前言
上篇文章已经梳理了整体流程,这次我们来看arthas-client 与 arthas-core 的交互.
首先,我们回到arthas-agent启动的arthas-core代码,我们查看agent server代码片段:
BuiltinCommandPack builtinCommands = new BuiltinCommandPack(disabledCommands);
List<CommandResolver> resolvers = new ArrayList<CommandResolver>();
resolvers.add(builtinCommands);
//worker group
workerGroup = new NioEventLoopGroup(new DefaultThreadFactory("arthas-TermServer", true));
// TODO: discover user provided command resolver
if (configure.getTelnetPort() != null && configure.getTelnetPort() > 0) {
logger().info("try to bind telnet server, host: {}, port: {}.", configure.getIp(), configure.getTelnetPort());
shellServer.registerTermServer(new HttpTelnetTermServer(configure.getIp(), configure.getTelnetPort(),
options.getConnectionTimeout(), workerGroup, httpSessionManager));
} else {
logger().info("telnet port is {}, skip bind telnet server.", configure.getTelnetPort());
}
if (configure.getHttpPort() != null && configure.getHttpPort() > 0) {
logger().info("try to bind http server, host: {}, port: {}.", configure.getIp(), configure.getHttpPort());
shellServer.registerTermServer(new HttpTermServer(configure.getIp(), configure.getHttpPort(),
options.getConnectionTimeout(), workerGroup, httpSessionManager));
} else {
// listen local address in VM communication
if (configure.getTunnelServer() != null) {
shellServer.registerTermServer(new HttpTermServer(configure.getIp(), configure.getHttpPort(),
options.getConnectionTimeout(), workerGroup, httpSessionManager));
}
logger().info("http port is {}, skip bind http server.", configure.getHttpPort());
}
for (CommandResolver resolver : resolvers) {
shellServer.registerCommandResolver(resolver);
}
这里我们可以看出,使用netty作为服务端,当他接收到客户端的交互的时候,会触发CommandResolver接口的解析,我们找到BuiltinCommandPack
这个类在实例化的时候,如下代码:
public BuiltinCommandPack(List<String> disabledCommands) {
initCommands(disabledCommands);
}
@Override
public List<Command> commands() {
return commands;
}
private void initCommands(List<String> disabledCommands) {
List<Class<? extends AnnotatedCommand>> commandClassList = new ArrayList<Class<? extends AnnotatedCommand>>(33);
commandClassList.add(HelpCommand.class);
commandClassList.add(AuthCommand.class);
commandClassList.add(KeymapCommand.class);
commandClassList.add(SearchClassCommand.class);
commandClassList.add(SearchMethodCommand.class);
commandClassList.add(ClassLoaderCommand.class);
commandClassList.add(JadCommand.class);
commandClassList.add(GetStaticCommand.class);
commandClassList.add(MonitorCommand.class);
commandClassList.add(StackCommand.class);
commandClassList.add(ThreadCommand.class);
commandClassList.add(TraceCommand.class);
commandClassList.add(WatchCommand.class);
commandClassList.add(TimeTunnelCommand.class);
commandClassList.add(JvmCommand.class);
commandClassList.add(MemoryCommand.class);
commandClassList.add(PerfCounterCommand.class);
// commandClassList.add(GroovyScriptCommand.class);
commandClassList.add(OgnlCommand.class);
commandClassList.add(MemoryCompilerCommand.class);
commandClassList.add(RedefineCommand.class);
commandClassList.add(RetransformCommand.class);
commandClassList.add(DashboardCommand.class);
commandClassList.add(DumpClassCommand.class);
commandClassList.add(HeapDumpCommand.class);
commandClassList.add(JulyCommand.class);
commandClassList.add(ThanksCommand.class);
commandClassList.add(OptionsCommand.class);
commandClassList.add(ClsCommand.class);
commandClassList.add(ResetCommand.class);
commandClassList.add(VersionCommand.class);
commandClassList.add(SessionCommand.class);
commandClassList.add(SystemPropertyCommand.class);
commandClassList.add(SystemEnvCommand.class);
commandClassList.add(VMOptionCommand.class);
commandClassList.add(LoggerCommand.class);
commandClassList.add(HistoryCommand.class);
commandClassList.add(CatCommand.class);
commandClassList.add(Base64Command.class);
commandClassList.add(EchoCommand.class);
commandClassList.add(PwdCommand.class);
commandClassList.add(MBeanCommand.class);
commandClassList.add(GrepCommand.class);
commandClassList.add(TeeCommand.class);
commandClassList.add(ProfilerCommand.class);
commandClassList.add(VmToolCommand.class);
commandClassList.add(StopCommand.class);
try {
if (ClassLoader.getSystemClassLoader().getResource("jdk/jfr/Recording.class") != null) {
commandClassList.add(JFRCommand.class);
}
} catch (Throwable e) {
logger.error("This jdk version not support jfr command");
}
for (Class<? extends AnnotatedCommand> clazz : commandClassList) {
Name name = clazz.getAnnotation(Name.class);
if (name != null && name.value() != null) {
if (disabledCommands.contains(name.value())) {
continue;
}
}
commands.add(Command.create(clazz));
}
}
从这里,我们可以看出,所有的命令,都在这里,对应的TraceCommand 我们进去看了一下,这里他其实用了设计模式,我们看一下父类,子类.不难看出,对于EnhancerCommand 实现的类,都会获取子类的监听器.getAdviceListener 具体的实现交由子类,弗雷做抽象处理,例如加锁,同步,任务调度,返回,命令解析等等.
@Override
protected AdviceListener getAdviceListener(CommandProcess process) {
if (pathPatterns == null || pathPatterns.isEmpty()) {
return new TraceAdviceListener(this, process, GlobalOptions.verbose || this.verbose);
} else {
return new PathTraceAdviceListener(this, process);
}
}
整体的流程如下:
protected void enhance(CommandProcess process) {
Session session = process.session();
if (!session.tryLock()) {
String msg = "someone else is enhancing classes, pls. wait.";
process.appendResult(new EnhancerModel(null, false, msg));
process.end(-1, msg);
return;
}
EnhancerAffect effect = null;
int lock = session.getLock();
try {
Instrumentation inst = session.getInstrumentation();
AdviceListener listener = getAdviceListenerWithId(process);
if (listener == null) {
logger.error("advice listener is null");
String msg = "advice listener is null, check arthas log";
process.appendResult(new EnhancerModel(effect, false, msg));
process.end(-1, msg);
return;
}
boolean skipJDKTrace = false;
if(listener instanceof AbstractTraceAdviceListener) {
skipJDKTrace = ((AbstractTraceAdviceListener) listener).getCommand().isSkipJDKTrace();
}
Enhancer enhancer = new Enhancer(listener, listener instanceof InvokeTraceable, skipJDKTrace, getClassNameMatcher(), getClassNameExcludeMatcher(), getMethodNameMatcher());
// 注册通知监听器
process.register(listener, enhancer);
effect = enhancer.enhance(inst, this.maxNumOfMatchedClass);
if (effect.getThrowable() != null) {
String msg = "error happens when enhancing class: "+effect.getThrowable().getMessage();
process.appendResult(new EnhancerModel(effect, false, msg));
process.end(1, msg + ", check arthas log: " + LogUtil.loggingFile());
return;
}
if (effect.cCnt() == 0 || effect.mCnt() == 0) {
// no class effected
if (!StringUtils.isEmpty(effect.getOverLimitMsg())) {
process.appendResult(new EnhancerModel(effect, false));
process.end(-1);
return;
}
// might be method code too large
process.appendResult(new EnhancerModel(effect, false, "No class or method is affected"));
String smCommand = Ansi.ansi().fg(Ansi.Color.GREEN).a("sm CLASS_NAME METHOD_NAME").reset().toString();
String optionsCommand = Ansi.ansi().fg(Ansi.Color.GREEN).a("options unsafe true").reset().toString();
String javaPackage = Ansi.ansi().fg(Ansi.Color.GREEN).a("java.*").reset().toString();
String resetCommand = Ansi.ansi().fg(Ansi.Color.GREEN).a("reset CLASS_NAME").reset().toString();
String logStr = Ansi.ansi().fg(Ansi.Color.GREEN).a(LogUtil.loggingFile()).reset().toString();
String issueStr = Ansi.ansi().fg(Ansi.Color.GREEN).a("https://github.com/alibaba/arthas/issues/47").reset().toString();
String msg = "No class or method is affected, try:\n"
+ "1. Execute `" + smCommand + "` to make sure the method you are tracing actually exists (it might be in your parent class).\n"
+ "2. Execute `" + optionsCommand + "`, if you want to enhance the classes under the `" + javaPackage + "` package.\n"
+ "3. Execute `" + resetCommand + "` and try again, your method body might be too large.\n"
+ "4. Match the constructor, use `<init>`, for example: `watch demo.MathGame <init>`\n"
+ "5. Check arthas log: " + logStr + "\n"
+ "6. Visit " + issueStr + " for more details.";
process.end(-1, msg);
return;
}
// 这里做个补偿,如果在enhance期间,unLock被调用了,则补偿性放弃
if (session.getLock() == lock) {
if (process.isForeground()) {
process.echoTips(Constants.Q_OR_CTRL_C_ABORT_MSG + "\n");
}
}
process.appendResult(new EnhancerModel(effect, true));
//异步执行，在AdviceListener中结束
} catch (Throwable e) {
String msg = "error happens when enhancing class: "+e.getMessage();
logger.error(msg, e);
process.appendResult(new EnhancerModel(effect, false, msg));
process.end(-1, msg);
} finally {
if (session.getLock() == lock) {
// enhance结束后解锁
process.session().unLock();
}
}
}
主要看这部分代码:
Enhancer enhancer = new Enhancer(listener, listener instanceof InvokeTraceable, skipJDKTrace, getClassNameMatcher(), getClassNameExcludeMatcher(), getMethodNameMatcher());
// 注册通知监听器
process.register(listener, enhancer);
effect = enhancer.enhance(inst, this.maxNumOfMatchedClass);
这里做的批量增强.
