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/*
* 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.ConnectException;
import java.net.SocketAddress;
import java.nio.channels.ClosedSelectorException;
import java.util.Iterator;
import java.util.Queue;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;
import java.util.concurrent.atomic.AtomicReference;
import org.apache.mina.core.RuntimeIoException;
import org.apache.mina.core.filterchain.IoFilter;
import org.apache.mina.core.future.ConnectFuture;
import org.apache.mina.core.future.DefaultConnectFuture;
import org.apache.mina.core.service.AbstractIoConnector;
import org.apache.mina.core.service.AbstractIoService;
import org.apache.mina.core.service.IoConnector;
import org.apache.mina.core.service.IoHandler;
import org.apache.mina.core.service.IoProcessor;
import org.apache.mina.core.service.SimpleIoProcessorPool;
import org.apache.mina.core.session.AbstractIoSession;
import org.apache.mina.core.session.IoSession;
import org.apache.mina.core.session.IoSessionConfig;
import org.apache.mina.core.session.IoSessionInitializer;
import org.apache.mina.transport.socket.nio.NioSocketConnector;
import org.apache.mina.util.ExceptionMonitor;
/**
* A base class for implementing client transport using a polling strategy. The
* underlying sockets will be checked in an active loop and woke up when an
* socket needed to be processed. This class handle the logic behind binding,
* connecting and disposing the client sockets. A {@link Executor} will be used
* for running client connection, and an {@link AbstractPollingIoProcessor} will
* be used for processing connected client I/O operations like reading, writing
* and closing.
*
* All the low level methods for binding, connecting, closing need to be
* provided by the subclassing implementation.
*
* @see NioSocketConnector for a example of implementation
* @param The type of IoHandler
* @param The type of IoSession
*
* @author Apache MINA Project
*/
public abstract class AbstractPollingIoConnector extends AbstractIoConnector {
private final Queue connectQueue = new ConcurrentLinkedQueue<>();
private final Queue cancelQueue = new ConcurrentLinkedQueue<>();
private final IoProcessor processor;
private final boolean createdProcessor;
private final ServiceOperationFuture disposalFuture = new ServiceOperationFuture();
private volatile boolean selectable;
/** The connector thread */
private final AtomicReference connectorRef = new AtomicReference<>();
/**
* Constructor for {@link AbstractPollingIoConnector}. You need to provide a
* default session configuration, a class of {@link IoProcessor} which will
* be instantiated in a {@link SimpleIoProcessorPool} for better scaling in
* multiprocessor systems. The default pool size will be used.
*
* @see SimpleIoProcessorPool
*
* @param sessionConfig
* the default configuration for the managed {@link IoSession}
* @param processorClass
* a {@link Class} of {@link IoProcessor} for the associated
* {@link IoSession} type.
*/
protected AbstractPollingIoConnector(IoSessionConfig sessionConfig, Class> processorClass) {
this(sessionConfig, null, new SimpleIoProcessorPool(processorClass), true);
}
/**
* Constructor for {@link AbstractPollingIoConnector}. You need to provide a
* default session configuration, a class of {@link IoProcessor} which will
* be instantiated in a {@link SimpleIoProcessorPool} for using multiple
* thread for better scaling in multiprocessor systems.
*
* @see SimpleIoProcessorPool
*
* @param sessionConfig
* the default configuration for the managed {@link IoSession}
* @param processorClass
* a {@link Class} of {@link IoProcessor} for the associated
* {@link IoSession} type.
* @param processorCount
* the amount of processor to instantiate for the pool
*/
protected AbstractPollingIoConnector(IoSessionConfig sessionConfig, Class> processorClass,
int processorCount) {
this(sessionConfig, null, new SimpleIoProcessorPool(processorClass, processorCount), true);
}
/**
* Constructor for {@link AbstractPollingIoConnector}. You need to provide a
* default session configuration, a default {@link Executor} will be created
* using {@link Executors#newCachedThreadPool()}.
*
* @see AbstractIoService#AbstractIoService(IoSessionConfig, Executor)
*
* @param sessionConfig
* the default configuration for the managed {@link IoSession}
* @param processor
* the {@link IoProcessor} for processing the {@link IoSession}
* of this transport, triggering events to the bound
* {@link IoHandler} and processing the chains of
* {@link IoFilter}
*/
protected AbstractPollingIoConnector(IoSessionConfig sessionConfig, IoProcessor processor) {
this(sessionConfig, null, processor, false);
}
/**
* Constructor for {@link AbstractPollingIoConnector}. You need to provide a
* default session configuration and an {@link Executor} for handling I/O
* events. If null {@link Executor} is provided, a default one will be
* created using {@link Executors#newCachedThreadPool()}.
*
* @see AbstractIoService#AbstractIoService(IoSessionConfig, Executor)
*
* @param sessionConfig
* the default configuration for the managed {@link IoSession}
* @param executor
* the {@link Executor} used for handling asynchronous execution
* of I/O events. Can be null.
* @param processor
* the {@link IoProcessor} for processing the {@link IoSession}
* of this transport, triggering events to the bound
* {@link IoHandler} and processing the chains of
* {@link IoFilter}
*/
protected AbstractPollingIoConnector(IoSessionConfig sessionConfig, Executor executor, IoProcessor processor) {
this(sessionConfig, executor, processor, false);
}
/**
* Constructor for {@link AbstractPollingIoAcceptor}. You need to provide a
* default session configuration and an {@link Executor} for handling I/O
* events. If null {@link Executor} is provided, a default one will be
* created using {@link Executors#newCachedThreadPool()}.
*
* @see AbstractIoService#AbstractIoService(IoSessionConfig, Executor)
*
* @param sessionConfig
* the default configuration for the managed {@link IoSession}
* @param executor
* the {@link Executor} used for handling asynchronous execution
* of I/O events. Can be null.
* @param processor
* the {@link IoProcessor} for processing the {@link IoSession}
* of this transport, triggering events to the bound
* {@link IoHandler} and processing the chains of
* {@link IoFilter}
* @param createdProcessor
* tagging the processor as automatically created, so it will be
* automatically disposed
*/
private AbstractPollingIoConnector(IoSessionConfig sessionConfig, Executor executor, IoProcessor processor,
boolean createdProcessor) {
super(sessionConfig, executor);
if (processor == null) {
throw new IllegalArgumentException("processor");
}
this.processor = processor;
this.createdProcessor = createdProcessor;
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);
}
}
}
}
/**
* Initialize the polling system, will be called at construction time.
*
* @throws Exception
* any exception thrown by the underlying system calls
*/
protected abstract void init() throws Exception;
/**
* Destroy the polling system, will be called when this {@link IoConnector}
* implementation will be disposed.
*
* @throws Exception
* any exception thrown by the underlying systems calls
*/
protected abstract void destroy() throws Exception;
/**
* Create a new client socket handle from a local {@link SocketAddress}
*
* @param localAddress
* the socket address for binding the new client socket
* @return a new client socket handle
* @throws Exception
* any exception thrown by the underlying systems calls
*/
protected abstract H newHandle(SocketAddress localAddress) throws Exception;
/**
* Connect a newly created client socket handle to a remote
* {@link SocketAddress}. This operation is non-blocking, so at end of the
* call the socket can be still in connection process.
*
* @param handle the client socket handle
* @param remoteAddress the remote address where to connect
* @return true if a connection was established, false if
* this client socket is in non-blocking mode and the connection
* operation is in progress
* @throws Exception If the connect failed
*/
protected abstract boolean connect(H handle, SocketAddress remoteAddress) throws Exception;
/**
* Finish the connection process of a client socket after it was marked as
* ready to process by the {@link #select(int)} call. The socket will be
* connected or reported as connection failed.
*
* @param handle
* the client socket handle to finish to connect
* @return true if the socket is connected
* @throws Exception
* any exception thrown by the underlying systems calls
*/
protected abstract boolean finishConnect(H handle) throws Exception;
/**
* Create a new {@link IoSession} from a connected socket client handle.
* Will assign the created {@link IoSession} to the given
* {@link IoProcessor} for managing future I/O events.
*
* @param processor
* the processor in charge of this session
* @param handle
* the newly connected client socket handle
* @return a new {@link IoSession}
* @throws Exception
* any exception thrown by the underlying systems calls
*/
protected abstract S newSession(IoProcessor processor, H handle) throws Exception;
/**
* Close a client socket.
*
* @param handle
* the client socket
* @throws Exception
* any exception thrown by the underlying systems calls
*/
protected abstract void close(H handle) throws Exception;
/**
* Interrupt the {@link #select(int)} method. Used when the poll set need to
* be modified.
*/
protected abstract void wakeup();
/**
* Check for connected sockets, interrupt when at least a connection is
* processed (connected or failed to connect). All the client socket
* descriptors processed need to be returned by {@link #selectedHandles()}
*
* @param timeout The timeout for the select() method
* @return The number of socket having received some data
* @throws Exception any exception thrown by the underlying systems calls
*/
protected abstract int select(int timeout) throws Exception;
/**
* {@link Iterator} for the set of client sockets found connected or failed
* to connect during the last {@link #select(int)} call.
*
* @return the list of client socket handles to process
*/
protected abstract Iterator selectedHandles();
/**
* {@link Iterator} for all the client sockets polled for connection.
*
* @return the list of client sockets currently polled for connection
*/
protected abstract Iterator allHandles();
/**
* Register a new client socket for connection, add it to connection polling
*
* @param handle
* client socket handle
* @param request
* the associated {@link ConnectionRequest}
* @throws Exception
* any exception thrown by the underlying systems calls
*/
protected abstract void register(H handle, ConnectionRequest request) throws Exception;
/**
* get the {@link ConnectionRequest} for a given client socket handle
*
* @param handle
* the socket client handle
* @return the connection request if the socket is connecting otherwise
* null
*/
protected abstract ConnectionRequest getConnectionRequest(H handle);
/**
* {@inheritDoc}
*/
@Override
protected final void dispose0() throws Exception {
startupWorker();
wakeup();
}
/**
* {@inheritDoc}
*/
@Override
@SuppressWarnings("unchecked")
protected final ConnectFuture connect0(SocketAddress remoteAddress, SocketAddress localAddress,
IoSessionInitializer sessionInitializer) {
H handle = null;
boolean success = false;
try {
handle = newHandle(localAddress);
if (connect(handle, remoteAddress)) {
ConnectFuture future = new DefaultConnectFuture();
S session = newSession(processor, handle);
initSession(session, future, sessionInitializer);
// Forward the remaining process to the IoProcessor.
session.getProcessor().add(session);
success = true;
return future;
}
success = true;
} catch (Exception e) {
return DefaultConnectFuture.newFailedFuture(e);
} finally {
if (!success && handle != null) {
try {
close(handle);
} catch (Exception e) {
ExceptionMonitor.getInstance().exceptionCaught(e);
}
}
}
ConnectionRequest request = new ConnectionRequest(handle, sessionInitializer);
connectQueue.add(request);
startupWorker();
wakeup();
return request;
}
private void startupWorker() {
if (!selectable) {
connectQueue.clear();
cancelQueue.clear();
}
Connector connector = connectorRef.get();
if (connector == null) {
connector = new Connector();
if (connectorRef.compareAndSet(null, connector)) {
executeWorker(connector);
}
}
}
private class Connector implements Runnable {
/**
* {@inheritDoc}
*/
@Override
public void run() {
assert connectorRef.get() == this;
int nHandles = 0;
while (selectable) {
try {
// the timeout for select shall be smaller of the connect
// timeout or 1 second...
int timeout = (int) Math.min(getConnectTimeoutMillis(), 1000L);
int selected = select(timeout);
nHandles += registerNew();
// get a chance to get out of the connector loop, if we
// don't have any more handles
if (nHandles == 0) {
connectorRef.set(null);
if (connectQueue.isEmpty()) {
assert connectorRef.get() != this;
break;
}
if (!connectorRef.compareAndSet(null, this)) {
assert connectorRef.get() != this;
break;
}
assert connectorRef.get() == this;
}
if (selected > 0) {
nHandles -= processConnections(selectedHandles());
}
processTimedOutSessions(allHandles());
nHandles -= cancelKeys();
} catch (ClosedSelectorException cse) {
// If the selector has been closed, we can exit the loop
ExceptionMonitor.getInstance().exceptionCaught(cse);
break;
} catch (Exception e) {
ExceptionMonitor.getInstance().exceptionCaught(e);
try {
Thread.sleep(1000);
} catch (InterruptedException e1) {
ExceptionMonitor.getInstance().exceptionCaught(e1);
}
}
}
if (selectable && isDisposing()) {
selectable = false;
try {
if (createdProcessor) {
processor.dispose();
}
} finally {
try {
synchronized (disposalLock) {
if (isDisposing()) {
destroy();
}
}
} catch (Exception e) {
ExceptionMonitor.getInstance().exceptionCaught(e);
} finally {
disposalFuture.setDone();
}
}
}
}
private int registerNew() {
int nHandles = 0;
for (;;) {
ConnectionRequest req = connectQueue.poll();
if (req == null) {
break;
}
H handle = req.handle;
try {
register(handle, req);
nHandles++;
} catch (Exception e) {
req.setException(e);
try {
close(handle);
} catch (Exception e2) {
ExceptionMonitor.getInstance().exceptionCaught(e2);
}
}
}
return nHandles;
}
private int cancelKeys() {
int nHandles = 0;
for (;;) {
ConnectionRequest req = cancelQueue.poll();
if (req == null) {
break;
}
H handle = req.handle;
try {
close(handle);
} catch (Exception e) {
ExceptionMonitor.getInstance().exceptionCaught(e);
} finally {
nHandles++;
}
}
if (nHandles > 0) {
wakeup();
}
return nHandles;
}
/**
* Process the incoming connections, creating a new session for each valid
* connection.
*/
private int processConnections(Iterator handlers) {
int nHandles = 0;
// Loop on each connection request
while (handlers.hasNext()) {
H handle = handlers.next();
handlers.remove();
ConnectionRequest connectionRequest = getConnectionRequest(handle);
if (connectionRequest == null) {
continue;
}
boolean success = false;
try {
if (finishConnect(handle)) {
S session = newSession(processor, handle);
initSession(session, connectionRequest, connectionRequest.getSessionInitializer());
// Forward the remaining process to the IoProcessor.
session.getProcessor().add(session);
nHandles++;
}
success = true;
} catch (Exception e) {
connectionRequest.setException(e);
} finally {
if (!success) {
// The connection failed, we have to cancel it.
cancelQueue.offer(connectionRequest);
}
}
}
return nHandles;
}
private void processTimedOutSessions(Iterator handles) {
long currentTime = System.currentTimeMillis();
while (handles.hasNext()) {
H handle = handles.next();
ConnectionRequest connectionRequest = getConnectionRequest(handle);
if ((connectionRequest != null) && (currentTime >= connectionRequest.deadline)) {
connectionRequest.setException(new ConnectException("Connection timed out."));
cancelQueue.offer(connectionRequest);
}
}
}
}
/**
* A ConnectionRequest's Iouture
*/
public final class ConnectionRequest extends DefaultConnectFuture {
/** The handle associated with this connection request */
private final H handle;
/** The time up to this connection request will be valid */
private final long deadline;
/** The callback to call when the session is initialized */
private final IoSessionInitializer sessionInitializer;
/**
* Creates a new ConnectionRequest instance
*
* @param handle The IoHander
* @param callback The IoFuture callback
*/
public ConnectionRequest(H handle, IoSessionInitializer callback) {
this.handle = handle;
long timeout = getConnectTimeoutMillis();
if (timeout <= 0L) {
this.deadline = Long.MAX_VALUE;
} else {
this.deadline = System.currentTimeMillis() + timeout;
}
this.sessionInitializer = callback;
}
/**
* @return The IoHandler instance
*/
public H getHandle() {
return handle;
}
/**
* @return The connection deadline
*/
public long getDeadline() {
return deadline;
}
/**
* @return The session initializer callback
*/
public IoSessionInitializer getSessionInitializer() {
return sessionInitializer;
}
/**
* {@inheritDoc}
*/
@Override
public boolean cancel() {
if (!isDone()) {
boolean justCancelled = super.cancel();
// We haven't cancelled the request before, so add the future
// in the cancel queue.
if (justCancelled) {
cancelQueue.add(this);
startupWorker();
wakeup();
}
}
return true;
}
}
}
