org.apache.beam.sdk.coders

Class VoidCoder

java.lang.Object

org.apache.beam.sdk.coders.Coder<T>

org.apache.beam.sdk.coders.StructuredCoder<T>

org.apache.beam.sdk.coders.AtomicCoder<java.lang.Void>

org.apache.beam.sdk.coders.VoidCoder

All Implemented Interfaces:

java.io.Serializable

public class VoidCoder
extends AtomicCoder<java.lang.Void>

A Coder for Void. Uses zero bytes per Void.

See Also:

Serialized Form

Nested Class Summary

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

Coder.Context, Coder.NonDeterministicException

Method Summary

Modifier and Type	Method and Description
boolean	consistentWithEquals() Returns true if this Coder is injective with respect to Object.equals(java.lang.Object).
java.lang.Void	decode(java.io.InputStream inStream) Decodes a value of type T from the given input stream in the given context.
void	encode(java.lang.Void value, java.io.OutputStream outStream) Encodes the given value of type T onto the given output stream.
protected long	getEncodedElementByteSize(java.lang.Void value) Returns the size in bytes of the encoded value using this coder.
TypeDescriptor<java.lang.Void>	getEncodedTypeDescriptor() Returns the TypeDescriptor for the type encoded.
boolean	isRegisterByteSizeObserverCheap(java.lang.Void value) Returns whether Coder.registerByteSizeObserver(T, org.apache.beam.sdk.util.common.ElementByteSizeObserver) cheap enough to call for every element, that is, if this Coder can calculate the byte size of the element to be coded in roughly constant time (or lazily).
static VoidCoder	of()
void	verifyDeterministic() Throw Coder.NonDeterministicException if the coding is not deterministic.

Methods inherited from class org.apache.beam.sdk.coders.AtomicCoder

equals, getCoderArguments, getComponents, hashCode

Methods inherited from class org.apache.beam.sdk.coders.StructuredCoder

structuralValue, toString

Methods inherited from class org.apache.beam.sdk.coders.Coder

decode, encode, registerByteSizeObserver, verifyDeterministic, verifyDeterministic

Methods inherited from class java.lang.Object

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

Method Detail

of

public static VoidCoder of()

encode

public void encode(java.lang.Void value,
                   java.io.OutputStream outStream)

Description copied from class: Coder

Encodes the given value of type T onto the given output stream.

Specified by:

encode in class Coder<java.lang.Void>

decode

public java.lang.Void decode(java.io.InputStream inStream)

Description copied from class: Coder

Decodes a value of type T from the given input stream in the given context. Returns the decoded value.

Specified by:

decode in class Coder<java.lang.Void>

verifyDeterministic

public void verifyDeterministic()

Description copied from class: AtomicCoder

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.

.

Unless overridden, does not throw. An AtomicCoder is presumed to be deterministic

Overrides:

verifyDeterministic in class AtomicCoder<java.lang.Void>

consistentWithEquals

public boolean consistentWithEquals()

Returns true if this Coder is injective with respect to Object.equals(java.lang.Object).

Whenever the encoded bytes of two values are equal, then the original values are equal according to Objects.equals(). Note that this is well-defined for null.

This condition is most notably false for arrays. More generally, this condition is false whenever equals() compares object identity, rather than performing a semantic/structural comparison.

By default, returns false.

Overrides:

consistentWithEquals in class StructuredCoder<java.lang.Void>

Returns:

true. VoidCoder is (vacuously) injective.

isRegisterByteSizeObserverCheap

public boolean isRegisterByteSizeObserverCheap(java.lang.Void value)

Returns whether Coder.registerByteSizeObserver(T, org.apache.beam.sdk.util.common.ElementByteSizeObserver) cheap enough to call for every element, that is, if this Coder can calculate the byte size of the element to be coded in roughly constant time (or lazily).

Not intended to be called by user code, but instead by PipelineRunner implementations.

By default, returns false. The default Coder.registerByteSizeObserver(T, org.apache.beam.sdk.util.common.ElementByteSizeObserver) implementation invokes Coder.getEncodedElementByteSize(T) which requires re-encoding an element unless it is overridden. This is considered expensive.

Overrides:

isRegisterByteSizeObserverCheap in class Coder<java.lang.Void>

Returns:

true. getEncodedElementByteSize(java.lang.Void) runs in constant time.

getEncodedTypeDescriptor

public TypeDescriptor<java.lang.Void> getEncodedTypeDescriptor()

Description copied from class: Coder

Returns the TypeDescriptor for the type encoded.

Overrides:

getEncodedTypeDescriptor in class StructuredCoder<java.lang.Void>

getEncodedElementByteSize

protected long getEncodedElementByteSize(java.lang.Void value)
                                  throws java.lang.Exception

Description copied from class: Coder

Returns the size in bytes of the encoded value using this coder.

Overrides:

getEncodedElementByteSize in class Coder<java.lang.Void>

Throws:

java.lang.Exception