org.apache.samza.system

Interface SystemAdmin

All Known Subinterfaces:

ExtendedSystemAdmin

All Known Implementing Classes:

SinglePartitionWithoutOffsetsSystemAdmin

public interface SystemAdmin

Helper interface attached to an underlying system to fetch information about streams, partitions, offsets, etc. This interface is useful for providing utility methods that Samza needs in order to interact with a system.

Method Summary

Modifier and Type	Method and Description
void	createChangelogStream(java.lang.String streamName, int numOfPartitions) An API to create a change log stream
void	createCoordinatorStream(java.lang.String streamName) Create a stream for the job coordinator.
java.util.Map<SystemStreamPartition,java.lang.String>	getOffsetsAfter(java.util.Map<SystemStreamPartition,java.lang.String> offsets) Fetches the offsets for the messages immediately after the supplied offsets for a group of SystemStreamPartitions.
java.util.Map<java.lang.String,SystemStreamMetadata>	getSystemStreamMetadata(java.util.Set<java.lang.String> streamNames) Fetch metadata from a system for a set of streams.
java.lang.Integer	offsetComparator(java.lang.String offset1, java.lang.String offset2) Compare the two offsets.
void	validateChangelogStream(java.lang.String streamName, int numOfPartitions) Validates change log stream

Method Detail

getOffsetsAfter

java.util.Map<SystemStreamPartition,java.lang.String> getOffsetsAfter(java.util.Map<SystemStreamPartition,java.lang.String> offsets)

Fetches the offsets for the messages immediately after the supplied offsets for a group of SystemStreamPartitions.

Parameters:

offsets - Map from SystemStreamPartition to current offsets.

Returns:

Map from SystemStreamPartition to offsets immediately after the current offsets.

getSystemStreamMetadata

java.util.Map<java.lang.String,SystemStreamMetadata> getSystemStreamMetadata(java.util.Set<java.lang.String> streamNames)

Fetch metadata from a system for a set of streams.

Parameters:

streamNames - The streams to to fetch metadata for.

Returns:

A map from stream name to SystemStreamMetadata for each stream requested in the parameter set.

createChangelogStream

void createChangelogStream(java.lang.String streamName,
                           int numOfPartitions)

An API to create a change log stream

Parameters:

streamName - The name of the stream to be created in the underlying stream

numOfPartitions - The number of partitions in the changelog stream

validateChangelogStream

void validateChangelogStream(java.lang.String streamName,
                             int numOfPartitions)

Validates change log stream

Parameters:

streamName - The name of the stream to be created in the underlying stream

numOfPartitions - The number of partitions in the changelog stream

createCoordinatorStream

void createCoordinatorStream(java.lang.String streamName)

Create a stream for the job coordinator. If the stream already exists, this call should simply return.

Parameters:

streamName - The name of the coordinator stream to create.

offsetComparator

java.lang.Integer offsetComparator(java.lang.String offset1,
                                   java.lang.String offset2)

Compare the two offsets. -1, 0, +1 means offset1 < offset2, offset1 == offset2 and offset1 > offset2 respectively. Return null if those two offsets are not comparable

Parameters:

offset1 - First offset for comparison.

offset2 - Second offset for comparison.

Returns:

-1 if offset1 < offset2; 0 if offset1 == offset2; 1 if offset1 > offset2. Null if not comparable