org.apache.samza.util

Class SinglePartitionWithoutOffsetsSystemAdmin

java.lang.Object

org.apache.samza.util.SinglePartitionWithoutOffsetsSystemAdmin

All Implemented Interfaces:

SystemAdmin

public class SinglePartitionWithoutOffsetsSystemAdmin
extends java.lang.Object
implements SystemAdmin

A simple helper admin class that defines a single partition (partition 0) for a given system. The metadata uses null for all offsets, which means that the stream doesn't support offsets, and will be treated as empty. This class should be used when a system has no concept of partitioning or offsets, since Samza needs at least one partition for an input stream, in order to read it.

Constructor Summary

Constructors

Constructor and Description
SinglePartitionWithoutOffsetsSystemAdmin()

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

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.samza.system.SystemAdmin

createStream, validateStream

Constructor Detail

SinglePartitionWithoutOffsetsSystemAdmin

public SinglePartitionWithoutOffsetsSystemAdmin()

Method Detail

getSystemStreamMetadata

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

Description copied from interface: SystemAdmin

Fetch metadata from a system for a set of streams.

Specified by:

getSystemStreamMetadata in interface SystemAdmin

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

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

Description copied from interface: SystemAdmin

An API to create a change log stream

Specified by:

createChangelogStream in interface SystemAdmin

Parameters:

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

numOfPartitions - The number of partitions in the changelog stream

validateChangelogStream

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

Description copied from interface: SystemAdmin

Validates change log stream

Specified by:

validateChangelogStream in interface SystemAdmin

Parameters:

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

numOfPartitions - The number of partitions in the changelog stream

getOffsetsAfter

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

Description copied from interface: SystemAdmin

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

Specified by:

getOffsetsAfter in interface SystemAdmin

Parameters:

offsets - Map from SystemStreamPartition to current offsets.

Returns:

Map from SystemStreamPartition to offsets immediately after the current offsets.

createCoordinatorStream

public void createCoordinatorStream(java.lang.String streamName)

Description copied from interface: SystemAdmin

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

Specified by:

createCoordinatorStream in interface SystemAdmin

Parameters:

streamName - The name of the coordinator stream to create.

offsetComparator

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

Description copied from interface: SystemAdmin

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

Specified by:

offsetComparator in interface SystemAdmin

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