org.apache.beam.sdk.transforms.join

Class UnionCoder

java.lang.Object

org.apache.beam.sdk.coders.StandardCoder<RawUnionValue>

org.apache.beam.sdk.transforms.join.UnionCoder

All Implemented Interfaces:

Serializable, Coder<RawUnionValue>

public class UnionCoder
extends StandardCoder<RawUnionValue>

A UnionCoder encodes RawUnionValues.

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.beam.sdk.coders.Coder

Coder.Context, Coder.NonDeterministicException

Method Summary

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, org.apache.beam.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 org.apache.beam.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, org.apache.beam.sdk.util.common.ElementByteSizeObserver, org.apache.beam.sdk.coders.Coder.Context) invokes StandardCoder.getEncodedElementByteSize(T, org.apache.beam.sdk.coders.Coder.Context) which requires re-encoding an element unless it is overridden. This is considered expensive.

registerByteSizeObserver

public void registerByteSizeObserver(RawUnionValue union,
                                     org.apache.beam.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.