Make internal classloader instrumentation indy compatible

Author: JonasKunz

instrumentation/internal/internal-class-loader/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/internal/classloader/BootDelegationInstrumentation.java

@@ -50,7 +50,8 @@ public ElementMatcher<TypeDescription> typeMatcher() {
     return not(namedOneOf(
             "java.lang.ClassLoader",
             "com.ibm.oti.vm.BootstrapClassLoader",
-            "io.opentelemetry.javaagent.bootstrap.AgentClassLoader"))
+            "io.opentelemetry.javaagent.bootstrap.AgentClassLoader",
+            "io.opentelemetry.javaagent.tooling.instrumentation.indy.InstrumentationModuleClassLoader"))
         .and(extendsClass(named("java.lang.ClassLoader")));
   }
 
@@ -136,13 +137,14 @@ public static Class<?> onEnter(@Advice.Argument(0) String name) {
       return null;
     }
 
-    @Advice.OnMethodExit(onThrowable = Throwable.class)
-    public static void onExit(
-        @Advice.Return(readOnly = false) Class<?> result,
-        @Advice.Enter Class<?> resultFromBootstrapLoader) {
+    @Advice.OnMethodExit(onThrowable = Throwable.class, suppress = Throwable.class)
+    @Advice.AssignReturned.ToReturned
+    public static Class<?> onExit(
+        @Advice.Return Class<?> result, @Advice.Enter Class<?> resultFromBootstrapLoader) {
       if (resultFromBootstrapLoader != null) {
-        result = resultFromBootstrapLoader;
+        return resultFromBootstrapLoader;
       }
+      return result;
     }
   }
 }

instrumentation/internal/internal-class-loader/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/internal/classloader/ClassLoaderInstrumentationModule.java

@@ -10,11 +10,13 @@
 import com.google.auto.service.AutoService;
 import io.opentelemetry.javaagent.extension.instrumentation.InstrumentationModule;
 import io.opentelemetry.javaagent.extension.instrumentation.TypeInstrumentation;
+import io.opentelemetry.javaagent.extension.instrumentation.internal.ExperimentalInstrumentationModule;
 import io.opentelemetry.sdk.autoconfigure.spi.ConfigProperties;
 import java.util.List;
 
 @AutoService(InstrumentationModule.class)
-public class ClassLoaderInstrumentationModule extends InstrumentationModule {
+public class ClassLoaderInstrumentationModule extends InstrumentationModule implements
+    ExperimentalInstrumentationModule {
   public ClassLoaderInstrumentationModule() {
     super("internal-class-loader");
   }
@@ -25,22 +27,35 @@ public boolean defaultEnabled(ConfigProperties config) {
     return true;
   }
 
-  @Override
-  public boolean isIndyModule() {
-    return false;
-  }
 
   @Override
   public boolean isHelperClass(String className) {
+    // TODO: this can be removed when we drop inlined-advice support
+    // The advices can directly access this class in the AgentClassLoader with invokedynamic Advice
     return className.equals("io.opentelemetry.javaagent.tooling.Constants");
   }
 
+  @Override
+  public boolean loadAdviceClassesEagerly() {
+    // This is required due to DefineClassInstrumentation
+    // Without this, we would get an infinite recursion on bootstrapping of that instrumentation:
+    // 1. ClassLoader.defineClass is invoked somewhere
+    // 2. The inserted invokedynamic for the instrumentation is reached
+    // 3. To bootstrap the advice, IndyBootstrap is invoked
+    // 4. IndyBootstrap tries to load the DefineClassInstrumentation Advice class
+    // 5. The loading calls ClassLoader.defineClass -> recursion, BOOM!
+    // We avoid this recursion by ensuring that the DefineClassInstrumentation Advice class
+    // is loaded eagerly before the corresponding invokedynamic is reached
+    return true;
+  }
+
   @Override
   public List<TypeInstrumentation> typeInstrumentations() {
     return asList(
         new BootDelegationInstrumentation(),
         new LoadInjectedClassInstrumentation(),
         new ResourceInjectionInstrumentation(),
-        new DefineClassInstrumentation());
+        new DefineClassInstrumentation()
+      );
   }
 }

instrumentation/internal/internal-class-loader/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/internal/classloader/DefineClassInstrumentation.java

@@ -52,9 +52,17 @@ public static DefineClassContext onEnter(
           classLoader, className, classBytes, offset, length);
     }
 
+    // TODO: the ToReturened does nothing except for signaling the AdviceTransformer that it must
+    // not touch this advice
+    // this is done to ensure that ClassLoaderInstrumentationModule.loadAdviceClassesEagerly works
+    // correctly
+    // we can therfore remove it, as soon as the AdviceTransformer is not applied anymore
     @Advice.OnMethodExit(onThrowable = Throwable.class, suppress = Throwable.class)
-    public static void onExit(@Advice.Enter DefineClassContext context) {
+    @Advice.AssignReturned.ToReturned
+    public static Class<?> onExit(
+        @Advice.Enter DefineClassContext context, @Advice.Return Class<?> returned) {
       DefineClassHelper.afterDefineClass(context);
+      return returned;
     }
   }
 
@@ -68,9 +76,17 @@ public static DefineClassContext onEnter(
       return DefineClassHelper.beforeDefineClass(classLoader, className, classBytes);
     }
 
+    // TODO: the ToReturened does nothing except for signaling the AdviceTransformer that it must
+    // not touch this advice
+    // this is done to ensure that ClassLoaderInstrumentationModule.loadAdviceClassesEagerly works
+    // correctly
+    // we can therfore remove it, as soon as the AdviceTransformer is not applied anymore
     @Advice.OnMethodExit(onThrowable = Throwable.class, suppress = Throwable.class)
-    public static void onExit(@Advice.Enter DefineClassContext context) {
+    @Advice.AssignReturned.ToReturned
+    public static Class<?> onExit(
+        @Advice.Enter DefineClassContext context, @Advice.Return Class<?> returned) {
       DefineClassHelper.afterDefineClass(context);
+      return returned;
     }
   }
 }

instrumentation/internal/internal-class-loader/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/internal/classloader/LoadInjectedClassInstrumentation.java

@@ -11,6 +11,7 @@
 import static net.bytebuddy.matcher.ElementMatchers.isPublic;
 import static net.bytebuddy.matcher.ElementMatchers.isStatic;
 import static net.bytebuddy.matcher.ElementMatchers.named;
+import static net.bytebuddy.matcher.ElementMatchers.namedOneOf;
 import static net.bytebuddy.matcher.ElementMatchers.not;
 import static net.bytebuddy.matcher.ElementMatchers.takesArgument;
 import static net.bytebuddy.matcher.ElementMatchers.takesArguments;
@@ -30,7 +31,15 @@ public class LoadInjectedClassInstrumentation implements TypeInstrumentation {
 
   @Override
   public ElementMatcher<TypeDescription> typeMatcher() {
-    return extendsClass(named("java.lang.ClassLoader"));
+    // We explicitly exclude our own classloaders:
+    // The invokedynamic bootstrapping involves calling loadClass on those, which would cause
+    // an infinite recursion
+    return extendsClass(named("java.lang.ClassLoader"))
+        .and(
+            not(
+                namedOneOf(
+                    "io.opentelemetry.javaagent.bootstrap.AgentClassLoader",
+                    "io.opentelemetry.javaagent.tooling.instrumentation.indy.InstrumentationModuleClassLoader")));
   }
 
   @Override
@@ -65,11 +74,13 @@ public static Class<?> onEnter(
     }
 
     @Advice.OnMethodExit(onThrowable = Throwable.class)
-    public static void onExit(
-        @Advice.Return(readOnly = false) Class<?> result, @Advice.Enter Class<?> loadedClass) {
+    @Advice.AssignReturned.ToReturned
+    public static Class<?> onExit(
+        @Advice.Return Class<?> result, @Advice.Enter Class<?> loadedClass) {
       if (loadedClass != null) {
-        result = loadedClass;
+        return loadedClass;
       }
+      return result;
     }
   }
 }

instrumentation/internal/internal-class-loader/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/internal/classloader/ResourceInjectionInstrumentation.java

@@ -8,6 +8,8 @@
 import static io.opentelemetry.javaagent.extension.matcher.AgentElementMatchers.extendsClass;
 import static net.bytebuddy.matcher.ElementMatchers.isMethod;
 import static net.bytebuddy.matcher.ElementMatchers.named;
+import static net.bytebuddy.matcher.ElementMatchers.namedOneOf;
+import static net.bytebuddy.matcher.ElementMatchers.not;
 import static net.bytebuddy.matcher.ElementMatchers.returns;
 import static net.bytebuddy.matcher.ElementMatchers.takesArguments;
 
@@ -32,7 +34,12 @@ public class ResourceInjectionInstrumentation implements TypeInstrumentation {
 
   @Override
   public ElementMatcher<TypeDescription> typeMatcher() {
-    return extendsClass(named("java.lang.ClassLoader"));
+    return extendsClass(named("java.lang.ClassLoader"))
+        .and(
+            not(
+                namedOneOf(
+                    "io.opentelemetry.javaagent.bootstrap.AgentClassLoader",
+                    "io.opentelemetry.javaagent.tooling.instrumentation.indy.InstrumentationModuleClassLoader")));
   }
 
   @Override
@@ -61,37 +68,37 @@ public void transform(TypeTransformer transformer) {
   public static class GetResourceAdvice {
 
     @Advice.OnMethodExit(suppress = Throwable.class)
-    public static void onExit(
+    @Advice.AssignReturned.ToReturned
+    public static URL onExit(
         @Advice.This ClassLoader classLoader,
         @Advice.Argument(0) String name,
-        @Advice.Return(readOnly = false) URL resource) {
-      if (resource != null) {
-        return;
-      }
-
-      URL helper = HelperResources.loadOne(classLoader, name);
-      if (helper != null) {
-        resource = helper;
+        @Advice.Return URL resource) {
+      if (resource == null) {
+        URL helper = HelperResources.loadOne(classLoader, name);
+        if (helper != null) {
+          return helper;
+        }
       }
+      return resource;
     }
   }
 
   @SuppressWarnings("unused")
   public static class GetResourcesAdvice {
 
     @Advice.OnMethodExit(suppress = Throwable.class)
-    public static void onExit(
+    @Advice.AssignReturned.ToReturned
+    public static Enumeration<URL> onExit(
         @Advice.This ClassLoader classLoader,
         @Advice.Argument(0) String name,
-        @Advice.Return(readOnly = false) Enumeration<URL> resources) {
+        @Advice.Return Enumeration<URL> resources) {
       List<URL> helpers = HelperResources.loadAll(classLoader, name);
       if (helpers.isEmpty()) {
-        return;
+        return resources;
       }
 
       if (!resources.hasMoreElements()) {
-        resources = Collections.enumeration(helpers);
-        return;
+        return Collections.enumeration(helpers);
       }
 
       List<URL> result = Collections.list(resources);
@@ -108,31 +115,30 @@ public static void onExit(
           result.add(helperUrl);
         }
       }
-
-      resources = Collections.enumeration(result);
+      return Collections.enumeration(result);
     }
   }
 
   @SuppressWarnings("unused")
   public static class GetResourceAsStreamAdvice {
 
     @Advice.OnMethodExit(suppress = Throwable.class)
-    public static void onExit(
+    @Advice.AssignReturned.ToReturned
+    public static InputStream onExit(
         @Advice.This ClassLoader classLoader,
         @Advice.Argument(0) String name,
-        @Advice.Return(readOnly = false) InputStream inputStream) {
-      if (inputStream != null) {
-        return;
-      }
-
-      URL helper = HelperResources.loadOne(classLoader, name);
-      if (helper != null) {
-        try {
-          inputStream = helper.openStream();
-        } catch (IOException ignored) {
-          // ClassLoader.getResourceAsStream also ignores io exceptions from opening the stream
+        @Advice.Return InputStream inputStream) {
+      if (inputStream == null) {
+        URL helper = HelperResources.loadOne(classLoader, name);
+        if (helper != null) {
+          try {
+            return helper.openStream();
+          } catch (IOException ignored) {
+            // ClassLoader.getResourceAsStream also ignores io exceptions from opening the stream
+          }
         }
       }
+      return inputStream;
     }
   }
 }

javaagent-bootstrap/src/main/java/io/opentelemetry/javaagent/bootstrap/AgentClassLoader.java

@@ -142,6 +142,14 @@ private static int getJavaVersion() {
     return Integer.parseInt(javaSpecVersion);
   }
 
+  @Override
+  public Class<?> loadClass(String name) throws ClassNotFoundException {
+    // We explicitly override loadClass from ClassLoader to ensure
+    // that loadClass is properly excluded from our internal ClassLoader Instrumentations
+    // Otherwise this will cause recursion in invokedynamic linkage
+    return loadClass(name, false);
+  }
+
   @Override
   public Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException {
     // ContextStorageOverride is meant for library instrumentation we don't want it to apply to our

javaagent-extension-api/src/main/java/io/opentelemetry/javaagent/extension/instrumentation/internal/ExperimentalInstrumentationModule.java

@@ -61,4 +61,15 @@ default String getModuleGroup() {
   default List<String> agentPackagesToHide() {
     return Collections.emptyList();
   }
+
+  /**
+   * By default, Advice classes are loaded lazily the first time the corresponding instrumented
+   * method is invoked. This function allows to change the behaviour so that all Advice classes are
+   * loaded and initialized as soon as a matching type is instrumented.
+   *
+   * @return true, if Advice classes should be loaded on instrumentation instead of first execution
+   */
+  default boolean loadAdviceClassesEagerly() {
+    return false;
+  }
 }

javaagent-tooling/src/main/java/io/opentelemetry/javaagent/tooling/instrumentation/indy/AdviceTransformer.java

@@ -67,6 +67,9 @@ static byte[] transform(byte[] bytes) {
             }));
 
     TransformationContext context = new TransformationContext();
+    if (justDelegateAdvice) {
+      context.disableReturnTypeChange();
+    }
     ClassVisitor cv =
         new ClassVisitor(AsmApi.VERSION, cw) {
 

javaagent-tooling/src/main/java/io/opentelemetry/javaagent/tooling/instrumentation/indy/IndyBootstrap.java

@@ -92,6 +92,12 @@ public class IndyBootstrap {
 
       IndyBootstrapDispatcher.init(
           MethodHandles.lookup().findStatic(IndyBootstrap.class, "bootstrap", bootstrapMethodType));
+
+      // Ensure that CallDepth is already loaded in case of bootstrapAdvice recursions with
+      // ClassLoader.loadClass
+      // This is required because CallDepth is a bootstrap class and therefore triggers our
+      // ClassLoader.loadClass instrumentations
+      Class.forName(CallDepth.class.getName());
     } catch (Exception e) {
       throw new IllegalStateException(e);
     }