UnionCoder (Google Cloud Dataflow SDK 1.9.1 API)

Google Cloud Dataflow SDK for Java, version 1.9.1

Warning: Dataflow SDK 1.x for Java is unsupported as of October 16, 2018. After August 12, 2020, you can use unsupported SDKs temporarily while you upgrade your pipelines. For more information, see Using an unsupported SDK.

For information on migrating from the 1.x SDK, see Migrating from Dataflow SDK 1.x for Java.

Note: If you are using Cloud Dataflow SDK version 2.x, see the Apache Beam API reference documentation.

com.google.cloud.dataflow.sdk.transforms.join

Class UnionCoder

• java.lang.Object
• • com.google.cloud.dataflow.sdk.coders.StandardCoder<RawUnionValue>
  • • com.google.cloud.dataflow.sdk.transforms.join.UnionCoder

• All Implemented Interfaces:

  Coder<RawUnionValue>, Serializable

  ---

  
  

  public class UnionCoder
  extends StandardCoder<RawUnionValue>

  A UnionCoder encodes RawUnionValues.

  See Also:

  Serialized Form

• • Nested Class Summary

    • Nested classes/interfaces inherited from interface com.google.cloud.dataflow.sdk.coders.Coder

      Coder.Context, Coder.NonDeterministicException

  • Method Summary

    All Methods Static Methods Instance Methods Concrete Methods 

    Modifier and Type	Method and Description
    RawUnionValue	decode(InputStream inStream, Coder.Context context) Decodes a value of type T from the given input stream in the given context.
    void	encode(RawUnionValue union, OutputStream outStream, Coder.Context context) Encodes the given value of type T onto the given output stream in the given context.
    List<? extends Coder<?>>	getCoderArguments() If this is a Coder for a parameterized type, returns the list of Coders being used for each of the parameters, or returns null if this cannot be done or this is not a parameterized type.
    List<? extends Coder<?>>	getComponents() Returns the list of Coders that are components of this Coder.
    boolean	isRegisterByteSizeObserverCheap(RawUnionValue union, Coder.Context context) Since this coder uses elementCoders.get(index) and coders that are known to run in constant time, we defer the return value to that coder.
    static UnionCoder	jsonOf(List<Coder<?>> elements)
    static UnionCoder	of(List<Coder<?>> elementCoders) Builds a union coder with the given list of element coders.
    void	registerByteSizeObserver(RawUnionValue union, com.google.cloud.dataflow.sdk.util.common.ElementByteSizeObserver observer, Coder.Context context) Notifies ElementByteSizeObserver about the byte size of the encoded value using this coder.
    void	verifyDeterministic() Throw Coder.NonDeterministicException if the coding is not deterministic.

    • Methods inherited from class com.google.cloud.dataflow.sdk.coders.StandardCoder

      asCloudObject, consistentWithEquals, equals, getAllowedEncodings, getEncodedElementByteSize, getEncodingId, hashCode, structuralValue, toString, verifyDeterministic, verifyDeterministic

    • Methods inherited from class java.lang.Object

      clone, finalize, getClass, notify, notifyAll, wait, wait, wait

• • Method Detail

    • of

      public static UnionCoder of(List<Coder<?>> elementCoders)

      Builds a union coder with the given list of element coders. This list corresponds to a mapping of union tag to Coder. Union tags start at 0.

    • jsonOf

      public static UnionCoder jsonOf(List<Coder<?>> elements)

    • encode

      public void encode(RawUnionValue union,
                         OutputStream outStream,
                         Coder.Context context)
                  throws IOException,
                         CoderException

      Description copied from interface: Coder
      Encodes the given value of type T onto the given output stream in the given context.

      Throws:

      IOException - if writing to the OutputStream fails for some reason

      CoderException - if the value could not be encoded for some reason

    • decode

      public RawUnionValue decode(InputStream inStream,
                                  Coder.Context context)
                           throws IOException,
                                  CoderException

      Description copied from interface: Coder
      Decodes a value of type T from the given input stream in the given context. Returns the decoded value.

      Throws:

      IOException - if reading from the InputStream fails for some reason

      CoderException - if the value could not be decoded for some reason

    • getCoderArguments

      public List<? extends Coder<?>> getCoderArguments()

      Description copied from interface: Coder
      If this is a Coder for a parameterized type, returns the list of Coders being used for each of the parameters, or returns null if this cannot be done or this is not a parameterized type.

    • getComponents

      public List<? extends Coder<?>> getComponents()

      Description copied from class: StandardCoder
      Returns the list of Coders that are components of this Coder.

      Overrides:

      getComponents in class StandardCoder<RawUnionValue>

    • isRegisterByteSizeObserverCheap

      public boolean isRegisterByteSizeObserverCheap(RawUnionValue union,
                                                     Coder.Context context)

      Since this coder uses elementCoders.get(index) and coders that are known to run in constant time, we defer the return value to that coder.

      Specified by:

      isRegisterByteSizeObserverCheap in interface Coder<RawUnionValue>

      Overrides:

      isRegisterByteSizeObserverCheap in class StandardCoder<RawUnionValue>

      Returns:

      false unless it is overridden. StandardCoder.registerByteSizeObserver(T, com.google.cloud.dataflow.sdk.util.common.ElementByteSizeObserver, com.google.cloud.dataflow.sdk.coders.Coder.Context) invokes StandardCoder.getEncodedElementByteSize(T, com.google.cloud.dataflow.sdk.coders.Coder.Context) which requires re-encoding an element unless it is overridden. This is considered expensive.

    • registerByteSizeObserver

      public void registerByteSizeObserver(RawUnionValue union,
                                           com.google.cloud.dataflow.sdk.util.common.ElementByteSizeObserver observer,
                                           Coder.Context context)
                                    throws Exception

      Notifies ElementByteSizeObserver about the byte size of the encoded value using this coder.

      Specified by:

      registerByteSizeObserver in interface Coder<RawUnionValue>

      Overrides:

      registerByteSizeObserver in class StandardCoder<RawUnionValue>

      Throws:

      Exception

    • verifyDeterministic

      public void verifyDeterministic()
                               throws Coder.NonDeterministicException

      Description copied from interface: Coder
      Throw Coder.NonDeterministicException if the coding is not deterministic.

      In order for a Coder to be considered deterministic, the following must be true:

      • two values that compare as equal (via Object.equals() or Comparable.compareTo(), if supported) have the same encoding.
      • the Coder always produces a canonical encoding, which is the same for an instance of an object even if produced on different computers at different times.

      Throws:

      Coder.NonDeterministicException - if this coder is not deterministic.