feat: experiment with javaagent

Author: algomaster99

classport-introspection/README.md

@@ -0,0 +1,13 @@
+We were trying `javaagent` instead of `jvmti` because we ended
+up using the same APIs in JVMTI
+1. getAllStackTraces
+2. getAnnotations
+
+However, upon trying to use `javaagent` we realized that we
+were not able to get the `Class<?>` instance in the running JVM.
+Thus, we can neither get its bytecode nor its annotations.
+
+Some advantages of using `jvmti` are:
+1. It uses `AsyncGetCallTrace` which is immune to [safepoint bias](https://seethawenner.medium.com/java-safepoint-and-async-profiling-cdce0818cd29) and does 
+   not stop the JVM for long periods of time.
+2. It gives us the `jclass` instance so we can call `getAnnotations` on it.

classport-introspection/pom.xml

@@ -0,0 +1,49 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <parent>
+        <groupId>io.github.chains-project</groupId>
+        <artifactId>classport</artifactId>
+        <version>0.1.0-SNAPSHOT</version>
+    </parent>
+
+    <artifactId>classport-introspection</artifactId>
+
+    <properties>
+        <maven.compiler.source>17</maven.compiler.source>
+        <maven.compiler.target>17</maven.compiler.target>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    </properties>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-shade-plugin</artifactId>
+                <configuration>
+                    <createDependencyReducedPom>false</createDependencyReducedPom>
+                    <transformers>
+                        <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
+                            <manifestEntries>
+                                <Agent-Class>io.github.chains_project.classport.introspector.Agent</Agent-Class>
+                                <Can-Retransform-Classes>false</Can-Retransform-Classes>
+                            </manifestEntries>
+                        </transformer>
+                    </transformers>
+                </configuration>
+                <executions>
+                    <execution>
+                        <id>shade</id>
+                        <goals>
+                            <goal>shade</goal>
+                        </goals>
+                        <phase>package</phase>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>

classport-introspection/src/main/java/io/github/chains_project/classport/introspector/Agent.java

@@ -0,0 +1,24 @@
+package io.github.chains_project.classport.introspector;
+
+import java.lang.instrument.Instrumentation;
+import java.util.Arrays;
+
+public class Agent {
+	public static void agentmain(String agentArgs, Instrumentation inst) {
+		Thread.getAllStackTraces().forEach((thread, stackTrace) -> {
+			System.out.println("Thread: " + thread.getName());
+			for (StackTraceElement stackTraceElement : stackTrace) {
+				String className = stackTraceElement.getClassName();
+				System.out.println("Target JVM " + stackTraceElement.getClassLoaderName());
+				System.out.println("this " + Agent.class.getClassLoader().getName());
+				try {
+					Class<?> c = Class.forName(className);
+					c.getAnnotations();
+					System.out.println(className + Arrays.toString(c.getAnnotations()));
+				} catch (ClassNotFoundException e) {
+					System.out.println("Class not found: " + className);
+				}
+			}
+		});
+	}
+}

pom.xml

@@ -36,6 +36,7 @@
     <module>maven-plugin</module>
     <module>classport-agent</module>
     <module>classport-analyser</module>
+      <module>classport-introspection</module>
   </modules>
 
   <scm>