Move graph logic into package

Graph logic moves into depgraph package and makes internal
fields inaccessible. Completes feedback from @LucasRoesler
from previous PR where the dependency graph was added for 0.9.1

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>

pkg/depends_on.go

@@ -1,37 +0,0 @@
-package pkg
-
-import (
-	"log"
-)
-
-func buildInstallOrder(svcs []Service) []string {
-	graph := Graph{nodes: []*Node{}}
-
-	nodeMap := map[string]*Node{}
-	for _, s := range svcs {
-		n := &Node{Name: s.Name}
-		nodeMap[s.Name] = n
-		graph.nodes = append(graph.nodes, n)
-	}
-
-	for _, s := range svcs {
-		for _, d := range s.DependsOn {
-			nodeMap[s.Name].Edges = append(nodeMap[s.Name].Edges, nodeMap[d])
-		}
-	}
-
-	resolved := &Graph{}
-	unresolved := &Graph{}
-	for _, g := range graph.nodes {
-		resolve(g, resolved, unresolved)
-	}
-
-	log.Printf("Start-up order:\n")
-	order := []string{}
-	for _, node := range resolved.nodes {
-		log.Printf("- %s\n", node.Name)
-		order = append(order, node.Name)
-	}
-
-	return order
-}

pkg/depgraph/depgraph.go

@@ -1,4 +1,4 @@
-package pkg
+package depgraph
 
 import "log"
 
@@ -14,6 +14,17 @@ type Graph struct {
 	nodes []*Node
 }
 
+func NewDepgraph() *Graph {
+	return &Graph{
+		nodes: []*Node{},
+	}
+}
+
+// Nodes returns the nodes within the graph
+func (g *Graph) Nodes() []*Node {
+	return g.nodes
+}
+
 // Contains returns true if the target Node is found
 // in its list
 func (g *Graph) Contains(target *Node) bool {
@@ -47,10 +58,31 @@ func (g *Graph) Remove(target *Node) {
 	}
 }
 
-// resolve finds the order of dependencies for a graph
+// Resolve retruns a list of node names in order of their dependencies.
-// of nodes.
+// A use case may be for determining the correct order to install
-// Inspired by algorithm from
+// software packages, or to start services.
+// Based upon the algorithm described by Ferry Boender in the following article
 // https://www.electricmonk.nl/log/2008/08/07/dependency-resolving-algorithm/
+func (g *Graph) Resolve() []string {
+	resolved := &Graph{}
+	unresolved := &Graph{}
+	for _, node := range g.nodes {
+		resolve(node, resolved, unresolved)
+	}
+
+	order := []string{}
+
+	for _, node := range resolved.Nodes() {
+		order = append(order, node.Name)
+	}
+
+	return order
+}
+
+// resolve mutates the resolved graph for a given starting
+// node. The unresolved graph is used to detect a circular graph
+// error and will throw a panic. This can be caught with a resolve
+// in a go routine.
 func resolve(node *Node, resolved, unresolved *Graph) {
 	unresolved.Add(node)
 

pkg/depgraph/depgraph_test.go

@@ -1,4 +1,4 @@
-package pkg
+package depgraph
 
 import "testing"
 

pkg/deployment_order.go

@@ -0,0 +1,41 @@
+package pkg
+
+import (
+	"log"
+
+	"github.com/openfaas/faasd/pkg/depgraph"
+)
+
+func buildDeploymentOrder(svcs []Service) []string {
+
+	graph := buildServiceGraph(svcs)
+
+	order := graph.Resolve()
+
+	log.Printf("Start-up order:\n")
+	for _, node := range order {
+		log.Printf("- %s\n", node)
+	}
+
+	return order
+}
+
+func buildServiceGraph(svcs []Service) *depgraph.Graph {
+	graph := depgraph.NewDepgraph()
+
+	nodeMap := map[string]*depgraph.Node{}
+	for _, s := range svcs {
+		n := &depgraph.Node{Name: s.Name}
+		nodeMap[s.Name] = n
+		graph.Add(n)
+
+	}
+
+	for _, s := range svcs {
+		for _, d := range s.DependsOn {
+			nodeMap[s.Name].Edges = append(nodeMap[s.Name].Edges, nodeMap[d])
+		}
+	}
+
+	return graph
+}

pkg/deployment_order_test.go

@@ -5,7 +5,7 @@ import (
 	"testing"
 )
 
-func Test_buildInstallOrder_ARequiresB(t *testing.T) {
+func Test_buildDeploymentOrder_ARequiresB(t *testing.T) {
 	svcs := []Service{
 		{
 			Name:      "A",
@@ -17,7 +17,7 @@ func Test_buildInstallOrder_ARequiresB(t *testing.T) {
 		},
 	}
 
-	order := buildInstallOrder(svcs)
+	order := buildDeploymentOrder(svcs)
 
 	if len(order) < len(svcs) {
 		t.Fatalf("length of order too short: %d", len(order))
@@ -30,7 +30,7 @@ func Test_buildInstallOrder_ARequiresB(t *testing.T) {
 	}
 }
 
-func Test_buildInstallOrder_ARequiresBAndC(t *testing.T) {
+func Test_buildDeploymentOrder_ARequiresBAndC(t *testing.T) {
 	svcs := []Service{
 		{
 			Name:      "A",
@@ -46,7 +46,7 @@ func Test_buildInstallOrder_ARequiresBAndC(t *testing.T) {
 		},
 	}
 
-	order := buildInstallOrder(svcs)
+	order := buildDeploymentOrder(svcs)
 
 	if len(order) < len(svcs) {
 		t.Fatalf("length of order too short: %d", len(order))
@@ -65,7 +65,7 @@ func Test_buildInstallOrder_ARequiresBAndC(t *testing.T) {
 
 }
 
-func Test_buildInstallOrder_ARequiresBRequiresC(t *testing.T) {
+func Test_buildDeploymentOrder_ARequiresBRequiresC(t *testing.T) {
 	svcs := []Service{
 		{
 			Name:      "A",
@@ -81,7 +81,7 @@ func Test_buildInstallOrder_ARequiresBRequiresC(t *testing.T) {
 		},
 	}
 
-	order := buildInstallOrder(svcs)
+	order := buildDeploymentOrder(svcs)
 
 	if len(order) < len(svcs) {
 		t.Fatalf("length of order too short: %d", len(order))
@@ -104,7 +104,7 @@ func Test_buildInstallOrder_ARequiresBRequiresC(t *testing.T) {
 	}
 }
 
-func Test_buildInstallOrderCircularARequiresBRequiresA(t *testing.T) {
+func Test_buildDeploymentOrderCircularARequiresBRequiresA(t *testing.T) {
 	svcs := []Service{
 		{
 			Name:      "A",
@@ -118,12 +118,12 @@ func Test_buildInstallOrderCircularARequiresBRequiresA(t *testing.T) {
 
 	defer func() { recover() }()
 
-	buildInstallOrder(svcs)
+	buildDeploymentOrder(svcs)
 
 	t.Fatalf("did not panic as expected")
 }
 
-func Test_buildInstallOrderComposeFile(t *testing.T) {
+func Test_buildDeploymentOrderComposeFile(t *testing.T) {
 	// svcs := []Service{}
 	file, err := LoadComposeFileWithArch("../", "docker-compose.yaml", func() (string, string) {
 		return "x86_64", "Linux"
@@ -145,7 +145,7 @@ func Test_buildInstallOrderComposeFile(t *testing.T) {
 		}
 	}
 
-	order := buildInstallOrder(svcs)
+	order := buildDeploymentOrder(svcs)
 
 	if len(order) < len(svcs) {
 		t.Fatalf("length of order too short: %d", len(order))
@@ -167,7 +167,7 @@ func Test_buildInstallOrderComposeFile(t *testing.T) {
 	}
 }
 
-func Test_buildInstallOrderOpenFaaS(t *testing.T) {
+func Test_buildDeploymentOrderOpenFaaS(t *testing.T) {
 	svcs := []Service{
 		{
 			Name:      "queue-worker",
@@ -191,7 +191,7 @@ func Test_buildInstallOrderOpenFaaS(t *testing.T) {
 		},
 	}
 
-	order := buildInstallOrder(svcs)
+	order := buildDeploymentOrder(svcs)
 
 	if len(order) < len(svcs) {
 		t.Fatalf("length of order too short: %d", len(order))

pkg/supervisor.go

@@ -112,7 +112,7 @@ func (s *Supervisor) Start(svcs []Service) error {
 		}
 	}
 
-	order := buildInstallOrder(svcs)
+	order := buildDeploymentOrder(svcs)
 
 	for _, key := range order {