make ClassLoaderMap not use unsafe

Author: laurit

javaagent-tooling/src/main/java/io/opentelemetry/javaagent/tooling/util/ClassLoaderMap.java

@@ -6,6 +6,7 @@
 package io.opentelemetry.javaagent.tooling.util;
 
 import io.opentelemetry.instrumentation.api.internal.cache.Cache;
+import io.opentelemetry.javaagent.tooling.HelperInjector;
 import java.lang.ref.WeakReference;
 import java.lang.reflect.Field;
 import java.util.Collections;
@@ -15,7 +16,6 @@
 import net.bytebuddy.ByteBuddy;
 import net.bytebuddy.description.modifier.Ownership;
 import net.bytebuddy.description.modifier.Visibility;
-import net.bytebuddy.dynamic.loading.ClassLoadingStrategy;
 
 class ClassLoaderMap {
   private static final Cache<ClassLoader, WeakReference<Map<Object, Object>>> data = Cache.weak();
@@ -51,20 +51,24 @@ private static Map<Object, Object> getClassLoaderData(
 
   @SuppressWarnings("unchecked")
   private static Map<Object, Object> createMap(ClassLoader classLoader) {
+    String className =
+        "io.opentelemetry.javaagent.ClassLoaderData$$"
+            + Integer.toHexString(System.identityHashCode(classLoader));
     // generate a class with a single static field named "data" and define it in the given class
     // loader
-    Class<?> clazz =
+    byte[] bytes =
         new ByteBuddy()
             .subclass(Object.class)
-            .name(
-                "io.opentelemetry.javaagent.ClassLoaderData$$"
-                    + Integer.toHexString(System.identityHashCode(classLoader)))
+            .name(className)
             .defineField("data", Object.class, Ownership.STATIC, Visibility.PUBLIC)
             .make()
-            .load(classLoader, ClassLoadingStrategy.Default.INJECTION.allowExistingTypes())
-            .getLoaded();
+            .getBytes();
+    HelperInjector.injectHelperClasses(
+        classLoader, Collections.singletonMap(className, () -> bytes));
     Map<Object, Object> map;
     try {
+      Class<?> clazz = Class.forName(className, false, classLoader);
+
       Field field = clazz.getField("data");
       synchronized (classLoader) {
         map = (Map<Object, Object>) field.get(classLoader);

muzzle/src/main/java/io/opentelemetry/javaagent/tooling/HelperInjector.java

@@ -297,6 +297,23 @@ private void injectHelperClasses(
     }
   }
 
+  public static void injectHelperClasses(
+      ClassLoader classLoader, Map<String, Supplier<byte[]>> classNameToBytes) {
+    if (isBootClassLoader(classLoader)) {
+      throw new UnsupportedOperationException("boot loader not supported");
+    }
+    if (classNameToBytes.isEmpty()) {
+      return;
+    }
+
+    Map<String, HelperClass> map =
+        helperClasses.computeIfAbsent(classLoader, (unused) -> new ConcurrentHashMap<>());
+    for (Map.Entry<String, Supplier<byte[]>> entry : classNameToBytes.entrySet()) {
+      HelperClass injector = new HelperClass(entry.getValue());
+      map.put(entry.getKey(), injector);
+    }
+  }
+
   private static Map<String, byte[]> resolve(Map<String, Supplier<byte[]>> classes) {
     Map<String, byte[]> result = new LinkedHashMap<>();
     for (Map.Entry<String, Supplier<byte[]>> entry : classes.entrySet()) {