X wcfs: threading.Lock -> sync.Mutex

prepares the code to be moved into pyx/nogil, as sync.Mutex - contrary
to threading.Lock - is present also in pyx/nogil world.

wcfs/__init__.py

@@ -43,7 +43,6 @@ from errno import ENOENT, EEXIST
 from golang import chan, select, default, func, defer
 from golang import sync, context
 from golang.gcompat import qq
-import threading
 
 from persistent import Persistent
 from ZODB.FileStorage import FileStorage
@@ -92,7 +91,7 @@ class Conn(object):
     # .at           Tid
     # ._wlink       WatchLink watch/receive pins for created mappings
     #
-    # ._filemu      threading.Lock
+    # ._filemu      sync.Mutex
     # ._filetab     {} foid -> _File
     #
     # ._pinWG
@@ -133,7 +132,7 @@ def connect(wc, at): # -> Conn
     wconn._wc       = wc
     wconn.at        = at
     wconn._wlink    = WatchLink(wc)
-    wconn._filemu   = threading.Lock()
+    wconn._filemu   = sync.Mutex()
     wconn._filetab  = {}
 
     pinCtx, wconn._pinCancel = context.with_cancel(context.background())
@@ -414,12 +413,12 @@ class WatchLink(object):
 
         # inv.protocol message IO
         wlink._acceptq  = chan() # (stream, msg)    server originated messages go here
-        wlink._rxmu     = threading.Lock()
+        wlink._rxmu     = sync.Mutex()
         wlink._rxtab    = {}     # stream -> rxq    server replies go via here
         wlink._accepted = set()  # of stream        streams we accepted but did not replied yet
 
         wlink._req_next = 1                 # stream ID for next client-originated request XXX -> atomic
-        wlink._txmu     = threading.Lock()  # serializes writes
+        wlink._txmu     = sync.Mutex()  # serializes writes
         wlink._txclosed = False
 
         serveCtx, wlink._serveCancel = context.with_cancel(context.background())
@@ -714,7 +713,7 @@ class FileH(object):
 
 # ---- join/run wcfs ----
 
-_wcmu = threading.Lock()
+_wcmu = sync.Mutex()
 _wcregistry = {} # mntpt -> WCFS
 
 @func(WCFS)

wcfs/wcfs_test.py

@@ -661,6 +661,9 @@ class tFile:
             # head/watch can receive pin message. Be careful to handle cancellation,
             # so that on error in another worker we don't get stuck and the
             # error can be propagated to wait and reported.
+            #
+            # XXX after WatchLink is moved to pyx/nogil, do we still need to do
+            # here with nogil?
             have_read = chan(1)
             def _():
                 b = read_nogil(blkview[0:1])
@@ -1720,7 +1723,8 @@ class tMapping(object):
         # wcfs.py side, _abort_ontimeout could run and kill WCFS.
         # FIXME also test with GIL locked, since wcfs.py pinner must be itself
         # running without GIL.  XXX
-        _ = read_nogil(blkview[:1])
+        #_ = read_nogil(blkview[:1])
+        _ = blkview[0] # NOTE with gil
         assert _ == dataok[0]
         assert blkview.tobytes() == dataok