.

wcfs/internal/set/set.go

+// Copyright (C) 2021  Nexedi SA and Contributors.
+//                     Kirill Smelkov <kirr@nexedi.com>
+//
+// This program is free software: you can Use, Study, Modify and Redistribute
+// it under the terms of the GNU General Public License version 3, or (at your
+// option) any later version, as published by the Free Software Foundation.
+//
+// You can also Link and Combine this program with other software covered by
+// the terms of any of the Free Software licenses or any of the Open Source
+// Initiative approved licenses and Convey the resulting work. Corresponding
+// source of such a combination shall include the source code for all other
+// software used.
+//
+// This program is distributed WITHOUT ANY WARRANTY; without even the implied
+// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+//
+// See COPYING file for full licensing terms.
+// See https://www.nexedi.com/licensing for rationale and options.
+
+package set
+
+//go:generate ./gen-set set I64 int64 zset_i64.go
+//go:generate ./gen-set set Oid _Oid  zset_oid.go
+
+import (
+	"lab.nexedi.com/kirr/neo/go/zodb"
+)
+
+type _Oid = zodb.Oid

wcfs/set.go.in → wcfs/internal/set/set.go.in

@@ -19,6 +19,12 @@
 
 package PACKAGE
 
+import (
+	"fmt"
+	"sort"
+	"strings"
+)
+
 // Set is a set of VALUE.
 type Set map[VALUE]struct{}
 
@@ -129,3 +135,22 @@ func (a Set) Equal(b Set) bool {
 
 	return true
 }
+
+// --------
+
+func (s Set) SortedElements() []VALUE {
+	ev := s.Elements()
+	sort.Slice(ev, func(i, j int) bool {
+		return ev[i] < ev[j]
+	})
+	return ev
+}
+
+func (s Set) String() string {
+	ev := s.SortedElements()
+	strv := make([]string, len(ev))
+	for i, v := range ev {
+		strv[i] = fmt.Sprintf("%v", v)
+	}
+	return "{" + strings.Join(strv, " ") + "}"
+}

wcfs/zset_i64.go → wcfs/internal/set/zset_i64.go

@@ -19,7 +19,13 @@
 // See COPYING file for full licensing terms.
 // See https://www.nexedi.com/licensing for rationale and options.
 
-package main
+package set
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+)
 
 // SetI64 is a set of int64.
 type SetI64 map[int64]struct{}
@@ -131,3 +137,22 @@ func (a SetI64) Equal(b SetI64) bool {
 
 	return true
 }
+
+// --------
+
+func (s SetI64) SortedElements() []int64 {
+	ev := s.Elements()
+	sort.Slice(ev, func(i, j int) bool {
+		return ev[i] < ev[j]
+	})
+	return ev
+}
+
+func (s SetI64) String() string {
+	ev := s.SortedElements()
+	strv := make([]string, len(ev))
+	for i, v := range ev {
+		strv[i] = fmt.Sprintf("%v", v)
+	}
+	return "{" + strings.Join(strv, " ") + "}"
+}

wcfs/zset_oid.go → wcfs/internal/set/zset_oid.go

-// Code generated by gen-set Oid Oid; DO NOT EDIT.
+// Code generated by gen-set Oid _Oid; DO NOT EDIT.
 
 // Copyright (C) 2015-2021  Nexedi SA and Contributors.
 //                          Kirill Smelkov <kirr@nexedi.com>
@@ -19,24 +19,30 @@
 // See COPYING file for full licensing terms.
 // See https://www.nexedi.com/licensing for rationale and options.
 
-package main
+package set
 
-// SetOid is a set of Oid.
-type SetOid map[Oid]struct{}
+import (
+	"fmt"
+	"sort"
+	"strings"
+)
+
+// SetOid is a set of _Oid.
+type SetOid map[_Oid]struct{}
 
 // Add adds v to the set.
-func (s SetOid) Add(v Oid) {
+func (s SetOid) Add(v _Oid) {
 	s[v] = struct{}{}
 }
 
 // Del removes v from the set.
 // it is noop if v was not in the set.
-func (s SetOid) Del(v Oid) {
+func (s SetOid) Del(v _Oid) {
 	delete(s, v)
 }
 
 // Has checks whether the set contains v.
-func (s SetOid) Has(v Oid) bool {
+func (s SetOid) Has(v _Oid) bool {
 	_, ok := s[v]
 	return ok
 }
@@ -49,8 +55,8 @@ func (s SetOid) Update(t SetOid) {
 }
 
 // Elements returns all elements of set as slice.
-func (s SetOid) Elements() []Oid {
-	ev := make([]Oid, len(s))
+func (s SetOid) Elements() []_Oid {
+	ev := make([]_Oid, len(s))
 	i := 0
 	for e := range s {
 		ev[i] = e
@@ -131,3 +137,22 @@ func (a SetOid) Equal(b SetOid) bool {
 
 	return true
 }
+
+// --------
+
+func (s SetOid) SortedElements() []_Oid {
+	ev := s.Elements()
+	sort.Slice(ev, func(i, j int) bool {
+		return ev[i] < ev[j]
+	})
+	return ev
+}
+
+func (s SetOid) String() string {
+	ev := s.SortedElements()
+	strv := make([]string, len(ev))
+	for i, v := range ev {
+		strv[i] = fmt.Sprintf("%v", v)
+	}
+	return "{" + strings.Join(strv, " ") + "}"
+}

wcfs/internal/xbtree/misc.go

+// Copyright (C) 2018-2021  Nexedi SA and Contributors.
+//                          Kirill Smelkov <kirr@nexedi.com>
+//
+// This program is free software: you can Use, Study, Modify and Redistribute
+// it under the terms of the GNU General Public License version 3, or (at your
+// option) any later version, as published by the Free Software Foundation.
+//
+// You can also Link and Combine this program with other software covered by
+// the terms of any of the Free Software licenses or any of the Open Source
+// Initiative approved licenses and Convey the resulting work. Corresponding
+// source of such a combination shall include the source code for all other
+// software used.
+//
+// This program is distributed WITHOUT ANY WARRANTY; without even the implied
+// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+//
+// See COPYING file for full licensing terms.
+// See https://www.nexedi.com/licensing for rationale and options.
+
+package xbtree
+
+import (
+	"fmt"
+)
+
+func panicf(format string, argv ...interface{}) {
+	panic(fmt.Sprintf(format, argv...))
+}

wcfs/pptreesubset.go → wcfs/internal/xbtree/pptreesubset.go

@@ -17,7 +17,7 @@
 // See COPYING file for full licensing terms.
 // See https://www.nexedi.com/licensing for rationale and options.
 
-package main
+package xbtree
 // PP-connected subset of tree nodes.
 
 import (

wcfs/treediff.go → wcfs/internal/xbtree/treediff.go

@@ -17,9 +17,8 @@
 // See COPYING file for full licensing terms.
 // See https://www.nexedi.com/licensing for rationale and options.
 
-package main
+package xbtree
 // diff for BTrees
-// XXX move -> btree? (needs generics)
 // XXX doc
 
 // FIXME the algorythm is different: recursion is implemented by expanding rangeSplit step by step.
@@ -71,45 +70,22 @@ package main
 // . -k(blk) -> invalidate #blk
 // . +k(blk) -> invalidate #blk (e.g. if blk was previously read as hole)
 
-//go:generate ./gen-set main Oid   Oid zset_oid.go
-
 import (
 	"context"
-	"math"
 	"fmt"
 	"reflect"
 	"sort"
 
 	"lab.nexedi.com/kirr/go123/xerr"
 	"lab.nexedi.com/kirr/neo/go/zodb"
-	"lab.nexedi.com/kirr/neo/go/zodb/btree"
 )
 
-type Tree   = btree.LOBTree
-type Bucket = btree.LOBucket
-type Node   = btree.LONode
-type TreeEntry   = btree.LOEntry
-type BucketEntry = btree.LOBucketEntry
-
-type Key    = int64
-const KeyMax Key = math.MaxInt64
-const KeyMin Key = math.MinInt64
-
-// value is assumed to be persistent reference.
-// deletion is represented as VDEL.
-type Value  = zodb.Oid
-const VDEL  = zodb.InvalidOid
-
 // ΔValue represents change in value.
 type ΔValue struct {
 	Old Value
 	New Value
 }
 
-type Oid    = zodb.Oid
-type SetKey = SetI64
-
-
 
 // treeSetKey represents ordered set of keys.
 // it can be point-queried and range-accessed.

wcfs/internal/xbtree/xbtree.go

+// Package xbtree complements package lab.nexedi.com/kirr/neo/go/zodb/btree.
+// XXX doc
+package xbtree
+
+
+import (
+	"math"
+
+	"lab.nexedi.com/kirr/neo/go/zodb"
+	"lab.nexedi.com/kirr/neo/go/zodb/btree"
+
+	"lab.nexedi.com/nexedi/wendelin.core/wcfs/internal/set"
+)
+
+
+// XXX instead of generics
+type Tree   = btree.LOBTree
+type Bucket = btree.LOBucket
+type Node   = btree.LONode
+type TreeEntry   = btree.LOEntry
+type BucketEntry = btree.LOBucketEntry
+
+type Key    = int64
+const KeyMax Key = math.MaxInt64
+const KeyMin Key = math.MinInt64
+
+// value is assumed to be persistent reference.
+// deletion is represented as VDEL.
+type Value  = zodb.Oid
+const VDEL  = zodb.InvalidOid
+
+type SetKey = set.SetI64
+type SetOid = set.SetOid

wcfs/δbtail.go → wcfs/internal/xbtree/δbtail.go

@@ -17,10 +17,8 @@
 // See COPYING file for full licensing terms.
 // See https://www.nexedi.com/licensing for rationale and options.
 
-package main
-// XXX -> Package xbtree complements package lab.nexedi.com/kirr/neo/go/zodb/btree.
-// TODO move -> btree when ΔTail matures.
-// XXX doc
+package xbtree
+// ΔBtail
 
 import (
 	"context"
@@ -30,6 +28,8 @@ import (
 	"lab.nexedi.com/kirr/go123/xerr"
 	"lab.nexedi.com/kirr/neo/go/transaction"
 	"lab.nexedi.com/kirr/neo/go/zodb"
+
+	"lab.nexedi.com/nexedi/wendelin.core/wcfs/internal/xtail"
 )
 
 // ΔBtail represents tail of revisional changes to BTrees.
@@ -80,7 +80,7 @@ import (
 // See also zodb.ΔTail
 // XXX naming -> ΔBTail ?
 type ΔBtail struct {
-	// raw ZODB changes; Kept to rebuild δBtail/byRoot after new Track.
+	// raw ZODB changes; Kept to rebuild .byRoot after new Track.
 	// includes all changed objects, not only tracked ones.
 	δZtail *zodb.ΔTail
 
@@ -544,7 +544,7 @@ func (δBtail *ΔBtail) GetAt(ctx context.Context, root *Tree, key Key, at zodb.
 
 // XXX don't need
 //func (δBtail *ΔBtail) SliceByRev(lo, hi zodb.Tid) /*readonly*/ []ΔB {
-//	δassertSlice(δBtail, lo, hi)
+//	xtail.AssertSlice(δBtail, lo, hi)
 //	panic("TODO")
 //}
 
@@ -560,7 +560,7 @@ func (δBtail *ΔBtail) GetAt(ctx context.Context, root *Tree, key Key, at zodb.
 //
 // XXX root -> *Tree ?
 func (δBtail *ΔBtail) SliceByRootRev(root zodb.Oid, lo, hi zodb.Tid) /*readonly*/[]ΔTree {
-	δassertSlice(δBtail, lo, hi)
+	xtail.AssertSlice(δBtail, lo, hi)
 	// XXX locking
 	δTtail, ok := δBtail.byRoot[root]
 	if !ok {
@@ -571,13 +571,9 @@ func (δBtail *ΔBtail) SliceByRootRev(root zodb.Oid, lo, hi zodb.Tid) /*readonl
 }
 
 
-// ---- misc ----
-
-// δassertSlice asserts that δ.tail ≤ lo ≤ hi ≤ δ.head
-func δassertSlice(δ interface { Head() zodb.Tid; Tail() zodb.Tid }, lo, hi zodb.Tid) {
-	tail := δ.Tail()
-	head := δ.Head()
-	if !(tail <= lo && lo <= hi && hi <= head) {
-		panicf("invalid slice: (%s, %s];  (tail, head] = (%s, %s]", lo, hi, tail, head)
-	}
+// ΔZtail returns raw ZODB changes accumulated in δBtail so far.
+//
+// the caller must not modify returned δZtail.
+func (δBtail *ΔBtail) ΔZtail() /*readonly*/*zodb.ΔTail {
+	return δBtail.δZtail
 }

wcfs/δbtail_test.go → wcfs/internal/xbtree/δbtail_test.go

@@ -17,7 +17,7 @@
 // See COPYING file for full licensing terms.
 // See https://www.nexedi.com/licensing for rationale and options.
 
-package main
+package xbtree
 // tests for δbtail.go
 // XXX doc  (2 ways of testing: explicit + allstructs), treegen py helper
 
@@ -42,6 +42,9 @@ import (
 	"lab.nexedi.com/kirr/go123/xerr"
 	"lab.nexedi.com/kirr/neo/go/transaction"
 	"lab.nexedi.com/kirr/neo/go/zodb"
+	_ "lab.nexedi.com/kirr/neo/go/zodb/wks"
+
+	"lab.nexedi.com/nexedi/wendelin.core/wcfs/internal/xzodb"
 )
 
 const kInf Key = 10000 // inf key (TeX hack)
@@ -245,9 +248,9 @@ func (tg *AllStructsSrv) AllStructs(kv1, kv2 map[Key]string, maxdepth, maxsplit,
 
 		structv = append(structv, reply)
 	}
-
 }
 
+
 // RTree represents Tree node covering [lo, hi_] key range in its parent tree.
 type RTree struct {
 	oid    zodb.Oid
@@ -378,7 +381,7 @@ func XGetTree(db *zodb.DB, at zodb.Tid, root zodb.Oid) RBucketSet {
 	xztree, err := zconn.Get(ctx, root); X(err)
 	ztree, ok := xztree.(*Tree)
 	if !ok {
-		exc.Raisef("expected %s, got %s", typeOf(ztree), typeOf(xztree))
+		exc.Raisef("expected %s, got %s", xzodb.TypeOf(ztree), xzodb.TypeOf(xztree))
 	}
 
 	rbucketv := RBucketSet{}
@@ -402,28 +405,6 @@ func XGetTree(db *zodb.DB, at zodb.Tid, root zodb.Oid) RBucketSet {
 	return rbucketv
 }
 
-// ztreeGetBlk returns ztree[k] and tree path that lead to this block.
-// XXX naming, place
-// XXX +return blkRevMax and use it
-func ztreeGetBlk(ctx context.Context, ztree *Tree, k Key) (zblk ZBlk, ok bool, path []Node, err error) {
-	path = []Node{}
-	xzblk, ok, err := ztree.VGet(ctx, k, func(node Node) {
-		path = append(path, node)
-	})
-	if err != nil {
-		return nil, false, nil, err
-	}
-
-	if ok {
-		zblk, ok = xzblk.(ZBlk)
-		if !ok {
-			return nil, false, nil, fmt.Errorf("expect ZBlk*; got %s", typeOf(xzblk))  // XXX errctx
-		}
-	}
-
-	return zblk, ok, path, nil
-}
-
 // xwalkDFS walks ztree in depth-first order emitting bvisit callback on visited bucket nodes.
 func xwalkDFS(ctx context.Context, lo, hi_ Key, ztree *Tree, bvisit func(*RBucket)) {
 	_xwalkDFS(ctx, lo, hi_, ztree, /*rparent*/nil, bvisit)
@@ -461,13 +442,15 @@ func _xwalkDFS(ctx context.Context, lo, hi_ Key, ztree *Tree, rparent *RTree, bv
 		for _, __ := range bentryv {
 			k  := __.Key()
 			xv := __.Value()
-			zv, ok := xv.(ZBlk)
+			pv, ok := xv.(zodb.IPersistent)
 			if !ok {
-				exc.Raisef("[%d] -> %s;  want ZBlk", k, typeOf(xv))
+				exc.Raisef("[%d] -> %s;  want IPersistent", k, xzodb.TypeOf(xv))
 			}
-
-			data, _, err := zv.loadBlkData(ctx); X(err)
-			bkv[k] = string(data)
+			data, err := ZGetBlkData(ctx, pv.PJar(), pv.POid())
+			if err != nil {
+				exc.Raisef("[%d]: %s", k, err)
+			}
+			bkv[k] = data
 		}
 
 
@@ -497,31 +480,6 @@ func XGetδKV(db *zodb.DB, at1, at2 zodb.Tid, δkvOid map[Key]ΔValue) map[Key]
 	return δkv
 }
 
-// xzgetBlkData loads block data from ZBlk object specified by its oid.
-func xzgetBlkData(ctx context.Context, zconn *zodb.Connection, zblkOid zodb.Oid) string {
-	X := exc.Raiseif
-
-	if zblkOid == VDEL {
-		return DEL
-	}
-
-	xblk, err := zconn.Get(ctx, zblkOid); X(err)
-	zblk := xblk.(ZBlk)
-	data, _, err := zblk.loadBlkData(ctx); X(err)
-	return string(data)
-}
-
-// xzgetBlkDataAt loads block data from ZBlk object specified by oid@at.
-func xzgetBlkDataAt(db *zodb.DB, zblkOid zodb.Oid, at zodb.Tid) string {
-	X := exc.Raiseif
-
-	txn, ctx := transaction.New(context.Background())
-	defer txn.Abort()
-
-	zconn, err := db.Open(ctx, &zodb.ConnOptions{At: at});  X(err)
-	return xzgetBlkData(ctx, zconn, zblkOid)
-}
-
 // KAdjMatrix is adjacency matrix that describes how set of tracked keys
 // changes (always grow) when tree topology is updated from A to B.
 //
@@ -710,7 +668,7 @@ func xverifyΔBTail_Update1(t *testing.T, subj string, db *zodb.DB, treeRoot zod
 
 	kadjTracked = SetKey{} // kadj[Tracked]  (all keys adjacent to tracked keys)
 	for k := range initialTrackedKeys {
-		_, ok, path, err := ztreeGetBlk(ctx, ztree, k);  X(err)
+		_, ok, path, err := ZTreeGetBlkData(ctx, ztree, k);  X(err)
 		err = δbtail.Track(k, ok, path); X(err)
 
 		kadjTracked.Update(kadj[k])
@@ -1024,7 +982,7 @@ func xverifyΔBTail_rebuild_TR(t *testing.T, db *zodb.DB, δbtail *ΔBtail, tj *
 	xtree, err := zconn.Get(ctx, treeRoot);	 X(err)
 	ztree := xtree.(*Tree)
 	for k := range keys {
-		_, ok, path, err := ztreeGetBlk(ctx, ztree, k);  X(err)
+		_, ok, path, err := ZTreeGetBlkData(ctx, ztree, k);  X(err)
 		err = δbtail.Track(k, ok, path);  X(err)
 	}
 
@@ -1134,7 +1092,7 @@ func xverifyΔBTail_GetAt1(t *testing.T, db *zodb.DB, treeRoot zodb.Oid, vt []*t
 	ztree := xtree.(*Tree)
 
 	for k := range keys {
-		_, ok, path, err := ztreeGetBlk(ctx, ztree, k);  X(err)
+		_, ok, path, err := ZTreeGetBlkData(ctx, ztree, k);  X(err)
 		err = δbtail.Track(k, ok, path);  X(err)
 	}
 
@@ -1802,6 +1760,7 @@ func allTestKeys(vt ...*tTreeCommit) SetKey {
 	return allKeys
 }
 
+/*
 // easies debugging / makes error output stable from run to run.
 func (ks SetKey) SortedElements() []Key {
 	keyv := ks.Elements()
@@ -1818,7 +1777,7 @@ func (ks SetKey) String() string {
 	return "{" + strings.Join(strv, " ") + "}"
 }
 
-func (os SetOid) SortedElements() []Oid {
+func (os SetOid) SortedElements() []zodb.Oid {
 	oidv := os.Elements()
 	sort.Slice(oidv, func(i, j int) bool {
 		return oidv[i] < oidv[j]
@@ -1832,6 +1791,7 @@ func (os SetOid) String() string {
 	}
 	return "{" + strings.Join(strv, " ") + "}"
 }
+*/
 
 func sortedKeys(kv map[Key]Δstring) []Key {
 	keyv := []Key{}
@@ -1863,3 +1823,35 @@ func (δv ΔValue) String() string {
 	}
 	return fmt.Sprintf("{%s %s}", old, new)
 }
+
+
+// ----------------------------------------
+
+// ZBlk-related functions are imported at runtime by δbtail_x_test
+var (
+	ZTreeGetBlkData func(context.Context, *Tree, Key) (string, bool, []Node, error)
+	ZGetBlkData     func(context.Context, *zodb.Connection, zodb.Oid) (string, error)
+)
+
+// xzgetBlkData loads block data from ZBlk object specified by its oid.
+func xzgetBlkData(ctx context.Context, zconn *zodb.Connection, zblkOid zodb.Oid) string {
+	X := exc.Raiseif
+
+	if zblkOid == VDEL {
+		return DEL
+	}
+
+	data, err := ZGetBlkData(ctx, zconn, zblkOid); X(err)
+	return string(data)
+}
+
+// xzgetBlkDataAt loads block data from ZBlk object specified by oid@at.
+func xzgetBlkDataAt(db *zodb.DB, zblkOid zodb.Oid, at zodb.Tid) string {
+	X := exc.Raiseif
+
+	txn, ctx := transaction.New(context.Background())
+	defer txn.Abort()
+
+	zconn, err := db.Open(ctx, &zodb.ConnOptions{At: at});  X(err)
+	return xzgetBlkData(ctx, zconn, zblkOid)
+}

wcfs/internal/xbtree/δbtail_x_test.go

+// Copyright (C) 2020-2021  Nexedi SA and Contributors.
+//                          Kirill Smelkov <kirr@nexedi.com>
+//
+// This program is free software: you can Use, Study, Modify and Redistribute
+// it under the terms of the GNU General Public License version 3, or (at your
+// option) any later version, as published by the Free Software Foundation.
+//
+// You can also Link and Combine this program with other software covered by
+// the terms of any of the Free Software licenses or any of the Open Source
+// Initiative approved licenses and Convey the resulting work. Corresponding
+// source of such a combination shall include the source code for all other
+// software used.
+//
+// This program is distributed WITHOUT ANY WARRANTY; without even the implied
+// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+//
+// See COPYING file for full licensing terms.
+// See https://www.nexedi.com/licensing for rationale and options.
+
+package xbtree_test
+// ZBlk-related part of δbtail_test
+
+import (
+	"context"
+	"fmt"
+
+	"lab.nexedi.com/kirr/go123/xerr"
+	"lab.nexedi.com/kirr/neo/go/zodb"
+
+	"lab.nexedi.com/nexedi/wendelin.core/wcfs/internal/xbtree"
+	"lab.nexedi.com/nexedi/wendelin.core/wcfs/internal/xzodb"
+	"lab.nexedi.com/nexedi/wendelin.core/wcfs/internal/zdata"
+)
+
+type Tree = xbtree.Tree
+type Node = xbtree.Node
+type Key  = xbtree.Key
+
+type ZBlk = zdata.ZBlk
+
+// ztreeGetBlk returns ztree[k] and tree path that lead to this block.
+// XXX +return blkRevMax and use it ?
+func ztreeGetBlk(ctx context.Context, ztree *Tree, k Key) (zblk ZBlk, ok bool, path []Node, err error) {
+	path = []Node{}
+	xzblk, ok, err := ztree.VGet(ctx, k, func(node Node) {
+		path = append(path, node)
+	})
+	if err != nil {
+		return nil, false, nil, err
+	}
+
+	if ok {
+		zblk, ok = xzblk.(ZBlk)
+		if !ok {
+			return nil, false, nil, fmt.Errorf("expect ZBlk*; got %s", xzodb.TypeOf(xzblk))  // XXX errctx
+		}
+	}
+
+	return zblk, ok, path, nil
+}
+
+
+func init() {
+	xbtree.ZTreeGetBlkData = ZTreeGetBlkData
+	xbtree.ZGetBlkData     = ZGetBlkData
+}
+
+// ZTreeGetBlkData returns block data from block pointed to by ztree[k].
+func ZTreeGetBlkData(ctx context.Context, ztree *Tree, k Key) (data string, ok bool, path []Node, err error) {
+	defer xerr.Contextf(&err, "@%s: tree<%s>: get blkdata from [%d]", ztree.PJar().At(), ztree.POid(), k)
+
+	zblk, ok, path, err := ztreeGetBlk(ctx, ztree, k)
+	if err != nil || !ok {
+		return "", ok, path, err
+	}
+
+	bdata, _, err := zblk.LoadBlkData(ctx)
+	if err != nil {
+		return "", false, nil, err
+	}
+
+	return string(bdata), true, path, nil
+}
+
+// ZGetBlkData loads block data from ZBlk object specified by its oid.
+func ZGetBlkData(ctx context.Context, zconn *zodb.Connection, zblkOid zodb.Oid) (data string, err error) {
+	defer xerr.Contextf(&err, "@%s: get blkdata from obj %s", zconn.At(), zblkOid)
+
+	xblk, err := zconn.Get(ctx, zblkOid)
+	if err != nil {
+		return "", err
+	}
+	zblk, ok := xblk.(ZBlk)
+	if !ok {
+		return "", fmt.Errorf("expect ZBlk*; got %s", xzodb.TypeOf(xblk))
+	}
+	bdata, _, err := zblk.LoadBlkData(ctx)
+	if err != nil {
+		return "", err
+	}
+	return string(bdata), nil
+}

wcfs/internal/xtail/xtail.go

+// Copyright (C) 2018-2021  Nexedi SA and Contributors.
+//                          Kirill Smelkov <kirr@nexedi.com>
+//
+// This program is free software: you can Use, Study, Modify and Redistribute
+// it under the terms of the GNU General Public License version 3, or (at your
+// option) any later version, as published by the Free Software Foundation.
+//
+// You can also Link and Combine this program with other software covered by
+// the terms of any of the Free Software licenses or any of the Open Source
+// Initiative approved licenses and Convey the resulting work. Corresponding
+// source of such a combination shall include the source code for all other
+// software used.
+//
+// This program is distributed WITHOUT ANY WARRANTY; without even the implied
+// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+//
+// See COPYING file for full licensing terms.
+// See https://www.nexedi.com/licensing for rationale and options.
+
+// Package xtail provides utilities that are common to ΔBtail and ΔFtail.
+package xtail
+
+import (
+	"fmt"
+
+	"lab.nexedi.com/kirr/neo/go/zodb"
+)
+
+
+// AssertSlice asserts that δ.tail ≤ lo ≤ hi ≤ δ.head
+func AssertSlice(δ interface { Head() zodb.Tid; Tail() zodb.Tid }, lo, hi zodb.Tid) {
+	tail := δ.Tail()
+	head := δ.Head()
+	if !(tail <= lo && lo <= hi && hi <= head) {
+		panic(fmt.Sprintf("invalid slice: (%s, %s];  (tail, head] = (%s, %s]", lo, hi, tail, head))
+	}
+}

wcfs/internal/xzodb/xzodb.go

+// Copyright (C) 2018-2021  Nexedi SA and Contributors.
+//                          Kirill Smelkov <kirr@nexedi.com>
+//
+// This program is free software: you can Use, Study, Modify and Redistribute
+// it under the terms of the GNU General Public License version 3, or (at your
+// option) any later version, as published by the Free Software Foundation.
+//
+// You can also Link and Combine this program with other software covered by
+// the terms of any of the Free Software licenses or any of the Open Source
+// Initiative approved licenses and Convey the resulting work. Corresponding
+// source of such a combination shall include the source code for all other
+// software used.
+//
+// This program is distributed WITHOUT ANY WARRANTY; without even the implied
+// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+//
+// See COPYING file for full licensing terms.
+// See https://www.nexedi.com/licensing for rationale and options.
+
+// Package xzodb compements package zodb.
+package xzodb
+
+import (
+	"context"
+	"fmt"
+
+	"lab.nexedi.com/kirr/go123/xcontext"
+
+	"lab.nexedi.com/kirr/neo/go/transaction"
+	"lab.nexedi.com/kirr/neo/go/zodb"
+)
+
+
+// TypeOf returns string for object's type.
+//
+//	- for ZODB objects, it uses zodb.ClassOf, which in particular supports
+//	  printing zodb.Broken with details properly.
+//
+//	- for other objects, it uses %T.
+func TypeOf(obj interface{}) string {
+	switch obj := obj.(type) {
+	case zodb.IPersistent:
+		return zodb.ClassOf(obj)
+
+	default:
+		return fmt.Sprintf("%T", obj)
+	}
+}
+
+// ZConn is zodb.Connection + associated read-only transaction under which
+// objects of the connection are accessed.
+type ZConn struct {
+	*zodb.Connection
+
+	// read-only transaction under which we access zodb.Connection data.
+	TxnCtx context.Context // XXX -> better directly store txn
+}
+
+// ZOpen opens new connection to ZODB database + associated read-only transaction.
+func ZOpen(ctx context.Context, zdb *zodb.DB, zopt *zodb.ConnOptions) (_ *ZConn, err error) {
+	// create new read-only transaction
+	txn, txnCtx := transaction.New(context.Background())
+	defer func() {
+		if err != nil {
+			txn.Abort()
+		}
+	}()
+
+	// XXX better ctx = transaction.PutIntoContext(ctx, txn)
+	ctx, cancel := xcontext.Merge(ctx, txnCtx)
+	defer cancel()
+
+	zconn, err := zdb.Open(ctx, zopt)
+	if err != nil {
+		return nil, err
+	}
+
+	return &ZConn{
+		Connection: zconn,
+		TxnCtx:     txnCtx,
+	}, nil
+}

wcfs/internal/zdata/misc.go

+// Copyright (C) 2018-2021  Nexedi SA and Contributors.
+//                          Kirill Smelkov <kirr@nexedi.com>
+//
+// This program is free software: you can Use, Study, Modify and Redistribute
+// it under the terms of the GNU General Public License version 3, or (at your
+// option) any later version, as published by the Free Software Foundation.
+//
+// You can also Link and Combine this program with other software covered by
+// the terms of any of the Free Software licenses or any of the Open Source
+// Initiative approved licenses and Convey the resulting work. Corresponding
+// source of such a combination shall include the source code for all other
+// software used.
+//
+// This program is distributed WITHOUT ANY WARRANTY; without even the implied
+// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+//
+// See COPYING file for full licensing terms.
+// See https://www.nexedi.com/licensing for rationale and options.
+
+package zdata
+
+import (
+	"fmt"
+
+	"lab.nexedi.com/kirr/neo/go/zodb"
+)
+
+// tidmax returns latest revision.
+func tidmax(a, b zodb.Tid) zodb.Tid {
+	if a > b {
+		return a
+	} else {
+		return b
+	}
+}
+
+// tidmin returns earliest revision.
+func tidmin(a, b zodb.Tid) zodb.Tid {
+	if a < b {
+		return a
+	} else {
+		return b
+	}
+}
+
+func panicf(format string, argv ...interface{}) {
+	panic(fmt.Sprintf(format, argv...))
+}

wcfs/testdata/zblk_test_gen.py → wcfs/internal/zdata/testdata/zblk_test_gen.py

@@ -71,7 +71,7 @@ def main2():
         def emit(v):
             print >>f, v
         emit("// Code generated by %s; DO NOT EDIT." % __file__)
-        emit("package main\n")
+        emit("package zdata\n")
         emit('import "lab.nexedi.com/kirr/neo/go/zodb"\n')
 
         emit("const zf_blksize = %d" % zf.blksize)

wcfs/zblk.go → wcfs/internal/zdata/zblk.go

@@ -17,8 +17,10 @@
 // See COPYING file for full licensing terms.
 // See https://www.nexedi.com/licensing for rationale and options.
 
-package main
-// ZBlk* + ZBigFile loading
+// Package zdata provides access for wendelin.core in-ZODB data.
+//
+// ZBlk* + ZBigFile + ΔFtail for ZBigFile-level ZODB history.
+package zdata
 
 // module: "wendelin.bigfile.file_zodb"
 //
@@ -52,6 +54,7 @@ import (
 	"lab.nexedi.com/kirr/neo/go/zodb/btree"
 
 	"lab.nexedi.com/nexedi/wendelin.core/wcfs/internal/pycompat"
+	"lab.nexedi.com/nexedi/wendelin.core/wcfs/internal/xzodb"
 )
 
 // ZBlk is the interface that every ZBlk* block implements.
@@ -59,13 +62,13 @@ type ZBlk interface {
 	zodb.IPersistent
 	_ZBlkInΔFtail
 
-	// loadBlkData loads from database and returns data block stored by this ZBlk.
+	// LoadBlkData loads from database and returns data block stored by this ZBlk.
 	//
 	// If returned data size is less than the block size of containing ZBigFile,
 	// the block trailing is assumed to be trailing \0.
 	//
 	// returns data and revision of ZBlk.
-	loadBlkData(ctx context.Context) (data []byte, rev zodb.Tid, _ error)
+	LoadBlkData(ctx context.Context) (data []byte, rev zodb.Tid, _ error)
 }
 
 var _ ZBlk = (*ZBlk0)(nil)
@@ -98,15 +101,15 @@ func (zb *zBlk0State) PyGetState() interface{} {
 func (zb *zBlk0State) PySetState(pystate interface{}) error {
 	blkdata, ok := pystate.(string)
 	if !ok {
-		return fmt.Errorf("expect str; got %s", typeOf(pystate))
+		return fmt.Errorf("expect str; got %s", xzodb.TypeOf(pystate))
 	}
 
 	zb.blkdata = blkdata
 	return nil
 }
 
-// loadBlkData implements ZBlk.
-func (zb *ZBlk0) loadBlkData(ctx context.Context) (_ []byte, _ zodb.Tid, err error) {
+// LoadBlkData implements ZBlk.
+func (zb *ZBlk0) LoadBlkData(ctx context.Context) (_ []byte, _ zodb.Tid, err error) {
 	defer xerr.Contextf(&err, "ZBlk0(%s): loadBlkData", zb.POid())
 
 	err = zb.PActivate(ctx)
@@ -144,7 +147,7 @@ func (zd *zDataState) PyGetState() interface{} {
 func (zd *zDataState) PySetState(pystate interface{}) error {
 	data, ok := pystate.(string)
 	if !ok {
-		return fmt.Errorf("expect str; got %s", typeOf(pystate))
+		return fmt.Errorf("expect str; got %s", xzodb.TypeOf(pystate))
 	}
 
 	zd.data = data
@@ -175,15 +178,15 @@ func (zb *zBlk1State) PyGetState() interface{} {
 func (zb *zBlk1State) PySetState(pystate interface{}) error {
 	chunktab, ok := pystate.(*btree.IOBTree)
 	if !ok {
-		return fmt.Errorf("expect IOBTree; got %s", typeOf(pystate))
+		return fmt.Errorf("expect IOBTree; got %s", xzodb.TypeOf(pystate))
 	}
 
 	zb.chunktab = chunktab
 	return nil
 }
 
-// loadBlkData implements ZBlk.
-func (zb *ZBlk1) loadBlkData(ctx context.Context) (_ []byte, _ zodb.Tid, err error) {
+// LoadBlkData implements ZBlk.
+func (zb *ZBlk1) LoadBlkData(ctx context.Context) (_ []byte, _ zodb.Tid, err error) {
 	defer xerr.Contextf(&err, "ZBlk1(%s): loadBlkData", zb.POid())
 
 	err = zb.PActivate(ctx)
@@ -240,13 +243,13 @@ func (zb *ZBlk1) loadBlkData(ctx context.Context) (_ []byte, _ zodb.Tid, err err
 		defer b.PDeactivate()
 
 		// go through all bucket key/v -> chunktab
-		defer xerr.Contextf(&err, "%s(%s)", typeOf(b), b.POid())
+		defer xerr.Contextf(&err, "%s(%s)", xzodb.TypeOf(b), b.POid())
 
 		//fmt.Printf("\nbucket: %v\n\n", b.Entryv())
 		for i, e := range b.Entryv() {
 			zd, ok := e.Value().(*ZData)
 			if !ok {
-				return fmt.Errorf("[%d]: !ZData (%s)", i, typeOf(e.Value()))
+				return fmt.Errorf("[%d]: !ZData (%s)", i, xzodb.TypeOf(e.Value()))
 			}
 
 			offset := e.Key()
@@ -284,7 +287,7 @@ func (zb *ZBlk1) loadBlkData(ctx context.Context) (_ []byte, _ zodb.Tid, err err
 				})
 
 			default:
-				panicf("IOBTree has %s child", typeOf(child))
+				panicf("IOBTree has %s child", xzodb.TypeOf(child))
 			}
 		}
 
@@ -376,7 +379,7 @@ func (bf *zBigFileState) PyGetState() interface{} {
 func (bf *zBigFileState) PySetState(pystate interface{}) (err error) {
 	t, ok := pystate.(pickle.Tuple)
 	if !ok {
-		return fmt.Errorf("expect [2](); got %s", typeOf(pystate))
+		return fmt.Errorf("expect [2](); got %s", xzodb.TypeOf(pystate))
 	}
 	if len(t) != 2 {
 		return fmt.Errorf("expect [2](); got [%d]()", len(t))
@@ -384,7 +387,7 @@ func (bf *zBigFileState) PySetState(pystate interface{}) (err error) {
 
 	blksize, ok := pycompat.Int64(t[0])
 	if !ok {
-		return fmt.Errorf("blksize: expect integer; got %s", typeOf(t[0]))
+		return fmt.Errorf("blksize: expect integer; got %s", xzodb.TypeOf(t[0]))
 	}
 	if blksize <= 0 {
 		return fmt.Errorf("blksize: must be > 0; got %d", blksize)
@@ -392,7 +395,7 @@ func (bf *zBigFileState) PySetState(pystate interface{}) (err error) {
 
 	blktab, ok := t[1].(*btree.LOBTree)
 	if !ok {
-		return fmt.Errorf("blktab: expect LOBTree; got %s", typeOf(t[1]))
+		return fmt.Errorf("blktab: expect LOBTree; got %s", xzodb.TypeOf(t[1]))
 	}
 
 	bf.blksize = blksize
@@ -400,6 +403,13 @@ func (bf *zBigFileState) PySetState(pystate interface{}) (err error) {
 	return nil
 }
 
+// BlkSize returns size of block used by this file.
+//
+// The file must be activated.
+func (bf *ZBigFile) BlkSize() int64 {
+	return bf.blksize
+}
+
 // LoadBlk loads data for file block #blk.
 //
 // it also returns:
@@ -432,10 +442,10 @@ func (bf *ZBigFile) LoadBlk(ctx context.Context, blk int64) (_ []byte, treePath
 
 	zblk, ok = xzblk.(ZBlk)
 	if !ok {
-		return nil, nil, nil, 0, fmt.Errorf("expect ZBlk*; got %s", typeOf(xzblk))
+		return nil, nil, nil, 0, fmt.Errorf("expect ZBlk*; got %s", xzodb.TypeOf(xzblk))
 	}
 
-	blkdata, zblkrev, err := zblk.loadBlkData(ctx)
+	blkdata, zblkrev, err := zblk.LoadBlkData(ctx)
 	if err != nil {
 		return nil, nil, nil, 0, err
 	}

wcfs/zblk_test.go → wcfs/internal/zdata/zblk_test.go

@@ -17,7 +17,7 @@
 // See COPYING file for full licensing terms.
 // See https://www.nexedi.com/licensing for rationale and options.
 
-package main
+package zdata
 
 //go:generate ./testdata/zblk_test_gen.py
 
@@ -83,12 +83,12 @@ func TestZBlk(t *testing.T) {
 	}
 
 
-	z0Data, z0Rev, err := z0.loadBlkData(ctx);	X(err)
+	z0Data, z0Rev, err := z0.LoadBlkData(ctx);	X(err)
 	z0DataOK := brange32(z0_len)
 	assert.Equal(z0Data, z0DataOK,   "ZBlk0 data wrong")
 	assert.Equal(z0Rev,  z0_rev,	 "ZBlk0 rev wrong")
 
-	z1Data, z1Rev, err := z1.loadBlkData(ctx);	X(err)
+	z1Data, z1Rev, err := z1.LoadBlkData(ctx);	X(err)
 	z1DataOK := make([]byte, zf_blksize)                                  // zeros
 	copy(z1DataOK[0:],                      brange32(z1_htlen))           // head
 	copy(z1DataOK[len(z1DataOK)-z1_htlen:], breverse(brange32(z1_htlen))) // tail

wcfs/zset_bigfile.go → wcfs/internal/zdata/zset_bigfile.go

-// Code generated by gen-set BigFile *BigFile; DO NOT EDIT.
+// Code generated by gen-set ZBigFile *ZBigFile; DO NOT EDIT.
 
 // Copyright (C) 2015-2021  Nexedi SA and Contributors.
 //                          Kirill Smelkov <kirr@nexedi.com>
@@ -19,38 +19,38 @@
 // See COPYING file for full licensing terms.
 // See https://www.nexedi.com/licensing for rationale and options.
 
-package main
+package zdata
 
-// SetBigFile is a set of *BigFile.
-type SetBigFile map[*BigFile]struct{}
+// SetZBigFile is a set of *ZBigFile.
+type SetZBigFile map[*ZBigFile]struct{}
 
 // Add adds v to the set.
-func (s SetBigFile) Add(v *BigFile) {
+func (s SetZBigFile) Add(v *ZBigFile) {
 	s[v] = struct{}{}
 }
 
 // Del removes v from the set.
 // it is noop if v was not in the set.
-func (s SetBigFile) Del(v *BigFile) {
+func (s SetZBigFile) Del(v *ZBigFile) {
 	delete(s, v)
 }
 
 // Has checks whether the set contains v.
-func (s SetBigFile) Has(v *BigFile) bool {
+func (s SetZBigFile) Has(v *ZBigFile) bool {
 	_, ok := s[v]
 	return ok
 }
 
 // Update adds t values to s.
-func (s SetBigFile) Update(t SetBigFile) {
+func (s SetZBigFile) Update(t SetZBigFile) {
 	for v := range t {
 		s.Add(v)
 	}
 }
 
 // Elements returns all elements of set as slice.
-func (s SetBigFile) Elements() []*BigFile {
-	ev := make([]*BigFile, len(s))
+func (s SetZBigFile) Elements() []*ZBigFile {
+	ev := make([]*ZBigFile, len(s))
 	i := 0
 	for e := range s {
 		ev[i] = e
@@ -60,14 +60,14 @@ func (s SetBigFile) Elements() []*BigFile {
 }
 
 // Union returns s ∪ t
-func (s SetBigFile) Union(t SetBigFile) SetBigFile {
+func (s SetZBigFile) Union(t SetZBigFile) SetZBigFile {
 	// l = max(len(s), len(t))
 	l := len(s)
 	if lt := len(t); lt > l {
 		l = lt
 	}
 
-	u := make(SetBigFile, l)
+	u := make(SetZBigFile, l)
 
 	for v := range s {
 		u.Add(v)
@@ -79,8 +79,8 @@ func (s SetBigFile) Union(t SetBigFile) SetBigFile {
 }
 
 // Intersection returns s ∩ t
-func (s SetBigFile) Intersection(t SetBigFile) SetBigFile {
-	i := SetBigFile{}
+func (s SetZBigFile) Intersection(t SetZBigFile) SetZBigFile {
+	i := SetZBigFile{}
 	for v := range s {
 		if t.Has(v) {
 			i.Add(v)
@@ -90,8 +90,8 @@ func (s SetBigFile) Intersection(t SetBigFile) SetBigFile {
 }
 
 // Difference returns s\t.
-func (s SetBigFile) Difference(t SetBigFile) SetBigFile {
-	d := SetBigFile{}
+func (s SetZBigFile) Difference(t SetZBigFile) SetZBigFile {
+	d := SetZBigFile{}
 	for v := range s {
 		if !t.Has(v) {
 			d.Add(v)
@@ -101,8 +101,8 @@ func (s SetBigFile) Difference(t SetBigFile) SetBigFile {
 }
 
 // SymmetricDifference returns s Δ t.
-func (s SetBigFile) SymmetricDifference(t SetBigFile) SetBigFile {
-	d := SetBigFile{}
+func (s SetZBigFile) SymmetricDifference(t SetZBigFile) SetZBigFile {
+	d := SetZBigFile{}
 	for v := range s {
 		if !t.Has(v) {
 			d.Add(v)
@@ -117,7 +117,7 @@ func (s SetBigFile) SymmetricDifference(t SetBigFile) SetBigFile {
 }
 
 // Equal returns whether a == b.
-func (a SetBigFile) Equal(b SetBigFile) bool {
+func (a SetZBigFile) Equal(b SetZBigFile) bool {
 	if len(a) != len(b) {
 		return false
 	}

wcfs/ztestdata_zblk_test.go → wcfs/internal/zdata/ztestdata_zblk_test.go

 // Code generated by ./testdata/zblk_test_gen.py; DO NOT EDIT.
-package main
+package zdata
 
 import "lab.nexedi.com/kirr/neo/go/zodb"
 

wcfs/δftail.go → wcfs/internal/zdata/δftail.go

@@ -17,10 +17,9 @@
 // See COPYING file for full licensing terms.
 // See https://www.nexedi.com/licensing for rationale and options.
 
-package main
+package zdata
 
-//go:generate ./gen-set main I64     int64    zset_i64.go
-//go:generate ./gen-set main BigFile *BigFile zset_bigfile.go
+//go:generate ../set/gen-set zdata ZBigFile *ZBigFile zset_bigfile.go
 
 import (
 	"context"
@@ -31,8 +30,15 @@ import (
 	"lab.nexedi.com/kirr/go123/xerr"
 	"lab.nexedi.com/kirr/neo/go/zodb"
 	"lab.nexedi.com/kirr/neo/go/zodb/btree"
+
+	"lab.nexedi.com/nexedi/wendelin.core/wcfs/internal/set"
+	"lab.nexedi.com/nexedi/wendelin.core/wcfs/internal/xbtree"
+	"lab.nexedi.com/nexedi/wendelin.core/wcfs/internal/xtail"
+	"lab.nexedi.com/nexedi/wendelin.core/wcfs/internal/xzodb"
 )
 
+type SetI64 = set.SetI64
+
 // ΔFtail represents tail of revisional changes to files.
 //
 // It semantically consists of
@@ -71,8 +77,8 @@ import (
 // See also zodb.ΔTail
 type ΔFtail struct {
 	// ΔFtail merges ΔBtail with history of ZBlk
-	δBtail  *ΔBtail
-	fileIdx map[zodb.Oid]SetBigFile	// tree-root -> {} BigFile as of @head
+	δBtail  *xbtree.ΔBtail
+	fileIdx map[zodb.Oid]SetZBigFile // tree-root -> {} ZBigFile as of @head
 
 	// XXX don't need vδF - everything is reconstructed at runtime from .δBtail.vδT
 	//     this way we also don't need to keep up updating vδF from vδT on its rebuild during.
@@ -82,13 +88,13 @@ type ΔFtail struct {
 
 	// tracked ZBlk that are not yet taken into account in current vδF.
 	// grows on new track requests; flushes on queries and update.
-	trackNew map[*BigFile]map[zodb.Oid]*zblkInΔFtail // {} file -> {} oid -> zblk
+	trackNew map[*ZBigFile]map[zodb.Oid]*zblkInΔFtail // {} file -> {} oid -> zblk
 }
 
 // ΔF represents a change in files space.
 type ΔF struct {
 	Rev    zodb.Tid
-	ByFile map[*BigFile]*ΔFile // file -> δfile
+	ByFile map[*ZBigFile]*ΔFile // file -> δfile
 }
 
 // ΔFile represents a change to one file.
@@ -111,7 +117,7 @@ type zblkInΔFtail struct {
 	//  tree nodes and for tree_root->file)
 
 	// with which files/blocks this ZBlk is associated with as of @head state
-	infile map[*BigFile]SetI64 // {} file -> set(#blk)
+	infile map[*ZBigFile]SetI64 // {} file -> set(#blk)
 }
 
 type _ZBlkInΔFtail interface { inΔFtail() *zblkInΔFtail }
@@ -126,9 +132,9 @@ func (z *zblkInΔFtail) inΔFtail() *zblkInΔFtail { return z }
 // ZODB when needed.
 func NewΔFtail(at0 zodb.Tid, db *zodb.DB) *ΔFtail {
 	return &ΔFtail{
-		δBtail:   NewΔBtail(at0, db),
-		fileIdx:  make(map[zodb.Oid]SetBigFile),
-		trackNew: make(map[*BigFile]map[zodb.Oid]*zblkInΔFtail),
+		δBtail:   xbtree.NewΔBtail(at0, db),
+		fileIdx:  make(map[zodb.Oid]SetZBigFile),
+		trackNew: make(map[*ZBigFile]map[zodb.Oid]*zblkInΔFtail),
 	}
 }
 
@@ -149,10 +155,10 @@ func (δFtail *ΔFtail) Tail() zodb.Tid { return δFtail.δBtail.Tail() }
 // XXX objects in path and zblk must be with .PJar().At() == .head
 //
 // A root can be associated with several files (each provided on different Track call).
-func (δFtail *ΔFtail) Track(file *BigFile, blk int64, path []btree.LONode, zblk ZBlk) {
+func (δFtail *ΔFtail) Track(file *ZBigFile, blk int64, path []btree.LONode, zblk ZBlk) {
 	if blk == -1 {
 		// XXX blk = ∞ from beginning ?
-		blk = KeyMax
+		blk = xbtree.KeyMax
 	}
 	err := δFtail.δBtail.Track(blk, zblk != nil, path)
 	if err != nil {
@@ -161,7 +167,7 @@ func (δFtail *ΔFtail) Track(file *BigFile, blk int64, path []btree.LONode, zbl
 	root := path[0].(*btree.LOBTree)
 	files, ok := δFtail.fileIdx[root.POid()]
 	if !ok {
-		files = SetBigFile{}
+		files = SetZBigFile{}
 		δFtail.fileIdx[root.POid()] = files
 	}
 	files.Add(file)
@@ -174,7 +180,7 @@ func (δFtail *ΔFtail) Track(file *BigFile, blk int64, path []btree.LONode, zbl
 		if !ok {
 			blocks = make(SetI64, 1)
 			if z.infile == nil {
-				z.infile = make(map[*BigFile]SetI64)
+				z.infile = make(map[*ZBigFile]SetI64)
 			}
 			z.infile[file] = blocks
 		}
@@ -213,7 +219,7 @@ func (δFtail *ΔFtail) Track(file *BigFile, blk int64, path []btree.LONode, zbl
 // Zhead must be active connection at δFtail.Head() database state.
 // Objects in Zhead must not be modified.
 // During call to Update zhead must not be otherwise used - even for reading.
-func (δFtail *ΔFtail) Update(δZ *zodb.EventCommit, zhead *ZConn) (_ ΔF, err error) {
+func (δFtail *ΔFtail) Update(δZ *zodb.EventCommit, zhead *xzodb.ZConn) (_ ΔF, err error) {
 	defer xerr.Contextf(&err, "ΔFtail update %s -> %s", δFtail.Head(), δZ.Tid)
 	// XXX δFtail.update() first?
 
@@ -224,7 +230,7 @@ func (δFtail *ΔFtail) Update(δZ *zodb.EventCommit, zhead *ZConn) (_ ΔF, err
 		return ΔF{}, err
 	}
 
-	δF := ΔF{Rev: δB.Rev, ByFile: make(map[*BigFile]*ΔFile)}
+	δF := ΔF{Rev: δB.Rev, ByFile: make(map[*ZBigFile]*ΔFile)}
 
 	// take btree changes into account
 	for root, δt := range δB.ByRoot {
@@ -301,7 +307,7 @@ func (δFtail *ΔFtail) Update(δZ *zodb.EventCommit, zhead *ZConn) (_ ΔF, err
 //
 // If file != nil only track requests related to file are processed.
 // Otherwise all track requests are processed.
-func (δFtail *ΔFtail) update(file *BigFile) {
+func (δFtail *ΔFtail) update(file *ZBigFile) {
 	if file == nil {
 		panic("TODO")
 	}
@@ -318,7 +324,7 @@ func (δFtail *ΔFtail) update(file *BigFile) {
 	delete(δFtail.trackNew, file)
 	// XXX unlock here
 
-	for i, δZ := range δFtail.δBtail.δZtail.Data() {
+	for i, δZ := range δFtail.δBtail.ΔZtail().Data() {
 		δF := δFtail.vδF[i]
 		// XXX assert δF.Rev == δZ.Rev
 
@@ -348,7 +354,7 @@ func (δFtail *ΔFtail) ForgetPast(revCut zodb.Tid) {
 
 // XXX don't need
 func (δFtail *ΔFtail) SliceByRev(lo, hi zodb.Tid) /*readonly*/ []ΔF {
-	δassertSlice(δFtail, lo, hi)
+	xtail.AssertSlice(δFtail, lo, hi)
 	panic("TODO")
 }
 
@@ -361,8 +367,8 @@ func (δFtail *ΔFtail) SliceByRev(lo, hi zodb.Tid) /*readonly*/ []ΔF {
 // the caller must not modify returned slice.
 //
 // Note: contrary to regular go slicing, low is exclusive while high is inclusive.
-func (δFtail *ΔFtail) SliceByFileRev(file *BigFile, lo, hi zodb.Tid) /*readonly*/[]*ΔFile {
-	δassertSlice(δFtail, lo, hi)
+func (δFtail *ΔFtail) SliceByFileRev(file *ZBigFile, lo, hi zodb.Tid) /*readonly*/[]*ΔFile {
+	xtail.AssertSlice(δFtail, lo, hi)
 
 	// FIXME rework to just query .δBtail.SliceByRootRev(file.blktab, lo, hi) +
 	//       merge δZBlk history with that.
@@ -419,7 +425,7 @@ func (δFtail *ΔFtail) SliceByFileRev(file *BigFile, lo, hi zodb.Tid) /*readonl
 	// δFile	────────o───────o──────x─────x────────────────────────
 
 /*
-	vδZ := δFtail.δBtail.δZtail.SliceByRev(lo, hi)
+	vδZ := δFtail.δBtail.ΔZtail().SliceByRev(lo, hi)
 
 	// XXX stub that takes only ZBlk changes into account
 	// XXX dumb
@@ -467,19 +473,19 @@ func (δFtail *ΔFtail) SliceByFileRev(file *BigFile, lo, hi zodb.Tid) /*readonl
 //
 // if exact=False - what is returned is only an upper bound for last block revision.
 //
-// f must be from head/
+// zf must be from @head
 // at must ∈ (tail, head]
 // blk must be tracked
 //
 // XXX +ctx, error	rebuild []δF here
-func (δFtail *ΔFtail) LastBlkRev(ctx context.Context, f *BigFile, blk int64, at zodb.Tid) (_ zodb.Tid, exact bool) {
+func (δFtail *ΔFtail) LastBlkRev(ctx context.Context, zf *ZBigFile, blk int64, at zodb.Tid) (_ zodb.Tid, exact bool) {
 	//defer xerr.Contextf(&err, "")	// XXX text
 
 	// XXX assert δFtail == f.head.bfdir.δFtail ?
 
 	// XXX tabRev -> treeRev ?
 	// XXX activate zfile?
-	zblkOid, ok, tabRev, tabRevExact, err := δFtail.δBtail.GetAt(ctx, f.zfile.blktab, blk, at)
+	zblkOid, ok, tabRev, tabRevExact, err := δFtail.δBtail.GetAt(ctx, zf.blktab, blk, at)
 	if err != nil {
 		panic(err) // XXX
 	}
@@ -494,7 +500,7 @@ func (δFtail *ΔFtail) LastBlkRev(ctx context.Context, f *BigFile, blk int64, a
 	// blk revision is max rev and when zblk changed last in (rev, at] range.
 	//
 	// XXX need to use full δZ, not only connected to tracked subset?
-	zblkRev, zblkRevExact := δFtail.δBtail.δZtail.LastRevOf(zblkOid, at)
+	zblkRev, zblkRevExact := δFtail.δBtail.ΔZtail().LastRevOf(zblkOid, at)
 	if zblkRev > tabRev {
 		return zblkRev, zblkRevExact
 	} else {

wcfs/misc.go

@@ -36,10 +36,8 @@ import (
 	"github.com/hanwen/go-fuse/v2/fuse/nodefs"
 	"github.com/pkg/errors"
 
-	"lab.nexedi.com/kirr/go123/xcontext"
 	"lab.nexedi.com/kirr/go123/xio"
 
-	"lab.nexedi.com/kirr/neo/go/transaction"
 	"lab.nexedi.com/kirr/neo/go/zodb"
 )
 
@@ -430,76 +428,6 @@ func (f *skFile) Release() {
 }
 
 
-// ---- ZODB ---
-
-// typeOf returns string for object's type.
-//
-//	- for ZODB objects, it uses zodb.ClassOf, which in particular supports
-//	  printing zodb.Broken with details properly.
-//
-//	- for other objects, it uses %T.
-func typeOf(obj interface{}) string {
-	switch obj := obj.(type) {
-	case zodb.IPersistent:
-		return zodb.ClassOf(obj)
-
-	default:
-		return fmt.Sprintf("%T", obj)
-	}
-}
-
-// ZConn is zodb.Connection + associated read-only transaction under which
-// objects of the connection are accessed.
-type ZConn struct {
-	*zodb.Connection
-
-	// read-only transaction under which we access zodb.Connection data.
-	txnCtx context.Context // XXX -> better directly store txn
-}
-
-// zopen opens new connection to ZODB database + associated read-only transaction.
-func zopen(ctx context.Context, zdb *zodb.DB, zopt *zodb.ConnOptions) (_ *ZConn, err error) {
-	// create new read-only transaction
-	txn, txnCtx := transaction.New(context.Background())
-	defer func() {
-		if err != nil {
-			txn.Abort()
-		}
-	}()
-
-	// XXX better ctx = transaction.PutIntoContext(ctx, txn)
-	ctx, cancel := xcontext.Merge(ctx, txnCtx)
-	defer cancel()
-
-	zconn, err := zdb.Open(ctx, zopt)
-	if err != nil {
-		return nil, err
-	}
-
-	return &ZConn{
-		Connection: zconn,
-		txnCtx:     txnCtx,
-	}, nil
-}
-
-// tidmax returns latest revision.
-func tidmax(a, b zodb.Tid) zodb.Tid {
-	if a > b {
-		return a
-	} else {
-		return b
-	}
-}
-
-// tidmin returns earliest revision.
-func tidmin(a, b zodb.Tid) zodb.Tid {
-	if a < b {
-		return a
-	} else {
-		return b
-	}
-}
-
 // ---- parsing ----
 
 // parseWatchFrame parses line going through /head/watch into (stream, msg)