.

wcfs/wcfs.go

@@ -331,14 +331,14 @@ package main
 //   7.1) load blkdata for head/bigfile/file[blk] @zhead.at .
 //
 //	while loading this also gives upper bound estimate of when the block
-//	was last changed:	XXX kill upper bound -> populate and use δFtail
+//	was last changed:
 //
 //	  rev(blk) ≤ max(_.serial for _ in (ZBlk(#blk), all BTree/Bucket that lead to ZBlk))
 //
 //	it is not exact because BTree/Bucket can change (e.g. rebalance)
 //	but still point to the same k->ZBlk.
 //
-//	we also use file.δtail to find either exact blk revision:	XXX just use δFtail
+//	we also use file.δtail to find either exact blk revision:
 //
 //	  rev(blk) = max(file.δtail.by(#blk) -> []rev↑)
 //
@@ -352,6 +352,9 @@ package main
 //	  rev(blk) ≤ rev'(blk)		rev'(blk) = min(^^^)
 //
 //
+//	XXX we delay recomputing δFtail.LastBlkRev(file, #blk, head) because
+//	just cheap revmax estimate can frequently result in all watches being skipped.
+//
 //   7.2) for all registered client@at watchers of head/bigfile/file:
 //
 //	- rev'(blk) ≤ at: -> do nothing

wcfs/δftail.go

@@ -36,7 +36,7 @@ import (
 //
 //	δF:
 //		.rev↑
-//		[](file, []blk)
+//		{} file -> {}blk
 //
 // Only files and blocks explicitly requested to be tracked are guaranteed to
 // be present. In particular a block that was not explicitly requested to be
@@ -52,6 +52,12 @@ import (
 //   .SliceByFileRev(file, lo, hi) -> []δfile	- query for changes of file with rev ∈ (lo, hi]
 //   .LastBlkRev(file, #blk, at)		- query for what is last revision that changed
 //						  file[#blk] as of @at database state.
+//
+// XXX δfile:
+//	.rev↑
+//	[]blk
+//
+// XXX concurrent use
 type ΔFtail struct {
 	// ΔFtail merge btree.ΔTail with history of ZBlk
 	δBtail  *xbtree.ΔTail
@@ -88,6 +94,14 @@ func (δFtail *ΔFtail) Track(file *BigFile, path []btree.LONode) {
 		δFtail.fileIdx[root] = files
 	}
 	files.Add(file)
+
+	// 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.
@@ -118,6 +132,8 @@ func (δFtail *ΔFtail) Update(δZ *zodb.EventCommit) ΔF {
 	return δF
 }
 
+// XXX ForgetPast
+
 // LastBlkRev returns last revision that changed file[blk] as of @at database state.
 //
 // if exact=False - what is returned is only an upper bound for last block revision.
@@ -125,10 +141,11 @@ func (δFtail *ΔFtail) Update(δZ *zodb.EventCommit) ΔF {
 // at must ∈ (tail, head]	XXX [tail ?
 // XXX blk must be tracked?
 //
-// XXX -> LastTrackedBlkRev ?
+// XXX +ctx, error	rebuild []δF here
 func (f *BigFile) LastBlkRev(blk int64, at zodb.Tid) (_ zodb.Tid, exact bool) {
 	δFtail := f.head.bfdir.δFtail
 
+	// XXX tabRev -> treeRev ?
 	zblkOid, ok, tabRev, tabRevExact := δFtail.δBtail.Get(f.zfile.blktab, blk, at)
 
 	// block was removed
@@ -148,3 +165,6 @@ func (f *BigFile) LastBlkRev(blk int64, at zodb.Tid) (_ zodb.Tid, exact bool) {
 		return tabRev, tabRevExact
 	}
 }
+
+// XXX SliceByRev
+// XXX SliceByFileRev