Package org.apache.kafka.streams.processor

Interface ProcessorContext

All Known Implementing Classes:

MockProcessorContext

@Evolving
public interface ProcessorContext

Processor context interface.

Method Summary

Modifier and Type	Method	Description
java.util.Map<java.lang.String,java.lang.Object>	appConfigs()	Returns all the application config properties as key/value pairs.
java.util.Map<java.lang.String,java.lang.Object>	appConfigsWithPrefix(java.lang.String prefix)	Returns all the application config properties with the given key prefix, as key/value pairs stripping the prefix.
java.lang.String	applicationId()	Returns the application id
void	commit()	Requests a commit
<K,V> void	forward(K key, V value)	Forwards a key/value pair to all downstream processors.
<K,V> void	forward(K key, V value, int childIndex)	Deprecated. please use forward(Object, Object, To) instead
<K,V> void	forward(K key, V value, java.lang.String childName)	Deprecated. please use forward(Object, Object, To) instead
<K,V> void	forward(K key, V value, To to)	Forwards a key/value pair to the specified downstream processors.
StateStore	getStateStore(java.lang.String name)	Get the state store given the store name.
Headers	headers()	Returns the headers of the current input record; could be null if it is not available
Serde<?>	keySerde()	Returns the default key serde
StreamsMetrics	metrics()	Returns Metrics instance
long	offset()	Returns the offset of the current input record; could be -1 if it is not available (for example, if this method is invoked from the punctuate call)
int	partition()	Returns the partition id of the current input record; could be -1 if it is not available (for example, if this method is invoked from the punctuate call)
void	register(StateStore store, StateRestoreCallback stateRestoreCallback)	Registers and possibly restores the specified storage engine.
Cancellable	schedule(long intervalMs, PunctuationType type, Punctuator callback)	Schedules a periodic operation for processors.
java.io.File	stateDir()	Returns the state directory for the partition.
TaskId	taskId()	Returns the task id
long	timestamp()	Returns the current timestamp.
java.lang.String	topic()	Returns the topic name of the current input record; could be null if it is not available (for example, if this method is invoked from the punctuate call)
Serde<?>	valueSerde()	Returns the default value serde

Method Detail

applicationId

java.lang.String applicationId()

Returns the application id

Returns:

the application id

taskId

TaskId taskId()

Returns the task id

Returns:

the task id

keySerde

Serde<?> keySerde()

Returns the default key serde

Returns:

the key serializer

valueSerde

Serde<?> valueSerde()

Returns the default value serde

Returns:

the value serializer

stateDir

java.io.File stateDir()

Returns the state directory for the partition.

Returns:

the state directory

metrics

StreamsMetrics metrics()

Returns Metrics instance

Returns:

StreamsMetrics

register

void register(StateStore store,
              StateRestoreCallback stateRestoreCallback)

Registers and possibly restores the specified storage engine.

Parameters:

store - the storage engine

stateRestoreCallback - the restoration callback logic for log-backed state stores upon restart

Throws:

java.lang.IllegalStateException - If store gets registered after initialized is already finished

StreamsException - if the store's change log does not contain the partition

getStateStore

StateStore getStateStore(java.lang.String name)

Get the state store given the store name.

Parameters:

name - The store name

Returns:

The state store instance

schedule

Cancellable schedule(long intervalMs,
                     PunctuationType type,
                     Punctuator callback)

Schedules a periodic operation for processors. A processor may call this method during initialization or processing to schedule a periodic callback - called a punctuation - to Punctuator.punctuate(long). The type parameter controls what notion of time is used for punctuation:

• PunctuationType.STREAM_TIME - uses "stream time", which is advanced by the processing of messages in accordance with the timestamp as extracted by the TimestampExtractor in use. The first punctuation will be triggered by the first record that is processed. NOTE: Only advanced if messages arrive
• PunctuationType.WALL_CLOCK_TIME - uses system time (the wall-clock time), which is advanced at the polling interval (StreamsConfig.POLL_MS_CONFIG) independent of whether new messages arrive. The first punctuation will be triggered after interval has elapsed. NOTE: This is best effort only as its granularity is limited by how long an iteration of the processing loop takes to complete

Skipping punctuations: Punctuations will not be triggered more than once at any given timestamp. This means that "missed" punctuation will be skipped. It's possible to "miss" a punctuation if:

• with PunctuationType.STREAM_TIME, when stream time advances more than interval
• with PunctuationType.WALL_CLOCK_TIME, on GC pause, too short interval, ...

Parameters:

intervalMs - the time interval between punctuations in milliseconds

type - one of: PunctuationType.STREAM_TIME, PunctuationType.WALL_CLOCK_TIME

callback - a function consuming timestamps representing the current stream or system time

Returns:

a handle allowing cancellation of the punctuation schedule established by this method

forward

<K,V> void forward(K key,
                   V value)

Forwards a key/value pair to all downstream processors. Used the input record's timestamp as timestamp for the output record.

Parameters:

key - key

value - value

forward

<K,V> void forward(K key,
                   V value,
                   To to)

Forwards a key/value pair to the specified downstream processors. Can be used to set the timestamp of the output record.

Parameters:

key - key

value - value

to - the options to use when forwarding

forward

@Deprecated
<K,V> void forward(K key,
                   V value,
                   int childIndex)

Deprecated. please use forward(Object, Object, To) instead

Forwards a key/value pair to one of the downstream processors designated by childIndex

Parameters:

key - key

value - value

childIndex - index in list of children of this node

forward

@Deprecated
<K,V> void forward(K key,
                   V value,
                   java.lang.String childName)

Deprecated. please use forward(Object, Object, To) instead

Forwards a key/value pair to one of the downstream processors designated by the downstream processor name

Parameters:

key - key

value - value

childName - name of downstream processor

commit

void commit()

Requests a commit

topic

java.lang.String topic()

Returns the topic name of the current input record; could be null if it is not available (for example, if this method is invoked from the punctuate call)

Returns:

the topic name

partition

int partition()

Returns the partition id of the current input record; could be -1 if it is not available (for example, if this method is invoked from the punctuate call)

Returns:

the partition id

offset

long offset()

Returns the offset of the current input record; could be -1 if it is not available (for example, if this method is invoked from the punctuate call)

Returns:

the offset

headers

Headers headers()

Returns the headers of the current input record; could be null if it is not available

Returns:

the headers

timestamp

long timestamp()

Returns the current timestamp. If it is triggered while processing a record streamed from the source processor, timestamp is defined as the timestamp of the current input record; the timestamp is extracted from ConsumerRecord by TimestampExtractor. If it is triggered while processing a record generated not from the source processor (for example, if this method is invoked from the punctuate call), timestamp is defined as the current task's stream time, which is defined as the smallest among all its input stream partition timestamps.

Returns:

the timestamp

appConfigs

java.util.Map<java.lang.String,java.lang.Object> appConfigs()

Returns all the application config properties as key/value pairs. The config properties are defined in the StreamsConfig object and associated to the ProcessorContext.

The type of the values is dependent on the type of the property (e.g. the value of DEFAULT_KEY_SERDE_CLASS_CONFIG will be of type Class, even if it was specified as a String to StreamsConfig(Map)).

Returns:

all the key/values from the StreamsConfig properties

appConfigsWithPrefix

java.util.Map<java.lang.String,java.lang.Object> appConfigsWithPrefix(java.lang.String prefix)

Returns all the application config properties with the given key prefix, as key/value pairs stripping the prefix. The config properties are defined in the StreamsConfig object and associated to the ProcessorContext.

Parameters:

prefix - the properties prefix

Returns:

the key/values matching the given prefix from the StreamsConfig properties.