Merge pull request #1985 from dolthub/aaron/optimize-commitwalk

go/libraries/doltcore/env/actions/commitwalk: Optimize commitwalk a bit.

go/libraries/doltcore/doltdb/commit.go

@@ -151,11 +151,27 @@ func (c *Commit) NumParents() (int, error) {
 }
 
 func (c *Commit) Height() (uint64, error) {
-	ref, err := types.NewRef(c.commitSt, c.vrw.Format())
+	maxHeight, err := maxChunkHeight(c.commitSt, c.vrw.Format())
 	if err != nil {
 		return 0, err
 	}
-	return ref.Height(), nil
+	return maxHeight + 1, nil
+}
+
+func maxChunkHeight(v types.Value, nbf *types.NomsBinFormat) (max uint64, err error) {
+	err = v.WalkRefs(nbf, func(r types.Ref) error {
+		if height := r.Height(); height > max {
+			max = height
+		}
+
+		return nil
+	})
+
+	if err != nil {
+		return 0, err
+	}
+
+	return max, nil
 }
 
 func (c *Commit) getParent(ctx context.Context, idx int) (*types.Struct, error) {

go/libraries/doltcore/env/actions/commitwalk/commitwalk.go

@@ -15,6 +15,7 @@
 package commitwalk
 
 import (
+	"container/heap"
 	"context"
 	"io"
 
@@ -42,9 +43,37 @@ func (q *q) NumVisiblePending() int {
 	return q.numVisiblePending
 }
 
+func (q *q) Push(x interface{}) {
+	q.pending = append(q.pending, x.(*c))
+}
+
+func (q *q) Pop() interface{} {
+	old := q.pending
+	ret := old[len(old)-1]
+	q.pending = old[:len(old)-1]
+	return ret
+}
+
+func (q *q) Len() int {
+	return len(q.pending)
+}
+
+func (q *q) Swap(i, j int) {
+	q.pending[i], q.pending[j] = q.pending[j], q.pending[i]
+}
+
+func (q *q) Less(i, j int) bool {
+	if q.pending[i].height > q.pending[j].height {
+		return true
+	}
+	if q.pending[i].height == q.pending[j].height {
+		return q.pending[i].meta.UserTimestamp > q.pending[j].meta.UserTimestamp
+	}
+	return false
+}
+
 func (q *q) PopPending() *c {
-	c := q.pending[len(q.pending)-1]
-	q.pending = q.pending[:len(q.pending)-1]
+	c := heap.Pop(q).(*c)
 	if !c.invisible {
 		q.numVisiblePending--
 	}
@@ -58,25 +87,7 @@ func (q *q) AddPendingIfUnseen(ctx context.Context, ddb *doltdb.DoltDB, id hash.
 	}
 	if !c.queued {
 		c.queued = true
-		var i int
-		for i = 0; i < len(q.pending); i++ {
-			if q.pending[i].height > c.height {
-				break
-			}
-			if q.pending[i].height < c.height {
-				continue
-			}
-
-			// if the commits have equal height, tiebreak on timestamp
-			pendingMeta := q.pending[i].meta
-			commitMeta := c.meta
-			if pendingMeta.UserTimestamp > commitMeta.UserTimestamp {
-				break
-			}
-		}
-		q.pending = append(q.pending, nil)
-		copy(q.pending[i+1:], q.pending[i:])
-		q.pending[i] = c
+		heap.Push(q, c)
 		if !c.invisible {
 			q.numVisiblePending++
 		}