From 5cf5410bc82dd1ff3fbf03272c39f692df95108b Mon Sep 17 00:00:00 2001
From: Djordje Lukic <djordje.lukic@docker.com>
Date: Sat, 21 Nov 2020 22:57:39 +0100
Subject: [PATCH] Detect cycles
Signed-off-by: Djordje Lukic <djordje.lukic@docker.com>
---
local/dependencies.go | 61 ++++++++++++++++++++++++++++++++++++++++---
1 file changed, 58 insertions(+), 3 deletions(-)
diff --git a/local/dependencies.go b/local/dependencies.go
index 344eef918..92237370c 100644
--- a/local/dependencies.go
+++ b/local/dependencies.go
@@ -21,6 +21,7 @@ package local
import (
"context"
"fmt"
+ "strings"
"sync"
"github.com/compose-spec/compose-go/types"
@@ -36,6 +37,10 @@ const (
func inDependencyOrder(ctx context.Context, project *types.Project, fn func(context.Context, types.ServiceConfig) error) error {
g := NewGraph(project.Services)
+ if b, err := g.HasCycles(); b {
+ return err
+ }
+
leaves := g.Leaves()
eg, _ := errgroup.WithContext(ctx)
@@ -50,7 +55,7 @@ func inDependencyOrder(ctx context.Context, project *types.Project, fn func(cont
func run(ctx context.Context, graph *Graph, eg *errgroup.Group, nodes []*Vertex, fn func(context.Context, types.ServiceConfig) error) error {
for _, node := range nodes {
n := node
- // Don't start this service yet if all of their children have
+ // Don't start this service yet if all of its children have
// not been started yet.
if len(graph.FilterChildren(n.Service.Name, ServiceStopped)) != 0 {
continue
@@ -152,8 +157,6 @@ func (g *Graph) AddEdge(source string, destination string) error {
sourceVertex.Children[destination] = destinationVertex
destinationVertex.Parents[source] = sourceVertex
- g.Vertices[source] = sourceVertex
- g.Vertices[destination] = destinationVertex
return nil
}
@@ -192,3 +195,55 @@ func (g *Graph) FilterChildren(key string, status ServiceStatus) []*Vertex {
return res
}
+
+func (g *Graph) HasCycles() (bool, error) {
+ discovered := []string{}
+ finished := []string{}
+
+ for _, vertex := range g.Vertices {
+ path := []string{
+ vertex.Key,
+ }
+ if !contains(discovered, vertex.Key) && !contains(finished, vertex.Key) {
+ var err error
+ discovered, finished, err = g.visit(vertex.Key, path, discovered, finished)
+
+ if err != nil {
+ return true, err
+ }
+ }
+ }
+
+ return false, nil
+}
+
+func (g *Graph) visit(key string, path []string, discovered []string, finished []string) ([]string, []string, error) {
+ discovered = append(discovered, key)
+
+ for _, v := range g.Vertices[key].Children {
+ path := append(path, v.Key)
+ if contains(discovered, v.Key) {
+ return nil, nil, fmt.Errorf("cycle found: %s", strings.Join(path, " -> "))
+ }
+
+ if !contains(finished, v.Key) {
+ if _, _, err := g.visit(v.Key, path, discovered, finished); err != nil {
+ return nil, nil, err
+ }
+ }
+ }
+
+ discovered = remove(discovered, key)
+ finished = append(finished, key)
+ return discovered, finished, nil
+}
+
+func remove(slice []string, item string) []string {
+ var s []string
+ for _, i := range slice {
+ if i != item {
+ s = append(s, i)
+ }
+ }
+ return s
+}