.

wcfs/internal/zdata/δftail.go

@@ -379,13 +379,13 @@ func (δFtail *ΔFtail) Update(δZ *zodb.EventCommit) (_ ΔF, err error) {
 	}
 
 	// take btree changes into account
-//	fmt.Printf("δB.ΔByRoot: %v\n", δB.ΔByRoot)
+	//fmt.Printf("δB.ΔByRoot: %v\n", δB.ΔByRoot)
 	for root, δt := range δB.ΔByRoot {
-//		fmt.Printf("root: %v   δt: %v\n", root, δt)
+		//fmt.Printf("root: %v   δt: %v\n", root, δt)
 		files := δFtail.fileIdx[root]
-		if len(files) == 0 {
-			panicf("BUG: ΔFtail: root<%s> -> ø files", root)
-		}
+		// NOTE files might be empty e.g. if a zfile was tracked, then
+		// deleted, but the tree referenced by zfile.blktab is still
+		// not-deleted, remains tracked and is changed.
 		for file := range files {
 			δfile, ok := δF.ByFile[file]
 			if !ok {
@@ -393,7 +393,6 @@ func (δFtail *ΔFtail) Update(δZ *zodb.EventCommit) (_ ΔF, err error) {
 				δF.ByFile[file] = δfile
 			}
 			for blk /*, δzblk*/ := range δt {
-				// XXX document, and in particular how to include atTail
 				δfile.Blocks.Add(blk)
 			}
 
@@ -446,7 +445,7 @@ func (δFtail *ΔFtail) Update(δZ *zodb.EventCommit) (_ ΔF, err error) {
 			if len(inblk) == 0 {
 				continue
 			}
-//			fmt.Printf("root: %v   inblk: %v\n", root, inblk)
+			//fmt.Printf("root: %v   inblk: %v\n", root, inblk)
 			files := δFtail.fileIdx[root]
 			for file := range files {
 				δfile, ok := δF.ByFile[file]
@@ -473,10 +472,26 @@ func (δFtail *ΔFtail) Update(δZ *zodb.EventCommit) (_ ΔF, err error) {
 
 		// XXX + rebuild	XXX not here - in track(new file)
 
-		_ = δ
 		//fmt.Printf("δZBigFile: %v\n", δ)
 
-		// XXX update .fileIdx
+		// update .fileIdx
+		if δ.blktabOld != xbtree.VDEL {
+			files, ok := δFtail.fileIdx[δ.blktabOld]
+			if ok {
+				files.Del(foid)
+				if len(files) == 0 {
+					delete(δFtail.fileIdx, δ.blktabOld)
+				}
+			}
+		}
+		if δ.blktabNew != xbtree.VDEL {
+			files, ok := δFtail.fileIdx[δ.blktabNew]
+			if !ok {
+				files = setOid{}
+				δFtail.fileIdx[δ.blktabNew] = files
+			}
+			files.Add(foid)
+		}
 	}
 
 //	fmt.Printf("-> δF: %v\n", δF)

wcfs/internal/zdata/δftail_test.go

@@ -485,6 +485,16 @@ func testΔFtail(t_ *testing.T, testq chan ΔFTestEntry) {
 			vδE = vδE[icut:]
 		}
 
+		// verify δFtail.fileIdx
+		fileIdxOK := map[zodb.Oid]setOid{}
+		if !delfile {
+			__ := setOid{}; __.Add(foid)
+			fileIdxOK[t.Root()] = __
+		}
+		if !reflect.DeepEqual(δFtail.fileIdx, fileIdxOK) {
+			t.Errorf("fileIdx:\nhave: %v\nwant: %v", δFtail.fileIdx, fileIdxOK)
+		}
+
 		// verify δftail.root
 		δftail := δFtail.byFile[foid]
 		rootOK := t.Root()