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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DRILL-5052) Option to debug generated Java code using an IDE
Date Thu, 08 Dec 2016 15:26:59 GMT

    [ https://issues.apache.org/jira/browse/DRILL-5052?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15732489#comment-15732489

ASF GitHub Bot commented on DRILL-5052:

Github user arina-ielchiieva commented on a diff in the pull request:

    --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/expr/CodeGenerator.java ---
    @@ -67,26 +96,71 @@
         try {
           this.model = new JCodeModel();
           JDefinedClass clazz = model._package(PACKAGE_NAME)._class(className);
    +      if ( isPlainOldJava( ) ) {
    +        clazz._extends(definition.getTemplateClass( ) );
    +      }
           rootGenerator = new ClassGenerator<>(this, mappingSet, definition.getSignature(),
new EvaluationVisitor(
               funcRegistry), clazz, model, optionManager);
         } catch (JClassAlreadyExistsException e) {
           throw new IllegalStateException(e);
    +  /**
    +   * Indicates that the code for this class can be generated using the
    +   * "Plain Old Java" mechanism based on inheritance. The byte-code
    +   * method is more lenient, so some code is missing some features such
    +   * as proper exception labeling, etc. Set this option to true once
    +   * the generation mechanism for a class has been cleaned up to work
    +   * via the plain-old Java mechanism.
    +   *
    +   * @param flag true if the code generated from this instance is
    +   * ready to be compiled as a plain-old Java class
    +   */
    +  public void plainOldJavaCapable(boolean flag) {
    +    plainOldJavaCapable = flag;
    +  }
    +  /**
    +   * Identifies that this generated class should be generated via the
    +   * plain-old Java mechanism. This flag only has meaning if the
    +   * generated class is capable of plain-old Java generation.
    +   *
    +   * @param flag true if the class should be generated and compiled
    +   * as a plain-old Java class (rather than via byte-code manipulations)
    +   */
    +  public void preferPlainOJava(boolean flag) {
    +    usePlainOldJava = flag;
    --- End diff --
    preferPlainOJava -> preferPlainOldJava

> 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
side-effect of this behavior is that it is very difficult to visualize and debug the generated
> 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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