feat: add directed acyclic graph package (#1468)

Signed-off-by: Gaius <gaius.qi@gmail.com>
This commit is contained in:
Gaius 2022-07-18 19:52:12 +08:00
parent c6654cb4ae
commit c79bd943bb
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4 changed files with 931 additions and 0 deletions

222
pkg/dag/dag.go Normal file
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/*
* Copyright 2022 The Dragonfly Authors
*
* 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 dag
import (
"errors"
"sync"
)
var (
// ErrVertexNotFound represents vertex not found.
ErrVertexNotFound = errors.New("vertex not found")
// ErrVertexAlreadyExists represents vertex already exists.
ErrVertexAlreadyExists = errors.New("vertex already exists")
// ErrParnetAlreadyExists represents parent of vertex already exists.
ErrParnetAlreadyExists = errors.New("parent of vertex already exists")
// ErrChildAlreadyExists represents child of vertex already exists.
ErrChildAlreadyExists = errors.New("child of vertex already exists")
// ErrCycleBetweenVertices represents cycle between vertices.
ErrCycleBetweenVertices = errors.New("cycle between vertices")
)
// DAG is the interface used for directed acyclic graph.
type DAG interface {
// AddVertex adds vertex to graph.
AddVertex(id string, value any) error
// DeleteVertex deletes vertex graph.
DeleteVertex(id string)
// GetVertex gets vertex from graph.
GetVertex(id string) (*Vertex, error)
// AddEdge adds edge between two vertices.
AddEdge(fromVertexID, toVertexID string) error
// DeleteEdge deletes edge between two vertices.
DeleteEdge(fromVertexID, toVertexID string) error
}
// dag provides directed acyclic graph function.
type dag struct {
mu sync.RWMutex
vertices map[string]*Vertex
}
// New returns a new DAG interface.
func NewDAG() DAG {
return &dag{
vertices: make(map[string]*Vertex),
}
}
// AddVertex adds vertex to graph.
func (d *dag) AddVertex(id string, value any) error {
d.mu.Lock()
defer d.mu.Unlock()
if _, ok := d.vertices[id]; ok {
return ErrVertexAlreadyExists
}
d.vertices[id] = NewVertex(id, value)
return nil
}
// DeleteVertex deletes vertex graph.
func (d *dag) DeleteVertex(id string) {
d.mu.Lock()
defer d.mu.Unlock()
vertex, ok := d.vertices[id]
if !ok {
return
}
vertex.Parents.Range(func(item any) bool {
parent, ok := item.(*Vertex)
if !ok {
return true
}
parent.Children.Delete(vertex)
return true
})
vertex.Children.Range(func(item any) bool {
child, ok := item.(*Vertex)
if !ok {
return true
}
child.Parents.Delete(vertex)
return true
})
delete(d.vertices, id)
}
// GetVertex gets vertex from graph.
func (d *dag) GetVertex(id string) (*Vertex, error) {
d.mu.RLock()
defer d.mu.RUnlock()
vertex, ok := d.vertices[id]
if !ok {
return nil, ErrVertexNotFound
}
return vertex, nil
}
// AddEdge adds edge between two vertices.
func (d *dag) AddEdge(fromVertexID, toVertexID string) error {
d.mu.Lock()
defer d.mu.Unlock()
if fromVertexID == toVertexID {
return ErrCycleBetweenVertices
}
fromVertex, ok := d.vertices[fromVertexID]
if !ok {
return ErrVertexNotFound
}
toVertex, ok := d.vertices[toVertexID]
if !ok {
return ErrVertexNotFound
}
for _, child := range fromVertex.Children.Values() {
vertex, ok := child.(*Vertex)
if !ok {
continue
}
if vertex.ID == toVertexID {
return ErrCycleBetweenVertices
}
}
if d.depthFirstSearch(toVertexID, fromVertexID) {
return ErrCycleBetweenVertices
}
if ok := fromVertex.Children.Add(toVertex); !ok {
return ErrChildAlreadyExists
}
if ok := toVertex.Parents.Add(fromVertex); !ok {
return ErrParnetAlreadyExists
}
return nil
}
// DeleteEdge deletes edge between two vertices.
func (d *dag) DeleteEdge(fromVertexID, toVertexID string) error {
d.mu.Lock()
defer d.mu.Unlock()
fromVertex, ok := d.vertices[fromVertexID]
if !ok {
return ErrVertexNotFound
}
toVertex, ok := d.vertices[toVertexID]
if !ok {
return ErrVertexNotFound
}
fromVertex.Children.Delete(toVertex)
toVertex.Parents.Delete(fromVertex)
return nil
}
// depthFirstSearch is a depth-first search of the directed acyclic graph.
func (d *dag) depthFirstSearch(fromVertexID, toVertexID string) bool {
successors := make(map[string]struct{})
d.search(fromVertexID, successors)
_, ok := successors[toVertexID]
return ok
}
// depthFirstSearch finds successors of vertex.
func (d *dag) search(vertexID string, successors map[string]struct{}) {
vertex, ok := d.vertices[vertexID]
if !ok {
return
}
for _, child := range vertex.Children.Values() {
vertex, ok := child.(*Vertex)
if !ok {
continue
}
if _, ok := successors[vertex.ID]; !ok {
successors[vertex.ID] = struct{}{}
d.search(vertex.ID, successors)
}
}
}

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pkg/dag/dag_test.go Normal file
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/*
* Copyright 2022 The Dragonfly Authors
*
* 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 dag
import (
"fmt"
"reflect"
"testing"
"github.com/stretchr/testify/assert"
)
func TestNewDAG(t *testing.T) {
d := NewDAG()
assert := assert.New(t)
assert.Equal(reflect.TypeOf(d).Elem().Name(), "dag")
}
func TestDAGAddVertex(t *testing.T) {
tests := []struct {
name string
id string
value any
expect func(t *testing.T, d DAG, err error)
}{
{
name: "add vertex",
id: mockVertexID,
value: mockVertexValue,
expect: func(t *testing.T, d DAG, err error) {
assert := assert.New(t)
assert.NoError(err)
},
},
{
name: "vertex already exists",
id: mockVertexID,
value: mockVertexValue,
expect: func(t *testing.T, d DAG, err error) {
assert := assert.New(t)
assert.NoError(err)
assert.EqualError(d.AddVertex(mockVertexID, mockVertexValue), ErrVertexAlreadyExists.Error())
},
},
}
for _, tc := range tests {
t.Run(tc.name, func(t *testing.T) {
d := NewDAG()
tc.expect(t, d, d.AddVertex(tc.id, tc.name))
})
}
}
func TestDAGDeleteVertex(t *testing.T) {
tests := []struct {
name string
expect func(t *testing.T, d DAG)
}{
{
name: "delete vertex",
expect: func(t *testing.T, d DAG) {
assert := assert.New(t)
if err := d.AddVertex(mockVertexID, mockVertexValue); err != nil {
assert.NoError(err)
}
d.DeleteVertex(mockVertexID)
_, err := d.GetVertex(mockVertexID)
assert.EqualError(err, ErrVertexNotFound.Error())
},
},
{
name: "delete vertex with edges",
expect: func(t *testing.T, d DAG) {
assert := assert.New(t)
var (
mockToVertexID = "baz"
)
if err := d.AddVertex(mockToVertexID, mockVertexValue); err != nil {
assert.NoError(err)
}
if err := d.AddVertex(mockVertexID, mockVertexValue); err != nil {
assert.NoError(err)
}
if err := d.AddEdge(mockVertexID, mockToVertexID); err != nil {
assert.NoError(err)
}
d.DeleteVertex(mockVertexID)
_, err := d.GetVertex(mockVertexID)
assert.EqualError(err, ErrVertexNotFound.Error())
vertex, err := d.GetVertex(mockToVertexID)
assert.NoError(err)
assert.Equal(vertex.Parents.Len(), uint(0))
},
},
}
for _, tc := range tests {
t.Run(tc.name, func(t *testing.T) {
d := NewDAG()
tc.expect(t, d)
})
}
}
func TestDAGGetVertex(t *testing.T) {
tests := []struct {
name string
expect func(t *testing.T, d DAG)
}{
{
name: "get vertex",
expect: func(t *testing.T, d DAG) {
assert := assert.New(t)
if err := d.AddVertex(mockVertexID, mockVertexValue); err != nil {
assert.NoError(err)
}
vertex, err := d.GetVertex(mockVertexID)
assert.NoError(err)
assert.Equal(vertex.ID, mockVertexID)
assert.Equal(vertex.Value, mockVertexValue)
assert.Equal(vertex.Parents.Len(), uint(0))
assert.Equal(vertex.Children.Len(), uint(0))
},
},
{
name: "vertex not found",
expect: func(t *testing.T, d DAG) {
assert := assert.New(t)
_, err := d.GetVertex(mockVertexID)
assert.EqualError(err, ErrVertexNotFound.Error())
},
},
}
for _, tc := range tests {
t.Run(tc.name, func(t *testing.T) {
d := NewDAG()
tc.expect(t, d)
})
}
}
func TestDAGAddEdge(t *testing.T) {
tests := []struct {
name string
expect func(t *testing.T, d DAG)
}{
{
name: "add edge",
expect: func(t *testing.T, d DAG) {
assert := assert.New(t)
var (
mockVertexEID = "bae"
mockVertexFID = "baf"
mockVertexGID = "bag"
mockVertexHID = "bah"
mockVertexIID = "bai"
)
if err := d.AddVertex(mockVertexEID, mockVertexValue); err != nil {
assert.NoError(err)
}
if err := d.AddVertex(mockVertexFID, mockVertexValue); err != nil {
assert.NoError(err)
}
if err := d.AddVertex(mockVertexGID, mockVertexValue); err != nil {
assert.NoError(err)
}
if err := d.AddVertex(mockVertexHID, mockVertexValue); err != nil {
assert.NoError(err)
}
if err := d.AddVertex(mockVertexIID, mockVertexValue); err != nil {
assert.NoError(err)
}
if err := d.AddEdge(mockVertexEID, mockVertexFID); err != nil {
assert.NoError(err)
}
if err := d.AddEdge(mockVertexFID, mockVertexGID); err != nil {
assert.NoError(err)
}
if err := d.AddEdge(mockVertexFID, mockVertexHID); err != nil {
assert.NoError(err)
}
if err := d.AddEdge(mockVertexGID, mockVertexIID); err != nil {
assert.NoError(err)
}
if err := d.AddEdge(mockVertexIID, mockVertexHID); err != nil {
assert.NoError(err)
}
},
},
{
name: "cycle between vertices",
expect: func(t *testing.T, d DAG) {
assert := assert.New(t)
var (
mockVertexEID = "bae"
mockVertexFID = "baf"
mockVertexGID = "bag"
mockVertexHID = "bah"
mockVertexIID = "bai"
)
if err := d.AddVertex(mockVertexEID, mockVertexValue); err != nil {
assert.NoError(err)
}
if err := d.AddVertex(mockVertexFID, mockVertexValue); err != nil {
assert.NoError(err)
}
if err := d.AddVertex(mockVertexGID, mockVertexValue); err != nil {
assert.NoError(err)
}
if err := d.AddVertex(mockVertexHID, mockVertexValue); err != nil {
assert.NoError(err)
}
if err := d.AddVertex(mockVertexIID, mockVertexValue); err != nil {
assert.NoError(err)
}
if err := d.AddEdge(mockVertexEID, mockVertexEID); err != nil {
assert.EqualError(err, ErrCycleBetweenVertices.Error())
}
if err := d.AddEdge(mockVertexEID, mockVertexFID); err != nil {
assert.NoError(err)
}
if err := d.AddEdge(mockVertexFID, mockVertexEID); err != nil {
assert.EqualError(err, ErrCycleBetweenVertices.Error())
}
if err := d.AddEdge(mockVertexFID, mockVertexGID); err != nil {
assert.NoError(err)
}
if err := d.AddEdge(mockVertexGID, mockVertexEID); err != nil {
assert.EqualError(err, ErrCycleBetweenVertices.Error())
}
if err := d.AddEdge(mockVertexGID, mockVertexHID); err != nil {
assert.NoError(err)
}
if err := d.AddEdge(mockVertexHID, mockVertexIID); err != nil {
assert.NoError(err)
}
if err := d.AddEdge(mockVertexIID, mockVertexEID); err != nil {
assert.EqualError(err, ErrCycleBetweenVertices.Error())
}
},
},
{
name: "vertex not found",
expect: func(t *testing.T, d DAG) {
assert := assert.New(t)
var (
mockVertexEID = "bae"
mockVertexFID = "baf"
)
if err := d.AddVertex(mockVertexEID, mockVertexValue); err != nil {
assert.NoError(err)
}
if err := d.AddEdge(mockVertexEID, mockVertexFID); err != nil {
assert.EqualError(err, ErrVertexNotFound.Error())
}
if err := d.AddEdge(mockVertexFID, mockVertexEID); err != nil {
assert.EqualError(err, ErrVertexNotFound.Error())
}
},
},
}
for _, tc := range tests {
t.Run(tc.name, func(t *testing.T) {
d := NewDAG()
tc.expect(t, d)
})
}
}
func TestDAGDeleteEdge(t *testing.T) {
tests := []struct {
name string
expect func(t *testing.T, d DAG)
}{
{
name: "delete edge",
expect: func(t *testing.T, d DAG) {
assert := assert.New(t)
var (
mockVertexEID = "bae"
mockVertexFID = "baf"
)
if err := d.AddVertex(mockVertexEID, mockVertexValue); err != nil {
assert.NoError(err)
}
if err := d.AddVertex(mockVertexFID, mockVertexValue); err != nil {
assert.NoError(err)
}
if err := d.AddEdge(mockVertexEID, mockVertexFID); err != nil {
assert.NoError(err)
}
if err := d.DeleteEdge(mockVertexFID, mockVertexEID); err != nil {
assert.NoError(err)
}
vf, err := d.GetVertex(mockVertexFID)
assert.NoError(err)
assert.Equal(vf.Parents.Len(), uint(1))
ve, err := d.GetVertex(mockVertexEID)
assert.NoError(err)
assert.Equal(ve.Children.Len(), uint(1))
if err := d.DeleteEdge(mockVertexEID, mockVertexFID); err != nil {
assert.NoError(err)
}
vf, err = d.GetVertex(mockVertexFID)
assert.NoError(err)
assert.Equal(vf.Parents.Len(), uint(0))
ve, err = d.GetVertex(mockVertexEID)
assert.NoError(err)
assert.Equal(ve.Children.Len(), uint(0))
},
},
{
name: "vertex not found",
expect: func(t *testing.T, d DAG) {
assert := assert.New(t)
var (
mockVertexEID = "bae"
mockVertexFID = "baf"
)
if err := d.AddVertex(mockVertexEID, mockVertexValue); err != nil {
assert.NoError(err)
}
if err := d.AddEdge(mockVertexEID, mockVertexFID); err != nil {
assert.EqualError(err, ErrVertexNotFound.Error())
}
if err := d.AddEdge(mockVertexFID, mockVertexEID); err != nil {
assert.EqualError(err, ErrVertexNotFound.Error())
}
},
},
}
for _, tc := range tests {
t.Run(tc.name, func(t *testing.T) {
d := NewDAG()
tc.expect(t, d)
})
}
}
func BenchmarkDAGAddVertex(b *testing.B) {
var ids []string
d := NewDAG()
for n := 0; n < b.N; n++ {
ids = append(ids, fmt.Sprint(n))
}
b.ResetTimer()
for _, id := range ids {
if err := d.AddVertex(id, nil); err != nil {
b.Fatal(err)
}
}
}
func BenchmarkDAGDeleteVertex(b *testing.B) {
var ids []string
d := NewDAG()
for n := 0; n < b.N; n++ {
id := fmt.Sprint(n)
if err := d.AddVertex(id, nil); err != nil {
b.Fatal(err)
}
ids = append(ids, id)
}
b.ResetTimer()
for _, id := range ids {
d.DeleteVertex(id)
}
}
func BenchmarkDAGDeleteVertexWithMultiEdges(b *testing.B) {
var ids []string
d := NewDAG()
for n := 0; n < b.N; n++ {
id := fmt.Sprint(n)
if err := d.AddVertex(id, nil); err != nil {
b.Fatal(err)
}
ids = append(ids, id)
}
edgeCount := 5
for index, id := range ids {
if index+edgeCount > len(ids)-1 {
break
}
for n := 1; n < edgeCount; n++ {
if err := d.AddEdge(id, ids[index+n]); err != nil {
b.Fatal(err)
}
}
}
b.ResetTimer()
for _, id := range ids {
d.DeleteVertex(id)
}
}
func BenchmarkDAGAddEdge(b *testing.B) {
var ids []string
d := NewDAG()
for n := 0; n < b.N; n++ {
id := fmt.Sprint(n)
if err := d.AddVertex(id, nil); err != nil {
b.Fatal(err)
}
ids = append(ids, id)
}
b.ResetTimer()
for index, id := range ids {
if index < 1 {
continue
}
if err := d.AddEdge(id, ids[index-1]); err != nil {
b.Fatal(err)
}
}
}
func BenchmarkDAGAddEdgeWithMultiEdges(b *testing.B) {
var ids []string
d := NewDAG()
for n := 0; n < b.N; n++ {
id := fmt.Sprint(n)
if err := d.AddVertex(id, nil); err != nil {
b.Fatal(err)
}
ids = append(ids, id)
}
edgeCount := 5
for index, id := range ids {
if index+edgeCount > len(ids)-1 {
break
}
for n := 1; n < edgeCount; n++ {
if err := d.AddEdge(id, ids[index+n]); err != nil {
b.Fatal(err)
}
}
}
b.ResetTimer()
for index, id := range ids {
if index+edgeCount+1 > len(ids)-1 {
break
}
if err := d.AddEdge(id, ids[index+edgeCount+1]); err != nil {
b.Fatal(err)
}
}
}
func BenchmarkDAGDeleteEdge(b *testing.B) {
var ids []string
d := NewDAG()
for n := 0; n < b.N; n++ {
id := fmt.Sprint(n)
if err := d.AddVertex(id, nil); err != nil {
b.Fatal(err)
}
ids = append(ids, id)
}
for index, id := range ids {
if index < 1 {
continue
}
if err := d.AddEdge(id, ids[index-1]); err != nil {
b.Fatal(err)
}
}
b.ResetTimer()
for index, id := range ids {
if index < 1 {
continue
}
if err := d.DeleteEdge(id, ids[index-1]); err != nil {
b.Fatal(err)
}
}
}

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/*
* Copyright 2022 The Dragonfly Authors
*
* 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 dag
import "d7y.io/dragonfly/v2/pkg/container/set"
// Vertex is a vertex of the directed acyclic graph.
type Vertex struct {
ID string
Value any
Parents set.SafeSet
Children set.SafeSet
}
// New returns a new Vertex instance.
func NewVertex(id string, value any) *Vertex {
return &Vertex{
ID: id,
Value: value,
Parents: set.NewSafeSet(),
Children: set.NewSafeSet(),
}
}
// Degree returns the degree of vertex.
func (v *Vertex) Degree() int {
return int(v.Parents.Len() + v.Children.Len())
}
// InDegree returns the indegree of vertex.
func (v *Vertex) InDegree() int {
return int(v.Parents.Len())
}
// OutDegree returns the outdegree of vertex.
func (v *Vertex) OutDegree() int {
return int(v.Children.Len())
}

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/*
* Copyright 2022 The Dragonfly Authors
*
* 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 dag
import (
"testing"
"github.com/stretchr/testify/assert"
)
const (
mockVertexID = "foo"
mockVertexValue = "var"
)
func TestNewVertex(t *testing.T) {
v := NewVertex(mockVertexID, mockVertexValue)
assert := assert.New(t)
assert.Equal(v.ID, mockVertexID)
assert.Equal(v.Value, mockVertexValue)
assert.Equal(v.Parents.Len(), uint(0))
assert.Equal(v.Children.Len(), uint(0))
}
func TestVertexDegree(t *testing.T) {
v := NewVertex(mockVertexID, mockVertexValue)
assert := assert.New(t)
assert.Equal(v.ID, mockVertexID)
assert.Equal(v.Value, mockVertexValue)
assert.Equal(v.Degree(), 0)
v.Parents.Add(mockVertexID)
assert.Equal(v.Degree(), 1)
v.Children.Add(mockVertexID)
assert.Equal(v.Degree(), 2)
v.Parents.Delete(mockVertexID)
assert.Equal(v.Degree(), 1)
v.Children.Delete(mockVertexID)
assert.Equal(v.Degree(), 0)
}
func TestVertexInDegree(t *testing.T) {
v := NewVertex(mockVertexID, mockVertexValue)
assert := assert.New(t)
assert.Equal(v.ID, mockVertexID)
assert.Equal(v.Value, mockVertexValue)
assert.Equal(v.InDegree(), 0)
v.Parents.Add(mockVertexID)
assert.Equal(v.InDegree(), 1)
v.Children.Add(mockVertexID)
assert.Equal(v.InDegree(), 1)
v.Parents.Delete(mockVertexID)
assert.Equal(v.InDegree(), 0)
v.Children.Delete(mockVertexID)
assert.Equal(v.InDegree(), 0)
}
func TestVertexOutDegree(t *testing.T) {
v := NewVertex(mockVertexID, mockVertexValue)
assert := assert.New(t)
assert.Equal(v.ID, mockVertexID)
assert.Equal(v.Value, mockVertexValue)
assert.Equal(v.OutDegree(), 0)
v.Parents.Add(mockVertexID)
assert.Equal(v.OutDegree(), 0)
v.Children.Add(mockVertexID)
assert.Equal(v.OutDegree(), 1)
v.Parents.Delete(mockVertexID)
assert.Equal(v.OutDegree(), 1)
v.Children.Delete(mockVertexID)
assert.Equal(v.OutDegree(), 0)
}