Google Cloud Dataflow SDK for Java, version 1.9.1
Class FileBasedSource<T>
- java.lang.Object
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- com.google.cloud.dataflow.sdk.io.Source<T>
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- com.google.cloud.dataflow.sdk.io.BoundedSource<T>
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- com.google.cloud.dataflow.sdk.io.OffsetBasedSource<T>
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- com.google.cloud.dataflow.sdk.io.FileBasedSource<T>
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- Type Parameters:
T
- Type of records represented by the source.
- All Implemented Interfaces:
- HasDisplayData, Serializable
- Direct Known Subclasses:
- BlockBasedSource, CompressedSource, XmlSource
public abstract class FileBasedSource<T> extends OffsetBasedSource<T>
A common base class for all file-basedSource
s. Extend this class to implement your own file-based custom source.A file-based
Source
is aSource
backed by a file pattern defined as a Java glob, a single file, or a offset range for a single file. SeeOffsetBasedSource
andRangeTracker
for semantics of offset ranges.This source stores a
String
that is anIOChannelFactory
specification for a file or file pattern. There should be anIOChannelFactory
defined for the file specification provided. Please refer toIOChannelUtils
andIOChannelFactory
for more information on this.In addition to the methods left abstract from
BoundedSource
, subclasses must implement methods to create a sub-source and a reader for a range of a single file -createForSubrangeOfFile(java.lang.String, long, long)
andcreateSingleFileReader(com.google.cloud.dataflow.sdk.options.PipelineOptions)
. Please refer toXmlSource
for an example implementation ofFileBasedSource
.- See Also:
- Serialized Form
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Nested Class Summary
Nested Classes Modifier and Type Class and Description static class
FileBasedSource.FileBasedReader<T>
Areader
that implements code common to readers ofFileBasedSource
s.static class
FileBasedSource.Mode
A givenFileBasedSource
represents a file resource of one of these types.-
Nested classes/interfaces inherited from class com.google.cloud.dataflow.sdk.io.OffsetBasedSource
OffsetBasedSource.OffsetBasedReader<T>
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Nested classes/interfaces inherited from class com.google.cloud.dataflow.sdk.io.BoundedSource
BoundedSource.BoundedReader<T>
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Nested classes/interfaces inherited from class com.google.cloud.dataflow.sdk.io.Source
Source.Reader<T>
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Constructor Summary
Constructors Constructor and Description FileBasedSource(String fileOrPatternSpec, long minBundleSize)
Create aFileBaseSource
based on a file or a file pattern specification.FileBasedSource(String fileName, long minBundleSize, long startOffset, long endOffset)
Create aFileBasedSource
based on a single file.FileBasedSource(ValueProvider<String> fileOrPatternSpec, long minBundleSize)
Create aFileBaseSource
based on a file or a file pattern specification.
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Method Summary
All Methods Static Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method and Description protected abstract FileBasedSource<T>
createForSubrangeOfFile(String fileName, long start, long end)
Creates and returns a newFileBasedSource
of the same type as the currentFileBasedSource
backed by a given file and an offset range.BoundedSource.BoundedReader<T>
createReader(PipelineOptions options)
Returns a newBoundedSource.BoundedReader
that reads from this source.protected abstract FileBasedSource.FileBasedReader<T>
createSingleFileReader(PipelineOptions options)
Creates and returns an instance of aFileBasedReader
implementation for the current source assuming the source represents a single file.FileBasedSource<T>
createSourceForSubrange(long start, long end)
Returns anOffsetBasedSource
for a subrange of the current source.protected static Collection<String>
expandFilePattern(String fileOrPatternSpec)
long
getEstimatedSizeBytes(PipelineOptions options)
An estimate of the total size (in bytes) of the data that would be read from this source.String
getFileOrPatternSpec()
ValueProvider<String>
getFileOrPatternSpecProvider()
long
getMaxEndOffset(PipelineOptions options)
Returns the actual ending offset of the current source.FileBasedSource.Mode
getMode()
protected boolean
isSplittable()
Determines whether a file represented by this source is can be split into bundles.void
populateDisplayData(DisplayData.Builder builder)
Register display data for the given transform or component.List<? extends FileBasedSource<T>>
splitIntoBundles(long desiredBundleSizeBytes, PipelineOptions options)
Splits the source into bundles of approximatelydesiredBundleSizeBytes
.String
toString()
void
validate()
Checks that this source is valid, before it can be used in a pipeline.-
Methods inherited from class com.google.cloud.dataflow.sdk.io.OffsetBasedSource
allowsDynamicSplitting, getBytesPerOffset, getEndOffset, getMinBundleSize, getStartOffset
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Methods inherited from class com.google.cloud.dataflow.sdk.io.BoundedSource
producesSortedKeys
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Methods inherited from class com.google.cloud.dataflow.sdk.io.Source
getDefaultOutputCoder
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Constructor Detail
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FileBasedSource
public FileBasedSource(String fileOrPatternSpec, long minBundleSize)
Create aFileBaseSource
based on a file or a file pattern specification. This constructor must be used when creating a newFileBasedSource
for a file pattern.See
OffsetBasedSource
for a detailed description ofminBundleSize
.- Parameters:
fileOrPatternSpec
-IOChannelFactory
specification of file or file pattern represented by theFileBasedSource
.minBundleSize
- minimum bundle size in bytes.
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FileBasedSource
public FileBasedSource(ValueProvider<String> fileOrPatternSpec, long minBundleSize)
Create aFileBaseSource
based on a file or a file pattern specification. Same as theString
constructor, but accepting aValueProvider
to allow for runtime configuration of the source.
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FileBasedSource
public FileBasedSource(String fileName, long minBundleSize, long startOffset, long endOffset)
Create aFileBasedSource
based on a single file. This constructor must be used when creating a newFileBasedSource
for a subrange of a single file. Additionally, this constructor must be used to create newFileBasedSource
s when subclasses implement the methodcreateForSubrangeOfFile(java.lang.String, long, long)
.See
OffsetBasedSource
for detailed descriptions ofminBundleSize
,startOffset
, andendOffset
.- Parameters:
fileName
-IOChannelFactory
specification of the file represented by theFileBasedSource
.minBundleSize
- minimum bundle size in bytes.startOffset
- starting byte offset.endOffset
- ending byte offset. If the specified value>= #getMaxEndOffset()
it implies#getMaxEndOffSet()
.
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Method Detail
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getFileOrPatternSpec
public final String getFileOrPatternSpec()
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getFileOrPatternSpecProvider
public final ValueProvider<String> getFileOrPatternSpecProvider()
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getMode
public final FileBasedSource.Mode getMode()
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createSourceForSubrange
public final FileBasedSource<T> createSourceForSubrange(long start, long end)
Description copied from class:OffsetBasedSource
Returns anOffsetBasedSource
for a subrange of the current source. The subrange[start, end)
must be within the range[startOffset, endOffset)
of the current source, i.e.startOffset <= start < end <= endOffset
.- Specified by:
createSourceForSubrange
in classOffsetBasedSource<T>
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createForSubrangeOfFile
protected abstract FileBasedSource<T> createForSubrangeOfFile(String fileName, long start, long end)
Creates and returns a newFileBasedSource
of the same type as the currentFileBasedSource
backed by a given file and an offset range. When current source is being split, this method is used to generate new sub-sources. When creating the source subclasses must call the constructorFileBasedSource(String, long, long, long)
ofFileBasedSource
with corresponding parameter values passed here.- Parameters:
fileName
- file backing the newFileBasedSource
.start
- starting byte offset of the newFileBasedSource
.end
- ending byte offset of the newFileBasedSource
. May be Long.MAX_VALUE, in which case it will be inferred usinggetMaxEndOffset(com.google.cloud.dataflow.sdk.options.PipelineOptions)
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createSingleFileReader
protected abstract FileBasedSource.FileBasedReader<T> createSingleFileReader(PipelineOptions options)
Creates and returns an instance of aFileBasedReader
implementation for the current source assuming the source represents a single file. File patterns will be handled byFileBasedSource
implementation automatically.
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getEstimatedSizeBytes
public final long getEstimatedSizeBytes(PipelineOptions options) throws Exception
Description copied from class:BoundedSource
An estimate of the total size (in bytes) of the data that would be read from this source. This estimate is in terms of external storage size, before any decompression or other processing done by the reader.- Overrides:
getEstimatedSizeBytes
in classOffsetBasedSource<T>
- Throws:
Exception
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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 viaDisplayData.from(HasDisplayData)
. Implementations may callsuper.populateDisplayData(builder)
in order to register display data in the current namespace, but should otherwise usesubcomponent.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 interfaceHasDisplayData
- Overrides:
populateDisplayData
in classOffsetBasedSource<T>
- Parameters:
builder
- The builder to populate with display data.- See Also:
HasDisplayData
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splitIntoBundles
public final List<? extends FileBasedSource<T>> splitIntoBundles(long desiredBundleSizeBytes, PipelineOptions options) throws Exception
Description copied from class:BoundedSource
Splits the source into bundles of approximatelydesiredBundleSizeBytes
.- Overrides:
splitIntoBundles
in classOffsetBasedSource<T>
- Throws:
Exception
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isSplittable
protected boolean isSplittable() throws Exception
Determines whether a file represented by this source is can be split into bundles.By default, a file is splittable if it is on a file system that supports efficient read seeking. Subclasses may override to provide different behavior.
- Throws:
Exception
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createReader
public final BoundedSource.BoundedReader<T> createReader(PipelineOptions options) throws IOException
Description copied from class:BoundedSource
Returns a newBoundedSource.BoundedReader
that reads from this source.- Specified by:
createReader
in classBoundedSource<T>
- Throws:
IOException
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toString
public String toString()
- Overrides:
toString
in classOffsetBasedSource<T>
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validate
public void validate()
Description copied from class:Source
Checks that this source is valid, before it can be used in a pipeline.It is recommended to use
Preconditions
for implementing this method.- Overrides:
validate
in classOffsetBasedSource<T>
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getMaxEndOffset
public final long getMaxEndOffset(PipelineOptions options) throws Exception
Description copied from class:OffsetBasedSource
Returns the actual ending offset of the current source. The value returned by this function will be used to clip the end of the range[startOffset, endOffset)
such that the range used is[startOffset, min(endOffset, maxEndOffset))
.As an example in which
OffsetBasedSource
is used to implement a file source, suppose that this source was constructed with anendOffset
ofLong.MAX_VALUE
to indicate that a file should be read to the end. Then this function should determine the actual, exact size of the file in bytes and return it.- Specified by:
getMaxEndOffset
in classOffsetBasedSource<T>
- Throws:
Exception
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expandFilePattern
protected static final Collection<String> expandFilePattern(String fileOrPatternSpec) throws IOException
- Throws:
IOException
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