co.cask.cdap.data.file

Interface FileReader<T,P>

Type Parameters:

T - Type of data can be read.

P - Type of position object.

All Superinterfaces:

AutoCloseable, Closeable, PositionReporter<P>

All Known Implementing Classes:

LiveFileReader, LiveStreamFileReader, MultiLiveStreamFileReader, StreamDataFileReader

public interface FileReader<T,P>
extends Closeable, PositionReporter<P>

This interface represents classes that can read data from file.

Method Summary

Methods

Modifier and Type	Method and Description
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.

Methods inherited from interface java.io.Closeable

close

Methods inherited from interface co.cask.cdap.data.file.PositionReporter

getPosition

Method Detail

initialize

void initialize()
                throws IOException

Initialize the file reader.

Throws:

IOException - If initialization failed.

read

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

Reads as much data as possible until maxEvents.

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

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

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

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.