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, 146 insertions, 0 deletions

diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/compile/ClassCompilerSelector.java b/exec/java-exec/src/main/java/org/apache/drill/exec/compile/ClassCompilerSelector.java
new file mode 100644
index 000000000..c8afbc693
--- /dev/null
+++ b/exec/java-exec/src/main/java/org/apache/drill/exec/compile/ClassCompilerSelector.java
@@ -0,0 +1,146 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.drill.exec.compile;
+
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.Map;
+
+import org.apache.drill.common.config.DrillConfig;
+import org.apache.drill.common.exceptions.UserException;
+import org.apache.drill.exec.compile.ClassTransformer.ClassNames;
+import org.apache.drill.exec.exception.ClassTransformationException;
+import org.apache.drill.exec.server.options.OptionManager;
+import org.apache.drill.exec.server.options.OptionValidator;
+import org.apache.drill.exec.server.options.OptionValue;
+import org.apache.drill.exec.server.options.TypeValidators.BooleanValidator;
+import org.apache.drill.exec.server.options.TypeValidators.LongValidator;
+import org.apache.drill.exec.server.options.TypeValidators.StringValidator;
+import org.codehaus.commons.compiler.CompileException;
+
+/**
+ * Selects between the two supported Java compilers: Janino and
+ * the build-in Java compiler.
+ *
+ * <h4>Session Options</h4>
+ * <dl>
+ * <dt>exec.java_compiler</dt>
+ * <dd>The compiler to use. Valid options are defined in the
+ * {@link ClassCompilerSelector.CompilerPolicy} enum.</dd>
+ * <dt>exec.java_compiler_debug</dt>
+ * <dd>If debug logging is enabled, then {@link AbstractClassCompiler} writes the
+ * generated Java code to the log file prior to compilation. This option
+ * adds line numbers to the logged code.</dd>
+ * <dt>exec.java_compiler_janino_maxsize</dt>
+ * <dd>The maximum size of code that the Janio compiler can handle. Larger code is
+ * handled by the JDK compiler. Defaults to 256K.</dd>
+ * </dl>
+ * <h4>Configuration Options</h4>
+ * Configuration options are used when the above session options are unset.
+ * <dl>
+ * <dt>drill.exec.compile.compiler</dt>
+ * <dd>Default for <var>exec.java_compiler</var></dd>
+ * <dt>drill.exec.compile.debug</dt>
+ * <dd>Default for <var>exec.java_compiler_debug</var></dd>
+ * <dt>drill.exec.compile.janino_maxsize</dt>
+ * <dd>Default for <var>exec.java_compiler_janino_maxsize</var></dd>
+ * </dl>
+ */
+
+public class ClassCompilerSelector {
+  public enum CompilerPolicy {
+    DEFAULT, JDK, JANINO;
+  }
+
+  public static final String JAVA_COMPILER_JANINO_MAXSIZE_CONFIG = CodeCompiler.COMPILE_BASE + ".janino_maxsize";
+  public static final String JAVA_COMPILER_DEBUG_CONFIG = CodeCompiler.COMPILE_BASE + ".debug";
+  public static final String JAVA_COMPILER_CONFIG = CodeCompiler.COMPILE_BASE + ".compiler";
+
+  public static final String JAVA_COMPILER_OPTION = "exec.java_compiler";
+  public static final String JAVA_COMPILER_JANINO_MAXSIZE_OPTION = "exec.java_compiler_janino_maxsize";
+  public static final OptionValidator JAVA_COMPILER_JANINO_MAXSIZE = new LongValidator(JAVA_COMPILER_JANINO_MAXSIZE_OPTION, 256*1024);
+
+  public static final String JAVA_COMPILER_DEBUG_OPTION = "exec.java_compiler_debug";
+  public static final OptionValidator JAVA_COMPILER_DEBUG = new BooleanValidator(JAVA_COMPILER_DEBUG_OPTION, true);
+
+  public static final StringValidator JAVA_COMPILER_VALIDATOR = new StringValidator(JAVA_COMPILER_OPTION, CompilerPolicy.DEFAULT.toString()) {
+    @Override
+    public void validate(final OptionValue v, final OptionManager manager) {
+      super.validate(v, manager);
+      try {
+        CompilerPolicy.valueOf(v.string_val.toUpperCase());
+      } catch (IllegalArgumentException e) {
+        throw UserException.validationError()
+            .message("Invalid value '%s' specified for option '%s'. Valid values are %s.",
+              v.string_val, getOptionName(), Arrays.toString(CompilerPolicy.values()))
+            .build(QueryClassLoader.logger);
+      }
+    }
+  };
+
+  private final CompilerPolicy policy;
+  private final long janinoThreshold;
+
+  private final AbstractClassCompiler jdkClassCompiler;
+  private final AbstractClassCompiler janinoClassCompiler;
+
+  public ClassCompilerSelector(ClassLoader classLoader, DrillConfig config, OptionManager sessionOptions) {
+    OptionValue value = sessionOptions.getOption(JAVA_COMPILER_OPTION);
+    this.policy = CompilerPolicy.valueOf((value != null) ? value.string_val.toUpperCase() : config.getString(JAVA_COMPILER_CONFIG).toUpperCase());
+
+    value = sessionOptions.getOption(JAVA_COMPILER_JANINO_MAXSIZE_OPTION);
+    this.janinoThreshold = (value != null) ? value.num_val : config.getLong(JAVA_COMPILER_JANINO_MAXSIZE_CONFIG);
+
+    value = sessionOptions.getOption(JAVA_COMPILER_DEBUG_OPTION);
+    boolean debug = (value != null) ? value.bool_val : config.getBoolean(JAVA_COMPILER_DEBUG_CONFIG);
+
+    this.janinoClassCompiler = (policy == CompilerPolicy.JANINO || policy == CompilerPolicy.DEFAULT) ? new JaninoClassCompiler(classLoader, debug) : null;
+    this.jdkClassCompiler = (policy == CompilerPolicy.JDK || policy == CompilerPolicy.DEFAULT) ? JDKClassCompiler.newInstance(classLoader, debug) : null;
+  }
+
+  byte[][] getClassByteCode(ClassNames className, String sourceCode)
+      throws CompileException, ClassNotFoundException, ClassTransformationException, IOException {
+
+    byte[][] bc = getCompiler(sourceCode).getClassByteCode(className, sourceCode);
+
+    // Uncomment the following to save the generated byte codes.
+
+//    final String baseDir = System.getProperty("java.io.tmpdir") + File.separator + className;
+//    File classFile = new File(baseDir + className.clazz);
+//    classFile.getParentFile().mkdirs();
+//    try (BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(classFile))) {
+//      out.write(bc[0]);
+//    }
+
+    return bc;
+  }
+
+  public Map<String,byte[]> compile(ClassNames className, String sourceCode)
+      throws CompileException, ClassNotFoundException, ClassTransformationException, IOException {
+    return getCompiler(sourceCode).compile(className, sourceCode);
+  }
+
+  private AbstractClassCompiler getCompiler(String sourceCode) {
+    if (jdkClassCompiler != null &&
+        (policy == CompilerPolicy.JDK || (policy == CompilerPolicy.DEFAULT && sourceCode.length() > janinoThreshold))) {
+      return jdkClassCompiler;
+    } else {
+      return janinoClassCompiler;
+    }
+  }
+}
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