.

bigfile/_bigfile.c

@@ -120,6 +120,10 @@ struct PyBigFileH {
     PyObject *in_weakreflist;
 
     BigFileH;
+
+    /* if subclass, in addition to .loadblk/.storeblk, defines .mmapper XXX ... */
+    PyObject *pymmapper; // python object returned by .mmaper() that is holding virtmem_mapper pycapsule
+    //virt_mapper *virt_mmap_ops;	// XXX ok?
 };
 typedef struct PyBigFileH PyBigFileH;
 
@@ -968,6 +972,7 @@ out:
 static const struct bigfile_ops pybigfile_ops = {
     .loadblk    = pybigfile_loadblk,
     .storeblk   = pybigfile_storeblk,
+    // XXX .mmap*
     //.release    =
 };
 
@@ -983,9 +988,13 @@ pyfileh_open(PyObject *pyfile0, PyObject *args)
     int err;
 
 
-    if (!PyArg_ParseTuple(args, ""))
+    if (!PyArg_ParseTuple(args, ""))	// XXX parse mmap_overlay=None (True/False)
         return NULL;
 
+    // XXX verify if pyfile has .mmapper()
+    // if mmap_overlay or (mmap_overlay==None and has(pyfile.mmapper)):
+    //	  mmaper = pyfile.mmapper()
+
     pyfileh = PyType_New(PyBigFileH, &PyBigFileH_Type, NULL);
     if (!pyfileh)
         return NULL;

bigfile/file_zodb.py

@@ -642,6 +642,12 @@ class ZBigFile(LivePersistent):
             fileh.invalidate_page(blk)  # XXX assumes blksize == pagesize
 
 
+    # mmaper complemnts loadblk/storeblk and returns object with pycapsule with .mmap*
+    # methods to be used by virtmem to mmap base overlay of the file data. XXX text
+    def mmaper(self):
+        # XXX return wcfileh (= zconn.wconn.open(self._p_oid))
+        1/0
+
 
     # fileh_open is bigfile-like method that creates new file-handle object
     # that is given to user for mmap.
@@ -763,7 +769,9 @@ class _ZBigFileH(object):
     def __init__(self, zfile, wcfileh):
         self.zfile   = zfile
         self.wcfileh = wcfileh
-        self.zfileh = zfile._v_file.fileh_open(wcfileh)    # XXX pass wcfileh in
+        #self.zfileh = zfile._v_file.fileh_open(wcfileh)    # XXX pass wcfileh in
+        # XXX no - BigFile should fetch wcfileh itself from ZBigFile by calling ZBigFile.mmapper()
+        self.zfileh = zfile._v_file.fileh_open()
 
         # FIXME zfile._p_jar could be None (ex. ZBigFile is newly created
         #       before first commit)

wcfs/internal/wcfs_virtmem.cpp

@@ -349,9 +349,34 @@ pair<Mapping, error> _FileH::mmap(int64_t blk_start, int64_t blk_len, VMA *vma)
 
     f._mmaps.push_back(mmap);    // XXX keep f._mmaps ↑blk_start
 
+    if (vma != NULL) {
+	vma->mmap_overlay_server = mmap._ptr(); // XXX +giveref
+    }
+
     return make_pair(mmap, nil);
 }
 
+// functions that we give to virtmem bigfile_ops .mmap*
+void* virt_mmap_setup_read(VMA *vma, BigFile *file, blk_t blk, size_t blklen) {
+    FileH fileh; // XXX = ...
+    Mapping mmap;
+    error err;
+
+    tie(mmap, err) = fileh->mmap(blk, blklen, vma);
+    if (err != nil)
+	panic("TODO");	// XXX
+
+    panic("TODO");
+}
+
+// XXX virt_remmap_blk_read(VMA *vma, BigFile *file, blk_t blk)
+void virt_munmap(VMA *vma, BigFile *file) {
+    Mapping mmap = adoptref(static_cast<_Mapping*>(vma->mmap_overlay_server)); // NOTE taking 1 ref back
+    vma->mmap_overlay_server = NULL;
+
+    mmap->unmap();
+}
+
 // resync resyncs connection and its mappings onto different database view.
 error _Conn::resync(zodb::Tid at) {
     _Conn& wconn = *this;