.

wcfs/wcfs.go

@@ -850,7 +850,10 @@ retry:
 	// invalidate kernel cache for data in changed files
 	// NOTE no δFmu lock needed because zhead is WLocked
 
-	δF := bfdir.δFtail.Update(δZ, zhead) // δF <- δZ |tracked
+	δF, err := bfdir.δFtail.Update(δZ, zhead) // δF <- δZ |tracked
+	if err != nil {
+		return err
+	}
 
 	if false { // XXX -> V(2) ?
 		// debug dump δF
@@ -2364,7 +2367,7 @@ func _main() (err error) {
 		fsNode:   newFSNode(fSticky),
 		head:     head,
 		fileTab:  make(map[zodb.Oid]*BigFile),
-		δFtail:   NewΔFtail(zhead.At()),
+		δFtail:   NewΔFtail(zhead.At(), zdb),
 	}
 	head.bfdir = bfdir
 

wcfs/δbtail.go

@@ -30,6 +30,7 @@ import (
 	"fmt"
 
 	"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/btree"
 )
@@ -148,11 +149,15 @@ type ΔTree struct {
 //
 // Initial tracked set is empty.
 // Initial coverage is (at₀, at₀].
-func NewΔBtail(at0 zodb.Tid) *ΔBtail {
+//
+// db will be used by ΔBtail to open database connections ... XXX
+// XXX or caller provides zhead/zprev explicitly?
+func NewΔBtail(at0 zodb.Tid, db *zodb.DB) *ΔBtail {
 	return &ΔBtail{
 		δZtail:   zodb.NewΔTail(at0),
 		byRoot:   make(map[zodb.Oid]*ΔTtail),
 		trackIdx: make(map[zodb.Oid]SetOid),
+		db:       db,
 	}
 }
 
@@ -227,7 +232,10 @@ func (δBtail *ΔBtail) Track(path []Node, flags TrackFlags) {	// XXX Tree|Bucke
 // only those keys, that correspond to tracked subset of δZ.
 //
 // δZ should include all objects changed by ZODB transaction.
-func (δBtail *ΔBtail) Update(δZ *zodb.EventCommit) ΔB {
+func (δBtail *ΔBtail) Update(δZ *zodb.EventCommit) (_ ΔB, err error) {
+	headOld := δBtail.Head()
+	defer xerr.Contextf(&err, "ΔBtail update %s -> %s", headOld, δZ.Tid)
+
 	δBtail.δZtail.Append(δZ.Tid, δZ.Changev)
 
 	// {} root -> []oid changed under that root in tracked set
@@ -244,6 +252,27 @@ func (δBtail *ΔBtail) Update(δZ *zodb.EventCommit) ΔB {
 
 	δB := ΔB{Rev: δZ.Tid, ByRoot: make(map[zodb.Oid]map[Key]Value)}
 
+	// skip opening DB connections if there is no change to any tree node
+	if len(δZByRoot) == 0 {
+		return δB, nil
+	}
+
+	// open ZODB connections correponding to "old" and "new" states
+	// TODO caller should provide one of those (probably new)
+	txn, ctx := transaction.New(context.TODO()) // XXX
+	defer txn.Abort()
+	zconnOld, err := δBtail.db.Open(ctx, &zodb.ConnOptions{At: headOld})
+	if err != nil {
+		return ΔB{}, err
+	}
+	zconnNew, err := δBtail.db.Open(ctx, &zodb.ConnOptions{At: δZ.Tid})
+	if err != nil {
+		return ΔB{}, err
+	}
+
+	_ = zconnOld
+	_ = zconnNew
+
 	for root := range δZByRoot {
 		δT, ok := δB.ByRoot[root]
 		if !ok {
@@ -253,7 +282,7 @@ func (δBtail *ΔBtail) Update(δZ *zodb.EventCommit) ΔB {
 		// XXX stub to get file.size invalidation working
 		// TODO update δT
 	}
-	return δB
+	return δB, nil
 
 /*	TODO btree-diff:
 
@@ -275,6 +304,8 @@ func (δBtail *ΔBtail) Update(δZ *zodb.EventCommit) ΔB {
 */
 }
 
+
+
 func (δBtail *ΔBtail) ForgetPast(revCut zodb.Tid) {
 	δBtail.δZtail.ForgetPast(revCut) // XXX stub
 }

wcfs/δbtail_test.go

@@ -521,7 +521,7 @@ func xverifyΔBTail1(t *testing.T, subj string, db *zodb.DB, treeRoot zodb.Oid,
 
 	// zconn, δbtail @at1 with initial tracked set
 	zconn, err := db.Open(ctx, &zodb.ConnOptions{At: at1});	X(err)
-	δbtail := NewΔBtail(zconn.At())
+	δbtail := NewΔBtail(zconn.At(), db)
 
 	xtree, err := zconn.Get(ctx, treeRoot);	X(err)
 	ztree := xtree.(*Tree)
@@ -568,7 +568,7 @@ func xverifyΔBTail1(t *testing.T, subj string, db *zodb.DB, treeRoot zodb.Oid,
 	}
 
 	// δB <- δZ
-	δB := δbtail.Update(δZ)
+	δB, err := δbtail.Update(δZ); X(err)
 	if δB.Rev != δZ.Tid {
 		badf("δB: rev != δZ.Tid  ; rev=%s  δZ.Tid=%s", δB.Rev, δZ.Tid)
 		return

wcfs/δftail.go

@@ -27,6 +27,7 @@ import (
 	"runtime"
 	"sync"
 
+	"lab.nexedi.com/kirr/go123/xerr"
 	"lab.nexedi.com/kirr/neo/go/zodb"
 	"lab.nexedi.com/kirr/neo/go/zodb/btree"
 )
@@ -110,9 +111,11 @@ func (z *zblkInΔFtail) inΔFtail() *zblkInΔFtail { return z }
 //
 // Initial tracked set is empty.
 // Initial coverage of created ΔFtail is (at₀, at₀].
-func NewΔFtail(at0 zodb.Tid) *ΔFtail {
+//
+// XXX db
+func NewΔFtail(at0 zodb.Tid, db *zodb.DB) *ΔFtail {
 	return &ΔFtail{
-		δBtail:   NewΔBtail(at0),
+		δBtail:   NewΔBtail(at0, db),
 		fileIdx:  make(map[zodb.Oid]SetBigFile),
 		trackNew: make(map[*BigFile]map[zodb.Oid]*zblkInΔFtail),
 	}
@@ -194,10 +197,17 @@ 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 {
+func (δFtail *ΔFtail) Update(δZ *zodb.EventCommit, zhead *ZConn) (_ ΔF, err error) {
+	defer xerr.Contextf(&err, "ΔFtail update %s -> %s", δFtail.Head(), δZ.Tid)
 	// XXX δFtail.update() first?
 
-	δB := δFtail.δBtail.Update(δZ)
+	// XXX verify zhead.At() == δFtail.Head()
+
+	δB, err := δFtail.δBtail.Update(δZ)
+	if err != nil {
+		return ΔF{}, err
+	}
+
 	δF := ΔF{Rev: δB.Rev, ByFile: make(map[*BigFile]*ΔFile)}
 
 	// take btree changes into account
@@ -268,7 +278,7 @@ func (δFtail *ΔFtail) Update(δZ *zodb.EventCommit, zhead *ZConn) ΔF {
 	}
 
 	δFtail.vδF = append(δFtail.vδF, δF)
-	return δF
+	return δF, nil
 }
 
 // update processes new track requests and updates vδF.