.

wcfs/δftail.go

@@ -38,20 +38,23 @@ import (
 //		.rev↑
 //		[](file, []blk)
 //
-// It provides the following operations:
 //
+// 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
+// tracked, even if it was changed in δZ is not guaranteed to be present in δF.
+//
+// ΔFtail provides the following operations:
+//
+//   .Track(file, blkTreePath)			- add file and block reached via BTree path to
+//						  tracked set.
 //   .Update(δZ) -> δF				- update files δ tail given raw ZODB changes
 //   .ForgetPast(revCut)			- forget changes past revCut
-//   .Track			XXX
 //   .SliceByRev(lo, hi) -> []δF		- query for all changes with rev ∈ (lo, hi]
 //   .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 only tracked blocks.
-// XXX ΔFtail - merge btree.ΔTail with history of ZBlk
+//   .LastBlkRev(file, #blk, at)		- query for what is last revision that changed
+//						  file[#blk] as of @at database state.
 type ΔFtail struct {
+	// ΔFtail merge btree.ΔTail with history of ZBlk
 	δBtail  *xbtree.ΔTail
 	fileIdx map[*btree.LOBTree]SetBigFile	// root -> {} BigFile	XXX root -> oid?
 }