.

wcfs/client/wcfs.cpp

@@ -40,7 +40,7 @@
 // is completely blocked while wcfs server sends pins and waits to receive acks
 // from all clients. In other words on-client handling of pins has to be done
 // in separate thread, because wcfs server can also send pins to client that
-// trigerred the access.
+// triggered the access.
 //
 // Wcfs client implements pins handling in so-called "pinner" thread(+). The
 // pinner thread receives pin requests from wcfs server via watchlink handle
@@ -51,10 +51,17 @@
 // The same watchlink handle is used to send client-originated requests to wcfs
 // server. The requests are sent to tell wcfs that client wants to observe a
 // particular bigfile as of particular revision, or stop watching for it.
+// Such requests originate from regular client threads - not pinner - via entry
+// points like Conn.open, Conn.resync and FileH.close.
 //
-// XXX mmap zeros after .headfsize
-//     (mmap-in zeros after f.size (else access to memory after file.size will raise SIGBUS))
-//     (assumes head/f size ↑=)
+// In wendelin.core a bigfile has semantic that it is infinite in size and
+// reads as all zeros beyond region initialized with data. Memory-mapping of
+// OS-level files can also go beyond file size, however accessing memory
+// corresponding to file region after file.size triggers SIGBUS. To preserve
+// wendelin.core semantic wcfs client mmaps-in zeros for Mapping regions after
+// wcfs/head/f.size. For simplicity it is assumed that bigfiles only grow and
+// never shrink. It is indeed currently so, but will have to be revisited
+// if/when wendelin.core adds bigfile truncation.
 //
 // Every FileH maintains
 //