.

wcfs/client/wcfs.cpp

@@ -27,6 +27,13 @@
 // reduce to just directly using OS-level file wcfs/head/f for a bigfile f. On
 // the other hand there is a simple, but inefficient, way to support isolation:
 // for @at database view of bigfile f - directly use OS-level file wcfs/@at/f.
+// The latter works, but is very inefficient because OS-cache for f data is not
+// shared in between two connections with @at1 and @at2 views. The cache is
+// also lost when connection view of the database is resynced on transaction
+// boundary. To support isolation efficiently, wcfs client uses wcfs/head/f
+// most of the time, but injects wcfs/@revX/f parts into mappings to maintain
+// f@at view driven by pin messages that wcfs server sends to client in
+// accordance with WCFS isolation protocol(*).
 //
 //
 //
@@ -52,6 +59,9 @@
 //   ↑↓          ↑↓ (XXX here ?)
 // Mapping     FileH
 //
+// --------
+//
+// (*) see wcfs.go documentation for WCFS isolation protocol overview and details.
 
 // XXX locking -> explain atMu + slaves and refer to "Locking" in wcfs.go
 //