.

wcfs/wcfs_test.py

@@ -856,6 +856,12 @@ class tSrvReq:
 #
 # The automatic computation of pinok is verified against explicitly provided
 # pinok when it is present.
+#
+# Criteria for when blk must be pinned:
+#
+#   blk ∈ pin(at)   <=>   ∃ r = rev(blk):
+#                           1) at < r                   ; block was changed after at
+#                           2) r  ≤ headOfAccess(blk)   ; block revision changed after at was accessed
 @func(tWatchLink)
 def watch(twlink, zf, at, pinok=None): # -> tWatch
     t = twlink.tdb
@@ -900,9 +906,6 @@ def watch(twlink, zf, at, pinok=None): # -> tWatch
             assert t._blkRevAt(blk, headOfAccess[blk]) > at_prev
 
             # blk ∉ pin      means XXX
-
-
-
             assert headOfAccess[blk] >= t._blkRevAt(blk, t.head)
 
             pin[blk] = None     # @head