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

Provides a second compilation path for generated code: “plan old Java”
in which generated code inherit from their templates. Such code can be
compiled directly, allowing easy debugging of generated code.

Also show to generate two classes in the External Sort Batch as “plain
old Java” to enable IDE debugging of that generated code. Required
minor clean-up of the templates.

Fixes some broken toString( ) methods in code generation classes
Fixes a variety of small compilation warnings
Adds Java doc to a few classes

Includes clean-up from code review comments.

close apache/drill#660

1 files changed, 22 insertions, 5 deletions

diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/compile/ClassTransformer.java b/exec/java-exec/src/main/java/org/apache/drill/exec/compile/ClassTransformer.java
index 02323a985..3c3c30e7d 100644
--- a/exec/java-exec/src/main/java/org/apache/drill/exec/compile/ClassTransformer.java
+++ b/exec/java-exec/src/main/java/org/apache/drill/exec/compile/ClassTransformer.java
@@ -22,12 +22,13 @@ import java.util.LinkedList;
 import java.util.Map;
 import java.util.Set;
 
+import org.apache.drill.common.config.DrillConfig;
 import org.apache.drill.common.util.DrillStringUtils;
 import org.apache.drill.common.util.FileUtils;
 import org.apache.drill.exec.compile.MergeAdapter.MergedClassResult;
 import org.apache.drill.exec.exception.ClassTransformationException;
+import org.apache.drill.exec.expr.CodeGenerator;
 import org.apache.drill.exec.server.options.OptionManager;
-import org.apache.drill.exec.server.options.OptionValue;
 import org.apache.drill.exec.server.options.TypeValidators.EnumeratedStringValidator;
 import org.codehaus.commons.compiler.CompileException;
 import org.objectweb.asm.ClassReader;
@@ -39,12 +40,21 @@ import com.google.common.collect.Lists;
 import com.google.common.collect.Maps;
 import com.google.common.collect.Sets;
 
+/**
+ * Compiles generated code, merges the resulting class with the
+ * template class, and performs byte-code cleanup on the resulting
+ * byte codes. The most important transform is scalar replacement
+ * which replaces occurences of non-escaping objects with a
+ * collection of member variables.
+ */
+
 public class ClassTransformer {
   private static final org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(ClassTransformer.class);
 
   private static final int MAX_SCALAR_REPLACE_CODE_SIZE = 2*1024*1024; // 2meg
 
   private final ByteCodeLoader byteCodeLoader = new ByteCodeLoader();
+  private final DrillConfig config;
   private final OptionManager optionManager;
 
   public final static String SCALAR_REPLACEMENT_OPTION =
@@ -73,13 +83,14 @@ public class ClassTransformer {
         return TRY;
       case "on":
         return ON;
+      default:
+        throw new IllegalArgumentException("Invalid ScalarReplacementOption \"" + s + "\"");
       }
-
-      throw new IllegalArgumentException("Invalid ScalarReplacementOption \"" + s + "\"");
     }
   }
 
-  public ClassTransformer(final OptionManager optionManager) {
+  public ClassTransformer(final DrillConfig config, final OptionManager optionManager) {
+    this.config = config;
     this.optionManager = optionManager;
   }
 
@@ -210,6 +221,12 @@ public class ClassTransformer {
     }
   }
 
+  public Class<?> getImplementationClass(CodeGenerator<?> cg) throws ClassTransformationException {
+    final QueryClassLoader loader = new QueryClassLoader(config, optionManager);
+    return getImplementationClass(loader, cg.getDefinition(),
+        cg.getGeneratedCode(), cg.getMaterializedClassName());
+  }
+
   public Class<?> getImplementationClass(
       final QueryClassLoader classLoader,
       final TemplateClassDefinition<?> templateDefinition,
@@ -248,7 +265,7 @@ public class ClassTransformer {
         final ClassNames nextGenerated = nextSet.generated;
         final ClassNode generatedNode = classesToMerge.get(nextGenerated.slash);
 
-        /**
+        /*
          * TODO
          * We're having a problem with some cases of scalar replacement, but we want to get
          * the code in so it doesn't rot anymore.