.

wcfs/δbtail.go

@@ -28,6 +28,7 @@ package main
 import (
 	"context"
 	"fmt"
+	"math"
 
 	"lab.nexedi.com/kirr/go123/xerr"
 	"lab.nexedi.com/kirr/neo/go/transaction"
@@ -40,8 +41,11 @@ type Bucket = btree.LOBucket
 type Node   = btree.LONode
 
 type Key    = int64
+const KeyMax Key = math.MaxInt64
 type Value  = zodb.Oid // assumes key points to IPersistent
-                       // deletion is represented as InvalidOid
+                       // deletion is represented as VDEL
+const VDEL  = zodb.InvalidOid
+
 type Oid    = zodb.Oid
 type SetKey = SetI64
 
@@ -310,13 +314,79 @@ func (δBtail *ΔBtail) Update(δZ *zodb.EventCommit) (_ ΔB, err error) {
 // treediff computes δT for tree specified by root in between old..new.
 //
 // XXX only for tracked
-// δZT is δZ/T - subset of δZ touching tracked nodes of T.
+// δZT is δZ/T - subset of δZ(old..new) that touches tracked nodes of T.
 func (δBtail *ΔBtail) treediff(ctx context.Context, root zodb.Oid, δZT SetOid, zconnOld, zconnNew *zodb.Connection) (δT map[Key]Value, err error) {
-	defer xerr.Contextf(&err, "treediff %s", root)
+	defer xerr.Contextf(&err, "treediff %s..%s %s", zconnOld.At(), zconnNew.At(), root)
+	// XXX zconnX -> a, b ?
+
+	// XXX stub
+	for oid := range δZT {
+		xa, err1 := zconnOld.Get(ctx, oid)
+		xb, err2 := zconnNew.Get(ctx, oid)
+		err := xerr.Merge(err1, err2)
+		if err != nil {
+			return nil, err
+		}
+
+		ta := zodb.ClassOf(xa)
+		tb := zodb.ClassOf(xb)
+		if ta != tb {
+			return nil, fmt.Errorf("object %s: type mutated: %s -> %s", oid, ta, tb)
+		}
+
+		// XXX activate/deactivate
+
+		switch a := xa.(type) {
+		default:
+			return nil, fmt.Errorf("object %s: type unexpected: %s", oid, ta)
+
+		case *Bucket:
+			b := xb.(*Bucket) // must not fail
+			diffB(a, b)
+
+		case *Tree:
+			b := xb.(*Tree)   // must not fail
+			// TODO handle
+		}
+	}
 
 	return nil, nil // XXX stub
 }
 
+// diffB computes difference in between two buckets.
+// the buckets must be already activated
+func diffB(a, b *Bucket) map[Key]Value {
+	av := a.Entryv()
+	bv := b.Entryv()
+	δ  := map[Key]Value{}
+
+	for len(av) > 0 || len(bv) > 0 {
+		ka, va := KeyMax, VDEL
+		kb, vb := KeyMax, VDEL
+
+		if len(av) > 0 {
+			ka, va = av[0].Key(), av[0].Value()
+		}
+		if len(bv) > 0 {
+			kb, vb = bv[0].Key(), bv[0].Value()
+		}
+
+		switch {
+		case ka < kb: // -a[0]
+			av = av[1:]
+			δ[ka] = VDEL
+
+		case ka > kb: // +b[0]
+
+		// ka == kb   // va->vb
+		default:
+			av = av[1:]
+			bv = bv[1:]
+			δ[ka] = vb
+		}
+	}
+}
+
 
 
 func (δBtail *ΔBtail) ForgetPast(revCut zodb.Tid) {

wcfs/δbtail_test.go

@@ -402,7 +402,7 @@ func XGetKV(db *zodb.DB, at zodb.Tid, kvOid map[Key]Value) map[Key]string {
 
 	kv := map[Key]string{}
 	for k, vOid := range kvOid {
-		if vOid == zodb.InvalidOid {
+		if vOid == VDEL {
 			kv[k] = DEL
 			continue
 		}