org.apache.beam.sdk.coders

Class SerializableCoder<T extends java.io.Serializable>

java.lang.Object

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

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

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

Type Parameters:

T - the type of elements handled by this coder

All Implemented Interfaces:

java.io.Serializable

public class SerializableCoder<T extends java.io.Serializable>
extends CustomCoder<T>

A Coder for Java classes that implement Serializable.

To use, specify the coder type on a PCollection:

 
   PCollection<MyRecord> records =
       foo.apply(...).setCoder(SerializableCoder.of(MyRecord.class));
 
 

SerializableCoder does not guarantee a deterministic encoding, as Java serialization may produce different binary encodings for two equivalent objects.

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	SerializableCoder.SerializableCoderProviderRegistrar A CoderProviderRegistrar which registers a CoderProvider which can handle serializable types.

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

Coder.Context, Coder.NonDeterministicException

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	SerializableCoder(java.lang.Class<T> type, TypeDescriptor<T> typeDescriptor)

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).
T	decode(java.io.InputStream inStream) Decodes a value of type T from the given input stream in the given context.
void	encode(T value, java.io.OutputStream outStream) Encodes the given value of type T onto the given output stream.
boolean	equals(java.lang.Object other)
static CoderProvider	getCoderProvider() Returns a CoderProvider which uses the SerializableCoder if possible for all types.
TypeDescriptor<T>	getEncodedTypeDescriptor() Returns the TypeDescriptor for the type encoded.
java.lang.Class<T>	getRecordType()
int	hashCode()
static <T extends java.io.Serializable> SerializableCoder<T>	of(java.lang.Class<T> clazz) Returns a SerializableCoder instance for the provided element class.
static <T extends java.io.Serializable> SerializableCoder<T>	of(TypeDescriptor<T> type) Returns a SerializableCoder instance for the provided element type.
java.lang.Object	structuralValue(T value) The structural value of the object is the object itself.
void	verifyDeterministic() Throw Coder.NonDeterministicException if the coding is not deterministic.

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

getCoderArguments

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

decode, encode, getEncodedElementByteSize, isRegisterByteSizeObserverCheap, registerByteSizeObserver, verifyDeterministic, verifyDeterministic

Methods inherited from class java.lang.Object

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

Constructor Detail

SerializableCoder

protected SerializableCoder(java.lang.Class<T> type,
                            TypeDescriptor<T> typeDescriptor)

Method Detail

of

public static <T extends java.io.Serializable> SerializableCoder<T> of(TypeDescriptor<T> type)

Returns a SerializableCoder instance for the provided element type.

Type Parameters:

T - the element type

consistentWithEquals

public boolean consistentWithEquals()

Description copied from class: Coder

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 Coder<T extends java.io.Serializable>

structuralValue

public java.lang.Object structuralValue(T value)

The structural value of the object is the object itself. The SerializableCoder should be only used for objects with a proper Object.equals(java.lang.Object) implementation.

Overrides:

structuralValue in class Coder<T extends java.io.Serializable>

of

public static <T extends java.io.Serializable> SerializableCoder<T> of(java.lang.Class<T> clazz)

Returns a SerializableCoder instance for the provided element class.

Type Parameters:

T - the element type

getCoderProvider

public static CoderProvider getCoderProvider()

Returns a CoderProvider which uses the SerializableCoder if possible for all types.

This method is invoked reflectively from DefaultCoder.

getRecordType

public java.lang.Class<T> getRecordType()

encode

public void encode(T value,
                   java.io.OutputStream outStream)
            throws java.io.IOException

Description copied from class: Coder

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

Specified by:

encode in class Coder<T extends java.io.Serializable>

Throws:

java.io.IOException - if writing to the OutputStream fails for some reason

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

decode

public T decode(java.io.InputStream inStream)
         throws java.io.IOException,
                CoderException

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<T extends java.io.Serializable>

Throws:

java.io.IOException - if reading from the InputStream fails for some reason

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

verifyDeterministic

public void verifyDeterministic()
                         throws Coder.NonDeterministicException

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.

Overrides:

verifyDeterministic in class CustomCoder<T extends java.io.Serializable>

Throws:

NonDeterministicException - always. Java serialization is not deterministic with respect to Object.equals(java.lang.Object) for all types.

Coder.NonDeterministicException - if this coder is not deterministic.

equals

public boolean equals(java.lang.Object other)

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

getEncodedTypeDescriptor

public TypeDescriptor<T> getEncodedTypeDescriptor()

Description copied from class: Coder

Returns the TypeDescriptor for the type encoded.

Overrides:

getEncodedTypeDescriptor in class Coder<T extends java.io.Serializable>