字节伙伴的方法委派导致StackOverflowError

时间：2019-01-10 21:02:32

标签： java stack-overflow byte-buddy javaagents

我试图创建一个代理来代理方法，以便在方法之前和之后执行一些逻辑。为此，我将Byte Buddy与方法委托一起使用。

代理商：

//Agent code before...
private static void instrument(String agentOps, Instrumentation inst) {
    new AgentBuilder.Default().with(new Eager())
            .ignore(ElementMatchers.nameContains("com.dvelopp.agenttest"))
            .or(ElementMatchers.hasAnnotation(ElementMatchers.annotationType(ElementMatchers.nameContains("SpringBootApplication"))))
            .type((ElementMatchers.any()))
            .transform((builder, typeDescription, classLoader, module) -> builder.method(ElementMatchers.any())
                    .intercept(MethodDelegation.to(Interceptor.class)))
            .installOn(inst);
}
//Agent code after...

拦截器：

public static class Interceptor {

    @RuntimeType
    public static Object intercept(@SuperCall Callable<?> superCall, @SuperMethod Method superMethod, @Origin Method currentMethod,
                                   @AllArguments Object[] args, @This(optional = true) Object me) throws Exception {
        //... logic
        Object call = superCall.call();
        //... logic
        return call;
    }
}

在一个简单的控制台应用程序上它完美地工作。但是，当我在类路径中有一些通用库（例如简单的Spring Boot项目）时，它无法按预期工作。它会产生不同的错误，但是大多数错误都与这样的意外反射有关：

Exception in thread "main" java.lang.NoClassDefFoundError: sun/reflect/GeneratedMethodAccessor24
at sun.reflect.GeneratedMethodAccessor24.<clinit>(Unknown Source)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at java.lang.Class.newInstance(Class.java:442)
at sun.reflect.MethodAccessorGenerator$1.run(MethodAccessorGenerator.java:403)
at sun.reflect.MethodAccessorGenerator$1.run(MethodAccessorGenerator.java:394)
at java.security.AccessController.doPrivileged(Native Method)
at sun.reflect.MethodAccessorGenerator.generate(MethodAccessorGenerator.java:393)
at sun.reflect.MethodAccessorGenerator.generateMethod(MethodAccessorGenerator.java:75)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:53)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.logging.log4j.status.StatusLogger.<clinit>(StatusLogger.java:85)
at org.apache.logging.log4j.LogManager.<clinit>(LogManager.java:60)
at org.apache.commons.logging.LogAdapter$Log4jLog.<clinit>(LogAdapter.java:135)
at org.apache.commons.logging.LogAdapter$Log4jAdapter.createLog$original$snrPR67N(LogAdapter.java:102)
at org.apache.commons.logging.LogAdapter$Log4jAdapter.createLog$original$snrPR67N$accessor$5P1QZaof(LogAdapter.java)
at org.apache.commons.logging.LogAdapter$Log4jAdapter$auxiliary$pVmPc64S.call(Unknown Source)
at com.dvelopp.agenttest.Main$Interceptor.intercept(Main.java:126)
at org.apache.commons.logging.LogAdapter$Log4jAdapter.createLog(LogAdapter.java)
at org.apache.commons.logging.LogAdapter.createLog$original$4Ty3vM8s(LogAdapter.java:79)
at org.apache.commons.logging.LogAdapter.createLog$original$4Ty3vM8s$accessor$z3gv7aJK(LogAdapter.java)
at org.apache.commons.logging.LogAdapter$auxiliary$6cBoraQE.call(Unknown Source)
at com.dvelopp.agenttest.Main$Interceptor.intercept(Main.java:126)
at org.apache.commons.logging.LogAdapter.createLog(LogAdapter.java)
at org.apache.commons.logging.LogFactory.getLog$original$MoDHp2B7(LogFactory.java:67)
at org.apache.commons.logging.LogFactory.getLog$original$MoDHp2B7$accessor$VdtqA6Wx(LogFactory.java)
at org.apache.commons.logging.LogFactory$auxiliary$ak9XEBl0.call(Unknown Source)
at com.dvelopp.agenttest.Main$Interceptor.intercept(Main.java:126)
at org.apache.commons.logging.LogFactory.getLog(LogFactory.java)
at org.apache.commons.logging.LogFactory.getLog$original$MoDHp2B7(LogFactory.java:59)
at org.apache.commons.logging.LogFactory.getLog$original$MoDHp2B7$accessor$VdtqA6Wx(LogFactory.java)
at org.apache.commons.logging.LogFactory$auxiliary$8JhBdK8k.call(Unknown Source)
at com.dvelopp.agenttest.Main$Interceptor.intercept(Main.java:126)
at org.apache.commons.logging.LogFactory.getLog(LogFactory.java)
at org.springframework.boot.SpringApplication.<clinit>(SpringApplication.java:194)
at hello.Application.main(Application.java:15)
Caused by: java.lang.ClassNotFoundException: sun.reflect.GeneratedMethodAccessor24
at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
... 39 more

正如我所看到的，这些错误发生在代理对象上：

e.g. org.apache.commons.logging.LogFactory.getLog$original$MoDHp2B7

我尝试了更深入的调试，发现超级方法和起源有不同的类。 “超级”具有代理类。 

@SuperMethod Method superMethod, @Origin Method currentMethod

是否有一种方法可以使委托与此类对象一起工作？

添加：

在这个Spring Boot 2示例（https://spring.io/guides/gs/spring-boot/）上，有一个明显的StackOverflowError：

java.lang.StackOverflowError: null
at com.dvelopp.agenttest.MethodCallContext.getCaller(MethodCallContext.java:18)
at com.dvelopp.agenttest.Main$Interceptor.intercept(Main.java:108)
at org.springframework.core.env.SystemEnvironmentPropertySource.getSource(SystemEnvironmentPropertySource.java)
at org.springframework.core.env.MapPropertySource.getSource(MapPropertySource.java)
at org.springframework.core.env.SystemEnvironmentPropertySource.getSource$accessor$d92Pg8OK(SystemEnvironmentPropertySource.java)
at org.springframework.core.env.SystemEnvironmentPropertySource$auxiliary$ATPz5tSr.call(Unknown Source)
at com.dvelopp.agenttest.Main$Interceptor.intercept(Main.java:122)
at org.springframework.core.env.SystemEnvironmentPropertySource.getSource(SystemEnvironmentPropertySource.java)
at org.springframework.core.env.MapPropertySource.getSource(MapPropertySource.java)
at org.springframework.core.env.SystemEnvironmentPropertySource.getSource$accessor$d92Pg8OK(SystemEnvironmentPropertySource.java)
at org.springframework.core.env.SystemEnvironmentPropertySource$auxiliary$ATPz5tSr.call(Unknown Source)
at com.dvelopp.agenttest.Main$Interceptor.intercept(Main.java:122)
at org.springframework.core.env.SystemEnvironmentPropertySource.getSource(SystemEnvironmentPropertySource.java)
at org.springframework.core.env.MapPropertySource.getSource(MapPropertySource.java)
at org.springframework.core.env.SystemEnvironmentPropertySource.getSource$accessor$d92Pg8OK(SystemEnvironmentPropertySource.java)
at org.springframework.core.env.SystemEnvironmentPropertySource$auxiliary$ATPz5tSr.call(Unknown Source)
at com.dvelopp.agenttest.Main$Interceptor.intercept(Main.java:122)

1 个答案:

答案 0 :(得分：1)

似乎您使用了错误的注释或功能。

我建议检查更简单的情况。例如，替换您的实现：

    @RuntimeType
    public static Object intercept(@SuperCall Callable<?> superCall, @SuperMethod Method superMethod, @Origin Method currentMethod,
                                   @AllArguments Object[] args, @This(optional = true) Object me) throws Exception {
        return superCall.call();
    }

与下一个：

    @RuntimeType
    public static Object intercept(@RuntimeType Object value) throws Exception {
        return value;
    }

在这种情况下，您避免了递归调用，但是有可能会发现并分析不同的问题，这很明显并且与您的情况有关。

可能您还应该注意概念上的问题。您知道使用java对象的Callable开发人员切勿直接使用call()。

以下@RuntimeType的API描述用于将一个对象映射到另一个对象。出现新问题：为什么需要转换callable对象？将要转换为哪种类型（您确定没有Future包装器在那里会有一个对象。可能有null可能导致您的异常，不是吗？）？

相关问题
最新问题