From 9c5be87f42b976565452900309f19eef92a37826 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E9=87=91=E6=88=9F?= <jinji.lf@alibaba-inc.com>
Date: Wed, 22 Jul 2020 23:57:23 +0800
Subject: [PATCH] refactor and add comments

---
 .../java/com/alibaba/testable/PreMain.java    |  5 +++--
 .../handler/TestableClassHandler.java         | 19 ++++++++-----------
 .../transformer/TestableClassTransformer.java |  7 ++++---
 3 files changed, 15 insertions(+), 16 deletions(-)

diff --git a/agent/src/main/java/com/alibaba/testable/PreMain.java b/agent/src/main/java/com/alibaba/testable/PreMain.java
index 09020f7..8459c0c 100755
--- a/agent/src/main/java/com/alibaba/testable/PreMain.java
+++ b/agent/src/main/java/com/alibaba/testable/PreMain.java
@@ -1,16 +1,17 @@
 package com.alibaba.testable;
 
-import com.alibaba.testable.transformer.TestableFileTransformer;
+import com.alibaba.testable.transformer.TestableClassTransformer;
 
 import java.lang.instrument.Instrumentation;
 
 /**
+ * Agent entry, dynamically modify the byte code of classes under testing
  * @author flin
  */
 public class PreMain {
 
     public static void premain(String agentArgs, Instrumentation inst) {
-        inst.addTransformer(new TestableFileTransformer());
+        inst.addTransformer(new TestableClassTransformer());
     }
 
 }
diff --git a/agent/src/main/java/com/alibaba/testable/handler/TestableClassHandler.java b/agent/src/main/java/com/alibaba/testable/handler/TestableClassHandler.java
index dbb6659..bf99b9c 100644
--- a/agent/src/main/java/com/alibaba/testable/handler/TestableClassHandler.java
+++ b/agent/src/main/java/com/alibaba/testable/handler/TestableClassHandler.java
@@ -1,4 +1,4 @@
-package com.alibaba.testable.transformer;
+package com.alibaba.testable.handler;
 
 import com.alibaba.testable.model.TravelStatus;
 import com.alibaba.testable.util.ClassUtil;
@@ -17,25 +17,22 @@ import static com.alibaba.testable.constant.Const.SYS_CLASSES;
 /**
  * @author flin
  */
-public class TestableClassTransformer implements Opcodes {
+public class TestableClassHandler implements Opcodes {
 
     private static final String CONSTRUCTOR = "<init>";
     private static final String TESTABLE_NE = "n/e";
-    private final ClassNode cn = new ClassNode();
 
-    public TestableClassTransformer(String className) throws IOException {
+    public byte[] getBytes(String className) throws IOException {
         ClassReader cr = new ClassReader(className);
+        ClassNode cn = new ClassNode();
         cr.accept(cn, 0);
-    }
-
-    public byte[] getBytes() {
-        transform();
+        transform(cn);
         ClassWriter cw = new ClassWriter( 0);
         cn.accept(cw);
         return cw.toByteArray();
     }
 
-    private void transform() {
+    private void transform(ClassNode cn) {
         List<String> methodNames = new ArrayList<String>();
         for (MethodNode m : cn.methods) {
             if (!CONSTRUCTOR.equals(m.name)) {
@@ -43,11 +40,11 @@ public class TestableClassTransformer implements Opcodes {
             }
         }
         for (MethodNode m : cn.methods) {
-            transformMethod(m, methodNames);
+            transformMethod(cn, m, methodNames);
         }
     }
 
-    private void transformMethod(MethodNode mn, List<String> methodNames) {
+    private void transformMethod(ClassNode cn, MethodNode mn, List<String> methodNames) {
         AbstractInsnNode[] instructions = mn.instructions.toArray();
         TravelStatus status = TravelStatus.INIT;
         String target = "";
diff --git a/agent/src/main/java/com/alibaba/testable/transformer/TestableClassTransformer.java b/agent/src/main/java/com/alibaba/testable/transformer/TestableClassTransformer.java
index 47e8197..eb4d989 100644
--- a/agent/src/main/java/com/alibaba/testable/transformer/TestableClassTransformer.java
+++ b/agent/src/main/java/com/alibaba/testable/transformer/TestableClassTransformer.java
@@ -1,5 +1,6 @@
 package com.alibaba.testable.transformer;
 
+import com.alibaba.testable.handler.TestableClassHandler;
 import com.alibaba.testable.util.ClassUtil;
 
 import java.io.IOException;
@@ -13,7 +14,7 @@ import java.util.Set;
 /**
  * @author flin
  */
-public class TestableFileTransformer implements ClassFileTransformer {
+public class TestableClassTransformer implements ClassFileTransformer {
 
     private static final String ENABLE_TESTABLE = "com.alibaba.testable.annotation.EnableTestable";
     private static final String ENABLE_TESTABLE_INJECT = "com.alibaba.testable.annotation.EnableTestableInject";
@@ -22,7 +23,7 @@ public class TestableFileTransformer implements ClassFileTransformer {
     private static final Set<String> loadedClassNames = new HashSet<String>();
 
     public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined,
-                            ProtectionDomain protectionDomain, byte[] classfileBuffer) {
+                            ProtectionDomain protectionDomain, byte[] classFileBuffer) {
         if (isSystemClass(loader, className) || loadedClassNames.contains(className)) {
             // Ignore system class and duplicate class
             return null;
@@ -37,7 +38,7 @@ public class TestableFileTransformer implements ClassFileTransformer {
 
         try {
             loadedClassNames.add(className);
-            return new TestableClassTransformer(className).getBytes();
+            return new TestableClassHandler().getBytes(className);
         } catch (IOException e) {
             return null;
         }