.

wcfs/δbtail.go

@@ -689,9 +689,10 @@ func (δBtail *ΔBtail) rebuild() (err error) {
 			δTtail, ok := δBtail.byRoot[root]
 			if !ok {
 				// this root was not tracked before -> create δTtail for it with empty changes
+				// XXX do not keep entries with empty δkv ?
 				var vδT []ΔTree
-				for j := 0; j < len(vδZ); j++ {
-					vδT = append(vδT, ΔTree{Rev: vδZ[j].Rev, ΔKV: make(map[Key]ΔValue)})
+				for _, δZj := range vδZ {
+					vδT = append(vδT, ΔTree{Rev: δZj.Rev, ΔKV: make(map[Key]ΔValue)})
 				}
 				δTtail = &ΔTtail{
 					vδT: vδT,
@@ -745,8 +746,6 @@ func (δBtail *ΔBtail) Update(δZ *zodb.EventCommit) (_ ΔB, err error) {
 	// update .trackIdx and vδB from .trackNew
 	δBtail.rebuild()
 
-	δBtail.δZtail.Append(δZ.Tid, δZ.Changev)
-
 	tracef("Update δZ: %v\n", δZ.Changev)
 	tracef("trackIdx:       %v\n", δBtail.trackIdx)
 	tracef("holeIdxByRoot:  %v\n", δBtail.holeIdxByRoot)
@@ -787,7 +786,12 @@ func (δBtail *ΔBtail) Update(δZ *zodb.EventCommit) (_ ΔB, err error) {
 			δB.ByRoot[root] = δT
 			δTtail, ok := δBtail.byRoot[root]
 			if !ok {
-				// this root was not tracked before ... XXX
+				// this root was not tracked before -> create δTtail for it with empty changes
+				// XXX do not keep entries with empty δkv ?
+				var vδT []ΔTree
+				for _, δZj := range δBtail.δZtail.Data() {
+					vδT = append(vδT, ΔTree{Rev: δZj.Rev, ΔKV: make(map[Key]ΔValue)})
+				}
 				δTtail = &ΔTtail {
 					// XXX vδT: ...
 					// XXX KVAtTail: ...,
@@ -803,6 +807,7 @@ func (δBtail *ΔBtail) Update(δZ *zodb.EventCommit) (_ ΔB, err error) {
 		}
 	}
 
+	δBtail.δZtail.Append(δZ.Tid, δZ.Changev)
 	return δB, nil
 }