Throw NoSuchFieldException when call getInt() method

[GGGGGHT]

Enviroment Infomation

OS

macOS Monterey
Version 12.3.1

java -version

java version "17.0.3" 2022-04-19 LTS
Java(TM) SE Runtime Environment (build 17.0.3+8-LTS-111)
Java HotSpot(TM) 64-Bit Server VM (build 17.0.3+8-LTS-111, mixed mode, sharing)

btrace version

BTrace v.2.2.2 (c8f81cc)

target

public abstract class HelloWorld extends HelloWorldBase {
    protected int field = 0;

    public static void main(String[] args) throws Exception {
        System.out.println(ProcessHandle.current().pid());
        System.out.println("ready when you are ...");
        System.in.read();

        callA();
    }

    private static void callA() {
        System.out.println("HelloWorld#callA");
        HelloWorld instance = new HelloWorldExt();
        long x = System.nanoTime();
        instance.callA("hello", 13);
        System.out.println("dur = " + (System.nanoTime() - x));
    }
    

    private void callA(String a, int b) {
        field++;
        callB(callC(a, b));
        field--;
    }

    private void callB(String s) {
        field++;
        System.out.println("You want " + s);
        field--;
    }

    protected abstract String callC(String a, int b);
}

final class HelloWorldExt extends HelloWorld {
    @Override
    protected String callC(String a, int b) {
        try {
            field++;
            String s = a + "-" + b;
            for (int i = 0; i < 100; i++) {
                s = callD(s);
            }
            return s;
        } finally {
            field--;
        }
    }
}

abstract class HelloWorldBase {
    protected final String callD(String s) {
        return "# " + s;
    }
}

script content

import org.openjdk.btrace.core.annotations.BTrace;
import org.openjdk.btrace.core.annotations.Kind;
import org.openjdk.btrace.core.annotations.Location;
import org.openjdk.btrace.core.annotations.OnMethod;
import org.openjdk.btrace.core.annotations.ProbeMethodName;
import org.openjdk.btrace.core.annotations.Self;

import static org.openjdk.btrace.core.BTraceUtils.Reflective.getInt;
import static org.openjdk.btrace.core.BTraceUtils.println;
import static org.openjdk.btrace.core.BTraceUtils.str;

@BTrace
public class HelloWorldTrace {
    @OnMethod(clazz="HelloWorld", method="/call.*/", type="void (java.lang.String, int)",location=@Location(Kind.ENTRY))
    public static void onMethod(@ProbeMethodName(fqn = true) String pmn, @Self Object thiz) {
        println("Hello from method " + pmn);
        println("field = " + str(getInt("field", thiz)));
    }
}

command

btrace ${pid} HelloWorldTrace.java

what happen

Java HotSpot(TM) 64-Bit Server VM warning: Option AllowRedefinitionToAddDeleteMethods was deprecated in version 13.0 and will likely be removed in a future release.
btrace INFO: Attaching BTrace to PID: 69347
btrace INFO: Successfully started BTrace probe: HelloWorldTrace.java
Hello from method private void HelloWorld#callA(java.lang.String, int)

! ERROR
java.lang.RuntimeException: java.lang.NoSuchFieldException: field
	at org.openjdk.btrace.core.BTraceUtils.translate(BTraceUtils.java:3124)
	at org.openjdk.btrace.core.BTraceUtils.lambda$getField$0(BTraceUtils.java:3044)
	at java.base/java.security.AccessController.doPrivileged(AccessController.java:318)
	at org.openjdk.btrace.core.BTraceUtils.getField(BTraceUtils.java:3035)
	at org.openjdk.btrace.core.BTraceUtils.access$400(BTraceUtils.java:65)
	at org.openjdk.btrace.core.BTraceUtils$Reflective.getInt(BTraceUtils.java:5395)
	at HelloWorld.callA(HelloWorld.java)
	at HelloWorld.callA(HelloWorld.java:16)
	at HelloWorld.main(Unknown Source)
Caused by: java.lang.NoSuchFieldException: field
	at java.base/java.lang.Class.getDeclaredField(Class.java:2610)
	at org.openjdk.btrace.core.BTraceUtils.lambda$getField$0(BTraceUtils.java:3039)
	... 7 more

modify script

import org.openjdk.btrace.core.annotations.BTrace;
import org.openjdk.btrace.core.annotations.Kind;
import org.openjdk.btrace.core.annotations.Location;
import org.openjdk.btrace.core.annotations.OnMethod;
import org.openjdk.btrace.core.annotations.ProbeMethodName;
import org.openjdk.btrace.core.annotations.Self;
import java.lang.Class;
import java.lang.reflect.Field;
import static org.openjdk.btrace.core.BTraceUtils.*;

@BTrace
public class HelloWorldTrace {
    @OnMethod(clazz = "HelloWorld", method = "callA", type = "void (java.lang.String,int)", location = @Location(Kind.RETURN))
    public static void onMethod(@ProbeMethodName(fqn = true) String pmn, @Self Object thiz) {
        println("clazz = " + name(classOf(thiz)));
        println("Hello from method " + pmn);
    }
}

Reprint when I modify the script, the clazz print HelloWorldExt. The complete information is as follows

btrace INFO: Attaching BTrace to PID: 21811
btrace INFO: Successfully started BTrace probe: HelloWorldTrace.java
clazz = HelloWorldExt

Hello from method private void HelloWorld#callA(java.lang.String, int)

confused

• I marked clazz on the annotation of onmethod is HelloWorld but clazz print HelloWorldExt
• Why is NoSuchFieldException thrown

[GGGGGHT]

@jbachorik Hello, My friend can you help me.

[jbachorik]

Sorry for long time to reply. My main job was keeping me busy ...

This seems like a bug in the code resolving the fields by reflection.

The problem here is that the actual class name of the intercepted instance will be HelloWorldEx as the HelloWorld class is abstract and can not be instantiated. However, the intercepted method callA() is defined in HelloWorld and will be matched and instrumented because of that.

The reason for NoSuchFieldxception is the fact that the field field is declared in HelloWorld and the getDeclaredField() method used by BTrace does not perform search in type hierarchy, therefore missing the field declared in the base class.
I think this should be fixed but in the meantime you can use

Field fld = field("HelloWorld", "field");
int value = getInt(fld, thiz);
...

[GGGGGHT]

In fact, this is a bug. Is that right.

[jbachorik]

Yes. Any contributions would be welcome.
The fix would include only standard reflection API calls so it should be pretty easy to tackle even for newcomers.

[GGGGGHT]

Ok, I've fixed the issue, I'll add unit tests later and I'll make a pull request after verification.