Package io.pravega.client.stream.impl

Class EventStreamReaderImpl<Type>

java.lang.Object

io.pravega.client.stream.impl.EventStreamReaderImpl<Type>

All Implemented Interfaces:

EventStreamReader<Type>, java.lang.AutoCloseable

public class EventStreamReaderImpl<Type>
extends java.lang.Object
implements EventStreamReader<Type>

Method Summary

Modifier and Type	Method	Description
void	close()	Close the reader.
void	closeAt(Position position)	Close the reader at a specific position.
Type	fetchEvent(EventPointer pointer)	Re-read an event that was previously read, by passing the pointer returned from EventRead.getEventPointer().
ReaderConfig	getConfig()	Gets the configuration that this reader was created with.
TimeWindow	getCurrentTimeWindow(Stream stream)	Returns a window which represents the range of time that this reader is currently reading as provided by writers via the EventStreamWriter.noteTime(long) API.
EventRead<Type>	readNextEvent(long timeoutMillis)	Gets the next event in the stream.
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Method Detail

readNextEvent

public EventRead<Type> readNextEvent(long timeoutMillis)
                              throws ReinitializationRequiredException,
                                     TruncatedDataException

Description copied from interface: EventStreamReader

Gets the next event in the stream. If there are no events currently available this will block up for timeoutMillis waiting for them to arrive. If none do, an EventRead will be returned with null for EventRead.getEvent(). (As well as for most other fields) An EventRead with null for EventRead.getEvent() is returned when the Reader has read all events up to the configured end StreamCut specified using ReaderGroupConfig.

Note: An EventRead with null for EventRead.getEvent() is returned when EventRead.isCheckpoint() is true. A null can also be returned due to delays in the Pravega cluster.

Specified by:

readNextEvent in interface EventStreamReader<Type>

Parameters:

timeoutMillis - An upper bound on how long the call may block before returning null.

Returns:

An instance of EventRead, which contains the next event in the stream. In the case the timeoutMillis is reached, EventRead.getEvent() returns null.

Throws:

ReinitializationRequiredException - Is thrown in the event that ReaderGroup.resetReaderGroup(ReaderGroupConfig) was called which requires readers to be reinitialized.

TruncatedDataException - if the data that would be read next has been truncated away and can no longer be read. (If following this readNextEvent is called again it will resume from the next available event.)

getConfig

public ReaderConfig getConfig()

Description copied from interface: EventStreamReader

Gets the configuration that this reader was created with.

Specified by:

getConfig in interface EventStreamReader<Type>

Returns:

Reader configuration

close

public void close()

Description copied from interface: EventStreamReader

Close the reader. No further actions may be performed. If this reader is part of a reader group, this will automatically invoke ReaderGroup.readerOffline(String, Position)

Specified by:

close in interface java.lang.AutoCloseable

Specified by:

close in interface EventStreamReader<Type>

See Also:

AutoCloseable.close()

closeAt

public void closeAt(Position position)

Description copied from interface: EventStreamReader

Close the reader at a specific position. No further actions may be performed. If this reader is part of a ReaderGroup, this will automatically invoke ReaderGroup.readerOffline(String, Position) with the supplied position.

Specified by:

closeAt in interface EventStreamReader<Type>

Parameters:

position - Position to use while reporting readerOffline on the ReaderGroup.

fetchEvent

public Type fetchEvent(EventPointer pointer)
                throws NoSuchEventException

Description copied from interface: EventStreamReader

Re-read an event that was previously read, by passing the pointer returned from EventRead.getEventPointer(). This does not affect the current position of the reader.

This is a blocking call. Passing invalid offsets has undefined behavior.

Specified by:

fetchEvent in interface EventStreamReader<Type>

Parameters:

pointer - The pointer object to enable a random read of the event.

Returns:

The event at the position specified by the provided pointer or null if the event has been deleted.

Throws:

NoSuchEventException - Reader was not able to fetch the event.

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

getCurrentTimeWindow

public TimeWindow getCurrentTimeWindow(Stream stream)

Description copied from interface: EventStreamReader

Returns a window which represents the range of time that this reader is currently reading as provided by writers via the EventStreamWriter.noteTime(long) API. If no writers were providing timestamps at the current position in the stream `null` will be returned.

Specified by:

getCurrentTimeWindow in interface EventStreamReader<Type>

Parameters:

stream - the stream to obtain a time window for.

Returns:

A TimeWindow which bounds the current location in the stream, or null if one cannot be established.