org.apache.flink.streaming.api.operators

Enum ChainingStrategy

java.lang.Object

java.lang.Enum<ChainingStrategy>

org.apache.flink.streaming.api.operators.ChainingStrategy

All Implemented Interfaces:

Serializable, Comparable<ChainingStrategy>

@PublicEvolving
public enum ChainingStrategy
extends Enum<ChainingStrategy>

Defines the chaining scheme for the operator. When an operator is chained to the predecessor, it means that they run in the same thread. They become one operator consisting of multiple steps.

The default value used by the StreamOperator is HEAD, which means that the operator is not chained to its predecessor. Most operators override this with ALWAYS, meaning they will be chained to predecessors whenever possible.

Enum Constant Summary

Enum Constants

Enum Constant and Description
ALWAYS Operators will be eagerly chained whenever possible.
HEAD The operator will not be chained to the predecessor, but successors may chain to this operator.
HEAD_WITH_SOURCES This operator will run at the head of a chain (similar as in HEAD, but it will additionally try to chain source inputs if possible.
NEVER The operator will not be chained to the preceding or succeeding operators.

Field Summary

Fields

Modifier and Type	Field and Description
static ChainingStrategy	DEFAULT_CHAINING_STRATEGY

Method Summary

Modifier and Type	Method and Description
static ChainingStrategy	valueOf(String name) Returns the enum constant of this type with the specified name.
static ChainingStrategy[]	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

ALWAYS

public static final ChainingStrategy ALWAYS

Operators will be eagerly chained whenever possible.

To optimize performance, it is generally a good practice to allow maximal chaining and increase operator parallelism.

NEVER

public static final ChainingStrategy NEVER

The operator will not be chained to the preceding or succeeding operators.

HEAD

public static final ChainingStrategy HEAD

The operator will not be chained to the predecessor, but successors may chain to this operator.

HEAD_WITH_SOURCES

public static final ChainingStrategy HEAD_WITH_SOURCES

This operator will run at the head of a chain (similar as in HEAD, but it will additionally try to chain source inputs if possible. This allows multi-input operators to be chained with multiple sources into one task.

Field Detail

DEFAULT_CHAINING_STRATEGY

public static final ChainingStrategy DEFAULT_CHAINING_STRATEGY

Method Detail

values

public static ChainingStrategy[] 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 (ChainingStrategy c : ChainingStrategy.values())
    System.out.println(c);

Returns:

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

valueOf

public static ChainingStrategy 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