X start of ΔFtail.SliceByFileRev rework to function via merging δB and δZ histories on the fly

wcfs/internal/zdata/δftail.go

@@ -81,7 +81,7 @@ type ΔFtail struct {
 	trackSetZBlk  map[zodb.Oid]*zblkTrack // zblk -> {} root -> {}blk	as of @head
 
 // XXX kill
-///*
+/*
 	// XXX don't need vδF - everything is reconstructed at runtime from .δBtail.vδT
 	//     this way we also don't need to keep up updating vδF from vδT on its rebuild during.
 	// data with δF changes. Actual for part of tracked set that was taken
@@ -91,7 +91,7 @@ type ΔFtail struct {
 	// tracked ZBlk that are not yet taken into account in current vδF.
 	// grows on new track requests; flushes on queries and update.
 	trackNew map[zodb.Oid]map[zodb.Oid]*zblkTrack // {} foid -> {} zoid -> zblk
-//*/
+*/
 }
 
 // zblkTrack keeps information in which root/blocks ZBlk is present as of @head.
@@ -126,7 +126,7 @@ func NewΔFtail(at0 zodb.Tid, db *zodb.DB) *ΔFtail {
 		fileIdx:       map[zodb.Oid]setOid{},
 		trackSetZFile: setOid{},
 		trackSetZBlk:  map[zodb.Oid]*zblkTrack{},
-		trackNew:      map[zodb.Oid]map[zodb.Oid]*zblkTrack{},
+//		trackNew:      map[zodb.Oid]map[zodb.Oid]*zblkTrack{},
 	}
 }
 
@@ -190,6 +190,7 @@ func (δFtail *ΔFtail) Track(file *ZBigFile, blk int64, path []btree.LONode, zb
 		}
 		inblk.Add(blk)
 
+/* XXX kill
 		if !ok {
 			// zblk was not associated with this file
 			ft := δFtail.trackNew[foid]
@@ -199,17 +200,8 @@ func (δFtail *ΔFtail) Track(file *ZBigFile, blk int64, path []btree.LONode, zb
 			}
 			ft[zoid] = zt
 		}
-	}
-
-	// XXX mark something dirty so that LastBlkRev and Slice* know what to rebuild?
-
-	// XXX debug
-/*
-	leaf := path[len(path)-1].(*btree.LOBucket)
-	for _, e := range leaf.Entryv() { // XXX activate
-		δFtail.tracked.Add(e.Key())
-	}
 */
+	}
 }
 
 // Update updates δFtail given raw ZODB changes.
@@ -225,7 +217,6 @@ func (δFtail *ΔFtail) Track(file *ZBigFile, blk int64, path []btree.LONode, zb
 //func (δFtail *ΔFtail) Update(δZ *zodb.EventCommit, zhead *xzodb.ZConn) (_ ΔF, err error) {
 func (δFtail *ΔFtail) Update(δZ *zodb.EventCommit) (_ ΔF, err error) {
 	defer xerr.Contextf(&err, "ΔFtail update %s -> %s", δFtail.Head(), δZ.Tid)
-	// XXX δFtail.update() first?
 
 	// XXX verify zhead.At() == δFtail.Head()
 	// XXX locking
@@ -328,10 +319,11 @@ func (δFtail *ΔFtail) Update(δZ *zodb.EventCommit) (_ ΔF, err error) {
 
 //	fmt.Printf("-> δF: %v\n", δF)
 
-	δFtail.vδF = append(δFtail.vδF, δF)
+//	δFtail.vδF = append(δFtail.vδF, δF)
 	return δF, nil
 }
 
+/*
 // XXX kill after vδF is gone
 // update processes new track requests and updates vδF.
 //
@@ -378,6 +370,7 @@ func (δFtail *ΔFtail) update(file *ZBigFile) {
 		}
 	}
 }
+*/
 
 // ForgetPast discards all δFtail entries with rev ≤ revCut.
 func (δFtail *ΔFtail) ForgetPast(revCut zodb.Tid) {
@@ -399,50 +392,11 @@ func (δFtail *ΔFtail) ForgetPast(revCut zodb.Tid) {
 // the caller must not modify returned slice.
 //
 // Note: contrary to regular go slicing, low is exclusive while high is inclusive.
-func (δFtail *ΔFtail) SliceByFileRev(file *ZBigFile, lo, hi zodb.Tid) /*readonly*/[]*ΔFile {
+func (δFtail *ΔFtail) SliceByFileRev(zfile *ZBigFile, lo, hi zodb.Tid) /*readonly*/[]*ΔFile {
 	xtail.AssertSlice(δFtail, lo, hi)
 
-	// FIXME rework to just query .δBtail.SliceByRootRev(file.blktab, lo, hi) +
-	//       merge δZBlk history with that.
-
-	// XXX locking?
-	δFtail.update(file)
-
-	// find vδF range corresponding to (lo, hi]
-	// XXX linear scan
-	vδF := δFtail.vδF
-	if len(vδF) == 0 {
-		return nil
-	}
-
-	// find max j : [j].rev ≤ hi		XXX linear scan -> binary search
-	j := len(vδF)-1
-	for ; j >= 0 && vδF[j].Rev > hi; j-- {}
-	if j < 0 {
-		return nil // ø
-	}
-
-	// find max i : [i].rev > low		XXX linear scan -> binary search
-	i := j
-	for ; i >= 0 && vδF[i].Rev > lo; i-- {}
-	i++
-
-	vδF = vδF[i:j+1]
-
-	// filter found changed to have only file-related bits
-	foid := file.POid()
-	var vδfile []*ΔFile
-	for _, δF := range vδF {
-		δfile, ok := δF.ByFile[foid]
-		if ok {
-			vδfile = append(vδfile, δfile)
-		}
-	}
-
-	// XXX merge into vδF zblk from not yet handled tracked part
-
-	return vδfile
-
+	// query .δBtail.SliceByRootRev(file.blktab, lo, hi) +
+	// merge δZBlk history with that.
 
 	// merging tree (δT) and Zblk (δZblk) histories into file history (δFile):
 
@@ -457,19 +411,10 @@ func (δFtail *ΔFtail) SliceByFileRev(file *ZBigFile, lo, hi zodb.Tid) /*readon
 	//
 	// δFile	────────o───────o──────x─────x────────────────────────
 
-/*
-	vδZ := δFtail.δBtail.ΔZtail().SliceByRev(lo, hi)
 
-	// XXX stub that takes only ZBlk changes into account
-	// XXX dumb
-	for _, δZ := range vδZ {
-	}
-*/
-
-
-/*
-	// XXX activate zfile?
-	vδT := δFtail.δBtail.SliceByRootRev(file.zfile.blktab, lo, hi)
+	vδT := δFtail.δBtail.SliceByRootRev(zfile.blktab, lo, hi) // XXX needs activate zfile
+	vδZ := δFtail.δBtail.ΔZtail().SliceByRev(lo, hi)
+	var vδf []*ΔFile
 
 	// state of `{} blk -> zblk` as we are scanning ↓
 	δblktab := map[int64]struct {
@@ -497,8 +442,49 @@ func (δFtail *ΔFtail) SliceByFileRev(file *ZBigFile, lo, hi zodb.Tid) /*readon
 			...
 		}
 	}
-*/
 
+	return vδf
+
+
+/*
+	// XXX locking?
+	δFtail.update(file)
+
+	// find vδF range corresponding to (lo, hi]
+	// XXX linear scan
+	vδF := δFtail.vδF
+	if len(vδF) == 0 {
+		return nil
+	}
+
+	// find max j : [j].rev ≤ hi		XXX linear scan -> binary search
+	j := len(vδF)-1
+	for ; j >= 0 && vδF[j].Rev > hi; j-- {}
+	if j < 0 {
+		return nil // ø
+	}
+
+	// find max i : [i].rev > low		XXX linear scan -> binary search
+	i := j
+	for ; i >= 0 && vδF[i].Rev > lo; i-- {}
+	i++
+
+	vδF = vδF[i:j+1]
+
+	// filter found changed to have only file-related bits
+	foid := file.POid()
+	var vδfile []*ΔFile
+	for _, δF := range vδF {
+		δfile, ok := δF.ByFile[foid]
+		if ok {
+			vδfile = append(vδfile, δfile)
+		}
+	}
+
+	// XXX merge into vδF zblk from not yet handled tracked part
+
+	return vδfile
+*/
 }
 
 // XXX rename -> BlkRevAt