.

CHANGELOG.rst

 Wendelin.core change history
 ============================
 
+2.0.0 (2018-XX-YY)
+------------------
+
+- Switch to using kernel virtual memory manager. Bigfiles are now primarily
+  accessed with plain OS-level mmap to files from synthetic WCFS filesystem. This
+  removes overhead of handling pagefaults in userspace and makes bigfile's cache
+  (now it is the kernel's pagecache) to be shared in between several processes.
+
+  Additionally custom coherency protocol is provided, which allows clients
+  that want to receive isolation guarantee ("I" from ACID) to still use the shared
+  cache and at the same time get bigfile view isolated from other's changes.
+
+  By default wendelin.core python client provides full ACID semantics as before.
+
+
 0.12 (2018-04-16)
 -----------------
 

setup.py

@@ -261,6 +261,7 @@ setup(
                    'bench':         viamake('bench',    'run benchmarks'),
                   },
 
+    # TODO install wcfs exe along wcfs/ py package.
     entry_points= {'console_scripts': [
                         # start wcfs
                         'wcfs           = wendelin.wcfs:main',

wcfs/__init__.py

@@ -21,7 +21,7 @@
 """Module wcfs.py provides python gateway for spawning and interoperating with wcfs server
 
 Join(zurl) joins wcfs server. If wcfs server for zurl is not yet running, it
-can be automatically started if `autostart=True` parameter is passed to join.
+will be automatically started if `autostart=True` parameter is passed to join.
 It will also be automatically started by default unless
 $WENDELIN_CORE_WCFS_AUTOSTART=no is specified in environment.
 
@@ -122,6 +122,7 @@ def join(zurl, autostart=_default_autostart()):
     # start wcfs with telling it to automatically exit when there is no client activity.
     return _start(zurl, "-autoexit")
 
+
 # _start starts wcfs server for ZODB @ zurl.
 #
 # optv can be optionally given to pass flags to wcfs.
@@ -227,7 +228,6 @@ def _start(zurl, *optv):
             # wcfs, because we want spawned wcfs to potentially overlive our
             # process and to serve other processes. For the same reason we do
             # not preserve cancel channel in returned Conn.
-
             f = _rx
             startedok.close()
             return Conn(mntpt, f)
@@ -244,7 +244,6 @@ def _start(zurl, *optv):
 
 
 # _wcfs_exe returns path to wcfs executable.
-# TODO install wcfs exe along wcfs/ py package.
 def _wcfs_exe():
     return '%s/wcfs' % dirname(__file__)
 
@@ -253,21 +252,13 @@ def _wcfs_exe():
 # it also makes sure the mountpoint exists.
 def _mntpt_4zurl(zurl):
     # XXX what is zurl is zconfig://... ? -> then we have to look inside?
+    #     -> _zstor_2zurl extracts zurl in canonical form and zconfig:// is not possible there.
     m = hashlib.sha1()
     m.update(zurl)
     mntpt = "%s/wcfs/%s" % (tempfile.gettempdir(), m.hexdigest())
     _mkdir_p(mntpt)
     return mntpt
 
-# mkdir -p.
-def _mkdir_p(path):
-    try:
-        os.makedirs(path)
-    except OSError as e:
-        if e.errno != EEXIST:
-            raise
-
-
 
 # _zstor_2zurl converts a ZODB storage to URL to access it.
 def _zstor_2zurl(zstor):
@@ -285,6 +276,15 @@ def _zstor_2zurl(zstor):
     raise NotImplementedError("don't know how to extract url from %r" % zstor)
 
 
+# mkdir -p.
+def _mkdir_p(path):
+    try:
+        os.makedirs(path)
+    except OSError as e:
+        if e.errno != EEXIST:
+            raise
+
+
 
 
 # if called as main just -> serve(argv[1])

wcfs/todo.dot

@@ -30,5 +30,5 @@ digraph {
 	test		[label="? tests"]
 	zodburl		[label="zstor -> zurl", style=filled fillcolor=grey95]
 
-	autoexit	[label="autoexit if\nautostart && !activity"]
+	autoexit	[label="autoexit\nif !activity"]
 }

wcfs/todo.svg

@@ -68,21 +68,21 @@
 <!-- autoexit -->
 <g id="node6" class="node">
 <title>autoexit</title>
-<ellipse fill="none" stroke="#000000" cx="460.0456" cy="-26.8701" rx="97.6615" ry="26.7407"/>
-<text text-anchor="middle" x="460.0456" y="-30.6701" font-family="Times,serif" font-size="14.00" fill="#000000">autoexit if</text>
-<text text-anchor="middle" x="460.0456" y="-15.6701" font-family="Times,serif" font-size="14.00" fill="#000000">autostart &amp;&amp; !activity</text>
+<ellipse fill="none" stroke="#000000" cx="438.0456" cy="-26.8701" rx="52.1524" ry="26.7407"/>
+<text text-anchor="middle" x="438.0456" y="-30.6701" font-family="Times,serif" font-size="14.00" fill="#000000">autoexit</text>
+<text text-anchor="middle" x="438.0456" y="-15.6701" font-family="Times,serif" font-size="14.00" fill="#000000">if !activity</text>
 </g>
 <!-- wcfs&#45;&gt;autoexit -->
 <g id="edge5" class="edge">
 <title>wcfs&#45;&gt;autoexit</title>
-<path fill="none" stroke="#000000" d="M437.4092,-187.8647C455.1593,-179.1615 478.2928,-164.4722 489.0456,-143.4802 502.0598,-118.0735 492.8759,-86.511 481.5061,-62.6324"/>
-<polygon fill="#000000" stroke="#000000" points="484.5519,-60.8997 476.9096,-53.5617 478.3078,-64.0639 484.5519,-60.8997"/>
+<path fill="none" stroke="#000000" d="M437.4092,-187.8647C455.1593,-179.1615 478.2928,-164.4722 489.0456,-143.4802 499.9346,-122.2223 497.028,-112.2512 489.0456,-89.7401 485.013,-78.3678 477.9494,-67.5524 470.3413,-58.1994"/>
+<polygon fill="#000000" stroke="#000000" points="472.7666,-55.6532 463.5777,-50.3793 467.4721,-60.2324 472.7666,-55.6532"/>
 </g>
 <!-- wcfs_simple&#45;&gt;autoexit -->
 <g id="edge8" class="edge">
 <title>wcfs_simple&#45;&gt;autoexit</title>
-<path fill="none" stroke="#000000" d="M173.9291,-98.3925C182.215,-95.3125 190.8415,-92.2909 199.0456,-89.7401 255.7919,-72.0965 320.7548,-56.4326 371.6738,-45.153"/>
-<polygon fill="#000000" stroke="#000000" points="372.6488,-48.5223 381.6637,-42.9562 371.1454,-41.6856 372.6488,-48.5223"/>
+<path fill="none" stroke="#000000" d="M174.3504,-98.3929C182.516,-95.3465 190.9924,-92.3364 199.0456,-89.7401 260.1704,-70.034 331.5264,-51.878 380.2507,-40.1968"/>
+<polygon fill="#000000" stroke="#000000" points="381.0719,-43.5992 389.9881,-37.8763 379.4491,-36.7898 381.0719,-43.5992"/>
 </g>
 <!-- Btree_read -->
 <g id="node7" class="node">