/
topologysort.go
137 lines (119 loc) · 3.95 KB
/
topologysort.go
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/**
* @license
* Copyright 2020 Dynatrace LLC
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package project
import (
"fmt"
"github.com/dynatrace-oss/dynatrace-monitoring-as-code/pkg/config"
"github.com/dynatrace-oss/dynatrace-monitoring-as-code/pkg/util"
)
func sortProjects(projects []Project) (sorted []Project, err error) {
sorted = []Project{}
incomingDeps, inDegrees := calculateIncomingProjectDependencies(projects)
reverse, err, errorOn := topologySort(incomingDeps, inDegrees)
if err != nil {
return sorted, fmt.Errorf("failed to sort projects, circular dependency on project %s detected, please check dependencies in project configs", projects[errorOn].GetId())
}
for i := len(reverse) - 1; i >= 0; i-- {
sorted = append(sorted, projects[reverse[i]])
}
return sorted, nil
}
func calculateIncomingProjectDependencies(projects []Project) (adjacencyMatrix [][]bool, inDegrees []int) {
adjacencyMatrix = make([][]bool, len(projects))
inDegrees = make([]int, len(projects))
for i := range projects {
p1 := projects[i]
adjacencyMatrix[i] = make([]bool, len(projects))
for j := range projects {
if i != j {
p2 := projects[j]
if p2.HasDependencyOn(p1) {
util.Log.Debug("\t\t%s has dep on %s", p2.GetId(), p1.GetId())
adjacencyMatrix[i][j] = true
inDegrees[i]++
}
}
}
}
return adjacencyMatrix, inDegrees
}
func sortConfigurations(configs []config.Config) (sorted []config.Config, err error) {
sorted = []config.Config{}
incomingDeps, inDegrees := calculateIncomingConfigDependencies(configs)
reverse, err, errorOn := topologySort(incomingDeps, inDegrees)
if err != nil {
util.Log.Debug(err.Error())
return sorted, fmt.Errorf("failed to sort configs, circular dependency on config %s detected, please check dependencies", configs[errorOn].GetFullQualifiedId())
}
for i := len(reverse) - 1; i >= 0; i-- {
sorted = append(sorted, configs[reverse[i]])
util.Log.Debug("\t\t%s", configs[reverse[i]].GetFullQualifiedId())
}
return sorted, nil
}
func calculateIncomingConfigDependencies(configs []config.Config) (adjacencyMatrix [][]bool, inDegrees []int) {
adjacencyMatrix = make([][]bool, len(configs))
inDegrees = make([]int, len(configs))
for i := range configs {
c1 := configs[i]
adjacencyMatrix[i] = make([]bool, len(configs))
for j := range configs {
if i != j {
c2 := configs[j]
if c2.HasDependencyOn(c1) {
util.Log.Debug("\t\t%s has dep on %s", c2.GetFullQualifiedId(), c1.GetFullQualifiedId())
adjacencyMatrix[i][j] = true
inDegrees[i]++
}
}
}
}
return adjacencyMatrix, inDegrees
}
// https://en.wikipedia.org/wiki/Topological_sorting#Kahn's_algorithm
func topologySort(incomingEdges [][]bool, inDegrees []int) (topoSorted []int, err error, errorOnId int) {
nodes := getAllLeaves(inDegrees)
topoSorted = []int{}
for len(nodes) > 0 {
cur := nodes[0]
nodes = nodes[1:]
topoSorted = append(topoSorted, cur)
for i := range inDegrees {
if incomingEdges[i][cur] {
incomingEdges[i][cur] = false
inDegrees[i]--
if inDegrees[i] <= 0 {
nodes = append(nodes, i)
}
}
}
}
for i := range inDegrees {
if inDegrees[i] != 0 {
return topoSorted, fmt.Errorf("circular Dependency in Topology Sort, could not resolve dependencies still pointing to index %d", i), i
}
}
return topoSorted, nil, -1
}
func getAllLeaves(inDegrees []int) []int {
var nodes []int
for i := range inDegrees {
if inDegrees[i] == 0 {
nodes = append(nodes, i)
}
}
return nodes
}