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Add generator classes to generate platform-specific wrappers #15

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merged 3 commits into from
Apr 2, 2019
Merged

Add generator classes to generate platform-specific wrappers #15

merged 3 commits into from
Apr 2, 2019

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shardulm94
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  • Added platform-specific wrapper generators for Hive, Presto and Spark.
    • Hive and Presto wrapper generators use JavaPoet for Java code gen
    • Spark wrapper uses String templates and substitution for Scala code gen. Treehugger, the library for Scala code gen, was too complicated to use, its DSL did not have full support of complex Scala syntax and the resultant generation code did not have good readability. For our simple use case, string substitution should work as well, we can also consider if we should use string template for other wrappers.
  • Moved UDFProperties to transportable-udfs-compile-utils to share the class without having to put the annotation processor as compile dependency. (Gradle considers annotation processors in the compile classpath as being applied to the module, will be removed in future versions in favor of annotationProcessor classpath)
  • Added some helper methods to UDFProperties and changed to use LinkedHashMultimap internally to preserve ordering of UDFs (just looks prettier, no impact on functionality). Fixed a test case.

@shardulm94 shardulm94 self-assigned this Mar 23, 2019
antumbde
antumbde reviewed Mar 25, 2019
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transportable-udfs-codegen/src/main/java/com/linkedin/transport/codegen/CodegenUtils.java Show resolved Hide resolved
transportable-udfs-codegen/src/main/java/com/linkedin/transport/codegen/CodegenUtils.java Show resolved Hide resolved
...ortable-udfs-codegen/src/main/java/com/linkedin/transport/codegen/SparkWrapperGenerator.java Outdated
private void generateWrapper(String topLevelStdUDFClass, Collection<String> implementationClasses, File outputDir) {
final String wrapperTemplate;
try {
wrapperTemplate = IOUtils.toString(
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is this deprecated method?
Need to close stream

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This method is not marked as deprecated. Updated to use try-with-resources.

...-udfs-codegen/src/test/java/com/linkedin/transport/codegen/AbstractTestWrapperGenerator.java Show resolved Hide resolved
...portable-udfs-codegen/src/main/java/com/linkedin/transport/codegen/HiveWrapperGenerator.java
import javax.lang.model.element.Modifier;


public class HiveWrapperGenerator implements WrapperGenerator {
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javadoc all classes and non-private methods. (even package private ones to help contributors)

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I think a Javadoc here would be pretty redundant, it would convey that this class generates Hive wrappers which is already conveyed by the class name. The WrapperGenerator class contains the javadocs for interface as well as the public method.

transportable-udfs-codegen/src/main/java/com/linkedin/transport/codegen/ProjectContext.java Outdated Show resolved Hide resolved
...rtable-udfs-codegen/src/main/java/com/linkedin/transport/codegen/PrestoWrapperGenerator.java
try {
CodegenUtils.writeServiceFile(context.getResourcesOutputDir().toPath(), SERVICE_FILE, services);
} catch (IOException e) {
throw new RuntimeException("Error creating service file", e);
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why do you convert IOException to RuntimeException (multiple places)? Better to make caller explicitly handle it

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The caller in the case of these wrapper generators will be a Gradle task. The gradle task will not have a complete picture of what exactly the wrapper generator is doing. So I feel it is probably better to handle it here rather than pass to caller.

...ortable-udfs-codegen/src/main/java/com/linkedin/transport/codegen/SparkWrapperGenerator.java Outdated

@Override
public void generateWrappers(ProjectContext context) {
Multimap<String, String> udfs = context.getUdfProperties().getUdfs();
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didn't fully follow how this works - does the developer have to list all the functions in a json file? If yes, can they simply annotate the code and we scan the package for annotations instead of separate json file

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The JSON file is generated as an output of the annotation processor. The Gradle task will then pass this JSON file to the wrapper generators to generate the wrappers. This reasoning behind adopted this approach is mentioned in the design doc.

wmoustafa
wmoustafa reviewed Mar 25, 2019
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transportable-udfs-codegen/src/test/java/com/linkedin/transport/codegen/TestUtils.java
/**
* Asserts that the contents of both directories (and their subdirectories) are equal
*/
static void assertDirectoriesAreEqual(Path actualDir, Path expectedDir) {
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Sort listings of both directories. Go over sorted lists in parallel. Both names and contents should correspond.
See if you can stick to File all the way in this case.
Check if the chain of calling can be simplified after this approach.

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Lets discuss this tomorrow. I feel the current 2-step behaviour leads to a better error message in case of a failure.

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Added comments. Removed Path<-->File conversions. Kept the 2-step behaviour

wmoustafa
wmoustafa approved these changes Apr 2, 2019
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Thanks for the PR. Looks great!

@rdsr rdsr merged commit 35a3ffc into linkedin:master Apr 2, 2019
@shardulm94 shardulm94 deleted the codegen branch April 2, 2019 20:28
This was referenced Apr 2, 2019
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@wmoustafa wmoustafa wmoustafa approved these changes

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