.

wcfs/internal/xbtree/δbtail.go

@@ -828,6 +828,9 @@ func (δBtail *ΔBtail) GetAt(ctx context.Context, root *Tree, key Key, at zodb.
 	// @tail[key] is not present - key was not changing in (tail, head].
 	// since at ∈ (tail, head] we can use @head[key] as the result
 	xvalue, ok, err := root.Get(ctx, key)
+	if !ok {
+		value = VDEL
+	}
 	if err != nil || !ok {
 		return
 	}

wcfs/internal/zdata/δftail_test.go

@@ -262,7 +262,8 @@ func testΔFtail(t_ *testing.T, testq chan ΔFTestEntry) {
 			delfile = true
 		}
 
-		newEpoch := delfile || (!delfile && delfilePrev && !delfilePrev)
+		// new epoch starts when file is deleted or recreated
+		newEpoch := delfile || (!delfile && delfile != delfilePrev)
 		delfilePrev = delfile
 
 		// newEpoch -> reset
@@ -328,6 +329,14 @@ func testΔFtail(t_ *testing.T, testq chan ΔFTestEntry) {
 		if newEpoch {
 			epochv = append(epochv, commit.At)
 		}
+		xat[commit.At] = fmt.Sprintf("at%d", i)
+		flags := ""
+		if newEpoch {
+			flags += "\tEPOCH"
+		}
+		t.Logf("# → @%s (%s)  δT%s  δD%s\t; %s\tδ%s%s", xat[commit.At], commit.At, xbtreetest.KVTxt(test.δblkTab), test.δdataTab, commit.Tree, δblk, flags)
+		//t.Logf("#   vδf: %s", vδfstr(vδf))
+
 
 		// update blkRevAt
 		var blkRevPrev map[int64]zodb.Tid
@@ -346,6 +355,19 @@ func testΔFtail(t_ *testing.T, testq chan ΔFTestEntry) {
 			blkRev[blk] = commit.At
 		}
 		blkRevAt[commit.At] = blkRev
+		if false {
+			fmt.Printf("blkRevAt[@%s]:\n", xat[commit.At])
+			blkv := []int64{}
+			for blk := range blkRev {
+				blkv = append(blkv, blk)
+			}
+			sort.Slice(blkv, func(i, j int) bool {
+				return blkv[i] < blkv[j]
+			})
+			for _, blk := range blkv {
+				fmt.Printf("  #%d:  %v\n", blk, blkRev[blk])
+			}
+		}
 
 		// update zfile
 		txn.Abort()
@@ -363,11 +385,6 @@ func testΔFtail(t_ *testing.T, testq chan ΔFTestEntry) {
 			vδf = append(vδf, δfok)
 		}
 
-		xat[commit.At] = fmt.Sprintf("at%d", i)
-//		t.Logf("# → @%s (%s)  δT%s  δD%s\t; %s\tδ%s", xat[commit.At], commit.At, xbtreetest.KVTxt(test.δblkTab), test.δdataTab, tTxt, δblk)
-		t.Logf("# → @%s (%s)  δT%s  δD%s\t; %s\tδ%s", xat[commit.At], commit.At, xbtreetest.KVTxt(test.δblkTab), test.δdataTab, commit.Tree, δblk)
-		//t.Logf("#   vδf: %s", vδfstr(vδf))
-
 		//fmt.Printf("Zinblk: %v\n", Zinblk)
 
 		// update δFtail