();
// Release the lock
lock.release();
while (selectable) {
try {
int selected = select(SELECT_TIMEOUT);
nHandles += registerHandles();
if (nHandles == 0) {
try {
lock.acquire();
if (registerQueue.isEmpty() && cancelQueue.isEmpty()) {
acceptor = null;
break;
}
} finally {
lock.release();
}
}
if (selected > 0) {
processReadySessions(selectedHandles());
}
long currentTime = System.currentTimeMillis();
flushSessions(currentTime);
nHandles -= unregisterHandles();
notifyIdleSessions(currentTime);
} catch (ClosedSelectorException cse) {
// If the selector has been closed, we can exit the loop
break;
} catch (Exception e) {
ExceptionMonitor.getInstance().exceptionCaught(e);
try {
Thread.sleep(1000);
} catch (InterruptedException e1) {
}
}
}
if (selectable && isDisposing()) {
selectable = false;
try {
destroy();
} catch (Exception e) {
ExceptionMonitor.getInstance().exceptionCaught(e);
} finally {
disposalFuture.setValue(true);
}
}
}
}
@SuppressWarnings("unchecked")
private void processReadySessions(Set<SelectionKey> handles) {
Iterator<SelectionKey> iterator = handles.iterator();
while (iterator.hasNext()) {
SelectionKey key = iterator.next();
H handle = (H) key.channel();
iterator.remove();
try {
if ((key != null) && key.isValid() && key.isReadable()) {
readHandle(handle);
}
if ((key != null) && key.isValid() && key.isWritable()) {
for (IoSession session : getManagedSessions().values()) {
scheduleFlush((S) session);
}
}
} catch (Throwable t) {
ExceptionMonitor.getInstance().exceptionCaught(t);
}
}
}
private void readHandle(H handle) throws Exception {
IoBuffer readBuf = IoBuffer.allocate(getSessionConfig().getReadBufferSize());
SocketAddress remoteAddress = receive(handle, readBuf);
if (remoteAddress != null) {
IoSession session = newSessionWithoutLock(remoteAddress, localAddress(handle));
readBuf.flip();
session.getFilterChain().fireMessageReceived(readBuf);
}
}
private void flushSessions(long currentTime) {
for (;;) {
S session = flushingSessions.poll();
if (session == null) {
break;
}
// Reset the Schedule for flush flag for this session,
// as we are flushing it now
session.unscheduledForFlush();
try {
boolean flushedAll = flush(session, currentTime);
if (flushedAll && !session.getWriteRequestQueue().isEmpty(session) && !session.isScheduledForFlush()) {
scheduleFlush(session);
}
} catch (Exception e) {
session.getFilterChain().fireExceptionCaught(e);
}
}
}
private boolean flush(S session, long currentTime) throws Exception {
final WriteRequestQueue writeRequestQueue = session.getWriteRequestQueue();
final int maxWrittenBytes = session.getConfig().getMaxReadBufferSize()
+ (session.getConfig().getMaxReadBufferSize() >>> 1);
int writtenBytes = 0;
try {
for (;;) {
WriteRequest req = session.getCurrentWriteRequest();
if (req == null) {
req = writeRequestQueue.poll(session);
if (req == null) {
setInterestedInWrite(session, false);
break;
}
session.setCurrentWriteRequest(req);
}
IoBuffer buf = (IoBuffer) req.getMessage();
if (buf.remaining() == 0) {
// Clear and fire event
session.setCurrentWriteRequest(null);
buf.reset();
session.getFilterChain().fireMessageSent(req);
continue;
}
SocketAddress destination = req.getDestination();
if (destination == null) {
destination = session.getRemoteAddress();
}
int localWrittenBytes = send(session, buf, destination);
if ((localWrittenBytes == 0) || (writtenBytes >= maxWrittenBytes)) {
// Kernel buffer is full or wrote too much
setInterestedInWrite(session, true);
return false;
} else {
setInterestedInWrite(session, false);
// Clear and fire event
session.setCurrentWriteRequest(null);
writtenBytes += localWrittenBytes;
buf.reset();
session.getFilterChain().fireMessageSent(req);
}
}
} finally {
session.increaseWrittenBytes(writtenBytes, currentTime);
}
return true;
}
private int registerHandles() {
for (;;) {
AcceptorOperationFuture req = registerQueue.poll();
if (req == null) {
break;
}
Map<SocketAddress, H> newHandles = new HashMap<SocketAddress, H>();
List<SocketAddress> localAddresses = req.getLocalAddresses();
try {
for (SocketAddress socketAddress : localAddresses) {
H handle = open(socketAddress);
newHandles.put(localAddress(handle), handle);
}
boundHandles.putAll(newHandles);
getListeners().fireServiceActivated();
req.setDone();
return newHandles.size();
} catch (Exception e) {
req.setException(e);
} finally {
// Roll back if failed to bind all addresses.
if (req.getException() != null) {
for (H handle : newHandles.values()) {
try {
close(handle);
} catch (Exception e) {
ExceptionMonitor.getInstance().exceptionCaught(e);
}
}
wakeup();
}
}
}
return 0;
}
private int unregisterHandles() {
int nHandles = 0;
for (;;) {
AcceptorOperationFuture request = cancelQueue.poll();
if (request == null) {
break;
}
// close the channels
for (SocketAddress socketAddress : request.getLocalAddresses()) {
H handle = boundHandles.remove(socketAddress);
if (handle == null) {
continue;
}
try {
close(handle);
wakeup(); // wake up again to trigger thread death
} catch (Throwable e) {
ExceptionMonitor.getInstance().exceptionCaught(e);
} finally {
nHandles++;
}
}
request.setDone();
}
return nHandles;
}
private void notifyIdleSessions(long currentTime) {
// process idle sessions
if (currentTime - lastIdleCheckTime >= 1000) {
lastIdleCheckTime = currentTime;
AbstractIoSession.notifyIdleness(getListeners().getManagedSessions().values().iterator(), currentTime);
}
}
}