README
¶
Dependency Resolver (Golang)
Introduction
Layer-based scheduling algorithm for parallel tasks with dependencies. Determines which tasks can be executed in parallel, by evaluating dependencies.
Given a list of entries (each with its own dependency list), it can sort them in layers of execution, where all entries in the same layer can be executed in parallel, and have no other dependency than the previous layer.
For instance, given entries A, B, C, D, where B and C depend on A, and D depends on B and C, this function will return three layers of execution (as B and C can be executed in parallel after A completes):
Dependency tree:
A
/ \
B C
\ /
D
Resulting execution layers:
---------------------
Layer 1: A
---------------------
Layer 2: B C
---------------------
Layer 3: D
---------------------
Installation
go get github.com/quipo/dependencysolver
Sample usage
import (
"github.com/quipo/dependencysolver"
)
type Operation struct {
ID string,
Deps []string,
// some other properties of the operation
}
func SortByDependency(operations []Operation) (layers [][]string) {
entries := make([]dependencysolver.Entry, 0)
for _, op := range operations {
entries = append(entries, dependencysolver.Entry{ID: op.ID, Deps: op.Deps})
}
return dependencysolver.LayeredTopologicalSort(entries)
}
Credits
This package follows an algorithm described (albeit incorrectly implemented) here: http://msdn.microsoft.com/en-us/magazine/dd569760.aspx
Other interesting articles on the topic:
- http://en.wikipedia.org/wiki/Topological_sorting
- http://www.tu-chemnitz.de/informatik/PI/forschung/projekte/genMTS/index.php.en
- http://www.tu-chemnitz.de/informatik/PI/forschung/pub/download/DKR_parco07.pdf
- http://ertl.jp/~shinpei/papers/rtss10.pdf
- http://www.dur.ac.uk/pedro.gonnet/?page_id=6
- http://www.electricmonk.nl/log/2008/08/07/dependency-resolving-algorithm/
- http://ieeexplore.ieee.org/iel5/5538704/5547051/05547145.pdf?arnumber=5547145
- http://www.ier-institute.org/2070-1918/lnit25/lnit%20v25/141.pdf
Copyright
See LICENSE document
Documentation
¶
Overview ¶
Package dependencysolver implements a layer-based scheduling algorithm for parallel tasks with dependencies.
Given a list of entries (each with its own dependency list), it can sort the entries in layers of execution, where all entries in the same layer can be executed in parallel, and have no other dependency than the previous layer.
Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func HasCircularDependency ¶
HasCircularDependency returns false if there are no cycles in the dependency graph
func LayeredTopologicalSort ¶
LayeredTopologicalSort returns a list of layers of entries, the entries within each layer can be executed in parallel
Source Files