.

wcfs/wcfs.go

@@ -255,6 +255,9 @@ import (
 	"sync"
 	"syscall"
 
+	"lab.nexedi.com/kirr/go123/xcontext"
+
+	"lab.nexedi.com/kirr/neo/go/transaction"
 	"lab.nexedi.com/kirr/neo/go/zodb"
 	"lab.nexedi.com/kirr/neo/go/zodb/btree"
 	_ "lab.nexedi.com/kirr/neo/go/zodb/wks"
@@ -301,7 +304,13 @@ type BigFileData struct {
 	nodefs.Node
 	//parent *BigFileHead
 
-	zconn	*zodb.Connection // ZODB connection via whcih .zbf is accessed
+	// current read-only transaction under which we access ZODB data
+	txnCtx context.Context // XXX -> directly store txn
+
+	// connection via which ZODB object for this bigfile are accessed
+	// XXX do we need to keep it here explicitly?
+	zconn	*zodb.Connection
+
 	zbf	*ZBigFile
 
 	// TODO
@@ -312,7 +321,7 @@ type BigFileData struct {
 // /bigfile -> Mkdir receives client request to create /bigfile/<bigfileX>.
 //
 // It creates <bigfileX>/head/data along the way.
-func (bfroot *BigFileRoot) Mkdir(name string, mode uint32, fctx *fuse.Context) (*nodefs.Inode, fuse.Status) {
+func (bfroot *BigFileRoot) Mkdir(name string, mode uint32, fctx *fuse.Context) (_ *nodefs.Inode, status fuse.Status) {
 	oid, err := zodb.ParseOid(name)
 	if err != nil {
 		log.Printf("/bigfile: mkdir %q: not-oid", name)
@@ -330,11 +339,23 @@ func (bfroot *BigFileRoot) Mkdir(name string, mode uint32, fctx *fuse.Context) (
 		return nil, fuse.Status(syscall.EEXIST)
 	}
 
-	// no - without bfroot lock proceed to load corresponding objects from ZODB
-	ctx := asctx(fctx)
+	// not there - without bfroot lock proceed to load corresponding objects from ZODB:
+
+	// create new read-only transaction for this bigfile
+	txn, txnCtx := transaction.New(context.Background())
+	defer func() {
+		if status != fuse.OK {
+			txn.Abort()
+		}
+	}()
+
 
-	// XXX create txn
 	// create new DB/Connection for this bigfile
+
+	// XXX better ctx = transaction.PutIntoContext(ctx, txn)
+	ctx, cancel := xcontext.Merge(asctx(fctx), txnCtx)
+	defer cancel()
+
 	zdb := zodb.NewDB(bfroot.zstor)
 	zconn, err := zdb.Open(ctx, &zodb.ConnOptions{})	// XXX .NoSync=true ?
 	if err != nil {
@@ -342,8 +363,6 @@ func (bfroot *BigFileRoot) Mkdir(name string, mode uint32, fctx *fuse.Context) (
 		return nil, fuse.EIO
 	}
 
-	// XXX txn.Abort(), put conn back on error
-
 	xzbf, err := zconn.Get(ctx, oid)
 	if err != nil {
 		switch errors.Cause(err).(type) {
@@ -383,9 +402,10 @@ func (bfroot *BigFileRoot) Mkdir(name string, mode uint32, fctx *fuse.Context) (
 	}
 
 	bfdata := &BigFileData{
-		Node:  nodefs.NewDefaultNode(),
-		zconn: zconn,
-		zbf:   zbf,
+		Node:   nodefs.NewDefaultNode(),
+		txnCtx: txnCtx,
+		zconn:  zconn,
+		zbf:    zbf,
 	}
 
 	bfhead.data = bfdata