From a79c82efbd0eb6afcbf013db8a00e3c6b0985f6a Mon Sep 17 00:00:00 2001
From: hengyunabc <hengyunabc@gmail.com>
Date: Thu, 4 Jun 2020 14:24:25 +0800
Subject: [PATCH] fix stack command output null problem. #1231

---
 .../taobao/arthas/core/util/ThreadUtil.java   | 35 +++++++++++++++++--
 1 file changed, 33 insertions(+), 2 deletions(-)

diff --git a/core/src/main/java/com/taobao/arthas/core/util/ThreadUtil.java b/core/src/main/java/com/taobao/arthas/core/util/ThreadUtil.java
index 6d094cc6c..370e93ec4 100644
--- a/core/src/main/java/com/taobao/arthas/core/util/ThreadUtil.java
+++ b/core/src/main/java/com/taobao/arthas/core/util/ThreadUtil.java
@@ -2,6 +2,7 @@ package com.taobao.arthas.core.util;
 
 import com.taobao.arthas.core.view.Ansi;
 
+import java.arthas.SpyAPI;
 import java.lang.management.*;
 import java.lang.reflect.Field;
 import java.lang.reflect.Method;
@@ -339,6 +340,35 @@ abstract public class ThreadUtil {
 
     }
 
+    /**
+     * </pre>
+     * java.lang.Thread.getStackTrace(Thread.java:1559),
+     * com.taobao.arthas.core.util.ThreadUtil.getThreadStack(ThreadUtil.java:349),
+     * com.taobao.arthas.core.command.monitor200.StackAdviceListener.before(StackAdviceListener.java:33),
+     * com.taobao.arthas.core.advisor.AdviceListenerAdapter.before(AdviceListenerAdapter.java:49),
+     * com.taobao.arthas.core.advisor.SpyImpl.atEnter(SpyImpl.java:42),
+     * java.arthas.SpyAPI.atEnter(SpyAPI.java:40),
+     * demo.MathGame.print(MathGame.java), demo.MathGame.run(MathGame.java:25),
+     * demo.MathGame.main(MathGame.java:16)
+     * </pre>
+     */
+    private static int MAGIC_STACK_DEPTH = 0;
+
+    private static int findTheSpyAPIDepth(StackTraceElement[] stackTraceElementArray) {
+        if (MAGIC_STACK_DEPTH > 0) {
+            return MAGIC_STACK_DEPTH;
+        }
+        if (MAGIC_STACK_DEPTH > stackTraceElementArray.length) {
+            return 0;
+        }
+        for (int i = 0; i < stackTraceElementArray.length; ++i) {
+            if (SpyAPI.class.getName().equals(stackTraceElementArray[i].getClassName())) {
+                MAGIC_STACK_DEPTH = i + 1;
+                break;
+            }
+        }
+        return MAGIC_STACK_DEPTH;
+    }
 
     /**
      * 获取方法执行堆栈信息
@@ -347,15 +377,16 @@ abstract public class ThreadUtil {
      */
     public static String getThreadStack(Thread currentThread) {
         StackTraceElement[] stackTraceElementArray = currentThread.getStackTrace();
+        int magicStackDepth = findTheSpyAPIDepth(stackTraceElementArray);
 
-        StackTraceElement locationStackTraceElement = stackTraceElementArray[10];
+        StackTraceElement locationStackTraceElement = stackTraceElementArray[magicStackDepth];
         String locationString = String.format("    @%s.%s()", locationStackTraceElement.getClassName(),
                 locationStackTraceElement.getMethodName());
 
         StringBuilder builder = new StringBuilder();
         builder.append(getThreadTitle(currentThread)).append("\n").append(locationString).append("\n");
 
-        int skip = 11;
+        int skip = magicStackDepth + 1;
         for (int index = skip; index < stackTraceElementArray.length; index++) {
             StackTraceElement ste = stackTraceElementArray[index];
             builder.append("        at ")