co.cask.cdap.examples.wordcount

Class UniqueCountTable

java.lang.Object

co.cask.cdap.api.dataset.lib.AbstractDataset

co.cask.cdap.examples.wordcount.UniqueCountTable

All Implemented Interfaces:

Dataset, MeteredDataset, co.cask.tephra.TransactionAware, Closeable, AutoCloseable

public class UniqueCountTable
extends AbstractDataset

Counts the number of unique entries seen given any number of entries.

Constructor Summary

Constructors

Constructor and Description
UniqueCountTable(DatasetSpecification spec, Table uniqueCountTable, Table entryCountTable)

Method Summary

Methods

Modifier and Type	Method and Description
Long	readUniqueCount() Returns the current unique count.
void	updateUniqueCount(String entry) Adds the specified entry to the Table and augments the specified tuple with a special field that will be used in the downstream Flowlet that this tuple is sent to.

Methods inherited from class co.cask.cdap.api.dataset.lib.AbstractDataset

close, commitTx, getName, getTransactionAwareName, getTxChanges, postTxCommit, rollbackTx, setMetricsCollector, startTx, toString, updateTx

Methods inherited from class java.lang.Object

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

Constructor Detail

UniqueCountTable

public UniqueCountTable(DatasetSpecification spec,
                Table uniqueCountTable,
                Table entryCountTable)

Method Detail

readUniqueCount

public Long readUniqueCount()

Returns the current unique count.

Returns:

current number of unique entries

updateUniqueCount

public void updateUniqueCount(String entry)

Adds the specified entry to the Table and augments the specified tuple with a special field that will be used in the downstream Flowlet that this tuple is sent to. Continuously add entries into the Table using this method, pass the tuple to another downstream Flowlet, and in the second Flowlet pass the tuple to the updateUniqueCount(String).

Parameters:

entry - entry to add