protected void enhance()

in core/src/main/java/com/taobao/arthas/core/command/monitor200/EnhancerCommand.java [145:230]
73 lines of code
12 McCabe index (conditional complexity)

    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();
            }
        }
    }