BTrace学习笔记

BTrace可以安全地动态跟踪java应用程序执行。通过hotswap技术，向运行中的java应用程序插入跟踪代码（Trace actions ）。

BTrace三个概念：

1. Probe Point
2. Trace Actions or Actions
3. Action Methods

BTrace程序的限制：

1. can not create new objects.
2. can not create new arrays.
3. can not throw exceptions.
4. can not catch exceptions.
5. can not make arbitrary instance or static method calls - only the public static methods of com.sun.btrace.BTraceUtils class or methods declared in the same program may be called from a BTrace program.(pre 1.2) can not have instance fields and methods. Only static public void returning methods are allowed for a BTrace class. And all fields have to be static.
6. can not assign to static or instance fields of target program's classes and objects. But, BTrace class can assign to it's own static fields ("trace state" can be mutated).
7. can not have outer, inner, nested or local classes.
8. can not have synchronized blocks or synchronized methods.
9. can not have loops (for, while, do..while)
10. can not extend arbitrary class (super class has to be java.lang.Object)
11. can not implement interfaces.
12. can not contains assert statements.
13. can not use class literals.

BTrace定义的注解

1. Method Annotations

   @com.sun.btrace.annotations.OnMethod
   @com.sun.btrace.annotations.OnTimer
   @com.sun.btrace.annotations.OnError
   @com.sun.btrace.annotations.OnExit
   @com.sun.btrace.annotations.OnEvent
   @com.sun.btrace.annotations.OnLowMemory
   @com.sun.btrace.annotations.OnProbe

2. Argument Annotations

   @com.sun.btrace.annotations.Self
   @com.sun.btrace.annotations.Return
   @com.sun.btrace.annotations.ProbeClassName
   @com.sun.btrace.annotations.ProbeMethodName
   @com.sun.btrace.annotations.Duration
   @com.sun.btrace.annotations.TargetInstance
   @com.sun.btrace.annotations.TargetMethodOrField
   

   Kind.ENTRY, Kind.RETURN- the probed method arguments
   Kind.THROW - the thrown exception
   Kind.ARRAY_SET, Kind.ARRAY_GET - the array index
   Kind.CATCH - the caught exception
   Kind.FIELD_SET - the field value
   Kind.LINE - the line number
   Kind.NEW - the class name
   Kind.ERROR - the thrown exception

3. Field Annotations

   @com.sun.btrace.annotations.Export
   @com.sun.btrace.annotations.Property
   @com.sun.btrace.annotations.TLS

4. Class Annotations

   @com.sun.btrace.annotations.DTrace
   @com.sun.btrace.annotations.DTraceRef
   @com.sun.btrace.annotations.BTrace

    

参考文章：

• 官方网站：https://kenai.com/projects/btrace/pages/UserGuide
• 不错的一个博客： http://agapple.iteye.com/blog/1005918