Package org.apache.flink.table.functions

Class UserDefinedFunctionHelper

java.lang.Object
org.apache.flink.table.functions.UserDefinedFunctionHelper
@Internal public final class UserDefinedFunctionHelper extends Object
Utility for dealing with subclasses of UserDefinedFunction. The purpose of this class is to keep the user-facing APIs clean and offer methods/constants from here.

It contains methods for instantiating, validating and extracting types during function registration in a catalog.

  • Field Details

  • Method Details

    • getReturnTypeOfAggregateFunction

      public static <T, ACC> org.apache.flink.api.common.typeinfo.TypeInformation<T> getReturnTypeOfAggregateFunction(ImperativeAggregateFunction<T,ACC> aggregateFunction)
      Tries to infer the TypeInformation of an AggregateFunction's accumulator type.
      Parameters:
      aggregateFunction - The AggregateFunction for which the accumulator type is inferred.
      Returns:
      The inferred accumulator type of the AggregateFunction.

    • getReturnTypeOfAggregateFunction

      public static <T, ACC> org.apache.flink.api.common.typeinfo.TypeInformation<T> getReturnTypeOfAggregateFunction(ImperativeAggregateFunction<T,ACC> aggregateFunction, org.apache.flink.api.common.typeinfo.TypeInformation<T> scalaType)
      Tries to infer the TypeInformation of an AggregateFunction's accumulator type.
      Parameters:
      aggregateFunction - The AggregateFunction for which the accumulator type is inferred.
      scalaType - The implicitly inferred type of the accumulator type.
      Returns:
      The inferred accumulator type of the AggregateFunction.

    • getAccumulatorTypeOfAggregateFunction

      public static <T, ACC> org.apache.flink.api.common.typeinfo.TypeInformation<ACC> getAccumulatorTypeOfAggregateFunction(ImperativeAggregateFunction<T,ACC> aggregateFunction)
      Tries to infer the TypeInformation of an AggregateFunction's accumulator type.
      Parameters:
      aggregateFunction - The AggregateFunction for which the accumulator type is inferred.
      Returns:
      The inferred accumulator type of the AggregateFunction.

    • getAccumulatorTypeOfAggregateFunction

      public static <T, ACC> org.apache.flink.api.common.typeinfo.TypeInformation<ACC> getAccumulatorTypeOfAggregateFunction(ImperativeAggregateFunction<T,ACC> aggregateFunction, org.apache.flink.api.common.typeinfo.TypeInformation<ACC> scalaType)
      Tries to infer the TypeInformation of an AggregateFunction's accumulator type.
      Parameters:
      aggregateFunction - The AggregateFunction for which the accumulator type is inferred.
      scalaType - The implicitly inferred type of the accumulator type.
      Returns:
      The inferred accumulator type of the AggregateFunction.

    • getReturnTypeOfTableFunction

      public static <T> org.apache.flink.api.common.typeinfo.TypeInformation<T> getReturnTypeOfTableFunction(TableFunction<T> tableFunction)
      Tries to infer the TypeInformation of an AggregateFunction's accumulator type.
      Parameters:
      tableFunction - The TableFunction for which the accumulator type is inferred.
      Returns:
      The inferred accumulator type of the AggregateFunction.

    • getReturnTypeOfTableFunction

      public static <T> org.apache.flink.api.common.typeinfo.TypeInformation<T> getReturnTypeOfTableFunction(TableFunction<T> tableFunction, org.apache.flink.api.common.typeinfo.TypeInformation<T> scalaType)
      Tries to infer the TypeInformation of an AggregateFunction's accumulator type.
      Parameters:
      tableFunction - The TableFunction for which the accumulator type is inferred.
      scalaType - The implicitly inferred type of the accumulator type.
      Returns:
      The inferred accumulator type of the AggregateFunction.

    • instantiateFunction

      public static UserDefinedFunction instantiateFunction(ClassLoader classLoader, @Nullable org.apache.flink.configuration.ReadableConfig config, String name, CatalogFunction catalogFunction)
      Instantiates a UserDefinedFunction from a CatalogFunction.

      Requires access to ReadableConfig if Python functions should be supported.

    • instantiateFunction

      public static UserDefinedFunction instantiateFunction(Class<?> functionClass)
      Instantiates a UserDefinedFunction assuming a JVM function with default constructor.

    • prepareInstance

      public static void prepareInstance(org.apache.flink.configuration.ReadableConfig config, UserDefinedFunction function)
      Prepares a UserDefinedFunction instance for usage in the API.

    • isClassNameSerializable

      public static boolean isClassNameSerializable(UserDefinedFunction function)
      Returns whether a UserDefinedFunction can be easily serialized and identified by only a fully qualified class name. It must have a default constructor and no serializable fields.

      Other properties (such as checks for abstract classes) are validated at the entry points of the API, see prepareInstance(ReadableConfig, UserDefinedFunction).

    • generateInlineFunctionName

      public static String generateInlineFunctionName(UserDefinedFunction function)
      Name for anonymous, inline functions.

    • validateClass

      public static void validateClass(Class<? extends UserDefinedFunction> functionClass)
      Validates a UserDefinedFunction class for usage in the API.

      Note: This is an initial validation to indicate common errors early. The concrete signature validation happens in the code generation when the actual DataTypes for arguments and result are known.

    • validateClassForRuntime

      public static void validateClassForRuntime(Class<? extends UserDefinedFunction> functionClass, String methodName, Class<?>[] argumentClasses, Class<?> outputClass, String functionName)
      Validates a UserDefinedFunction class for usage in the runtime.

      Note: This is for the final validation when actual DataTypes for arguments and result are known.

    • createSpecializedFunction

      public static UserDefinedFunction createSpecializedFunction(String functionName, FunctionDefinition definition, CallContext callContext, ClassLoader builtInClassLoader, @Nullable org.apache.flink.configuration.ReadableConfig configuration, @Nullable SpecializedFunction.ExpressionEvaluatorFactory evaluatorFactory)
      Creates the runtime implementation of a FunctionDefinition as an instance of UserDefinedFunction.
      See Also: