tachyon.collections

Class DirectedAcyclicGraph<T>

java.lang.Object

tachyon.collections.DirectedAcyclicGraph<T>

Type Parameters:

T - the payload of each node.

public class DirectedAcyclicGraph<T>
extends Object

A Directed Acyclic Graph (DAG). This class is NOT thread-safe.

Constructor Summary

Constructors

Constructor and Description
DirectedAcyclicGraph()

Method Summary

Methods

Modifier and Type	Method and Description
void	add(T payload, List<T> parents) Adds a node to the DAG, that takes the given payload and depends on the specified parents.
boolean	contains(T payload)
void	deleteLeaf(T payload) Deletes a leaf DAG node that carries the given payload.
List<T>	getAllInTopologicalOrder()
List<T>	getChildren(T payload)
List<T>	getParents(T payload)
List<T>	getRoots()
boolean	isRoot(T payload)
List<T>	sortTopologically(Set<T> payloads) Sorts a given set of payloads topologically based on the DAG.

Methods inherited from class java.lang.Object

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

Constructor Detail

DirectedAcyclicGraph

public DirectedAcyclicGraph()

Method Detail

add

public void add(T payload,
       List<T> parents)

Adds a node to the DAG, that takes the given payload and depends on the specified parents.

Parameters:

payload - the payload

parents - the parents of the created node

deleteLeaf

public void deleteLeaf(T payload)

Deletes a leaf DAG node that carries the given payload.

Parameters:

payload - the payload of the node to delete

contains

public boolean contains(T payload)

Returns:

true if there a node in the DAG contains the given value as payload, false otherwise

getChildren

public List<T> getChildren(T payload)

Returns:

the children's payloads, an empty list if the given payload doesn't exist in the DAG

getParents

public List<T> getParents(T payload)

Returns:

the parents' payloads, an empty list if the given payload doesn't exist in the DAG

isRoot

public boolean isRoot(T payload)

Returns:

true if the payload is in the root of the DAG, false otherwise

getRoots

public List<T> getRoots()

Returns:

all the root payloads

sortTopologically

public List<T> sortTopologically(Set<T> payloads)

Sorts a given set of payloads topologically based on the DAG. This method requires all the payloads to be in the DAG. TODO(yupeng): optimize this implementation

Parameters:

payloads - the set of input payloads

Returns:

the payloads after topogological sort

getAllInTopologicalOrder

public List<T> getAllInTopologicalOrder()

Returns:

the payloads of all the nodes in toplogical order