.

lib/zodb.py

@@ -115,6 +115,7 @@ def _deactivate_bucket(bucket):
 # zconn_at returns tid as of which ZODB connection is viewing the database.
 def zconn_at(zconn): # -> tid
     assert isinstance(zconn, ZODB.Connection.Connection)
+    # XXX assert zconn is opened
 
     # ZODB5 uses MVCC uniformly
     if zmajor >= 5:

wcfs/internal/_wcfs.pyx

@@ -93,11 +93,22 @@ cdef extern from "wcfs.h" namespace "wcfs" nogil:
         pair[Conn, error]      connect(Tid at)
 
     cppclass _Conn:
-        error close()
+        pair[FileH, error]  open(Oid foid)
+        error               close()
 
     cppclass Conn (refptr[_Conn]):
         # Conn.X = Conn->X in C++
-        error   close       "_ptr()->close"     ()
+        pair[FileH, error]  open        "_ptr()->open"      (Oid foid)
+        error               close       "_ptr()->close"     ()
+
+    cppclass _FileH:
+        # XXX add mmap?
+        pass
+
+    cppclass FileH (refptr[_FileH]):
+        # FileH.X = FileH->X in C++
+        # XXX add mmap?
+        pass
 
 
 cdef class PyWCFS:
@@ -132,12 +143,32 @@ cdef class PyConn:
 
     def close(PyConn pywconn):
         with nogil:
-            err = pywconn.wconn.close()
+            err = wconn_close_pyexc(pywconn.wconn)
         if err != nil:
             raise pyerr(err)
 
+    def open(PyConn pywconn, pyfoid): # -> FileH
+        cdef Oid foid = u64(pyfoid)
+        with nogil:
+            _ = wconn_open_pyexc(pywconn.wconn, foid)
+            wfileh = _.first
+            err    = _.second
+        if err != nil:
+            raise pyerr(err)
+
+        cdef PyFileH pywfileh = PyFileH.__new__(PyFileH)
+        pywfileh.wfileh = wfileh
+        return pywfileh
+
     # XXX resync
 
+cdef class PyFileH:
+    cdef FileH wfileh
+
+    def __dealloc__(PyFileH pywfileh):
+        pywfileh.wfileh = nil
+
+# ----------------------------------------
 
 cdef class PyWatchLink:
     cdef WatchLink wlink
@@ -267,6 +298,12 @@ cdef nogil:
     pair[Conn, error] wcfs_connect_pyexc(WCFS *wcfs, Tid at)    except +topyexc:
         return wcfs.connect(at)
 
+    error wconn_close_pyexc(Conn wconn)                         except +topyexc:
+        return wconn.close()
+
+    pair[FileH, error] wconn_open_pyexc(Conn wconn, Oid foid)   except +topyexc:
+        return wconn.open(foid)
+
     error wlink_close_pyexc(WatchLink wlink)                    except +topyexc:
         return wlink.close()