com.pervasive.datarush.operators

Class ParallelismStrategy

java.lang.Object

com.pervasive.datarush.operators.ParallelismStrategy

public abstract class ParallelismStrategy
extends Object

A ParallelismStrategy is responsible for determining parallelization of an operator based on configured parallelism and source parallelism.

Implementations should rely on one of the following standard strategies:

1. NON_PARALLELIZABLE
2. CONFIGURED
3. ACCEPT_SOURCE
4. NEGOTIATE_BASED_ON_SOURCE

Field Summary

Fields

Modifier and Type	Field and Description
static ParallelismStrategy	ACCEPT_SOURCE Uses the maximum of the input ports' parallelism as this operator's max parallelism.
static ParallelismStrategy	CONFIGURED Indicates that the operator should use whatever parallelism has been explicitly configured via OperatorSettings.getMaxParallelism(), defaulting to EngineConfig#getParallelism().
static ParallelismStrategy	NEGOTIATE_BASED_ON_SOURCE Uses the maximum of the input ports' parallelism as this operator's max parallelism.
static ParallelismStrategy	NON_PARALLELIZABLE Indicates that the operator is non-parallelizable.

Constructor Summary

Constructors

Constructor and Description
ParallelismStrategy()

Method Summary

Modifier and Type	Method and Description
abstract Integer	maxParallelism(Integer configuredParallelism, MetadataCalculationContext ctx) Public only as a matter of implementation; operators should not call this method.

Methods inherited from class java.lang.Object

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

Field Detail

NON_PARALLELIZABLE

public static final ParallelismStrategy NON_PARALLELIZABLE

Indicates that the operator is non-parallelizable.

CONFIGURED

public static final ParallelismStrategy CONFIGURED

Indicates that the operator should use whatever parallelism has been explicitly configured via OperatorSettings.getMaxParallelism(), defaulting to EngineConfig#getParallelism().

NEGOTIATE_BASED_ON_SOURCE

public static final ParallelismStrategy NEGOTIATE_BASED_ON_SOURCE

Uses the maximum of the input ports' parallelism as this operator's max parallelism. If there are no parallel inputs, this will use Integer.MAX_VALUE as its parallelism, forcing a "scatter" from the inputs. If this operator has an explicit OperatorSettings.maxParallelism(int) specified on it or inherited from its parent, this will favor the explicit setting.

ACCEPT_SOURCE

public static final ParallelismStrategy ACCEPT_SOURCE

Uses the maximum of the input ports' parallelism as this operator's max parallelism. In contrast to NEGOTIATE_BASED_ON_SOURCE, parallelism of 1 is a valid value and thus we will only be parallel if the source is parallel. If this operator has an explicit OperatorSettings.maxParallelism(int) specified on it or inherited from its parent, this will favor the explicit setting.

Constructor Detail

ParallelismStrategy

public ParallelismStrategy()

Method Detail

maxParallelism

public abstract Integer maxParallelism(Integer configuredParallelism,
                                       MetadataCalculationContext ctx)

Public only as a matter of implementation; operators should not call this method. Computes the max parallelism to use.

Parameters:

configuredParallelism - the parallelism explicitly configured or null if unspecified

ctx - the context that the function can use to determine port inputs, etc

Returns:

the max parallelism. a value of null will be interpretted as Integer.MAX_VALUE (unconstrained).