[DRILL-5331] NPE in FunctionImplementationRegistry.findDrillFunction() if dynamic UDFs disabled

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.10.0
• Fix Version/s: 1.11.0
• Assignee: Paul Rogers
• Reporter: Paul Rogers
• Reviewer: Arina Ielchiieva
• Created: 08/Mar/17 00:35
• Updated: 21/Mar/17 10:16
• Resolved: 21/Mar/17 10:16

Description

Drill provides the Dynamic UDF (DUDF) functionality. DUFDs can be disabled using the following option in ExecConstants:

  String USE_DYNAMIC_UDFS_KEY = "exec.udf.use_dynamic";
  BooleanValidator USE_DYNAMIC_UDFS = new BooleanValidator(USE_DYNAMIC_UDFS_KEY, true);

In a unit test, we created a setup in which we wish to use only the local function registry, no DUDF support is needed. Run the code. The following code is invoked when asking for a non-existent function:

  public DrillFuncHolder findDrillFunction(FunctionResolver functionResolver, FunctionCall functionCall) {
    ...
    if (holder == null) {
      syncWithRemoteRegistry(version.get());
      List<DrillFuncHolder> updatedFunctions = localFunctionRegistry.getMethods(newFunctionName, version);
      holder = functionResolver.getBestMatch(updatedFunctions, functionCall);
    }

The result is an NPE:

ERROR o.a.d.e.e.f.r.RemoteFunctionRegistry - Problem during trying to access remote function registry [registry]
java.lang.NullPointerException: null
	at org.apache.drill.exec.expr.fn.registry.RemoteFunctionRegistry.getRegistryVersion(RemoteFunctionRegistry.java:119) ~[classes/:na]

The fix is simply to add a DUDF-enabled check:

    if (holder == null) {
      boolean useDynamicUdfs = optionManager != null && optionManager.getOption(ExecConstants.USE_DYNAMIC_UDFS);
      if (useDynamicUdfs) {
        syncWithRemoteRegistry(version.get());
        ...

Then, disable dynamic UDFs for the test case by setting ExecConstants.USE_DYNAMIC_UDFS to false.