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sort.go
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sort.go
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package visualize
import (
"github.com/lyft/flytepropeller/pkg/apis/flyteworkflow/v1alpha1"
"github.com/pkg/errors"
)
type VisitStatus int8
const (
NotVisited VisitStatus = iota
Visited
Completed
)
type NodeVisitor map[v1alpha1.NodeID]VisitStatus
func NewNodeVisitor(nodes []v1alpha1.NodeID) NodeVisitor {
v := make(NodeVisitor, len(nodes))
for _, n := range nodes {
v[n] = NotVisited
}
return v
}
func tsortHelper(g v1alpha1.ExecutableWorkflow, currentNode v1alpha1.ExecutableNode, visited NodeVisitor, reverseSortedNodes *[]v1alpha1.ExecutableNode) error {
if visited[currentNode.GetID()] == NotVisited {
visited[currentNode.GetID()] = Visited
defer func() {
visited[currentNode.GetID()] = Completed
}()
nodes, err := g.FromNode(currentNode.GetID())
if err != nil {
return err
}
for _, childID := range nodes {
child, ok := g.GetNode(childID)
if !ok {
return errors.Errorf("Unable to find Node [%s] in Workflow [%s]", childID, g.GetID())
}
if err := tsortHelper(g, child, visited, reverseSortedNodes); err != nil {
return err
}
}
*reverseSortedNodes = append(*reverseSortedNodes, currentNode)
return nil
}
// Node was successfully visited previously
if visited[currentNode.GetID()] == Completed {
return nil
}
// Node was partially visited and we are in the subgraph and that reached back to the parent
return errors.Errorf("Cycle detected. Node [%v]", currentNode.GetID())
}
func reverseSlice(sl []v1alpha1.ExecutableNode) []v1alpha1.ExecutableNode {
for i := len(sl)/2 - 1; i >= 0; i-- {
opp := len(sl) - 1 - i
sl[i], sl[opp] = sl[opp], sl[i]
}
return sl
}
func TopologicalSort(g v1alpha1.ExecutableWorkflow) ([]v1alpha1.ExecutableNode, error) {
reverseSortedNodes := make([]v1alpha1.ExecutableNode, 0, 25)
visited := NewNodeVisitor(g.GetNodes())
if err := tsortHelper(g, g.StartNode(), visited, &reverseSortedNodes); err != nil {
return nil, err
}
return reverseSlice(reverseSortedNodes), nil
}