[DRILL-5052] Option to debug generated Java code using an IDE

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.8.0
• Fix Version/s: 1.10.0
• Component/s: Execution - Codegen
• Labels: ready-to-commit
• Assignee: Paul Rogers
• Reporter: Paul Rogers
• Reviewer: Jinfeng Ni
• Created: 20/Nov/16 02:08
• Updated: 28/Mar/17 22:37
• Resolved: 20/Dec/16 17:04

Description

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 side-effect 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.

Issue Links

• incorporates: DRILL-5070 Code gen: create methods in fixed order to allow test verification
• links to: GitHub Pull Request #660