com.google.cloud.dataflow.sdk.coders

Class StandardCoder<T>

java.lang.Object

com.google.cloud.dataflow.sdk.coders.StandardCoder<T>

Type Parameters:

T - the type of the values being transcoded

All Implemented Interfaces:

Coder<T>, java.io.Serializable

Direct Known Subclasses:

AtomicCoder, AvroCoder, CoGbkResult.CoGbkResultCoder, IterableLikeCoder, KvCoderBase, MapCoderBase, TimestampedValue.TimestampedValueCoder

public abstract class StandardCoder<T>
extends java.lang.Object
implements Coder<T>

A StandardCoder is one that defines equality, hashing, and printing via the class name and recursively using getComponents().

See Also:

Serialized Form

Nested Class Summary

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

Coder.Context, Coder.NonDeterministicException

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	StandardCoder()

Method Summary

Methods

Modifier and Type	Method and Description
com.google.cloud.dataflow.sdk.util.CloudObject	asCloudObject() Returns the CloudObject that represents this Coder.
boolean	consistentWithEquals() Returns true if the encoded bytes of two objects are equal only when they are also equal according to Object.equals().
boolean	equals(java.lang.Object o)
java.util.List<? extends Coder<?>>	getComponents() Returns the list of Coders that are components of this Coder.
protected long	getEncodedElementByteSize(T value, Coder.Context context) Returns the size in bytes of the encoded value using this coder.
int	hashCode()
boolean	isRegisterByteSizeObserverCheap(T value, Coder.Context context) StandardCoder requires elements to be fully encoded and copied into a byte stream to determine the byte size of the element, which is considered expensive.
void	registerByteSizeObserver(T value, 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.
java.lang.Object	structuralValue(T value) Returns an object with an Object.equals() method that represents structural equality on the argument.
java.lang.String	toString()
void	verifyDeterministic() Throw Coder.NonDeterministicException if the coding is not deterministic.
protected void	verifyDeterministic(java.lang.String message, Coder<?>... coders)
protected void	verifyDeterministic(java.lang.String message, java.lang.Iterable<Coder<?>> coders)

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.google.cloud.dataflow.sdk.coders.Coder

decode, encode, getCoderArguments, isDeterministic

Constructor Detail

StandardCoder

protected StandardCoder()

Method Detail

getComponents

public java.util.List<? extends Coder<?>> getComponents()

Returns the list of Coders that are components of this Coder. Returns an empty list if this is an AtomicCoder (or other Coder with no components).

equals

public boolean equals(java.lang.Object o)

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

asCloudObject

public com.google.cloud.dataflow.sdk.util.CloudObject asCloudObject()

Description copied from interface: Coder

Returns the CloudObject that represents this Coder.

Specified by:

asCloudObject in interface Coder<T>

isRegisterByteSizeObserverCheap

public boolean isRegisterByteSizeObserverCheap(T value,
                                      Coder.Context context)

StandardCoder requires elements to be fully encoded and copied into a byte stream to determine the byte size of the element, which is considered expensive.

Specified by:

isRegisterByteSizeObserverCheap in interface Coder<T>

getEncodedElementByteSize

protected long getEncodedElementByteSize(T value,
                             Coder.Context context)
                                  throws java.lang.Exception

Returns the size in bytes of the encoded value using this coder. Derived classes override this method if byte size can be computed with less computation or copying.

Throws:

java.lang.Exception

registerByteSizeObserver

public void registerByteSizeObserver(T value,
                            com.google.cloud.dataflow.sdk.util.common.ElementByteSizeObserver observer,
                            Coder.Context context)
                              throws java.lang.Exception

Notifies ElementByteSizeObserver about the byte size of the encoded value using this coder. Calls getEncodedElementByteSize() and notifies ElementByteSizeObserver.

Specified by:

registerByteSizeObserver in interface Coder<T>

Throws:

java.lang.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.

Specified by:

verifyDeterministic in interface Coder<T>

Throws:

Coder.NonDeterministicException - if this coder is not deterministic.

verifyDeterministic

protected void verifyDeterministic(java.lang.String message,
                       java.lang.Iterable<Coder<?>> coders)
                            throws Coder.NonDeterministicException

Throws:

Coder.NonDeterministicException

verifyDeterministic

protected void verifyDeterministic(java.lang.String message,
                       Coder<?>... coders)
                            throws Coder.NonDeterministicException

Throws:

Coder.NonDeterministicException

consistentWithEquals

public boolean consistentWithEquals()

Description copied from interface: Coder

Returns true if the encoded bytes of two objects are equal only when they are also equal according to Object.equals(). (and also implements a compatible Object.hasCode())

This most notably false for arrays. It will generally be false when Object.equals() compares object identity, rather than performing a semantic/structural comparison.

Specified by:

consistentWithEquals in interface Coder<T>

structuralValue

public java.lang.Object structuralValue(T value)
                                 throws java.lang.Exception

Description copied from interface: Coder

Returns an object with an Object.equals() method that represents structural equality on the argument. (and also implements a compatible Object.hashCode()).

For any two objects of type T, if their encoded bytes are the same, then their structural values are equal according to Object.equals().

Most notably, the structural value for an array coder should perform a structural comparison of the contents of the arrays, rather than the default behavior of comparing according to object identity.

See also Coder.consistentWithEquals().

Specified by:

structuralValue in interface Coder<T>

Throws:

java.lang.Exception