org.apache.gobblin.service.modules.flowgraph

Class Dag<T>

java.lang.Object

org.apache.gobblin.service.modules.flowgraph.Dag<T>

@Alpha
public class Dag<T>
extends Object

An implementation of Dag. Assumes that nodes have unique values. Nodes with duplicate values will produce unpredictable behavior.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Dag.DagNode<T> DagNode is essentially a job within a Dag, usually they are used interchangeably.

Constructor Summary

Constructors

Constructor and Description
Dag(List<Dag.DagNode<T>> dagNodes)

Method Summary

Modifier and Type	Method and Description
Dag<T>	concatenate(Dag<T> other) Concatenate two dags together.
Dag<T>	concatenate(Dag<T> other, Set<Dag.DagNode<T>> forkNodes) Concatenate two dags together.
List<Dag.DagNode<T>>	getChildren(Dag.DagNode node)
Set<Dag.DagNode<T>>	getDependencyNodes(Set<Dag.DagNode<T>> forkNodes) This method computes a set of Dag.DagNodes which are the dependency nodes for concatenating this Dag with any other Dag.
List<Dag.DagNode<T>>	getParents(Dag.DagNode node)
boolean	isEmpty()
Dag<T>	merge(Dag<T> other) Merge the "other" dag to "this" dag and return "this" dag as a forest of the two dags.
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

Dag

public Dag(List<Dag.DagNode<T>> dagNodes)

Method Detail

getChildren

public List<Dag.DagNode<T>> getChildren(Dag.DagNode node)

getParents

public List<Dag.DagNode<T>> getParents(Dag.DagNode node)

getDependencyNodes

public Set<Dag.DagNode<T>> getDependencyNodes(Set<Dag.DagNode<T>> forkNodes)

This method computes a set of Dag.DagNodes which are the dependency nodes for concatenating this Dag with any other Dag. The set of dependency nodes is the union of:

• The endNodes of this dag which are not forkable, and
• The parents of forkable nodes, such that no parent is an ancestor of another parent.

Parameters:

forkNodes - set of nodes of this Dag which are forkable

Returns:

set of dependency nodes of this dag for concatenation with any other dag.

isEmpty

public boolean isEmpty()

concatenate

public Dag<T> concatenate(Dag<T> other)

Concatenate two dags together. Join the "other" dag to "this" dag and return "this" dag. The concatenate method ensures that all the jobs of "this" dag (which may have multiple end nodes) are completed before starting any job of the "other" dag. This is done by adding each endNode of this dag as a parent of every startNode of the other dag.

Parameters:

other - dag to concatenate to this dag

Returns:

the concatenated dag

concatenate

public Dag<T> concatenate(Dag<T> other,
                          Set<Dag.DagNode<T>> forkNodes)

Concatenate two dags together. Join the "other" dag to "this" dag and return "this" dag. The concatenate method ensures that all the jobs of "this" dag (which may have multiple end nodes) are completed before starting any job of the "other" dag. This is done by adding each endNode of this dag, which is not a fork node, as a parent of every startNode of the other dag.

Parameters:

other - dag to concatenate to this dag

forkNodes - a set of nodes from this dag which are marked as forkable nodes. Each of these nodes will be added to the list of end nodes of the concatenated dag. Essentially, a forkable node has no dependents in the concatenated dag.

Returns:

the concatenated dag

merge

public Dag<T> merge(Dag<T> other)

Merge the "other" dag to "this" dag and return "this" dag as a forest of the two dags. More specifically, the merge() operation takes two dags and returns a disjoint union of the two dags.

Parameters:

other - dag to merge to this dag

Returns:

the disjoint union of the two dags

toString

public String toString()

Overrides:

toString in class Object

Returns:

A string representation of the Dag as a JSON Array.