com.google.cloud.dataflow.sdk.coders

Class IterableLikeCoder<T,IT extends java.lang.Iterable<T>>

java.lang.Object

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

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

Type Parameters:

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

IT - the type of the Iterables being transcoded

All Implemented Interfaces:

Coder<IT>, java.io.Serializable

Direct Known Subclasses:

CollectionCoder, IterableCoder, ListCoder, SetCoder

public abstract class IterableLikeCoder<T,IT extends java.lang.Iterable<T>>
extends StandardCoder<IT>

The base class of Coders for Iterable subclasses.

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

Methods

Modifier and Type	Method and Description
IT	decode(java.io.InputStream inStream, Coder.Context context) Decodes a value of type T from the given input stream in the given context.
protected abstract IT	decodeToIterable(java.util.List<T> decodedElements) Builds an instance of the coder's associated Iterable from a list of decoded elements.
void	encode(IT iterable, java.io.OutputStream outStream, Coder.Context context) Encodes the given value of type T onto the given output stream in the given context.
java.util.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,IT extends java.lang.Iterable<T>> java.util.List<java.lang.Object>	getInstanceComponentsHelper(IT exampleValue) Returns the first element in this iterable-like if it is non-empty, otherwise returns null.
boolean	isDeterministic() Deprecated.
boolean	isRegisterByteSizeObserverCheap(IT iterable, Coder.Context context) Returns whether iterable can use lazy counting, since that requires minimal extra computation.
void	registerByteSizeObserver(IT 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() Throw Coder.NonDeterministicException if the coding is not deterministic.

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

asCloudObject, equals, getComponents, getEncodedElementByteSize, hashCode, 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 IT decodeToIterable(java.util.List<T> decodedElements)

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

getInstanceComponentsHelper

protected static <T,IT extends java.lang.Iterable<T>> java.util.List<java.lang.Object> getInstanceComponentsHelper(IT exampleValue)

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

encode

public void encode(IT iterable,
          java.io.OutputStream outStream,
          Coder.Context context)
            throws java.io.IOException,
                   CoderException

Description copied from interface: Coder

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

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 IT decode(java.io.InputStream inStream,
        Coder.Context context)
                                        throws java.io.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:

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

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

getCoderArguments

public java.util.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.

isDeterministic

@Deprecated
public boolean isDeterministic()

Deprecated.

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.

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 which 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<IT extends java.lang.Iterable<T>>

Overrides:

verifyDeterministic in class StandardCoder<IT extends java.lang.Iterable<T>>

Throws:

Coder.NonDeterministicException - if this coder is not deterministic.

isRegisterByteSizeObserverCheap

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

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

Specified by:

isRegisterByteSizeObserverCheap in interface Coder<IT extends java.lang.Iterable<T>>

Overrides:

isRegisterByteSizeObserverCheap in class StandardCoder<IT extends java.lang.Iterable<T>>

registerByteSizeObserver

public void registerByteSizeObserver(IT iterable,
                            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.

Specified by:

registerByteSizeObserver in interface Coder<IT extends java.lang.Iterable<T>>

Overrides:

registerByteSizeObserver in class StandardCoder<IT extends java.lang.Iterable<T>>

Throws:

java.lang.Exception