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本文次要钻研一下 arthas 的 HttpTermServer
TermServer
com/taobao/arthas/core/shell/term/TermServer.java
public abstract class TermServer {
/**
* Create a term server for the Telnet protocol.
*
* @param configure
* @return the term server
*/
public static TermServer createTelnetTermServer(Configure configure, ShellServerOptions options) {int port = configure.getTelnetPort() != null ? configure.getTelnetPort() : ArthasConstants.TELNET_PORT;
return new TelnetTermServer(configure.getIp(), port, options.getConnectionTimeout());
}
/**
* Create a term server for the HTTP protocol, using an existing router.
*
* @return the term server
*/
public static TermServer createHttpTermServer() {
// TODO
return null;
}
/**
* Set the term handler that will receive incoming client connections. When a remote terminal connects
* the {@code handler} will be called with the {@link Term} which can be used to interact with the remote
* terminal.
*
* @param handler the term handler
* @return this object
*/
public abstract TermServer termHandler(Handler<Term> handler);
/**
* Bind the term server, the {@link #termHandler(Handler)} must be set before.
*
* @return this object
*/
public TermServer listen() {return listen(null);
}
/**
* Bind the term server, the {@link #termHandler(Handler)} must be set before.
*
* @param listenHandler the listen handler
* @return this object
*/
public abstract TermServer listen(Handler<Future<TermServer>> listenHandler);
/**
* The actual port the server is listening on. This is useful if you bound the server specifying 0 as port number
* signifying an ephemeral port
*
* @return the actual port the server is listening on.
*/
public abstract int actualPort();
/**
* Close the server. This will close any currently open connections. The close may not complete until after this
* method has returned.
*/
public abstract void close();
/**
* Like {@link #close} but supplying a handler that will be notified when close is complete.
*
* @param completionHandler the handler to be notified when the term server is closed
*/
public abstract void close(Handler<Future<Void>> completionHandler);
}TermServer 是一个抽象类，它定义了 termHandler、listen、actualPort、close 形象办法
HttpTermServer
com/taobao/arthas/core/shell/term/impl/HttpTermServer.java
public class HttpTermServer extends TermServer {private static final Logger logger = LoggerFactory.getLogger(HttpTermServer.class);
private Handler<Term> termHandler;
private NettyWebsocketTtyBootstrap bootstrap;
private String hostIp;
private int port;
private long connectionTimeout;
private EventExecutorGroup workerGroup;
private HttpSessionManager httpSessionManager;
public HttpTermServer(String hostIp, int port, long connectionTimeout, EventExecutorGroup workerGroup, HttpSessionManager httpSessionManager) {
this.hostIp = hostIp;
this.port = port;
this.connectionTimeout = connectionTimeout;
this.workerGroup = workerGroup;
this.httpSessionManager = httpSessionManager;
}
@Override
public TermServer termHandler(Handler<Term> handler) {
this.termHandler = handler;
return this;
}
@Override
public TermServer listen(Handler<Future<TermServer>> listenHandler) {
// TODO: charset and inputrc from options
bootstrap = new NettyWebsocketTtyBootstrap(workerGroup, httpSessionManager).setHost(hostIp).setPort(port);
try {bootstrap.start(new Consumer<TtyConnection>() {
@Override
public void accept(final TtyConnection conn) {termHandler.handle(new TermImpl(Helper.loadKeymap(), conn));
}
}).get(connectionTimeout, TimeUnit.MILLISECONDS);
listenHandler.handle(Future.<TermServer>succeededFuture());
} catch (Throwable t) {logger.error("Error listening to port" + port, t);
listenHandler.handle(Future.<TermServer>failedFuture(t));
}
return this;
}
@Override
public int actualPort() {return bootstrap.getPort();
}
@Override
public void close() {close(null);
}
@Override
public void close(Handler<Future<Void>> completionHandler) {if (bootstrap != null) {bootstrap.stop();
if (completionHandler != null) {completionHandler.handle(Future.<Void>succeededFuture());
}
} else {if (completionHandler != null) {completionHandler.handle(Future.<Void>failedFuture("telnet term server not started"));
}
}
}
}HttpTermServer 继承了 TermServer，其 listen 办法创立 NettyWebsocketTtyBootstrap，而后执行其 start 办法，其 accept 办法执行的是 termHandler.handle(new TermImpl(Helper.loadKeymap(), conn))，最初执行 listenHandler.handle(Future.<TermServer>succeededFuture())；其 close 办法执行的是 bootstrap.stop()
Handler
com/taobao/arthas/core/shell/handlers/Handler.java
public interface Handler<E> {
/**
* Something has happened, so handle it.
*
* @param event the event to handle
*/
void handle(E event);
}Handler 定义了 handle 办法
TermServerTermHandler
com/taobao/arthas/core/shell/handlers/server/TermServerTermHandler.java
public class TermServerTermHandler implements Handler<Term> {
private ShellServerImpl shellServer;
public TermServerTermHandler(ShellServerImpl shellServer) {this.shellServer = shellServer;}
@Override
public void handle(Term term) {shellServer.handleTerm(term);
}
}TermServerTermHandler 实现了 Handler 接口，其 handle 办法执行的是 shellServer.handleTerm(term)
ShellServerImpl
com/taobao/arthas/core/shell/impl/ShellServerImpl.java
public void handleTerm(Term term) {synchronized (this) {
// That might happen with multiple ser
if (closed) {term.close();
return;
}
}
ShellImpl session = createShell(term);
tryUpdateWelcomeMessage();
session.setWelcome(welcomeMessage);
session.closedFuture.setHandler(new SessionClosedHandler(this, session));
session.init();
sessions.put(session.id, session); // Put after init so the close handler on the connection is set
session.readline(); // Now readline}ShellServerImpl 的 handleTerm 办法创立 ShellImpl，而后执行 init，最初执行 readline
readline
com/taobao/arthas/core/shell/impl/ShellImpl.java
public void readline() {term.readline(prompt, new ShellLineHandler(this),
new CommandManagerCompletionHandler(commandManager));
}ShellImpl 的 readline 委托给了 Term，传入 ShellLineHandler
ShellLineHandler
com/taobao/arthas/core/shell/handlers/shell/ShellLineHandler.java
public void handle(String line) {if (line == null) {
// EOF
handleExit();
return;
}
List<CliToken> tokens = CliTokens.tokenize(line);
CliToken first = TokenUtils.findFirstTextToken(tokens);
if (first == null) {
// For now do like this
shell.readline();
return;
}
String name = first.value();
if (name.equals("exit") || name.equals("logout") || name.equals("q") || name.equals("quit")) {handleExit();
return;
} else if (name.equals("jobs")) {handleJobs();
return;
} else if (name.equals("fg")) {handleForeground(tokens);
return;
} else if (name.equals("bg")) {handleBackground(tokens);
return;
} else if (name.equals("kill")) {handleKill(tokens);
return;
}
Job job = createJob(tokens);
if (job != null) {job.run();
}
}ShellLineHandler 的 handle 办法才是真正解决命令的中央，它反对了 exit、logout、q、quit、jobs、fg、bg、kill 命令
小结
HttpTermServer 继承了 TermServer，其 listen 办法创立 NettyWebsocketTtyBootstrap，而后执行其 start 办法，其 accept 办法执行的是 termHandler.handle(new TermImpl(Helper.loadKeymap(), conn))，最初执行 listenHandler.handle(Future.<TermServer>succeededFuture())；其 close 办法执行的是 bootstrap.stop()。