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>, Serializable

Direct Known Subclasses:

AvroCoder, BigQueryIO.ShardedKeyCoder, CoGbkResult.CoGbkResultCoder, DeterministicStandardCoder, IterableLikeCoder, KvCoderBase, MapCoderBase, NullableCoder, TimestampedValue.TimestampedValueCoder

public abstract class StandardCoder<T>
extends Object
implements Coder<T>

A StandardCoder is a Coder 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

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 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).
boolean	equals(Object o)
Collection<String>	getAllowedEncodings() A collection of encodings supported by Coder.decode(java.io.InputStream, com.google.cloud.dataflow.sdk.coders.Coder.Context) in addition to the value of getEncodingId().
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.
String	getEncodingId() A unique identifier for the binary format written by Coder.encode(T, java.io.OutputStream, com.google.cloud.dataflow.sdk.coders.Coder.Context).
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 observer about the byte size of the encoded value using this coder.
Object	structuralValue(T value) Returns an object with an Object.equals() method that represents structural equality on the argument.
String	toString()
protected void	verifyDeterministic(String message, Coder<?>... coders)
protected void	verifyDeterministic(String message, 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, verifyDeterministic

Constructor Detail

StandardCoder

protected StandardCoder()

Method Detail

getEncodingId

public String getEncodingId()

A unique identifier for the binary format written by Coder.encode(T, java.io.OutputStream, com.google.cloud.dataflow.sdk.coders.Coder.Context). If a subclass is modified to write a new format, it is imperative that this method be overridden to return a distinct value.

By default, this is an empty string so only the fully qualified name of the class is used.

Specified by:

getEncodingId in interface Coder<T>

See Also:

getAllowedEncodings()

getAllowedEncodings

public Collection<String> getAllowedEncodings()

A collection of encodings supported by Coder.decode(java.io.InputStream, com.google.cloud.dataflow.sdk.coders.Coder.Context) in addition to the value of getEncodingId().

By default, this is empty.

Specified by:

getAllowedEncodings in interface Coder<T>

See Also:

getEncodingId()

getComponents

public 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(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class 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 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:

Exception

registerByteSizeObserver

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

Notifies observer about the byte size of the encoded value using this coder. Calls getEncodedElementByteSize(T, com.google.cloud.dataflow.sdk.coders.Coder.Context) and notifies observer using ElementByteSizeObserver.update(Object).

Specified by:

registerByteSizeObserver in interface Coder<T>

Throws:

Exception

verifyDeterministic

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

Throws:

Coder.NonDeterministicException

verifyDeterministic

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

Throws:

Coder.NonDeterministicException

consistentWithEquals

public boolean consistentWithEquals()

Description copied from interface: Coder

Returns true if 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). In other words, encoding is injective.

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.

Specified by:

consistentWithEquals in interface Coder<T>

structuralValue

public Object structuralValue(T value)
                       throws Exception

Description copied from interface: Coder

Returns an object with an Object.equals() method that represents structural equality on the argument.

For any two values x and y of type T, if their encoded bytes are the same, then it must be the case that structuralValue(x).equals(@code structuralValue(y).

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.
• The structural value for a coder accepting null should be a proper object with an equals() method, even if the input value is null.

See also Coder.consistentWithEquals().

Specified by:

structuralValue in interface Coder<T>

Throws:

Exception