package dag
import (
"encoding/json"
"fmt"
"io"
"log"
"reflect"
"sort"
"strconv"
"sync"
)
const (
typeOperation = "Operation"
typeTransform = "Transform"
typeWalk = "Walk"
typeDepthFirstWalk = "DepthFirstWalk"
typeReverseDepthFirstWalk = "ReverseDepthFirstWalk"
typeTransitiveReduction = "TransitiveReduction"
typeEdgeInfo = "EdgeInfo"
typeVertexInfo = "VertexInfo"
typeVisitInfo = "VisitInfo"
)
// the marshal* structs are for serialization of the graph data.
type marshalGraph struct {
// Type is always "Graph", for identification as a top level object in the
// JSON stream.
Type string
// Each marshal structure requires a unique ID so that it can be referenced
// by other structures.
ID string `json:",omitempty"`
// Human readable name for this graph.
Name string `json:",omitempty"`
// Arbitrary attributes that can be added to the output.
Attrs map[string]string `json:",omitempty"`
// List of graph vertices, sorted by ID.
Vertices []*marshalVertex `json:",omitempty"`
// List of edges, sorted by Source ID.
Edges []*marshalEdge `json:",omitempty"`
// Any number of subgraphs. A subgraph itself is considered a vertex, and
// may be referenced by either end of an edge.
Subgraphs []*marshalGraph `json:",omitempty"`
// Any lists of vertices that are included in cycles.
Cycles [][]*marshalVertex `json:",omitempty"`
}
// The add, remove, connect, removeEdge methods mirror the basic Graph
// manipulations to reconstruct a marshalGraph from a debug log.
func (g *marshalGraph) add(v *marshalVertex) {
g.Vertices = append(g.Vertices, v)
sort.Sort(vertices(g.Vertices))
}
func (g *marshalGraph) remove(v *marshalVertex) {
for i, existing := range g.Vertices {
if v.ID == existing.ID {
g.Vertices = append(g.Vertices[:i], g.Vertices[i+1:]...)
return
}
}
}
func (g *marshalGraph) connect(e *marshalEdge) {
g.Edges = append(g.Edges, e)
sort.Sort(edges(g.Edges))
}
func (g *marshalGraph) removeEdge(e *marshalEdge) {
for i, existing := range g.Edges {
if e.Source == existing.Source && e.Target == existing.Target {
g.Edges = append(g.Edges[:i], g.Edges[i+1:]...)
return
}
}
}
func (g *marshalGraph) vertexByID(id string) *marshalVertex {
for _, v := range g.Vertices {
if id == v.ID {
return v
}
}
return nil
}
type marshalVertex struct {
// Unique ID, used to reference this vertex from other structures.
ID string
// Human readable name
Name string `json:",omitempty"`
Attrs map[string]string `json:",omitempty"`
// This is to help transition from the old Dot interfaces. We record if the
// node was a GraphNodeDotter here, so we can call it to get attributes.
graphNodeDotter GraphNodeDotter
}
func newMarshalVertex(v Vertex) *marshalVertex {
dn, ok := v.(GraphNodeDotter)
if !ok {
dn = nil
}
return &marshalVertex{
ID: marshalVertexID(v),
Name: VertexName(v),
Attrs: make(map[string]string),
graphNodeDotter: dn,
}
}
// vertices is a sort.Interface implementation for sorting vertices by ID
type vertices []*marshalVertex
func (v vertices) Less(i, j int) bool { return v[i].Name < v[j].Name }
func (v vertices) Len() int { return len(v) }
func (v vertices) Swap(i, j int) { v[i], v[j] = v[j], v[i] }
type marshalEdge struct {
// Human readable name
Name string
// Source and Target Vertices by ID
Source string
Target string
Attrs map[string]string `json:",omitempty"`
}
func newMarshalEdge(e Edge) *marshalEdge {
return &marshalEdge{
Name: fmt.Sprintf("%s|%s", VertexName(e.Source()), VertexName(e.Target())),
Source: marshalVertexID(e.Source()),
Target: marshalVertexID(e.Target()),
Attrs: make(map[string]string),
}
}
// edges is a sort.Interface implementation for sorting edges by Source ID
type edges []*marshalEdge
func (e edges) Less(i, j int) bool { return e[i].Name < e[j].Name }
func (e edges) Len() int { return len(e) }
func (e edges) Swap(i, j int) { e[i], e[j] = e[j], e[i] }
// build a marshalGraph structure from a *Graph
func newMarshalGraph(name string, g *Graph) *marshalGraph {
mg := &marshalGraph{
Type: "Graph",
Name: name,
Attrs: make(map[string]string),
}
for _, v := range g.Vertices() {
id := marshalVertexID(v)
if sg, ok := marshalSubgrapher(v); ok {
smg := newMarshalGraph(VertexName(v), sg)
smg.ID = id
mg.Subgraphs = append(mg.Subgraphs, smg)
}
mv := newMarshalVertex(v)
mg.Vertices = append(mg.Vertices, mv)
}
sort.Sort(vertices(mg.Vertices))
for _, e := range g.Edges() {
mg.Edges = append(mg.Edges, newMarshalEdge(e))
}
sort.Sort(edges(mg.Edges))
for _, c := range (&AcyclicGraph{*g}).Cycles() {
var cycle []*marshalVertex
for _, v := range c {
mv := newMarshalVertex(v)
cycle = append(cycle, mv)
}
mg.Cycles = append(mg.Cycles, cycle)
}
return mg
}
// Attempt to return a unique ID for any vertex.
func marshalVertexID(v Vertex) string {
val := reflect.ValueOf(v)
switch val.Kind() {
case reflect.Chan, reflect.Func, reflect.Map, reflect.Ptr, reflect.Slice, reflect.UnsafePointer:
return strconv.Itoa(int(val.Pointer()))
case reflect.Interface:
return strconv.Itoa(int(val.InterfaceData()[1]))
}
if v, ok := v.(Hashable); ok {
h := v.Hashcode()
if h, ok := h.(string); ok {
return h
}
}
// fallback to a name, which we hope is unique.
return VertexName(v)
// we could try harder by attempting to read the arbitrary value from the
// interface, but we shouldn't get here from terraform right now.
}
// check for a Subgrapher, and return the underlying *Graph.
func marshalSubgrapher(v Vertex) (*Graph, bool) {
sg, ok := v.(Subgrapher)
if !ok {
return nil, false
}
switch g := sg.Subgraph().DirectedGraph().(type) {
case *Graph:
return g, true
case *AcyclicGraph:
return &g.Graph, true
}
return nil, false
}
// The DebugOperationEnd func type provides a way to call an End function via a
// method call, allowing for the chaining of methods in a defer statement.
type DebugOperationEnd func(string)
// End calls function e with the info parameter, marking the end of this
// operation in the logs.
func (e DebugOperationEnd) End(info string) { e(info) }
// encoder provides methods to write debug data to an io.Writer, and is a noop
// when no writer is present
type encoder struct {
sync.Mutex
w io.Writer
}
// Encode is analogous to json.Encoder.Encode
func (e *encoder) Encode(i interface{}) {
if e == nil || e.w == nil {
return
}
e.Lock()
defer e.Unlock()
js, err := json.Marshal(i)
if err != nil {
log.Println("[ERROR] dag:", err)
return
}
js = append(js, '\n')
_, err = e.w.Write(js)
if err != nil {
log.Println("[ERROR] dag:", err)
return
}
}
func (e *encoder) Add(v Vertex) {
if e == nil {
return
}
e.Encode(marshalTransform{
Type: typeTransform,
AddVertex: newMarshalVertex(v),
})
}
// Remove records the removal of Vertex v.
func (e *encoder) Remove(v Vertex) {
if e == nil {
return
}
e.Encode(marshalTransform{
Type: typeTransform,
RemoveVertex: newMarshalVertex(v),
})
}
func (e *encoder) Connect(edge Edge) {
if e == nil {
return
}
e.Encode(marshalTransform{
Type: typeTransform,
AddEdge: newMarshalEdge(edge),
})
}
func (e *encoder) RemoveEdge(edge Edge) {
if e == nil {
return
}
e.Encode(marshalTransform{
Type: typeTransform,
RemoveEdge: newMarshalEdge(edge),
})
}
// BeginOperation marks the start of set of graph transformations, and returns
// an EndDebugOperation func to be called once the opration is complete.
func (e *encoder) BeginOperation(op string, info string) DebugOperationEnd {
if e == nil {
return func(string) {}
}
e.Encode(marshalOperation{
Type: typeOperation,
Begin: op,
Info: info,
})
return func(info string) {
e.Encode(marshalOperation{
Type: typeOperation,
End: op,
Info: info,
})
}
}
// structure for recording graph transformations
type marshalTransform struct {
// Type: "Transform"
Type string
AddEdge *marshalEdge `json:",omitempty"`
RemoveEdge *marshalEdge `json:",omitempty"`
AddVertex *marshalVertex `json:",omitempty"`
RemoveVertex *marshalVertex `json:",omitempty"`
}
func (t marshalTransform) Transform(g *marshalGraph) {
switch {
case t.AddEdge != nil:
g.connect(t.AddEdge)
case t.RemoveEdge != nil:
g.removeEdge(t.RemoveEdge)
case t.AddVertex != nil:
g.add(t.AddVertex)
case t.RemoveVertex != nil:
g.remove(t.RemoveVertex)
}
}
// this structure allows us to decode any object in the json stream for
// inspection, then re-decode it into a proper struct if needed.
type streamDecode struct {
Type string
Map map[string]interface{}
JSON []byte
}
func (s *streamDecode) UnmarshalJSON(d []byte) error {
s.JSON = d
err := json.Unmarshal(d, &s.Map)
if err != nil {
return err
}
if t, ok := s.Map["Type"]; ok {
s.Type, _ = t.(string)
}
return nil
}
// structure for recording the beginning and end of any multi-step
// transformations. These are informational, and not required to reproduce the
// graph state.
type marshalOperation struct {
Type string
Begin string `json:",omitempty"`
End string `json:",omitempty"`
Info string `json:",omitempty"`
}
// decodeGraph decodes a marshalGraph from an encoded graph stream.
func decodeGraph(r io.Reader) (*marshalGraph, error) {
dec := json.NewDecoder(r)
// a stream should always start with a graph
g := &marshalGraph{}
err := dec.Decode(g)
if err != nil {
return nil, err
}
// now replay any operations that occurred on the original graph
for dec.More() {
s := &streamDecode{}
err := dec.Decode(s)
if err != nil {
return g, err
}
// the only Type we're concerned with here is Transform to complete the
// Graph
if s.Type != typeTransform {
continue
}
t := &marshalTransform{}
err = json.Unmarshal(s.JSON, t)
if err != nil {
return g, err
}
t.Transform(g)
}
return g, nil
}
// marshalVertexInfo allows encoding arbitrary information about the a single
// Vertex in the logs. These are accumulated for informational display while
// rebuilding the graph.
type marshalVertexInfo struct {
Type string
Vertex *marshalVertex
Info string
}
func newVertexInfo(infoType string, v Vertex, info string) *marshalVertexInfo {
return &marshalVertexInfo{
Type: infoType,
Vertex: newMarshalVertex(v),
Info: info,
}
}
// marshalEdgeInfo allows encoding arbitrary information about the a single
// Edge in the logs. These are accumulated for informational display while
// rebuilding the graph.
type marshalEdgeInfo struct {
Type string
Edge *marshalEdge
Info string
}
func newEdgeInfo(infoType string, e Edge, info string) *marshalEdgeInfo {
return &marshalEdgeInfo{
Type: infoType,
Edge: newMarshalEdge(e),
Info: info,
}
}
// JSON2Dot reads a Graph debug log from and io.Reader, and converts the final
// graph dot format.
//
// TODO: Allow returning the output at a certain point during decode.
// Encode extra information from the json log into the Dot.
func JSON2Dot(r io.Reader) ([]byte, error) {
g, err := decodeGraph(r)
if err != nil {
return nil, err
}
return g.Dot(nil), nil
}
