.

wcfs/wcfs.go

@@ -604,12 +604,12 @@ type BigFile struct {
 
 	// things read/computed from .zfile; constant during lifetime of current transaction.
 	// i.e. changed under zhead.W
-	blksize int64    // zfile.blksize
-	size    int64    // zfile.Size()
-	rev     zodb.Tid // last revision that modified zfile data
-			 // XXX we can't know rev fully as some later blocks could be learnt only
-			 //     while populating δFtail lazily
-			 // XXX or then it is not "constant during lifetime of current txn"
+	blksize   int64    // zfile.blksize
+	size      int64    // zfile.Size()
+	revApprox zodb.Tid // approx last revision that modified zfile data
+			   // ( we can't know rev fully as some later blocks could be learnt only
+			   //   while populating δFtail lazily. For simplicity we don't delve into
+			   //   updating revApprox during lifetime of current transaction )
 
 	// inflight loadings of ZBigFile from ZODB.
 	// successful load results are kept here until blkdata is put into OS pagecache.
@@ -946,9 +946,9 @@ retry:
 			bfdir.δFtail.Track(zfile, -1, sizePath, blkCov, nil)
 		}
 
-		// XXX we can miss a change to file if δblk is not yet tracked
-		//     -> need to update file.rev at read time -> locking=XXX
-		file.rev = zhead.At()
+		// NOTE we can miss a change to file if δblk is not yet tracked
+		//      that's why revision is only approximated
+		file.revApprox = zhead.At()
 	}
 
 	// notify .wcfs/zhead
@@ -2194,12 +2194,10 @@ func (head *Head) bigfopen(ctx context.Context, oid zodb.Oid) (_ *BigFile, err e
 		return nil, err
 	}
 	blksize := zfile.BlkSize()
-	// XXX it should be revision of both ZBigFile and its data. But we
+	// NOTE file revision should be revision of both ZBigFile and its data. But we
 	// cannot get data revision without expensive scan of all ZBigFile's objects.
 	// -> approximate mtime initially with ZBigFile object mtime.
-	//
-	// XXX for @rev/... we can know initial mtime more exactly?
-	rev     := zfile.PSerial()
+	revApprox := zfile.PSerial()
 	zfile.PDeactivate()
 
 	size, sizePath, blkCov, err := zfile.Size(ctx)
@@ -2208,13 +2206,13 @@ func (head *Head) bigfopen(ctx context.Context, oid zodb.Oid) (_ *BigFile, err e
 	}
 
 	f := &BigFile{
-		fsNode:  newFSNode(&fsOptions{Sticky: false}),	// XXX + BigFile.OnForget -> del .head.bfdir.fileTab[]
-		head:    head,
-		zfile:   zfile,
-		blksize: blksize,
-		size:    size,
-		rev:     rev,
-		loading: make(map[int64]*blkLoadState),
+		fsNode:    newFSNode(&fsOptions{Sticky: false}),	// XXX + BigFile.OnForget -> del .head.bfdir.fileTab[]
+		head:      head,
+		zfile:     zfile,
+		blksize:   blksize,
+		size:      size,
+		revApprox: revApprox,
+		loading:   make(map[int64]*blkLoadState),
 	}
 
 	// only head/ needs δFtail and watches.
@@ -2280,7 +2278,7 @@ func (f *BigFile) getattr(out *fuse.Attr) {
 	out.Blksize = uint32(f.blksize)	// NOTE truncating 64 -> 32
 	// .Blocks
 
-	mtime := f.rev.Time().Time
+	mtime := f.revApprox.Time().Time
 	out.SetTimes(/*atime=*/nil, /*mtime=*/&mtime, /*ctime=*/&mtime)
 }
 
@@ -2487,7 +2485,7 @@ func _main() (err error) {
 	// add entries to /
 	mkdir(root, "head", head)
 	mkdir(head, "bigfile", bfdir)
-	mkfile(head, "at", NewSmallFile(head.readAt))   // TODO mtime(at) = tidtime(at)
+	mkfile(head, "at", NewSmallFile(head.readAt)) // TODO mtime(at) = tidtime(at)
 	mkfile(head, "watch", wnode)
 
 	// for debugging/testing
@@ -2537,7 +2535,7 @@ func _main() (err error) {
 	if errors.Cause(err) != context.Canceled {
 		log.Error(err)
 		log.Errorf("zwatcher failed -> switching filesystem to EIO mode (TODO)")
-		//panic("TODO: switch fs to EIO mode") // XXX
+		// TODO: switch fs to EIO mode
 	}
 
 	// wait for unmount