add module opener

Author: SylvainJuge

instrumentation/rmi/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/rmi/context/RmiContextPropagationInstrumentationModule.java

@@ -10,12 +10,17 @@
 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.javaagent.instrumentation.rmi.context.client.RmiClientContextInstrumentation;
 import io.opentelemetry.javaagent.instrumentation.rmi.context.server.RmiServerContextInstrumentation;
+import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
+import java.util.Map;
 
 @AutoService(InstrumentationModule.class)
-public class RmiContextPropagationInstrumentationModule extends InstrumentationModule {
+public class RmiContextPropagationInstrumentationModule extends InstrumentationModule
+    implements ExperimentalInstrumentationModule {
   public RmiContextPropagationInstrumentationModule() {
     super("rmi", "rmi-context-propagation");
   }
@@ -24,4 +29,11 @@ public RmiContextPropagationInstrumentationModule() {
   public List<TypeInstrumentation> typeInstrumentations() {
     return asList(new RmiClientContextInstrumentation(), new RmiServerContextInstrumentation());
   }
+
+  @Override
+  public Map<String, List<String>> jpmsModulesToOpen() {
+    String witnessClass = "sun.rmi.transport.StreamRemoteCall";
+    return Collections.singletonMap(
+        witnessClass, Arrays.asList("sun.rmi.server", "sun.rmi.transport"));
+  }
 }

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

@@ -11,6 +11,7 @@
 import io.opentelemetry.javaagent.extension.instrumentation.internal.injection.ClassInjector;
 import java.util.Collections;
 import java.util.List;
+import java.util.Map;
 
 /**
  * This class is internal and is hence not for public use. Its APIs are unstable and can change at
@@ -61,4 +62,18 @@ default String getModuleGroup() {
   default List<String> agentPackagesToHide() {
     return Collections.emptyList();
   }
+
+  /**
+   * Some instrumentation need to access JPMS modules that are not accessible by default, this
+   * method provides a way to access those classes like the "--add-opens" JVM command. <br>
+   * Map key is the name of a "witness class" belonging to the module that will be loaded and used
+   * to get a reference to the module. <br>
+   * Map value is a list of packages to open in the module
+   *
+   * @return map of "witness class" name as key, list of packages as value.
+   */
+  // TODO: copy the javadoc of the original implementation
+  default Map<String, List<String>> jpmsModulesToOpen() {
+    return Collections.emptyMap();
+  }
 }

javaagent-tooling/javaagent-tooling-java9/src/main/java/io/opentelemetry/javaagent/tooling/ModuleOpener.java

@@ -0,0 +1,76 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.javaagent.tooling;
+
+import static java.util.logging.Level.FINE;
+import static java.util.logging.Level.WARNING;
+
+import java.lang.instrument.Instrumentation;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.logging.Logger;
+
+public class ModuleOpener {
+
+  private static final Logger logger = Logger.getLogger(ModuleOpener.class.getName());
+
+  private ModuleOpener() {}
+
+  /**
+   * Opens JPMS module to a class loader unnamed module
+   *
+   * @param classFromTargetModule class from target module
+   * @param openTo class loader to open module for
+   * @param packagesToOpen packages to open
+   */
+  public static void open(
+      Instrumentation instrumentation,
+      Class<?> classFromTargetModule,
+      ClassLoader openTo,
+      Collection<String> packagesToOpen) {
+
+    Module targetModule = classFromTargetModule.getModule();
+    Module openToModule = openTo.getUnnamedModule();
+    Set<Module> openToModuleSet = Collections.singleton(openToModule);
+    Map<String, Set<Module>> missingOpens = new HashMap<>();
+    for (String packageName : packagesToOpen) {
+      if (!targetModule.isOpen(packageName, openToModule)) {
+        missingOpens.put(packageName, openToModuleSet);
+        logger.log(
+            FINE,
+            () ->
+                String.format(
+                    "Exposing package '%s' in module '%s' to module '%s'",
+                    packageName, targetModule, openToModule));
+      }
+    }
+    if (missingOpens.isEmpty()) {
+      return;
+    }
+
+    if (!instrumentation.isModifiableModule(targetModule)) {
+      logger.log(WARNING, "Module '{}' can't be modified", targetModule);
+      return;
+    }
+
+    try {
+      instrumentation.redefineModule(
+          targetModule,
+          Collections.<Module>emptySet(), // reads
+          Collections.<String, Set<Module>>emptyMap(), // exports
+          missingOpens, // opens
+          Collections.<Class<?>>emptySet(), // uses
+          Collections.<Class<?>, List<Class<?>>>emptyMap() // provides
+          );
+    } catch (Exception e) {
+      logger.log(WARNING, "unable to redefine module", e);
+    }
+  }
+}

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

@@ -5,9 +5,12 @@
 
 package io.opentelemetry.javaagent.tooling.instrumentation.indy;
 
+import io.opentelemetry.javaagent.bootstrap.InstrumentationHolder;
 import io.opentelemetry.javaagent.extension.instrumentation.InstrumentationModule;
 import io.opentelemetry.javaagent.extension.instrumentation.internal.ExperimentalInstrumentationModule;
+import io.opentelemetry.javaagent.tooling.ModuleOpener;
 import io.opentelemetry.javaagent.tooling.util.ClassLoaderValue;
+import java.lang.instrument.Instrumentation;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 import net.bytebuddy.agent.builder.AgentBuilder;
@@ -65,6 +68,40 @@ public static InstrumentationModuleClassLoader getInstrumentationClassLoader(
               + " yet");
     }
 
+    if (module instanceof ExperimentalInstrumentationModule) {
+      ExperimentalInstrumentationModule experimentalModule =
+          (ExperimentalInstrumentationModule) module;
+
+      // Opening JPMS modules requires to use a 'witness class' in the target module to get a
+      // reference to the module, which means we have to eagerly load the class.
+      //
+      // However, this code here triggered when the advice is being executed for the first time so
+      // this only creates a very small eager loading that is unlikely to have impact on the
+      // application.
+      //
+      // Also, using a class that is already loaded like the one that is being instrumented or a
+      // related one would increase the likeliness of not having an effect on application class
+      // loading.
+
+      Instrumentation instrumentation = InstrumentationHolder.getInstrumentation();
+      if (instrumentation == null) {
+        throw new IllegalStateException("global instrumentation not available");
+      }
+
+      experimentalModule
+          .jpmsModulesToOpen()
+          .forEach(
+              (className, packages) -> {
+                Class<?> type;
+                try {
+                  type = Class.forName(className, false, instrumentedClassLoader);
+                } catch (ClassNotFoundException e) {
+                  throw new IllegalStateException("missing witness class " + className, e);
+                }
+
+                ModuleOpener.open(instrumentation, type, loader, packages);
+              });
+    }
     return loader;
   }