Profiler Instrumentation Using Metaprogramming Techniques
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This document discusses different techniques for instrumenting code with a profiler using metaprogramming, including OpenJava, Javassist, and AspectJ. It provides examples of implementing a profiler using each technique. OpenJava inserts profiler calls by extending the metaclass. Javassist inserts calls by extending the classloader. AspectJ isolates the profiler logic in an aspect module and uses pointcuts and advice to insert calls.
Editor's Notes
- #2: <number><number>
- #3: Source for profiler: http://www.filebuzz.com/software_screenshot/full/4146-LTProf.gif
- #5: - Source program (written in OpenC++ or OpenJava) is translated into top-level definitions for classes and member-functions.A metaobject is created for each top-level definition.metaobject then translates the top-level definitions into appropriate C++ or Java codeTranslated code is then collected and assembled into a contiguous source code. <number><number>
- #6: Achieved by customizing the Java class loaderi.e., through bytecode manipulation Can be used to modify the structure and behavior of the classExample: Javassist APIsFour ways of intercepting classes at load-time: use of a custom class loader, extension of the class java.lang.ClassLoader, use of a custom JVM implementation, and use of a custom I/O DLL. Only the second option provides portable generic interception.
- #8: -red shows lines of code that handle logging in org.apache.tomcat server-not in just one place-not even in a small number of places<number>
- #9: <number>
- #12: Supports structural reflectionAbility to alter the structure of existing classesNew classes can be definedByte-code can be transformed at either the load-time or compile-time<number>