.

wcfs/client/wcfs.cpp

@@ -50,8 +50,8 @@
 // Conn.atMu > Conn.mu > FileH.mu
 //
 // Several locks are RWMutex instead of just Mutex not only to allow more
-// concurrency, but, in the first place for correctness: pinner being core
-// element in handling WCFS isolation protocol, is effectively invoked
+// concurrency, but, in the first place for correctness: pinner thread being
+// core element in handling WCFS isolation protocol, is effectively invoked
 // synchronously from other threads via messages coming through wcfs server.
 // For example Conn.resync sends watch request to wcfs and waits for the
 // answer. Wcfs server, in turn, sends corresponding pin messages to the pinner
@@ -66,7 +66,6 @@
 //        - - - - - -
 //       client process
 //
-//
 // This creates the neccessity to use RWMutex for locks that pinner and other
 // parts of the code could be using at the same time in sychronous mode similar
 // to the above. This locks are:
@@ -139,6 +138,12 @@ pair<Conn, error> WCFS::connect(zodb::Tid at) {
     // FIXME ^^^ not right - Conn.open waits for wcfs/head/at only in the end
     // and stats head/f to get f.headfsize _before_ that.
     // -> just wait here.
+    // XXX atMu.RLock ?
+    err = wconn._headWait(at);
+    if (err != nil) {
+        // XXX bring conn down - stop pinner
+        return make_pair(nil, E(err));
+    }
 
     return make_pair(wconn, nil);
 }
@@ -626,8 +631,20 @@ error _Mapping::unmap() {
 // XXX place=? -> closer to pinner & connect
 error _Conn::resync(zodb::Tid at) {
     _Conn& wconn = *this;
+    error err;
+
+    wconn._atMu.Lock();
+    xerr::Contextf E("%s: resync -> @%s", v(wconn), v(at));
+    wconn._atMu.Unlock();
+
+    // XXX downErr -> E
+    // XXX at ^ (increases)
+
+    // first wait for wcfs/head to be >= at
+    err = wconn._headWait(at);
+    if (err != nil)
+        return err;
 
-    // FIXME first wait for wcfs/head to be >= at
 
     // write-lock wconn._atMu . This excludes everything else, and in
     // particular _pinner_, from running and mutating files and mappings.
@@ -646,10 +663,6 @@ error _Conn::resync(zodb::Tid at) {
             wconn._atMu.RUnlock();
     });
 
-    xerr::Contextf E("%s: resync -> @%s", v(wconn), v(at));
-
-    error err;
-
     err = wconn._downErr;
     if (err != nil)
         return E(err);