co.cask.cdap.data.file

Class LiveFileReader<T,P>

java.lang.Object

co.cask.cdap.data.file.LiveFileReader<T,P>

Type Parameters:

T - Type of event.

P - Type of position object.

All Implemented Interfaces:

FileReader<T,P>, PositionReporter<P>, Closeable, AutoCloseable

Direct Known Subclasses:

LiveStreamFileReader

@NotThreadSafe
public abstract class LiveFileReader<T,P>
extends Object
implements FileReader<T,P>

A FileReader that provides continuous event stream that never end.

Constructor Summary

Constructors

Constructor and Description
LiveFileReader()

Method Summary

Methods

Modifier and Type	Method and Description
void	close()
P	getPosition() Returns the position information.
void	initialize() Initialize the file reader.
int	read(Collection<? super T> events, int maxEvents, long timeout, TimeUnit unit) Reads as much data as possible until maxEvents.
int	read(Collection<? super T> events, int maxEvents, long timeout, TimeUnit unit, ReadFilter readFilter) Reads as much data as possible that passes the given filter until maxEvents.
protected abstract FileReader<T,P>	renewReader()

Methods inherited from class java.lang.Object

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

Constructor Detail

LiveFileReader

public LiveFileReader()

Method Detail

initialize

public void initialize()
                throws IOException

Description copied from interface: FileReader

Initialize the file reader.

Specified by:

initialize in interface FileReader<T,P>

Throws:

IOException - If initialization failed.

read

public int read(Collection<? super T> events,
       int maxEvents,
       long timeout,
       TimeUnit unit)
         throws IOException,
                InterruptedException

Description copied from interface: FileReader

Reads as much data as possible until maxEvents.

Specified by:

read in interface FileReader<T,P>

Parameters:

events - Collection for storing data read.

maxEvents - Maximum number of events to read.

timeout - Maximum of time to spend on trying to read events

unit - Unit for the timeout.

Returns:

Number of events read, could be 0. If -1 is returned, meaning it reached EOF and all sub-sequence call to this method will also return -1.

Throws:

IOException - If failed to read.

InterruptedException - If the reading is interrupted.

read

public int read(Collection<? super T> events,
       int maxEvents,
       long timeout,
       TimeUnit unit,
       ReadFilter readFilter)
         throws IOException,
                InterruptedException

Description copied from interface: FileReader

Reads as much data as possible that passes the given filter until maxEvents.

Specified by:

read in interface FileReader<T,P>

Parameters:

events - Collection for storing data read.

maxEvents - Maximum number of events to read.

timeout - Maximum of time to spend on trying to read events

unit - Unit for the timeout.

readFilter - Filter to apply during reading

Returns:

Number of events read, could be 0. If -1 is returned, meaning it reached EOF and all sub-sequence call to this method will also return -1.

Throws:

IOException - If failed to read.

InterruptedException - If the reading is interrupted.

close

public void close()
           throws IOException

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Throws:

IOException

getPosition

public P getPosition()

Description copied from interface: PositionReporter

Returns the position information.

Specified by:

getPosition in interface PositionReporter<P>

Returns:

An instance of type <P>

renewReader

@Nullable
protected abstract FileReader<T,P> renewReader()
                                        throws IOException

Returns:

A new FileReader or null if no update.

Throws:

IOException