.

wcfs/wcfs.go

@@ -218,7 +218,16 @@
 // data directly into the file.
 package main
 
-
+// WCFS organization
+//
+// TODO
+//
+// - 1 ZODB connection per 1 bigfile (each bigfile can be at its different @at,
+//   because invalidations for different bigfiles can be processed with different
+//   timings depending on clients). No harm here as different bigfiles use
+//   completely different ZODB BTree and data objects.
+//
+//
 // Notes on OS pagecache control:
 //
 // the cache of snapshotted bigfile can be pre-made hot, if invalidated region
@@ -241,12 +250,6 @@ package main
 // link above), but better we have proper FUSE flag for filesystem server to
 // tell the kernel it is fully responsible for invalidating pagecache.
 
-// TODO implementation organization.
-// - 1 ZODB connection per 1 bigfile (each bigfile can be at its different @at,
-//   because invalidations for different bigfiles can be processed with different
-//   timings depending on clients). No harm here as different bigfiles use
-//   completely different ZODB BTree and data objects.
-
 import (
 	"context"
 	"flag"
@@ -283,49 +286,44 @@ type BigFileRoot struct {
 type BigFileDir struct {
 	nodefs.Node
 
-	zdb   *zodb.DB
-//	zconn *zodb.Conn
-
-	//oid  zodb.Oid
-	//root *BigFileRoot
+	zdb *zodb.DB
 }
 
 // BigFileHead represents "/bigfile/<bigfileX>/head"
 // XXX -> BigFileRev  (with head | @tid) ?
 type BigFileHead struct {
 	nodefs.Node
-	//x *BigFileDir
 
 	data *BigFileData
 	//inv  *BigFileInvalidations
 }
 
-// BigFile is object that serves "/bigfile/<bigfileX>/<rev>/{data,at}"
+// BigFile is object that serves "/bigfile/<bigfileX>/(head|<rev>)/{data,at}"
 type BigFile struct {
 	// current read-only transaction under which we access ZODB data
 	txnCtx context.Context // XXX -> better directly store txn
 
-	// connection via which ZODB object for this bigfile are accessed
+	// connection via which ZODB objects for this bigfile are accessed
 	// XXX do we need to keep it here explicitly?
 	zconn	*zodb.Connection
 
-	zbf	*ZBigFile	// XXX kept always activated
+	// ZBigFile top-level object. Kept always activated (XXX clarify)
+	zbf	*ZBigFile
 
 	// TODO
 	// lastChange	zodb.Tid // last change to whole bigfile as of .zconn.At view
-
 }
 
-// BigFileData represents "/bigfile/<bigfileX>/head/data"
-// XXX also @<tidX>/data ?
+// BigFileData represents "/bigfile/<bigfileX>/(head|<rev>)/data"
 type BigFileData struct {
 	nodefs.Node
 
 	bigfile *BigFile
 
-	// inflight loadings of ZBigFile from ZODB
+	// inflight loadings of ZBigFile from ZODB.
+	// successfull load results are kept here until blkdata is put to OS pagecache.
 	loadMu  sync.Mutex
-	loading map[int64]*blkLoadState // #blk -> ...
+	loading map[int64]*blkLoadState // #blk -> {... blkdata}
 }
 
 // blkLoadState represents a ZBlk load state/result.
@@ -340,6 +338,9 @@ type blkLoadState struct {
 }
 
 
+// ----------------------------------------
+
+
 // /bigfile -> Mkdir receives client request to create /bigfile/<bigfileX>.
 //
 // It creates <bigfileX>/head/data along the way.
@@ -391,7 +392,7 @@ func (bfroot *BigFileRoot) Mkdir(name string, mode uint32, fctx *fuse.Context) (
 		case *zodb.NoObjectError:
 			return nil, fuse.EINVAL
 		case *zodb.NoDataError:
-			return nil, fuse.EINVAL // XXX ok?
+			return nil, fuse.EINVAL // XXX what to do if it was existing and got deleted?
 		default:
 			log.Printf("/bigfile: mkdir %q: %s", name, err)
 			return nil, fuse.EIO
@@ -677,12 +678,10 @@ func main() {
 		Name:   "wcfs",
 
 		DisableXAttrs: true, // we don't use
-
-		Debug:  *debug,
+		Debug:         *debug,
 	}
 
 	root := nodefs.NewDefaultNode()
-
 	fssrv, fsconn, err := mount(mntpt, root, opts)
 	if err != nil {
 		log.Fatal(err)
@@ -692,7 +691,7 @@ func main() {
 	// we require proper pagecache control (added to Linux 2.6.36 in 2010)
 	supports := fssrv.KernelSettings().SupportsNotify
 	if !(supports(fuse.NOTIFY_STORE) && supports(fuse.NOTIFY_RETRIEVE)) {
-		log.Fatalf("kernel FUSE does not support pagecache control") // XXX more details?
+		log.Fatalf("kernel FUSE does not support pagecache control")
 	}
 
 	// add entries to /