flow: add initial flow dag

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

flow/dag.go

@@ -0,0 +1,21 @@
+package flow
+
+type node struct {
+	name string
+}
+
+func (n *node) ID() string {
+	return n.name
+}
+
+func (n *node) Name() string {
+	return n.name
+}
+
+func (n *node) String() string {
+	return n.name
+}
+
+func (n *node) Hashcode() interface{} {
+	return n.name
+}

flow/dag_test.go

@@ -0,0 +1,68 @@
+package flow
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/silas/dag"
+)
+
+func checkErr(t *testing.T, err error) {
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestDag(t *testing.T) {
+	d1 := &dag.AcyclicGraph{}
+	d2 := &dag.AcyclicGraph{}
+	d2v1 := d2.Add(&node{"Substep.Create"})
+	v1 := d1.Add(&node{"AccountService.Create"})
+	v2 := d1.Add(&node{"AuthzService.Create"})
+	v3 := d1.Add(&node{"AuthnService.Create"})
+	v4 := d1.Add(&node{"ProjectService.Create"})
+	v5 := d1.Add(&node{"ContactService.Create"})
+	v6 := d1.Add(&node{"NetworkService.Create"})
+	v7 := d1.Add(&node{"MailerService.Create"})
+	v8 := d1.Add(&node{"NestedService.Create"})
+	v9 := d1.Add(d2v1)
+	d1.Connect(dag.BasicEdge(v1, v2))
+	d1.Connect(dag.BasicEdge(v1, v3))
+	d1.Connect(dag.BasicEdge(v1, v4))
+	d1.Connect(dag.BasicEdge(v1, v5))
+	d1.Connect(dag.BasicEdge(v1, v6))
+	d1.Connect(dag.BasicEdge(v1, v7))
+	d1.Connect(dag.BasicEdge(v7, v8))
+	d1.Connect(dag.BasicEdge(v8, v9))
+
+	if err := d1.Validate(); err != nil {
+		t.Fatal(err)
+	}
+
+	d1.TransitiveReduction()
+
+	var steps [][]string
+	fn := func(n dag.Vertex, idx int) error {
+		if idx == 0 {
+			steps = make([][]string, 1, 1)
+			steps[0] = make([]string, 0, 1)
+		} else if idx >= len(steps) {
+			tsteps := make([][]string, idx+1, idx+1)
+			copy(tsteps, steps)
+			steps = tsteps
+			steps[idx] = make([]string, 0, 1)
+		}
+		steps[idx] = append(steps[idx], fmt.Sprintf("%s", n))
+		return nil
+	}
+
+	start := &node{"AccountService.Create"}
+	err := d1.SortedDepthFirstWalk([]dag.Vertex{start}, fn)
+	checkErr(t, err)
+	if len(steps) != 4 {
+		t.Fatalf("invalid steps: %#+v", steps)
+	}
+	if steps[3][0] != "Substep.Create" {
+		t.Fatalf("invalid last step: %#+v", steps)
+	}
+}

flow/flow.go

@@ -0,0 +1,7 @@
+// Package flow is an interface used for saga pattern messaging
+package flow
+
+type Step interface {
+	// Endpoint returns service_name.service_method
+	Endpoint() string
+}