Package org.apache.beam.sdk.coders

Class RowCoderGenerator

java.lang.Object

org.apache.beam.sdk.coders.RowCoderGenerator

@Experimental(SCHEMAS)
public abstract class RowCoderGenerator
extends java.lang.Object

A utility for automatically generating a Coder for Row objects corresponding to a specific schema. The resulting coder is loaded into the default ClassLoader and returned.

When generate(Schema) is called, a new subclass of Coder<Row> is generated for the specified schema. This class is generated using low-level bytecode generation, and hardcodes encodings for all fields of the Schema. Empirically, this is 30-40% faster than a coder that introspects the schema.

The generated class corresponds to the following Java class:

 class SchemaRowCoder extendsCoder<Row> {
   // Generated array containing a coder for each field in the Schema.
   private static final Coder[] FIELD_CODERS;

   // Generated method to return the schema this class corresponds to. Used during code
   // generation.
   private static getSchema() {
     return schema;
   }

  @Override
   public void encode(T value, OutputStream outStream) {
     // Delegate to a method that evaluates each coder in the static array.
     encodeDelegate(FIELD_CODERS, value, outStream);
   }

  @Overide
   public abstract T decode(InputStream inStream) {
     // Delegate to a method that evaluates each coder in the static array.
     return decodeDelegate(FIELD_CODERS, inStream);
   }
 }
 

Constructor Summary

Constructors

Constructor	Description
RowCoderGenerator()

Method Summary

Modifier and Type	Method	Description
static Coder<Row>	generate(Schema schema)
static void	overrideEncodingPositions(java.util.UUID uuid, java.util.Map<java.lang.String,java.lang.Integer> encodingPositions)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

RowCoderGenerator

public RowCoderGenerator()

Method Detail

overrideEncodingPositions

public static void overrideEncodingPositions(java.util.UUID uuid,
                                             java.util.Map<java.lang.String,java.lang.Integer> encodingPositions)

generate

public static Coder<Row> generate(Schema schema)