Use ClassLoaderIndex to compare class-loader related information over time

Author: mcculls

dd-java-agent/agent-tooling/src/main/java/datadog/trace/agent/tooling/bytebuddy/TypeInfoCache.java

@@ -1,8 +1,7 @@
 package datadog.trace.agent.tooling.bytebuddy;
 
-import datadog.trace.api.cache.DDCache;
-import datadog.trace.api.cache.DDCaches;
-import java.lang.ref.WeakReference;
+import static datadog.instrument.utils.ClassLoaderIndex.getClassLoaderKeyId;
+
 import java.net.URL;
 import java.util.Arrays;
 import java.util.Objects;
@@ -132,25 +131,17 @@ public final T get() {
 
   /** Includes the classloader and class file resource it originated from. */
   static final class DisambiguatingTypeInfo<T> extends SharedTypeInfo<T> {
-    private static final ClassLoader BOOTSTRAP_LOADER = null;
-    private static final LoaderId BOOTSTRAP_LOADER_ID = null;
-
-    private static final DDCache<ClassLoader, LoaderId> loaderIds =
-        DDCaches.newFixedSizeWeakKeyCache(64);
-
-    private final LoaderId loaderId;
+    private final int loaderId;
     private final URL classFile;
 
     DisambiguatingTypeInfo(String className, T typeInfo, ClassLoader loader, URL classFile) {
       super(className, typeInfo);
-      this.loaderId = loaderId(loader);
+      this.loaderId = getClassLoaderKeyId(loader);
       this.classFile = classFile;
     }
 
     public boolean sameClassLoader(ClassLoader loader) {
-      return BOOTSTRAP_LOADER_ID == loaderId
-          ? BOOTSTRAP_LOADER == loader
-          : loaderId.sameClassLoader(loader);
+      return loaderId == getClassLoaderKeyId(loader);
     }
 
     public boolean sameClassFile(URL classFile) {
@@ -159,12 +150,6 @@ public boolean sameClassFile(URL classFile) {
           && sameClassFile(this.classFile, classFile);
     }
 
-    private static LoaderId loaderId(ClassLoader loader) {
-      return BOOTSTRAP_LOADER == loader
-          ? BOOTSTRAP_LOADER_ID
-          : loaderIds.computeIfAbsent(loader, LoaderId::new);
-    }
-
     /** Matches class file resources without triggering network lookups. */
     private static boolean sameClassFile(URL lhs, URL rhs) {
       return Objects.equals(lhs.getFile(), rhs.getFile())
@@ -173,18 +158,4 @@ private static boolean sameClassFile(URL lhs, URL rhs) {
           && Objects.equals(lhs.getProtocol(), rhs.getProtocol());
     }
   }
-
-  /** Supports classloader comparisons without strongly referencing the classloader. */
-  static final class LoaderId extends WeakReference<ClassLoader> {
-    private final int loaderHash;
-
-    LoaderId(ClassLoader loader) {
-      super(loader);
-      this.loaderHash = System.identityHashCode(loader);
-    }
-
-    boolean sameClassLoader(ClassLoader loader) {
-      return loaderHash == System.identityHashCode(loader) && loader == get();
-    }
-  }
 }