问题描述
我需要你的帮助来找出我的实现有什么问题...
I need your help in finding what's wrong with my implementation...
我正在尝试使用字节伙伴实现一个简单的 JVM 运行时分析器.一般来说，我需要的是每个方法调用都将记录在我在单独对象中管理的堆栈中.
I'm trying to implement a simple JVM runtime profiler using byte-buddy.In general, what I need is that every method call will be logged in a stack which I manage in a separate object.
在阅读了几篇文章后，我明白最好使用Advise"方法而不是MethodDelegation"，这是我得出的结论:
After reading several posts, I understood that it's better to use the "Advise" approach instead of "MethodDelegation", and here's what I came out with:
Agent.java:
Agent.java:
package com.panaya.java.agent;
import net.bytebuddy.agent.builder.AgentBuilder;
import net.bytebuddy.asm.Advice;
import net.bytebuddy.description.type.TypeDescription;
import net.bytebuddy.matcher.ElementMatchers;
import net.bytebuddy.utility.JavaModule;
import java.lang.instrument.Instrumentation;
import java.security.ProtectionDomain;
import java.util.ArrayList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;
public class Agent {
private static List<Pattern> pkgIncl = new ArrayList<Pattern>();
private static List<Pattern> pkgExcl = new ArrayList<Pattern>();
private static void initMatcherPatterns(String argument) {
if (argument == null) {
System.out.println("Missing configuration argument");
return;
}
System.out.println("Argument is: " + argument);
String[] tokens = argument.split(";");
if (tokens.length < 1) {
System.out.println("Missing delimeter ;");
return;
}
for (String token : tokens) {
String[] args = token.split("=");
if (args.length < 2) {
System.out.println("Missing argument delimeter =:" + token);
return;
}
String argtype = args[0];
if (!argtype.equals("incl") && !argtype.equals("excl")) {
System.out.println("Wrong argument: " + argtype);
return;
}
String[] patterns = args[1].split(",");
for (String pattern : patterns) {
Pattern p = null;
System.out.println("Compiling " + argtype + " pattern:" + pattern + "$");
try {
p = Pattern.compile(pattern + "$");
} catch (PatternSyntaxException pse) {
System.out.println("pattern: " + pattern + " not valid, ignoring");
}
if (argtype.equals("incl"))
pkgIncl.add(p);
else
pkgExcl.add(p);
}
}
}
private static boolean isShouldInstrumentClass(String className) {
System.out.println("Testing " + className + " for match.");
boolean match = false;
String name = className.replace("/", ".");
for (Pattern p : pkgIncl) {
Matcher m = p.matcher(name);
if (m.matches()) {
match = true;
break;
}
}
for (Pattern p : pkgExcl) {
Matcher m = p.matcher(name);
if (m.matches()) {
match = false;
break;
}
}
if (match) {
System.out.println("Class " + name + "should be instrumented.");
} else {
System.out.println("Skipping class: " + name);
}
return match;
}
public static void premain(String agentArgument, Instrumentation instrumentation) {
System.out.println("Premain started");
try {
initMatcherPatterns(agentArgument);
new AgentBuilder.Default()
.with(AgentBuilder.TypeStrategy.Default.REBASE)
.type(new AgentBuilder.RawMatcher() {
public boolean matches(TypeDescription typeDescription, ClassLoader classLoader, JavaModule javaModule, Class<?> aClass, ProtectionDomain protectionDomain) {
return isShouldInstrumentClass(typeDescription.getActualName());
}
})
.transform((builder, typeDescription, classLoader) -> builder
.visit(Advice.to(ProfilingAdvice.class)
.on(ElementMatchers.any()))).installOn(instrumentation);
} catch (RuntimeException e) {
System.out.println("Exception instrumenting code : " + e);
e.printStackTrace();
}
}
}
和 ProfilingAdvice.java:
And ProfilingAdvice.java:
package com.panaya.java.agent;
import com.panaya.java.profiler.MethodStackCollector;
import net.bytebuddy.asm.Advice;
public class ProfilingAdvice {
@Advice.OnMethodEnter
public static void enter(@Advice.Origin("#t.#m") String signature) {
System.out.println("OnEnter :" + signature);
try {
MethodStackCollector.getInstance().push(signature);
} catch (Exception e) {
e.printStackTrace();
}
}
@Advice.OnMethodExit
public static void exit(@Advice.Return long value) {
System.out.println("OnExit - value = " + value);
try {
MethodStackCollector.getInstance().pop();
} catch (Exception e) {
e.printStackTrace();
}
}
}
出于某种原因，ProfilingAdvice 类中的进入"和退出"方法根本没有被调用.
For some reason, the "enter" and "exit" methods in ProfilingAdvice class, aren't invoked at all.
我做错了什么?
谢谢，艾拉德.
推荐答案
我尝试了您的示例，并在将退出建议减少到打印命令和您的匹配器以仅匹配某些类 foo.Bar 之后:
I tried your example and after reducing the exit advice to the print commands and your matcher to only match some class foo.Bar:
package foo;
public class Bar {
public long qux() { return 0L; }
}
仪器工作没有问题.我觉得你的 Advice 匹配器指定 any() 而你的 ProfilingAdvice 需要 long 返回类型有点可疑.您是否尝试只打印到控制台，而您的建议中没有任何注释?
the instrumentation works without problem. I find it a bit fishy that your Advice matcher specifies any() while your ProfilingAdvice requires a long return type. Did you try only printing to the console without any annotations in your advice?
您可以通过设置调试此类问题:
You can debug such issues by settting:
new AgentBuilder.Default()
.with(AgentBuilder.Listener.StreamWriting.toSystemOut());
检测过程中的潜在错误被打印到控制台.
where potential errors during the instrumentation are printed to the console.
这篇关于使用 Byte-Buddy 的 Java 代理不起作用的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！