com.google.cloud.dataflow.sdk.coders

Class IterableLikeCoder<T,IterableT extends Iterable<T>>

java.lang.Object

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

com.google.cloud.dataflow.sdk.coders.IterableLikeCoder<T,IterableT>

Type Parameters:

T - the type of the elements of the Iterables being transcoded

IterableT - the type of the Iterables being transcoded

All Implemented Interfaces:

Coder<IterableT>, Serializable

Direct Known Subclasses:

CollectionCoder, IterableCoder, ListCoder, SetCoder

public abstract class IterableLikeCoder<T,IterableT extends Iterable<T>>
extends StandardCoder<IterableT>

An abstract base class with functionality for assembling a Coder for a class that implements Iterable.

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	IterableLikeCoder(Coder<T> elementCoder)

Method Summary

Modifier and Type	Method and Description
IterableT	decode(InputStream inStream, Coder.Context context) Decodes a value of type T from the given input stream in the given context.
protected abstract IterableT	decodeToIterable(List<T> decodedElements) Builds an instance of the coder's associated Iterable from a list of decoded elements.
void	encode(IterableT iterable, 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.
Coder<T>	getElemCoder()
protected static <T,IterableT extends Iterable<T>> List<Object>	getInstanceComponentsHelper(IterableT exampleValue) Returns the first element in this iterable-like if it is non-empty, otherwise returns null.
boolean	isRegisterByteSizeObserverCheap(IterableT iterable, Coder.Context context) Returns whether iterable can use lazy counting, since that requires minimal extra computation.
void	registerByteSizeObserver(IterableT iterable, 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.
void	verifyDeterministic() Encoding is not deterministic for the general Iterable case, as it depends upon the type of iterable.

Methods inherited from class com.google.cloud.dataflow.sdk.coders.StandardCoder

asCloudObject, consistentWithEquals, equals, getComponents, getEncodedElementByteSize, hashCode, structuralValue, toString, verifyDeterministic, verifyDeterministic

Methods inherited from class java.lang.Object

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

Constructor Detail

IterableLikeCoder

protected IterableLikeCoder(Coder<T> elementCoder)

Method Detail

getElemCoder

public Coder<T> getElemCoder()

decodeToIterable

protected abstract IterableT decodeToIterable(List<T> decodedElements)

Builds an instance of the coder's associated Iterable from a list of decoded elements. If IterableT is a supertype of List<T>, the derived class implementation is permitted to return decodedElements directly.

getInstanceComponentsHelper

protected static <T,IterableT extends Iterable<T>> List<Object> getInstanceComponentsHelper(IterableT exampleValue)

Returns the first element in this iterable-like if it is non-empty, otherwise returns null.

encode

public void encode(IterableT iterable,
                   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 IterableT 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.

verifyDeterministic

public void verifyDeterministic()
                         throws Coder.NonDeterministicException

Encoding is not deterministic for the general Iterable case, as it depends upon the type of iterable. This may allow two objects to compare as equal while the encoding differs.

Throws:

Coder.NonDeterministicException - if this coder is not deterministic.

isRegisterByteSizeObserverCheap

public boolean isRegisterByteSizeObserverCheap(IterableT iterable,
                                               Coder.Context context)

Returns whether iterable can use lazy counting, since that requires minimal extra computation.

Specified by:

isRegisterByteSizeObserverCheap in interface Coder<IterableT extends Iterable<T>>

Overrides:

isRegisterByteSizeObserverCheap in class StandardCoder<IterableT extends Iterable<T>>

registerByteSizeObserver

public void registerByteSizeObserver(IterableT iterable,
                                     com.google.cloud.dataflow.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<IterableT extends Iterable<T>>

Overrides:

registerByteSizeObserver in class StandardCoder<IterableT extends Iterable<T>>

Throws:

Exception