Package org.apache.storm.kafka.spout

Enum KafkaSpoutConfig.ProcessingGuarantee

java.lang.Object

java.lang.Enum<KafkaSpoutConfig.ProcessingGuarantee>

org.apache.storm.kafka.spout.KafkaSpoutConfig.ProcessingGuarantee

All Implemented Interfaces:

Serializable, Comparable<KafkaSpoutConfig.ProcessingGuarantee>

Enclosing class:

KafkaSpoutConfig<K,V>

@Unstable
public static enum KafkaSpoutConfig.ProcessingGuarantee
extends Enum<KafkaSpoutConfig.ProcessingGuarantee>

This enum controls when the tuple with the ConsumerRecord for an offset is marked as processed, i.e. when the offset can be committed to Kafka. The default value is AT_LEAST_ONCE. The commit interval is controlled by KafkaSpoutConfig.getOffsetsCommitPeriodMs(), if the mode commits on an interval. NO_GUARANTEE may be removed in a later release without warning, we're still evaluating whether it makes sense to keep.

Enum Constant Summary

Enum Constants

Enum Constant	Description
AT_LEAST_ONCE	An offset is ready to commit only after the corresponding tuple has been processed and acked (at least once).
AT_MOST_ONCE	Every offset will be synchronously committed to Kafka right after being polled but before being emitted to the downstream components of the topology.
NO_GUARANTEE	The polled offsets are ready to commit immediately after being polled.

Method Summary

Modifier and Type	Method	Description
static KafkaSpoutConfig.ProcessingGuarantee	valueOf(String name)	Returns the enum constant of this type with the specified name.
static KafkaSpoutConfig.ProcessingGuarantee[]	values()	Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Detail

AT_LEAST_ONCE

public static final KafkaSpoutConfig.ProcessingGuarantee AT_LEAST_ONCE

An offset is ready to commit only after the corresponding tuple has been processed and acked (at least once). If a tuple fails or times out it will be re-emitted, as controlled by the KafkaSpoutRetryService. Commits synchronously on the defined interval.

AT_MOST_ONCE

public static final KafkaSpoutConfig.ProcessingGuarantee AT_MOST_ONCE

Every offset will be synchronously committed to Kafka right after being polled but before being emitted to the downstream components of the topology. The commit interval is ignored. This mode guarantees that the offset is processed at most once by ensuring the spout won't retry tuples that fail or time out after the commit to Kafka has been done

NO_GUARANTEE

public static final KafkaSpoutConfig.ProcessingGuarantee NO_GUARANTEE

The polled offsets are ready to commit immediately after being polled. The offsets are committed periodically, i.e. a message may be processed 0, 1 or more times. This behavior is similar to setting enable.auto.commit=true in the consumer, but allows the spout to control when commits occur. Commits asynchronously on the defined interval.

Method Detail

values

public static KafkaSpoutConfig.ProcessingGuarantee[] values()

Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:

for (KafkaSpoutConfig.ProcessingGuarantee c : KafkaSpoutConfig.ProcessingGuarantee.values())
    System.out.println(c);

Returns:

an array containing the constants of this enum type, in the order they are declared

valueOf

public static KafkaSpoutConfig.ProcessingGuarantee valueOf(String name)

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)

Parameters:

name - the name of the enum constant to be returned.

Returns:

the enum constant with the specified name

Throws:

IllegalArgumentException - if this enum type has no constant with the specified name

NullPointerException - if the argument is null