.

bigfile/_bigfile.c

@@ -951,11 +951,11 @@ static const struct bigfile_ops pybigfile_ops = {
     .loadblk    = pybigfile_loadblk,
     .storeblk   = pybigfile_storeblk,
 
+    //.release    =
+
     .mmap_setup_read    = pybigfile_mmap_setup_read,
     .remmap_blk_read    = pybigfile_remmap_blk_read,
     .munmap             = pybigfile_munmap,
-
-    //.release    =
 };
 
 

bigfile/_bigfile.h

@@ -25,12 +25,15 @@
 /* Package _bigfile provides Python bindings to virtmem.
  *
  * - `BigFile` is base class that allows implementing BigFile backends in Python.
- *   Users can inherit from BigFile, implement loadblk/storeblk/blkmmapper and      XXX review
- *   this way provide access to data managed from Python to virtmem subsystem.
+ *   Users can inherit from BigFile, implement loadblk/storeblk and this way
+ *   provide access to data managed from Python to virtmem subsystem(*).
  * - `BigFileH` represents virtmem file handle for opened BigFile.
  *   It can be mmap'ed and provides writeout control.
  * - `VMA` represents mmap'ed part of a BigFileH.
  *   It provides buffer/memoryview interface for data access.
+ *
+ * (*) A subclass may additionally provide functionality to map file data into
+ *     memory. Please see BigFile documentation for details.
  */
 
 #include <Python.h>
@@ -91,9 +94,11 @@ struct PyBigFileH {
 
     BigFileH fileh;
 
-    /* if subclass, in addition to .loadblk/.storeblk, defines .blkmmapper XXX ... */
+#if 0
+    /* if BigFile subclass, in addition to .loadblk/.storeblk, defines .blkmmapper XXX ... */
     PyObject *pymmapper; // python object returned by .blkmmapper() that is holding virtmem_mapper pycapsule
     //virt_mapper *virt_mmap_ops;       // XXX ok?
+#endif
 };
 typedef struct PyBigFileH PyBigFileH;
 
@@ -101,8 +106,18 @@ typedef struct PyBigFileH PyBigFileH;
 /*
  * BigFile that can be implemented in python
  *
- * Allows subclasses to implement .loadblk() (& friends) in python.     XXX blkmmapper doc
+ * Allows subclasses to implement .loadblk() and .storeblk() in python.
  * For users .fileh_open() is exposed to get to file handles.
+ *
+ * A subclass may additionally provide functionality to map file data into
+ * memory: if subclass provides .blkmmapper attribute, it is treated as
+ * pycapsule with type "wendelin.bigfile.IBlkMMapper" and C-level bigfile_ops
+ * struct that provides .mmap_setup_read and other operations related to
+ * mmapping data. To avoid deadlocks all mmap-related functionality must be
+ * nogil and so cannot be implemented in Python.
+ *
+ * One example user of .blkmmapper functionality is _ZBigFile which uses WCFS
+ * and mmaps files from it to provide memory mappings for ZBigFile data.
  */
 struct PyBigFile {
     PyObject pyobj;

bigfile/file_zodb.cpp

@@ -18,7 +18,7 @@
 // See https://www.nexedi.com/licensing for rationale and options.
 
 // File file_zodb.cpp provides blkmmapper functions for _ZBigFile.
-// MMapping is implemented via WCFS.
+// MMapping is implemented via wcfs client.
 
 #include "wcfs/client/wcfs.h"
 #include "wendelin/bigfile/file.h"

wcfs/client/client_test.py

@@ -28,8 +28,8 @@ wcfs.py/wcfs.go while running tox tests in wcfs mode.
 from __future__ import print_function, absolute_import
 
 from golang import func, defer
-from wendelin.wcfs.wcfs_test import tDB, tAt
-from wendelin.wcfs import wcfs_test
+from ..wcfs_test import tDB, tAt    # XXX -> absolute
+from .. import wcfs_test            # XXX -> absolute
 
 # XXX so that e.g. testdb is set up + ...
 def setup_module():         wcfs_test.setup_module()