search: add EdgesTo handler and tests

pkg/index/indextest/tests.go

@@ -137,6 +137,12 @@ func (id *IndexDeps) AddAttribute(permaNode *blobref.BlobRef, attr, value string
 	return id.uploadAndSignMap(m)
 }
 
+func (id *IndexDeps) DelAttribute(permaNode *blobref.BlobRef, attr string) *blobref.BlobRef {
+	m := schema.NewDelAttributeClaim(permaNode, attr)
+	m["claimDate"] = id.advanceTime()
+	return id.uploadAndSignMap(m)
+}
+
 func (id *IndexDeps) UploadFile(fileName string, contents string) (fileRef, wholeRef *blobref.BlobRef) {
 	cb := &test.Blob{Contents: contents}
 	id.BlobSource.AddBlob(cb)

pkg/search/handler.go

@@ -123,6 +123,9 @@ func (sh *Handler) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 		case "camli/search/signerpaths":
 			sh.serveSignerPaths(rw, req)
 			return
+		case "camli/search/edgesto":
+			sh.serveEdgesTo(rw, req)
+			return
 		}
 	}
 
@@ -775,6 +778,81 @@ func (sh *Handler) serveSignerAttrValue(rw http.ResponseWriter, req *http.Reques
 	}
 }
 
+// Unlike the index interface's EdgesTo method, the "edgesto" Handler
+// here additionally filters out since-deleted permanode edges.
+func (sh *Handler) serveEdgesTo(rw http.ResponseWriter, req *http.Request) {
+	ret := jsonMap()
+	defer httputil.ReturnJSON(rw, ret)
+	defer setPanicError(ret)
+
+	toRef := blobref.MustParse(mustGet(req, "blobref"))
+	toRefStr := toRef.String()
+	blobInfo := jsonMap()
+	ret[toRefStr] = blobInfo
+
+	jsonEdges := jsonMapList()
+
+	edges, err := sh.index.EdgesTo(toRef, nil)
+	if err != nil {
+		panic(err)
+	}
+
+	type mapOrError struct {
+		m   map[string]interface{} // nil if no map
+		err error
+	}
+	resc := make(chan mapOrError)
+	verify := func(edge *Edge) {
+		fromStr := edge.From.String()
+		db, err := sh.NewDescribeRequest().DescribeSync(edge.From)
+		if err != nil {
+			resc <- mapOrError{err: err}
+			return
+		}
+		found := false
+		if db.Permanode != nil {
+			for attr, vv := range db.Permanode.Attr {
+				if IsBlobReferenceAttribute(attr) {
+					for _, v := range vv {
+						if v == toRefStr {
+							found = true
+						}
+					}
+				}
+			}
+		}
+		var em map[string]interface{}
+		if found {
+			em = jsonMap()
+			em["from"] = fromStr
+			em["fromType"] = "permanode"
+		}
+		resc <- mapOrError{m: em}
+	}
+	verifying := 0
+	for _, edge := range edges {
+		if edge.FromType == "permanode" {
+			verifying++
+			go verify(edge)
+			continue
+		}
+		em := jsonMap()
+		em["from"] = edge.From.String()
+		em["fromType"] = edge.FromType
+		jsonEdges = append(jsonEdges, em)
+	}
+	for i := 0; i < verifying; i++ {
+		res := <-resc
+		if res.err != nil {
+			panic(res.err) // caught and put in JSON response
+		}
+		if res.m != nil {
+			jsonEdges = append(jsonEdges, res.m)
+		}
+	}
+	blobInfo["edgesTo"] = jsonEdges
+}
+
 func (sh *Handler) serveSignerPaths(rw http.ResponseWriter, req *http.Request) {
 	ret := jsonMap()
 	defer httputil.ReturnJSON(rw, ret)

pkg/search/handler_test.go

@@ -165,6 +165,33 @@ var handlerTests = []handlerTest{
                 }
                }`),
 	},
+
+	// edgeto handler: put a permanode (member) in two parent
+	// permanodes, then delete the second and verify that edges
+	// back from member only reveal the first parent.
+	{
+		setup: func(*test.FakeIndex) Index {
+			// Ignore the fakeindex and use the real (but in-memory) implementation,
+			// using IndexDeps to populate it.
+			idx := index.NewMemoryIndex()
+			id := indextest.NewIndexDeps(idx)
+
+			parent1 := id.NewPlannedPermanode("pn1") // sha1-7ca7743e38854598680d94ef85348f2c48a44513
+			parent2 := id.NewPlannedPermanode("pn2")
+			member := id.NewPlannedPermanode("member") // always sha1-9ca84f904a9bc59e6599a53f0a3927636a6dbcae
+			id.AddAttribute(parent1, "camliMember", member.String())
+			id.AddAttribute(parent2, "camliMember", member.String())
+			id.DelAttribute(parent2, "camliMember")
+			return indexAndOwner{idx, id.SignerBlobRef}
+		},
+		query: "edgesto?blobref=sha1-9ca84f904a9bc59e6599a53f0a3927636a6dbcae",
+		want: parseJSON(`{"sha1-9ca84f904a9bc59e6599a53f0a3927636a6dbcae": {
+                   "edgesTo": [
+                      {"from": "sha1-7ca7743e38854598680d94ef85348f2c48a44513",
+                       "fromType": "permanode"}
+                   ]
+                }}`),
+	},
 }
 
 func TestHandler(t *testing.T) {