.

wcfs/internal/xbtree/blib/rangemap.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 blib
+// map [lo,hi) Key ranges to values.
+
+import (
+	"fmt"
+)
+
+const traceRangeMap = true
+const debugRangeMap = true
+
+type VALUE = interface{}
+
+// RangedMap is Key->VALUE map with adjacent keys mapped to the same value coalesced into Ranges.
+//
+// Zero value represents empty map.
+type RangedMap struct {
+	// XXX -> BTree
+	entryv []mapEntry // lo↑
+}
+
+type mapEntry struct {
+	keycov KeyRange
+	value  VALUE
+}
+
+
+// Set changes m to map key k to value v.
+func (m *RangedMap) Set(k Key, v VALUE) {
+	m.SetRange(KeyRange{Lo: k, Hi_: k}, v)
+}
+
+// Del removes key k.
+func (m *RangedMap) Del(k Key) {
+	m.DelRange(KeyRange{Lo: k, Hi_: k})
+}
+
+// Has returns whether key k is present in the map.
+func (m *RangedMap) Has(k Key) bool {
+	_, ok := m.Get_(k)
+	return ok
+}
+
+// Get returns value associated with key k.
+func (m *RangedMap) Get(k Key) VALUE {
+	v, _ := m.Get_(k)
+	return v
+}
+
+// Get_ is comma-ok version of Get.
+func (m *RangedMap) Get_(k Key) (VALUE, bool) {
+	panic("TODO") // XXX
+}
+
+
+// SetRange changes m to map key range r to value v.
+func (m *RangedMap) SetRange(r KeyRange, v VALUE) {
+	panic("TODO") // XXX
+}
+
+// DelRange removes range r from the map.
+func (m *RangedMap) DelRange(r KeyRange) {
+	panic("TODO") // XXX
+}
+
+// XXX HasRange ?
+
+
+// --------
+
+// verify checks RangedMap for internal consistency:
+// - XXX
+func (m *RangedMap) verify() {
+	// XXX
+}
+
+
+// Empty returns whether the map is empty.
+func (m *RangedMap) Empty() bool {
+	return len(m.entryv) == 0
+}
+
+// XXX Equal ?
+// XXX Clear ?
+
+// XXX AllEntries ?
+
+func (m *RangedMap) String() string {
+	s := "{"
+	for i, e := range m.entryv {
+		if i > 0 {
+			s += " "
+		}
+		s += fmt.Sprintf("%s:%v", e.keycov, e.value)
+	}
+	s += "}"
+	return s
+}

wcfs/internal/xbtree/blib/rangeset.go

@@ -294,7 +294,7 @@ func (A *RangedKeySet) DifferenceInplace(B *RangedKeySet) {
 
 // --------
 
-// verify check RangedKeySet for internal consistency:
+// verify checks RangedKeySet for internal consistency:
 // - ranges must be not overlapping nor adjacent and ↑
 func (S *RangedKeySet) verify() {
 	// TODO !debug -> return
@@ -365,6 +365,7 @@ func (S *RangedKeySet) AllRanges() /*readonly*/[]KeyRange {
 	return S.rangev
 }
 
+// XXX -> ptr?
 func (S RangedKeySet) String() string {
 	s := "{"
 	for i, r := range S.rangev {

wcfs/internal/xbtree/δbtail.go

@@ -160,7 +160,9 @@ type _ΔTtail struct {
 	// set of nodes that were requested to be tracked in this tree, but for
 	// which vδT was not yet rebuilt
 	trackNew blib.PPTreeSubSet
+
 	// XXX + trackNewKeys RangedKeySet (concurrency)
+	// XXX + trackSetKeys RangedKeySet
 }
 
 // _ΔBroots represents roots-only part of ΔB.
@@ -882,6 +884,8 @@ func (δBtail *ΔBtail) GetAt(root zodb.Oid, key Key, at zodb.Tid) (value Value,
 	rev = tail
 	revExact = false
 
+	// XXX need to rebuild only if key was not rebuilt yet
+	// XXX need to rebuild only for key, not for whole trackNew
 	err = δBtail.rebuild1IfNeeded(root)
 	if err != nil {
 		return value, rev, valueExact, revExact, err