com.google.cloud.dataflow.sdk.io

Class CompressedSource<T>

java.lang.Object

com.google.cloud.dataflow.sdk.io.Source<T>

com.google.cloud.dataflow.sdk.io.BoundedSource<T>

com.google.cloud.dataflow.sdk.io.OffsetBasedSource<T>

com.google.cloud.dataflow.sdk.io.FileBasedSource<T>

com.google.cloud.dataflow.sdk.io.CompressedSource<T>

Type Parameters:

T - The type to read from the compressed file.

All Implemented Interfaces:

HasDisplayData, Serializable

@Experimental(value=SOURCE_SINK)
public class CompressedSource<T>
extends FileBasedSource<T>

A Source that reads from compressed files. A CompressedSources wraps a delegate FileBasedSource that is able to read the decompressed file format.

For example, use the following to read from a gzip-compressed XML file:

 
 XmlSource mySource = XmlSource.from(...);
 PCollection<T> collection = p.apply(Read.from(CompressedSource
     .from(mySource)
     .withDecompression(CompressedSource.CompressionMode.GZIP)));
  

Supported compression algorithms are CompressedSource.CompressionMode.GZIP and CompressedSource.CompressionMode.BZIP2. User-defined compression types are supported by implementing CompressedSource.DecompressingChannelFactory.

By default, the compression algorithm is selected from those supported in CompressedSource.CompressionMode based on the file name provided to the source, namely ".bz2" indicates CompressedSource.CompressionMode.BZIP2 and ".gz" indicates CompressedSource.CompressionMode.GZIP. If the file name does not match any of the supported algorithms, it is assumed to be uncompressed data.

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	CompressedSource.CompressedReader<T> Reader for a CompressedSource.
static class	CompressedSource.CompressionMode Default compression types supported by the CompressedSource.
static interface	CompressedSource.DecompressingChannelFactory Factory interface for creating channels that decompress the content of an underlying channel.

Nested classes/interfaces inherited from class com.google.cloud.dataflow.sdk.io.FileBasedSource

FileBasedSource.FileBasedReader<T>, FileBasedSource.Mode

Nested classes/interfaces inherited from class com.google.cloud.dataflow.sdk.io.OffsetBasedSource

OffsetBasedSource.OffsetBasedReader<T>

Nested classes/interfaces inherited from class com.google.cloud.dataflow.sdk.io.BoundedSource

BoundedSource.BoundedReader<T>

Nested classes/interfaces inherited from class com.google.cloud.dataflow.sdk.io.Source

Source.Reader<T>

Method Summary

Modifier and Type	Method and Description
protected FileBasedSource<T>	createForSubrangeOfFile(String fileName, long start, long end) Creates a CompressedSource for a subrange of a file.
protected FileBasedSource.FileBasedReader<T>	createSingleFileReader(PipelineOptions options) Creates a FileBasedReader to read a single file.
static <T> CompressedSource<T>	from(FileBasedSource<T> sourceDelegate) Creates a CompressedSource from an underlying FileBasedSource.
CompressedSource.DecompressingChannelFactory	getChannelFactory()
Coder<T>	getDefaultOutputCoder() Returns the delegate source's default output coder.
protected boolean	isSplittable() Determines whether a single file represented by this source is splittable.
void	populateDisplayData(DisplayData.Builder builder) Register display data for the given transform or component.
boolean	producesSortedKeys(PipelineOptions options) Returns whether the delegate source produces sorted keys.
static <T> Read.Bounded<T>	readFromSource(FileBasedSource<T> sourceDelegate, CompressedSource.DecompressingChannelFactory channelFactory) Creates a Read transform that reads from that reads from the underlying FileBasedSource sourceDelegate after decompressing it with a CompressedSource.DecompressingChannelFactory.
void	validate() Validates that the delegate source is a valid source and that the channel factory is not null.
CompressedSource<T>	withDecompression(CompressedSource.DecompressingChannelFactory channelFactory) Return a CompressedSource that is like this one but will decompress its underlying file with the given CompressedSource.DecompressingChannelFactory.

Methods inherited from class com.google.cloud.dataflow.sdk.io.FileBasedSource

createReader, createSourceForSubrange, expandFilePattern, getEstimatedSizeBytes, getFileOrPatternSpec, getMaxEndOffset, getMode, splitIntoBundles, toString

Methods inherited from class com.google.cloud.dataflow.sdk.io.OffsetBasedSource

allowsDynamicSplitting, getBytesPerOffset, getEndOffset, getMinBundleSize, getStartOffset

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Detail

readFromSource

public static <T> Read.Bounded<T> readFromSource(FileBasedSource<T> sourceDelegate,
                                                 CompressedSource.DecompressingChannelFactory channelFactory)

Creates a Read transform that reads from that reads from the underlying FileBasedSource sourceDelegate after decompressing it with a CompressedSource.DecompressingChannelFactory.

from

public static <T> CompressedSource<T> from(FileBasedSource<T> sourceDelegate)

Creates a CompressedSource from an underlying FileBasedSource. The type of compression used will be based on the file name extension unless explicitly configured via withDecompression(com.google.cloud.dataflow.sdk.io.CompressedSource.DecompressingChannelFactory).

withDecompression

public CompressedSource<T> withDecompression(CompressedSource.DecompressingChannelFactory channelFactory)

Return a CompressedSource that is like this one but will decompress its underlying file with the given CompressedSource.DecompressingChannelFactory.

validate

public void validate()

Validates that the delegate source is a valid source and that the channel factory is not null.

Overrides:

validate in class FileBasedSource<T>

createForSubrangeOfFile

protected FileBasedSource<T> createForSubrangeOfFile(String fileName,
                                                     long start,
                                                     long end)

Creates a CompressedSource for a subrange of a file. Called by superclass to create a source for a single file.

Specified by:

createForSubrangeOfFile in class FileBasedSource<T>

Parameters:

fileName - file backing the new FileBasedSource.

start - starting byte offset of the new FileBasedSource.

end - ending byte offset of the new FileBasedSource. May be Long.MAX_VALUE, in which case it will be inferred using FileBasedSource.getMaxEndOffset(com.google.cloud.dataflow.sdk.options.PipelineOptions).

isSplittable

protected final boolean isSplittable()
                              throws Exception

Determines whether a single file represented by this source is splittable. Returns true if we are using the default decompression factory and and it determines from the requested file name that the file is not compressed.

Overrides:

isSplittable in class FileBasedSource<T>

Throws:

Exception

createSingleFileReader

protected final FileBasedSource.FileBasedReader<T> createSingleFileReader(PipelineOptions options)

Creates a FileBasedReader to read a single file.

Uses the delegate source to create a single file reader for the delegate source. Utilizes the default decompression channel factory to not wrap the source reader if the file name does not represent a compressed file allowing for splitting of the source.

Specified by:

createSingleFileReader in class FileBasedSource<T>

producesSortedKeys

public final boolean producesSortedKeys(PipelineOptions options)
                                 throws Exception

Returns whether the delegate source produces sorted keys.

Specified by:

producesSortedKeys in class BoundedSource<T>

Throws:

Exception

populateDisplayData

public void populateDisplayData(DisplayData.Builder builder)

Description copied from class: Source

Register display data for the given transform or component.

populateDisplayData(DisplayData.Builder) is invoked by Pipeline runners to collect display data via DisplayData.from(HasDisplayData). Implementations may call super.populateDisplayData(builder) in order to register display data in the current namespace, but should otherwise use subcomponent.populateDisplayData(builder) to use the namespace of the subcomponent.

By default, does not register any display data. Implementors may override this method to provide their own display data.

Specified by:

populateDisplayData in interface HasDisplayData

Overrides:

populateDisplayData in class FileBasedSource<T>

Parameters:

builder - The builder to populate with display data.

See Also:

HasDisplayData

getDefaultOutputCoder

public final Coder<T> getDefaultOutputCoder()

Returns the delegate source's default output coder.

Specified by:

getDefaultOutputCoder in class Source<T>

getChannelFactory

public final CompressedSource.DecompressingChannelFactory getChannelFactory()