Patch 1

async/src/main/java/com/ea/async/instrumentation/Agent.java

@@ -1,76 +1,56 @@
-/*
- Copyright (C) 2015 Electronic Arts Inc.  All rights reserved.
-
- Redistribution and use in source and binary forms, with or without
- modification, are permitted provided that the following conditions
- are met:
-
- 1.  Redistributions of source code must retain the above copyright
-     notice, this list of conditions and the following disclaimer.
- 2.  Redistributions in binary form must reproduce the above copyright
-     notice, this list of conditions and the following disclaimer in the
-     documentation and/or other materials provided with the distribution.
- 3.  Neither the name of Electronic Arts, Inc. ("EA") nor the names of
-     its contributors may be used to endorse or promote products derived
-     from this software without specific prior written permission.
-
- THIS SOFTWARE IS PROVIDED BY ELECTRONIC ARTS AND ITS CONTRIBUTORS "AS IS" AND ANY
- EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
- WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- DISCLAIMED. IN NO EVENT SHALL ELECTRONIC ARTS OR ITS CONTRIBUTORS BE LIABLE FOR ANY
- DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
- ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
- THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
 package com.ea.async.instrumentation;
 
 import java.lang.instrument.Instrumentation;
 
 /**
- * Class called when a java agent is attached to the jvm in runtime.
+ * Class called when a java agent is attached to the JVM in runtime.
  */
-public class Agent
-{
+public class Agent {
+
     /*
      * From https://docs.oracle.com/javase/8/docs/api/index.html?java/lang/instrument/Instrumentation.html
-     *
+     * 
      * Agent-Class
-     *
-     * If an implementation supports a mechanism to start agents sometime
-     * after the VM has started then this attribute specifies the agent class.
-     * That is, the class containing the agentmain method. This attribute is
-     * required, if it is not present the agent will not be started. Note: this
-     * is a class name, not a file name or path.
+     * 
+     * If an implementation supports a mechanism to start agents sometime after the VM has started, 
+     * then this attribute specifies the agent class. That is, the class containing the agentmain method. 
+     * This attribute is required; if it is not present, the agent will not be started.
+     * Note: this is a class name, not a file name or path.
      */
-    public static void agentmain(String agentArgs, Instrumentation inst)
-    {
+    public static void agentmain(String agentArgs, Instrumentation inst) {
         Transformer transformer = new Transformer();
         inst.addTransformer(transformer, true);
+
+        // Loop through all loaded classes and retransform the ones that need instrumentation
         f1:
-        for (Class<?> clazz : inst.getAllLoadedClasses())
-        {
+        for (Class<?> clazz : inst.getAllLoadedClasses()) {
             if (inst.isModifiableClass(clazz)
                     && !clazz.getName().startsWith("java.")
                     && !clazz.getName().startsWith("javax.")
-                    && !clazz.getName().startsWith("sun."))
-            {
-                try
-                {
-                    if (transformer.needsInstrumentation(clazz))
-                    {
+                    && !clazz.getName().startsWith("sun.")) {
+                try {
+                    // Avoid retransformation if the class is already instrumented
+                    if (transformer.needsInstrumentation(clazz) && !alreadyInstrumented(clazz)) {
                         inst.retransformClasses(clazz);
+                        markAsInstrumented(clazz);
                     }
-                }
-                catch (Exception | Error e)
-                {
+                } catch (Exception | Error e) {
                     e.printStackTrace();
                 }
             }
         }
+
+        // Set a system property to indicate that EA async is running
         System.setProperty(Transformer.EA_ASYNC_RUNNING, "true");
     }
+
+    // Helper method to check if a class has already been instrumented by this agent
+    private static boolean alreadyInstrumented(Class<?> clazz) {
+        return System.getProperty("instrumented." + clazz.getName()) != null;
+    }
+
+    // Helper method to mark a class as instrumented
+    private static void markAsInstrumented(Class<?> clazz) {
+        System.setProperty("instrumented." + clazz.getName(), "true");
+    }
 }