wcfs: Make sure to remove mountpoint directory on Server.stop

Else every time test.py/wcfs is run several empty directories are left
in /dev/shm/wcfs - each corresponding to WCFS server that was
automatically spawned and stopped at the end of the test. Over time this
can accumulate to some big number as e.g. ~20000 of such directories
were left on the testnode during last 6 months.

wcfs/__init__.py

@@ -417,6 +417,15 @@ def __stop(wcsrv, ctx, _onstuck):
 
     # unmount and wait for wcfs to exit
     # kill wcfs and abort FUSE connection if clean unmount fails
+    # at the end make sure mountpoint directory is removed
+
+    def _():
+        # when stop runs:
+        # - wcsrv could be already `fusermount -u`'ed from outside
+        # - the mountpoint could be also already removed from outside
+        _rmdir_ifexists(wcsrv.mountpoint)
+    defer(_)
+
     def _():
         if wcsrv._fuseabort is not None:
             wcsrv._fuseabort.close()
@@ -521,6 +530,14 @@ def _mkdir_p(path, mode=0o777): # -> created(bool)
         return False
     return True
 
+# rmdir if path exists.
+def _rmdir_ifexists(path):
+    try:
+        os.rmdir(path)
+    except OSError as e:
+        if e.errno != ENOENT:
+            raise
+
 # _fuse_unmount calls `fusermount -u` + logs details if unmount failed.
 @func
 def _fuse_unmount(mntpt):
@@ -713,6 +730,7 @@ def main():
     elif cmd == "stop":
         mntpt = _mntpt_4zurl(zurl)
         _fuse_unmount(mntpt)
+        _rmdir_ifexists(mntpt)
 
     else:
         print("wcfs: unknown command %s" % qq(cmd), file=sys.stderr)

wcfs/wcfs_test.py

@@ -53,7 +53,7 @@ from pytest import raises, fail
 from wendelin.wcfs.internal import io, mm
 from wendelin.wcfs.internal.wcfs_test import _tWCFS, read_exfault_nogil, SegmentationFault, install_sigbus_trap, fadvise_dontneed
 from wendelin.wcfs.client._wcfs import _tpywlinkwrite as _twlinkwrite
-from wendelin.wcfs import _is_mountpoint as is_mountpoint, _procwait as procwait, _ready as ready
+from wendelin.wcfs import _is_mountpoint as is_mountpoint, _procwait as procwait, _ready as ready, _rmdir_ifexists as rmdir_ifexists
 
 
 # setup:
@@ -106,8 +106,7 @@ def teardown_function(f):
     mounted = is_mountpoint(testmntpt)
     if mounted:
         fuse_unmount(testmntpt)
-    if os.path.exists(testmntpt):
-        os.rmdir(testmntpt)
+    rmdir_ifexists(testmntpt)
     with raises(KeyError):
         procmounts_lookup_wcfs(testzurl)
 
@@ -384,7 +383,6 @@ class tWCFS(_tWCFS):
             if is_mountpoint(t.wc.mountpoint):
                 fuse_unmount(t.wc.mountpoint)
             assert not is_mountpoint(t.wc.mountpoint)
-            os.rmdir(t.wc.mountpoint)
         defer(_)
         def _():
             def onstuck():