org.apache.flink.api.java

Class Utils.CountHelper<T>

java.lang.Object

org.apache.flink.api.common.io.RichOutputFormat<T>

org.apache.flink.api.java.Utils.CountHelper<T>

Type Parameters:

T - Type of elements to count.

All Implemented Interfaces:

Serializable, OutputFormat<T>

Enclosing class:

Utils

public static class Utils.CountHelper<T>
extends RichOutputFormat<T>

Utility sink function that counts elements and writes the count into an accumulator, from which it can be retrieved by the client. This sink is used by the DataSet.count() function.

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.flink.api.common.io.OutputFormat

OutputFormat.InitializationContext

Constructor Summary

Constructors

Constructor and Description
CountHelper(String id)

Method Summary

Modifier and Type	Method and Description
void	close() Method that marks the end of the life-cycle of parallel output instance.
void	configure(Configuration parameters) Configures this output format.
void	open(int taskNumber, int numTasks) Opens a parallel instance of the output format to store the result of its parallel instance.
void	writeRecord(T record) Adds a record to the output.

Methods inherited from class org.apache.flink.api.common.io.RichOutputFormat

getRuntimeContext, setRuntimeContext

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.flink.api.common.io.OutputFormat

open

Constructor Detail

CountHelper

public CountHelper(String id)

Method Detail

configure

public void configure(Configuration parameters)

Description copied from interface: OutputFormat

Configures this output format. Since output formats are instantiated generically and hence parameterless, this method is the place where the output formats set their basic fields based on configuration values.

This method is always called first on a newly instantiated output format.

Parameters:

parameters - The configuration with all parameters.

open

public void open(int taskNumber,
                 int numTasks)

Description copied from interface: OutputFormat

Opens a parallel instance of the output format to store the result of its parallel instance.

When this method is called, the output format it guaranteed to be configured.

Parameters:

taskNumber - The number of the parallel instance.

numTasks - The number of parallel tasks.

writeRecord

public void writeRecord(T record)

Description copied from interface: OutputFormat

Adds a record to the output.

When this method is called, the output format it guaranteed to be opened.

Parameters:

record - The records to add to the output.

close

public void close()

Description copied from interface: OutputFormat

Method that marks the end of the life-cycle of parallel output instance. Should be used to close channels and streams and release resources. After this method returns without an error, the output is assumed to be correct.

When this method is called, the output format it guaranteed to be opened.