[jira] [Created] (DRILL-5052) Option to debug generated Java code using an IDE

["Paul Rogers (JIRA)" <ji...@apache.org>]

Paul Rogers created DRILL-5052:
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             Summary: Option to debug generated Java code using an IDE
                 Key: DRILL-5052
                 URL: https://issues.apache.org/jira/browse/DRILL-5052
             Project: Apache Drill
          Issue Type: Improvement
          Components: Execution - Codegen
    Affects Versions: 1.8.0
            Reporter: Paul Rogers
            Assignee: Paul Rogers
            Priority: Minor


Drill makes extensive use of Java code generation to implement its operators. Drill uses sophisticated techniques to blend generated code with pre-compiled template code. An unfortunate down-site of this behavior is that it is very difficult to visualize and debug the generated code.

As it turns out, Drill's code-merge facility is, in essence, a do-it-yourself version of subclassing. The Drill "template" is the parent class, the generated code is the subclass. But, rather than using plain-old subclassing, Drill combines the code from the two classes into a single "artificial" packet of byte codes for which no source exists.

Modify the code generation path to optionally allow "plain-old Java" compilation: the generated code is a subclass of the template. Compile the generated code as a plain-old Java class with no byte-code fix-up. Write the code to a known location that the IDE can search when looking for source files.

With this change, developers can turn on the above feature, set a breakpoint in a template, then step directly into the generated Java code called from the template.

This feature should be an option, enabled by developers when needed. The existing byte-code technique should be used for production code generation.



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