Mina代码跟踪（1）
1 NioSocketAcceptor类关系图
1.1 NioSocketAcceptor acceptor = new NioSocketAcceptor(5);
NioSocketAcceptor 初始化顺序
AbstractIoService构造函数
protected AbstractIoService(IoSessionConfig sessionConfig, Executor executor) { if (sessionConfig == null) { throw new IllegalArgumentException("sessionConfig"); } if (getTransportMetadata() == null) { throw new IllegalArgumentException("TransportMetadata"); } if (!getTransportMetadata().getSessionConfigType().isAssignableFrom( sessionConfig.getClass())) { throw new IllegalArgumentException("sessionConfig type: " + sessionConfig.getClass() + " (expected: " + getTransportMetadata().getSessionConfigType() + ")"); } // Create the listeners, and add a first listener : a activation listener // for this service, which will give information on the service state. listeners = new IoServiceListenerSupport(this); listeners.add(serviceActivationListener); // Stores the given session configuration this.sessionConfig = sessionConfig; // Make JVM load the exception monitor before some transports // change the thread context class loader. ExceptionMonitor.getInstance(); if (executor == null) { this.executor = Executors.newCachedThreadPool(); createdExecutor = true; } else { this.executor = executor; createdExecutor = false; } threadName = getClass().getSimpleName() + '-' + id.incrementAndGet(); }
protected AbstractIoAcceptor(IoSessionConfig sessionConfig, Executor executor) {
super(sessionConfig, executor);
defaultLocalAddresses.add(null);
}
AbstractPollingIoAcceptor 构造函数
private AbstractPollingIoAcceptor(IoSessionConfig sessionConfig, Executor executor, IoProcessor<S> processor, boolean createdProcessor) { super(sessionConfig, executor); if (processor == null) { throw new IllegalArgumentException("processor"); } this.processor = processor; this.createdProcessor = createdProcessor; try { // Initialize the selector init(); // The selector is now ready, we can switch the // flag to true so that incoming connection can be accepted 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); } } } }
NioSocketAcceptor 构造函数
public NioSocketAcceptor(int processorCount) {
super(new DefaultSocketSessionConfig(), NioProcessor.class, processorCount);
((DefaultSocketSessionConfig) getSessionConfig()).init(this);
}
1.2 IoFilterChain 过滤链
acceptor.getFilterChain().addLast("logger", new LoggingFilter());
/** AbstractIoService * {@inheritDoc} */ public final DefaultIoFilterChainBuilder getFilterChain() { if (filterChainBuilder instanceof DefaultIoFilterChainBuilder) { return (DefaultIoFilterChainBuilder) filterChainBuilder; } throw new IllegalStateException( "Current filter chain builder is not a DefaultIoFilterChainBuilder."); }
源代码：
public class DefaultIoFilterChainBuilder implements IoFilterChainBuilder { private final static Logger LOGGER = LoggerFactory.getLogger(DefaultIoFilterChainBuilder.class); private final List<Entry> entries; /** * Creates a new instance with an empty filter list. */ public DefaultIoFilterChainBuilder() { entries = new CopyOnWriteArrayList<Entry>(); } /** * Creates a new copy of the specified {@link DefaultIoFilterChainBuilder}. */ public DefaultIoFilterChainBuilder(DefaultIoFilterChainBuilder filterChain) { if (filterChain == null) { throw new IllegalArgumentException("filterChain"); } entries = new CopyOnWriteArrayList<Entry>(filterChain.entries); }
addLast
/** * @see IoFilterChain#addLast(String, IoFilter) */ public synchronized void addLast(String name, IoFilter filter) { register(entries.size(), new EntryImpl(name, filter)); }
private void register(int index, Entry e) {
if (contains(e.getName())) {
throw new IllegalArgumentException(
"Other filter is using the same name: " + e.getName());
}
entries.add(index, e);
}
1.3 IoFilter
1.4 IoSessionConfig
1.4 IoProcess
1.5 acceptor.bind(new InetSocketAddress(this.serverAddr, this.serverPort));
最终会运行AbstractPollingIoAcceptor.bindInternal
AbstractPollingIoAcceptor
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. wakeup(); // 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; }
1.5.1 startupAcceptor（） 使用线程池执行Acceptor
/**
* This method is called by the doBind() and doUnbind()
* methods. If the acceptor is null, the acceptor object will
* be created and kicked off by the executor. If the acceptor
* object is null, probably already created and this class
* is now working, then nothing will happen and the method
* will just return.
*/
private void startupAcceptor() {
// If the acceptor is not ready, clear the queues
// TODO : they should already be clean : do we have to do that ?
if (!selectable) {
registerQueue.clear();
cancelQueue.clear();
}
// start the acceptor if not already started
Acceptor acceptor = acceptorRef.get();
if (acceptor == null) {
acceptor = new Acceptor();
if (acceptorRef.compareAndSet(null, acceptor)) {
executeWorker(acceptor);
}
}
}
Acceptor（） 实现了Runnable接口 不停的执行
/** * This class is called by the startupAcceptor() method and is * placed into a NamePreservingRunnable class. * It's a thread accepting incoming connections from clients. * The loop is stopped when all the bound handlers are unbound. */ private class Acceptor implements Runnable { public void run() { assert (acceptorRef.get() == this); int nHandles = 0; while (selectable) { try { // Detect if we have some keys ready to be processed // The select() will be woke up if some new connection // have occurred, or if the selector has been explicitly // woke up int selected = select(); // this actually sets the selector to OP_ACCEPT, // and binds to the port on which this class will // listen on nHandles += registerHandles(); // Now, if the number of registred handles is 0, we can // quit the loop: we don't have any socket listening // for incoming connection. if (nHandles == 0) { acceptorRef.set(null); if (registerQueue.isEmpty() && cancelQueue.isEmpty()) { assert (acceptorRef.get() != this); break; } if (!acceptorRef.compareAndSet(null, this)) { assert (acceptorRef.get() != this); break; } assert (acceptorRef.get() == this); } if (selected > 0) { // We have some connection request, let's process // them here. processHandles(selectedHandles()); } // check to see if any cancellation request has been made. nHandles -= unregisterHandles(); } catch (ClosedSelectorException cse) { // If the selector has been closed, we can exit the loop break; } catch (Throwable e) { ExceptionMonitor.getInstance().exceptionCaught(e); try { Thread.sleep(1000); } catch (InterruptedException e1) { ExceptionMonitor.getInstance().exceptionCaught(e1); } } } // Cleanup all the processors, and shutdown the acceptor. 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(); } } } }
NioSocketAcceptor /** * Check if we have at least one key whose corresponding channels is * ready for I/O operations. * * This method performs a blocking selection operation. * It returns only after at least one channel is selected, * this selector's wakeup method is invoked, or the current thread * is interrupted, whichever comes first. * * @return The number of keys having their ready-operation set updated * @throws IOException If an I/O error occurs * @throws ClosedSelectorException If this selector is closed */ @Override protected int select() throws Exception { return selector.select(); }
请问
/** * Sets up the socket communications. Sets items such as: * <p/> * Blocking * Reuse address * Receive buffer size * Bind to listen port * Registers OP_ACCEPT for selector */ private int registerHandles() { for (;;) { // The register queue contains the list of services to manage // in this acceptor. AcceptorOperationFuture future = registerQueue.poll(); if (future == null) { return 0; } // We create a temporary map to store the bound handles, // as we may have to remove them all if there is an exception // during the sockets opening. Map<SocketAddress, H> newHandles = new ConcurrentHashMap<SocketAddress, H>(); List<SocketAddress> localAddresses = future.getLocalAddresses(); try { // Process all the addresses for (SocketAddress a : localAddresses) { H handle = open(a); newHandles.put(localAddress(handle), handle); } // Everything went ok, we can now update the map storing // all the bound sockets. boundHandles.putAll(newHandles); // and notify. future.setDone(); return newHandles.size(); } catch (Exception e) { // We store the exception in the future future.setException(e); } finally { // Roll back if failed to bind all addresses. if (future.getException() != null) { for (H handle : newHandles.values()) { try { close(handle); } catch (Exception e) { ExceptionMonitor.getInstance().exceptionCaught(e); } } // TODO : add some comment : what is the wakeup() waking up ? wakeup(); } } } }
接上图open方法 jdk自带的NIO
/**
* {@inheritDoc}
*/
@Override
protected ServerSocketChannel open(SocketAddress localAddress)
throws Exception {
// Creates the listening ServerSocket
ServerSocketChannel channel = ServerSocketChannel.open();
boolean success = false;
try {
// This is a non blocking socket channel
channel.configureBlocking(false);
// Configure the server socket,
ServerSocket socket = channel.socket();
// Set the reuseAddress flag accordingly with the setting
socket.setReuseAddress(isReuseAddress());
// and bind.
socket.bind(localAddress, getBacklog());
// Register the channel within the selector for ACCEPT event
channel.register(selector, SelectionKey.OP_ACCEPT);
success = true;
} finally {
if (!success) {
close(channel);
}
}
return channel;
}
Acceptor接收数据
if (selected > 0) { // We have some connection request, let's process // them here. processHandles(selectedHandles()); }
/** * This method will process new sessions for the Worker class. All * keys that have had their status updates as per the Selector.selectedKeys() * method will be processed here. Only keys that are ready to accept * connections are handled here. * <p/> * Session objects are created by making new instances of SocketSessionImpl * and passing the session object to the SocketIoProcessor class. */ @SuppressWarnings("unchecked") private void processHandles(Iterator<H> handles) throws Exception { while (handles.hasNext()) { H handle = handles.next(); handles.remove(); // Associates a new created connection to a processor, // and get back a session S session = accept(processor, handle); if (session == null) { break; } //初始化session initSession(session, null, null); // add the session to the SocketIoProcessor 过滤链处理数据入口 session.getProcessor().add(session); } }
processHandles 的accept 获取SocketChannel 封装成NioSocketSession
protected NioSession accept(IoProcessor<NioSession> processor, ServerSocketChannel handle) throws Exception { SelectionKey key = handle.keyFor(selector); if ((key == null) || (!key.isValid()) || (!key.isAcceptable()) ) { return null; } // accept the connection from the client SocketChannel ch = handle.accept(); if (ch == null) { return null; } return new NioSocketSession(this, processor, ch); }
processor
/**
* {@inheritDoc}
*/
public final void add(S session) {
if (disposed || disposing) {
throw new IllegalStateException("Already disposed.");
}
// Adds the session to the newSession queue and starts the worker
newSessions.add(session);
startupProcessor();
}
/**
* Starts the inner Processor, asking the executor to pick a thread in its
* pool. The Runnable will be renamed
*/
private void startupProcessor() {
Processor processor = processorRef.get();
if (processor == null) {
processor = new Processor();
if (processorRef.compareAndSet(null, processor)) {
executor.execute(new NamePreservingRunnable(processor, threadName));
}
}
// Just stop the select() and start it again, so that the processor
// can be activated immediately.
wakeup();
}
主要接收数据处理代码逻辑
/** * The main loop. This is the place in charge to poll the Selector, and to * process the active sessions. It's done in * - handle the newly created sessions * - */ private class Processor implements Runnable { public void run() { assert (processorRef.get() == this); int nSessions = 0; lastIdleCheckTime = System.currentTimeMillis(); for (;;) { try { // This select has a timeout so that we can manage // idle session when we get out of the select every // second. (note : this is a hack to avoid creating // a dedicated thread). long t0 = System.currentTimeMillis(); int selected = select(SELECT_TIMEOUT); long t1 = System.currentTimeMillis(); long delta = (t1 - t0); if ((selected == 0) && !wakeupCalled.get() && (delta < 100)) { // Last chance : the select() may have been // interrupted because we have had an closed channel. if (isBrokenConnection()) { LOG.warn("Broken connection"); // we can reselect immediately // set back the flag to false wakeupCalled.getAndSet(false); continue; } else { LOG.warn("Create a new selector. Selected is 0, delta = " + (t1 - t0)); // Ok, we are hit by the nasty epoll // spinning. // Basically, there is a race condition // which causes a closing file descriptor not to be // considered as available as a selected channel, but // it stopped the select. The next time we will // call select(), it will exit immediately for the same // reason, and do so forever, consuming 100% // CPU. // We have to destroy the selector, and // register all the socket on a new one. registerNewSelector(); } // Set back the flag to false wakeupCalled.getAndSet(false); // and continue the loop continue; } // Manage newly created session first nSessions += handleNewSessions(); updateTrafficMask(); // Now, if we have had some incoming or outgoing events, // deal with them if (selected > 0) { //LOG.debug("Processing ..."); // This log hurts one of the MDCFilter test... process(); } // Write the pending requests long currentTime = System.currentTimeMillis(); flush(currentTime); // And manage removed sessions nSessions -= removeSessions(); // Last, not least, send Idle events to the idle sessions notifyIdleSessions(currentTime); // Get a chance to exit the infinite loop if there are no // more sessions on this Processor if (nSessions == 0) { processorRef.set(null); if (newSessions.isEmpty() && isSelectorEmpty()) { // newSessions.add() precedes startupProcessor assert (processorRef.get() != this); break; } assert (processorRef.get() != this); if (!processorRef.compareAndSet(null, this)) { // startupProcessor won race, so must exit processor assert (processorRef.get() != this); break; } assert (processorRef.get() == this); } // Disconnect all sessions immediately if disposal has been // requested so that we exit this loop eventually. if (isDisposing()) { for (Iterator<S> i = allSessions(); i.hasNext();) { scheduleRemove(i.next()); } wakeup(); } } catch (ClosedSelectorException cse) { // If the selector has been closed, we can exit the loop break; } catch (Throwable t) { ExceptionMonitor.getInstance().exceptionCaught(t); try { Thread.sleep(1000); } catch (InterruptedException e1) { ExceptionMonitor.getInstance().exceptionCaught(e1); } } } try { synchronized (disposalLock) { if (disposing) { doDispose(); } } } catch (Throwable t) { ExceptionMonitor.getInstance().exceptionCaught(t); } finally { disposalFuture.setValue(true); } } }
过滤链：
private void process() throws Exception { for (Iterator<S> i = selectedSessions(); i.hasNext();) { S session = i.next(); process(session); i.remove(); } } /** * Deal with session ready for the read or write operations, or both. */ private void process(S session) { // Process Reads if (isReadable(session) && !session.isReadSuspended()) { read(session); } // Process writes if (isWritable(session) && !session.isWriteSuspended()) { // add the session to the queue, if it's not already there if (session.setScheduledForFlush(true)) { flushingSessions.add(session); } } } private void read(S session) { IoSessionConfig config = session.getConfig(); int bufferSize = config.getReadBufferSize(); IoBuffer buf = IoBuffer.allocate(bufferSize); final boolean hasFragmentation = session.getTransportMetadata() .hasFragmentation(); try { int readBytes = 0; int ret; try { if (hasFragmentation) { while ((ret = read(session, buf)) > 0) { readBytes += ret; if (!buf.hasRemaining()) { break; } } } else { ret = read(session, buf); if (ret > 0) { readBytes = ret; } } } finally { buf.flip(); } if (readBytes > 0) { //处理逻辑 IoFilterChain filterChain = session.getFilterChain(); filterChain.fireMessageReceived(buf); buf = null; if (hasFragmentation) { if (readBytes << 1 < config.getReadBufferSize()) { session.decreaseReadBufferSize(); } else if (readBytes == config.getReadBufferSize()) { session.increaseReadBufferSize(); } } } if (ret < 0) { scheduleRemove(session); } } catch (Throwable e) { if (e instanceof IOException) { if (!(e instanceof PortUnreachableException) || !AbstractDatagramSessionConfig.class.isAssignableFrom(config.getClass()) || ((AbstractDatagramSessionConfig) config).isCloseOnPortUnreachable()) { scheduleRemove(session); } } IoFilterChain filterChain = session.getFilterChain(); filterChain.fireExceptionCaught(e); } }
调用过滤连： DefaultIoFilterChain
public void fireMessageReceived(Object message) { if (message instanceof IoBuffer) { session.increaseReadBytes(((IoBuffer) message).remaining(), System .currentTimeMillis()); } Entry head = this.head; callNextMessageReceived(head, session, message); } private void callNextMessageReceived(Entry entry, IoSession session, Object message) { try { IoFilter filter = entry.getFilter(); NextFilter nextFilter = entry.getNextFilter(); filter.messageReceived(nextFilter, session, message); } catch (Throwable e) { fireExceptionCaught(e); } }
业务处理handler总是最后处理
