.

wcfs/mman.pyx

+# Copyright (C) 2019  Nexedi SA and Contributors.
+#                     Kirill Smelkov <kirr@nexedi.com>
+#
+# This program is free software: you can Use, Study, Modify and Redistribute
+# it under the terms of the GNU General Public License version 3, or (at your
+# option) any later version, as published by the Free Software Foundation.
+#
+# You can also Link and Combine this program with other software covered by
+# the terms of any of the Free Software licenses or any of the Open Source
+# Initiative approved licenses and Convey the resulting work. Corresponding
+# source of such a combination shall include the source code for all other
+# software used.
+#
+# This program is distributed WITHOUT ANY WARRANTY; without even the implied
+# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+#
+# See COPYING file for full licensing terms.
+# See https://www.nexedi.com/licensing for rationale and options.
+
+# cython: language_level=2
+
+"""Module mman provides memory management utilities like mlock and mincore."""
+
+from posix cimport mman
+from cpython.exc cimport PyErr_SetFromErrno
+#from libc.stdio cimport printf
+
+cdef extern from "<sys/user.h>":
+    cpdef enum:
+        PAGE_SIZE
+
+cdef extern from "<sys/mman.h>":
+    cpdef enum:
+        MLOCK_ONFAULT
+
+    # XXX not in posix.mman
+    int mlock2(const void *addr, size_t len, int flags)
+
+
+# mincore returns bytearray vector indicating whether page of mem is in core or not.
+#
+# mem start must be page-aligned.
+def mincore(const unsigned char[::1] mem not None) -> bytearray:
+    cdef const void *addr = &mem[0]
+    cdef size_t      size = mem.shape[0]
+
+    # size in pages; rounded up
+    cdef size_t pgsize = (size + (PAGE_SIZE-1)) // PAGE_SIZE
+
+    #printf("\n\n%p %ld\n", addr, size)
+
+    incore = bytearray(pgsize)
+    cdef unsigned char[::1] incorev = incore
+
+    cdef err = mman.mincore(<void *>addr, size, &incorev[0])
+    if err:
+        PyErr_SetFromErrno(OSError)
+
+    return incore
+
+
+# mlock locks mem pages to be resident in RAM.
+#
+# see mlock2(2) for description of flags.
+def mlock(const unsigned char[::1] mem not None, int flags):
+    cdef const void *addr = &mem[0]
+    cdef size_t      size = mem.shape[0]
+
+    cdef err = mlock2(addr, size, flags)
+    if err:
+        PyErr_SetFromErrno(OSError)
+
+
+# munlock unlocks mem pages from being pinned in RAM.
+def munlock(const unsigned char[::1] mem not None):
+    cdef const void *addr = &mem[0]
+    cdef size_t      size = mem.shape[0]
+
+    cdef err = mman.munlock(addr, size)
+    if err:
+        PyErr_SetFromErrno(OSError)

wcfs/wcfs_test.py

@@ -38,6 +38,10 @@ from golang import func, defer
 from zodbtools.util import ashex as h, fromhex
 from pytest import raises
 
+from . import mman
+#print(mman.PAGE_SIZE)
+#mman.mincore(bytearray(b'hello world'))
+
 # setup:
 # - create test database, compute zurl and mountpoint for wcfs
 # - at every test: make sure wcfs is not running before & after the test.