K-Shortest path query fix

query/shortest.go

@@ -20,6 +20,7 @@ import (
 	"container/heap"
 	"context"
 	"math"
+	"sort"
 	"sync"
 
 	"github.com/dgraph-io/dgraph/algo"
@@ -63,6 +64,20 @@ var errFacet = errors.Errorf("Skip the edge")
 
 type priorityQueue []*queueItem
 
+func (r route) indexOf(uid uint64) int {
+	u := *r.route
+	tmp := make([]pathInfo, len(u))
+	copy(tmp, u)
+	sort.Slice(tmp, func(i, j int) bool {
+		return tmp[i].uid < tmp[j].uid
+	})
+	i := sort.Search(len(tmp), func(i int) bool { return tmp[i].uid >= uid })
+	if i < len(tmp) && tmp[i].uid == uid {
+		return i
+	}
+	return -1
+}
+
 func (h priorityQueue) Len() int { return len(h) }
 
 func (h priorityQueue) Less(i, j int) bool { return h[i].cost < h[j].cost }
@@ -303,7 +318,7 @@ func runKShortestPaths(ctx context.Context, sg *SubGraph) ([]*SubGraph, error) {
 	}
 	heap.Push(&pq, srcNode)
 
-	numHops := -1
+	numHops := 0
 	maxHops := math.MaxInt32
 	if sg.Params.ExploreDepth != nil {
 		maxHops = int(*sg.Params.ExploreDepth)
@@ -340,7 +355,7 @@ func runKShortestPaths(ctx context.Context, sg *SubGraph) ([]*SubGraph, error) {
 				break
 			}
 		}
-		if item.hop > numHops && numHops < maxHops {
+		if item.hop > numHops-1 && numHops < maxHops {
 			// Explore the next level by calling processGraph and add them
 			// to the queue.
 			if !stopExpansion {
@@ -364,8 +379,8 @@ func runKShortestPaths(ctx context.Context, sg *SubGraph) ([]*SubGraph, error) {
 		case <-ctx.Done():
 			return nil, ctx.Err()
 		default:
-			if stopExpansion {
-				continue
+			if len(kroutes) == numPaths {
+				break
 			}
 		}
 		neighbours := adjacencyMap[item.uid]
@@ -375,7 +390,9 @@ func runKShortestPaths(ctx context.Context, sg *SubGraph) ([]*SubGraph, error) {
 			if item.cost+cost > maxWeight {
 				continue
 			}
-
+			if len(*item.path.route) > 0 && item.path.indexOf(toUid) != -1 {
+				continue
+			}
 			curPath := pathPool.Get().(*[]pathInfo)
 			if curPath == nil {
 				return nil, errors.Errorf("Sync pool returned a nil pointer")