Tomcat 系列篇三-介绍下 Coyote
前面介绍了 connector，这里边还有个很重要的概念是 Coyote，真正将前面的 connector 跟后面的 container 做了连接，org.apache.tomcat.util.net.AbstractEndpoint#createSocketProcessor 从这里开始
然后会调用到 org.apache.tomcat.util.net.NioEndpoint#createSocketProcessor
@Override
protected SocketProcessorBase<NioChannel> createSocketProcessor(
SocketWrapperBase<NioChannel> socketWrapper, SocketEvent event) {
return new SocketProcessor(socketWrapper, event);
}里面实际的是 new 了org.apache.tomcat.util.net.NioEndpoint.SocketProcessor#SocketProcessor
protected class SocketProcessor extends SocketProcessorBase<NioChannel> {
public SocketProcessor(SocketWrapperBase<NioChannel> socketWrapper, SocketEvent event) {
super(socketWrapper, event);
}
@Override
protected void doRun() {
/*
* Do not cache and re-use the value of socketWrapper.getSocket() in
* this method. If the socket closes the value will be updated to
* CLOSED_NIO_CHANNEL and the previous value potentially re-used for
* a new connection. That can result in a stale cached value which
* in turn can result in unintentionally closing currently active
* connections.
*/
Poller poller = NioEndpoint.this.poller;
if (poller == null) {
socketWrapper.close();然后是 org.apache.tomcat.util.net.NioEndpoint.SocketProcessor#doRun 这里开始运行
protected void doRun() {
/*
* Do not cache and re-use the value of socketWrapper.getSocket() in
* this method. If the socket closes the value will be updated to
* CLOSED_NIO_CHANNEL and the previous value potentially re-used for
* a new connection. That can result in a stale cached value which
* in turn can result in unintentionally closing currently active
* connections.
*/
Poller poller = NioEndpoint.this.poller;
if (poller == null) {
socketWrapper.close();
return;
}
try {
int handshake = -1;
try {
if (socketWrapper.getSocket().isHandshakeComplete()) {
// No TLS handshaking required. Let the handler
// process this socket / event combination.
handshake = 0;
} else if (event == SocketEvent.STOP || event == SocketEvent.DISCONNECT ||
event == SocketEvent.ERROR) {
// Unable to complete the TLS handshake. Treat it as
// if the handshake failed.
handshake = -1;
} else {
handshake = socketWrapper.getSocket().handshake(event == SocketEvent.OPEN_READ, event == SocketEvent.OPEN_WRITE);
// The handshake process reads/writes from/to the
// socket. status may therefore be OPEN_WRITE once
// the handshake completes. However, the handshake
// happens when the socket is opened so the status
// must always be OPEN_READ after it completes. It
// is OK to always set this as it is only used if
// the handshake completes.
event = SocketEvent.OPEN_READ;
}
} catch (IOException x) {
handshake = -1;
if (log.isDebugEnabled()) {
log.debug("Error during SSL handshake",x);
}
} catch (CancelledKeyException ckx) {
handshake = -1;
}
if (handshake == 0) {
SocketState state = SocketState.OPEN;
// Process the request from this socket
if (event == null) {
state = getHandler().process(socketWrapper, SocketEvent.OPEN_READ);
} else {
state = getHandler().process(socketWrapper, event);
}
if (state == SocketState.CLOSED) {
poller.cancelledKey(getSelectionKey(), socketWrapper);
}org.apache.coyote.AbstractProtocol.ConnectionHandler#process 这个 getHandler 是哪个呢
public AbstractHttp11Protocol(AbstractEndpoint<S,?> endpoint) {
super(endpoint);
setConnectionTimeout(Constants.DEFAULT_CONNECTION_TIMEOUT);
ConnectionHandler<S> cHandler = new ConnectionHandler<>(this);
setHandler(cHandler);
getEndpoint().setHandler(cHandler);
}上面补充下这个 Handler，帮助后面的理解，而这个 connectionHandler 则是实现了 AbstractEndpoint.Handler
protected static class ConnectionHandler<S> implements AbstractEndpoint.Handler<S> {
private final AbstractProtocol<S> proto;
private final RequestGroupInfo global = new RequestGroupInfo();
private final AtomicLong registerCount = new AtomicLong(0);
private final RecycledProcessors recycledProcessors = new RecycledProcessors(this);
public ConnectionHandler(AbstractProtocol<S> proto) {
this.proto = proto;
}
protected AbstractProtocol<S> getProtocol() {
return proto;
}然后会继续寻找真实的 Processer
@Override
public SocketState process(SocketWrapperBase<S> wrapper, SocketEvent status) {
if (getLog().isDebugEnabled()) {
getLog().debug(sm.getString("abstractConnectionHandler.process",
wrapper.getSocket(), status));
}
if (wrapper == null) {
// Nothing to do. Socket has been closed.
return SocketState.CLOSED;
}
S socket = wrapper.getSocket();
Processor processor = (Processor) wrapper.getCurrentProcessor();
if (getLog().isDebugEnabled()) {
getLog().debug(sm.getString("abstractConnectionHandler.connectionsGet",
processor, socket));
}
// 省略代码
// 直到这里创建 processor
if (processor == null) {
processor = getProtocol().createProcessor();
register(processor);
if (getLog().isDebugEnabled()) {
getLog().debug(sm.getString("abstractConnectionHandler.processorCreate", processor));
}
}也就是 org.apache.coyote.http11.AbstractHttp11Protocol#createProcessor
@Override
protected Processor createProcessor() {
Http11Processor processor = new Http11Processor(this, adapter);
return processor;
}再往后就是调用 process 方法了，然后它是 Http11Processor 的抽象父类org.apache.coyote.AbstractProcessorLight
会调用 org.apache.coyote.AbstractProcessorLight#process 来处理前面说的 socket
接着会跑到这
@Override
public SocketState process(SocketWrapperBase<?> socketWrapper, SocketEvent status)
throws IOException {
SocketState state = SocketState.CLOSED;
Iterator<DispatchType> dispatches = null;
do {
if (dispatches != null) {
DispatchType nextDispatch = dispatches.next();
if (getLog().isDebugEnabled()) {
getLog().debug("Processing dispatch type: [" + nextDispatch + "]");
}
state = dispatch(nextDispatch.getSocketStatus());
if (!dispatches.hasNext()) {
state = checkForPipelinedData(state, socketWrapper);
}
} else if (status == SocketEvent.DISCONNECT) {
// Do nothing here, just wait for it to get recycled
} else if (isAsync() || isUpgrade() || state == SocketState.ASYNC_END) {
state = dispatch(status);
state = checkForPipelinedData(state, socketWrapper);
} else if (status == SocketEvent.OPEN_WRITE) {
// Extra write event likely after async, ignore
state = SocketState.LONG;
} else if (status == SocketEvent.OPEN_READ) {
state = service(socketWrapper);接下去就是org.apache.coyote.http11.Http11Processor#service
再就是调用coyote的 service 方法也就是 org.apache.catalina.connector.CoyoteAdapter#service
这里就会调用到
connector.getService().getContainer().getPipeline().getFirst().invoke(
request, response);
然后进行 valve 串的执行到 org.apache.catalina.core.StandardWrapperValve#invoke 中
会调用
filterChain.doFilter
(request.getRequest(), response.getResponse());就会执行 filter 链
最后到org.apache.catalina.core.ApplicationFilterChain#internalDoFilter
servlet.service(request, response);就到了 DispatcherServlet 处理的流程, 这样就和之前介绍 DispatcherServlet开始的请求处理接上了。