// DependencyGraph builds a dependency graph for the collection
func (c Collection) DependencyGraph() (*graph.Graph, error) {
g := graph.New()
// A map containing the resource ids and their nodes in the graph
nodes := make(map[string]*graph.Node)
for id := range c {
node := graph.NewNode(id)
nodes[id] = node
g.AddNode(node)
}
// Connect the nodes in the graph
for id, r := range c {
before := r.GetBefore()
after := r.GetAfter()
// Connect current resource with the ones that happen after it
for _, dep := range after {
if _, ok := c[dep]; !ok {
return g, fmt.Errorf("%s wants %s, which does not exist", id, dep)
}
g.AddEdge(nodes[id], nodes[dep])
}
// Connect current resource with the ones that happen before it
for _, dep := range before {
if _, ok := c[dep]; !ok {
return g, fmt.Errorf("%s wants %s, which does not exist", id, dep)
}
g.AddEdge(nodes[dep], nodes[id])
}
}
return g, nil
}
// DependencyGraph builds a dependency graph for the collection
func (c Collection) DependencyGraph() (*graph.Graph, error) {
g := graph.New()
// A map containing the resource ids and their nodes in the graph
nodes := make(map[string]*graph.Node)
for id := range c {
node := graph.NewNode(id)
nodes[id] = node
g.AddNode(node)
}
// Connect the nodes in the graph
for id, r := range c {
// Create edges between the nodes and the ones
// required by it
for _, dep := range r.Dependencies() {
if _, ok := c[dep]; !ok {
return g, fmt.Errorf("%s wants %s, which does not exist", id, dep)
}
g.AddEdge(nodes[id], nodes[dep])
}
// Create edges between the nodes and the resources for
// which we subscribe for changes to
for dep := range r.SubscribedTo() {
if _, ok := c[dep]; !ok {
return g, fmt.Errorf("%s subscribes to %s, which does not exist", id, dep)
}
g.AddEdge(nodes[id], nodes[dep])
}
}
return g, nil
}