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feat: start separation between dependency-graph and expression-manage…
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,3 +1,6 @@ | ||
| package skipper | ||
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| import "github.com/lukasjarosch/skipper/expression" | ||
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| // TODO: move to expression/dep.go ??? | ||
| type ExpressionRegistry map[string]*expression.ExpressionNode | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,119 @@ | ||
| package graph | ||
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| import ( | ||
| "errors" | ||
| "fmt" | ||
| "strings" | ||
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| "github.com/dominikbraun/graph" | ||
| ) | ||
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| type dependencyGraph graph.Graph[string, string] | ||
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| var ( | ||
| ErrSelfReferencingDependency = fmt.Errorf("self-referencing dependency") | ||
| ErrCyclicReference = fmt.Errorf("cyclic dependency") | ||
| ) | ||
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| type DependencyGraph struct { | ||
| graph dependencyGraph | ||
| } | ||
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| func NewDependencyGraph() *DependencyGraph { | ||
| g := graph.New(graph.StringHash, graph.Acyclic(), graph.Directed(), graph.PreventCycles()) | ||
| return &DependencyGraph{graph: g} | ||
| } | ||
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| func (dg *DependencyGraph) AddVertex(vertexHash string) error { | ||
| err := dg.graph.AddVertex(vertexHash) | ||
| if err != nil { | ||
| // ignore duplicate vertex errors | ||
| if !errors.Is(err, graph.ErrVertexAlreadyExists) { | ||
| return fmt.Errorf("cannot add vertex: %w", err) | ||
| } | ||
| } | ||
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| return nil | ||
| } | ||
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| func (dg *DependencyGraph) RegisterDependencies(dependerVertexHash string, dependeeVertexHashes []string) error { | ||
| for _, dependency := range dependeeVertexHashes { | ||
| dependeeVertex, err := dg.graph.Vertex(dependency) | ||
| if err != nil { | ||
| return fmt.Errorf("unexpectedly could not fetch dependency vertex %s: %w", dependency, err) | ||
| } | ||
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| // prevent self-referencing references | ||
| if strings.EqualFold(dependerVertexHash, dependeeVertex) { | ||
| return fmt.Errorf("%s: %w", dependerVertexHash, ErrSelfReferencingDependency) | ||
| } | ||
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| err = dg.graph.AddEdge(dependerVertexHash, dependeeVertex) | ||
| if err != nil { | ||
| if errors.Is(err, graph.ErrEdgeCreatesCycle) { | ||
| return fmt.Errorf("%s -> %s: %w", dependerVertexHash, dependeeVertex, ErrCyclicReference) | ||
| } | ||
| return fmt.Errorf("failed to register dependency %s: %w", dependency, err) | ||
| } | ||
| } | ||
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| return nil | ||
| } | ||
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| func (dg *DependencyGraph) RemoveVertex(vertexHash string) error { | ||
| edges, err := dg.graph.Edges() | ||
| if err != nil { | ||
| return err | ||
| } | ||
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| // Find all edges with either originate from or point to the reference and remove them. | ||
| for _, edge := range edges { | ||
| if edge.Source == vertexHash { | ||
| err = dg.graph.RemoveEdge(edge.Source, edge.Target) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| continue | ||
| } | ||
| if edge.Target == vertexHash { | ||
| err = dg.graph.RemoveEdge(edge.Source, edge.Target) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| continue | ||
| } | ||
| } | ||
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| return dg.graph.RemoveVertex(vertexHash) | ||
| } | ||
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| func (dg *DependencyGraph) TopologicalSort() (vertexHashes []string, err error) { | ||
| // Perform a stable topological sort of the dependency graph. | ||
| // The returned orderedHashes is stable in that the hashes are sorted | ||
| // by their length or alphabetically if they are the same length. | ||
| // This eliminates the issue that the actual topological sorting algorithm usually | ||
| // has multiple valid solutions. | ||
| orderedHashes, err := graph.StableTopologicalSort[string, string](dg.graph, func(s1, s2 string) bool { | ||
| // Strings are of different length, sort by length | ||
| if len(s1) != len(s2) { | ||
| return len(s1) < len(s2) | ||
| } | ||
| // Otherwise, sort alphabetically | ||
| return s1 > s2 | ||
| }) | ||
| if err != nil { | ||
| return nil, fmt.Errorf("failed to sort reference graph: %w", err) | ||
| } | ||
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| // The result of the topological sorting is reverse to what we want. | ||
| // We expect the vertex without any dependencies to be at the top. | ||
| for i := len(orderedHashes) - 1; i >= 0; i-- { | ||
| ref, err := dg.graph.Vertex(orderedHashes[i]) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| vertexHashes = append(vertexHashes, ref) | ||
| } | ||
|
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| return | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,25 @@ | ||
| package graph | ||
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| import ( | ||
| "os" | ||
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| "github.com/dominikbraun/graph" | ||
| "github.com/dominikbraun/graph/draw" | ||
| ) | ||
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| // Visualize is mainly a debugging function which will render a DOT file | ||
| // of the graph into the given filePath and add the label as graph description. | ||
| func Visualize[K comparable, T any](graph graph.Graph[K, T], filePath string, label string) error { | ||
| file, err := os.Create(filePath) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| err = draw.DOT(graph, file, | ||
| draw.GraphAttribute("label", label), | ||
| draw.GraphAttribute("overlap", "prism")) | ||
| if err != nil { | ||
| return err | ||
| } | ||
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| return nil | ||
| } |
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