APISession inherits from AbstractContextManager, and SMLog priorities are set.

SMlogs are set to LOG_DEBUG, except on failure to create a session.
Fixed some less readable code:
- lcache.py: import util on top instead of inside a method
- util.py; removed double tempfile import

Signed-off-by: Arnaud Garcia-Fernandez <arnaud.garcia-fernandez@vates.tech>

Author: Ythogtha

drivers/lcache.py

@@ -15,6 +15,7 @@
 # along with this program; if not, write to the Free Software Foundation, Inc.,
 # 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 
+import util
 from sm_typing import override
 
 import os
@@ -199,7 +200,6 @@ def from_uuid(cls, sr_uuid):
 
     @classmethod
     def from_session(cls, session):
-        import util
         import SR as sm
 
         host_ref = util.get_localhost_ref(session)
@@ -221,7 +221,6 @@ def from_session(cls, session):
 
     @classmethod
     def from_cli(cls):
-        import util
         with util.APISession("SM-lcache-CacheFileSR") as session:
             return cls.from_session(session)
 
@@ -236,8 +235,6 @@ def _fast_find_nodes(self):
         return list(found)
 
     def xapi_vfs_stats(self):
-        import util
-
         f = self.statvfs()
         if not f.f_frsize:
             raise util.SMException("Cache FS does not report utilization.")

drivers/util.py

@@ -47,7 +47,8 @@
 import traceback
 import glob
 import copy
-import tempfile
+import contextlib
+from sm_typing import override
 
 from functools import reduce
 from sm_typing import List, Optional
@@ -769,11 +770,11 @@ def getrootdevID():
     return rootdevID
 
 
-class APISession:
+class APISession(contextlib.AbstractContextManager):
     def __init__(self, originator="SM"):
         self.originator = originator
         self.session = self.login()
-        SMlog("APISession [{}] login".format(self.originator))
+        SMlog("APISession [{}] login".format(self.originator), priority=LOG_DEBUG)
         atexit.register(self.atexit)
 
     def login(self):
@@ -783,17 +784,17 @@ def login(self):
             session.xenapi.login_with_password('root', '', '', self.originator)
         except Exception as exc:
             msg = f"APISession [{self.originator}] Unable to open local XAPI session"
-            SMlog(msg)
+            SMlog(msg, priority=LOG_ERR)
             raise xs_errors.XenError(msg) from exc
         return session
 
     def _logout(self, log):
         """Closes an API session"""
         if self.session is None:
-            SMlog("APISession [{}] session is None {}".format(self.originator, log))
+            SMlog("APISession [{}] session is None {}".format(self.originator, log), priority=LOG_DEBUG)
             return
         self.session.xenapi.session.logout()
-        SMlog("APISession [{}] {}".format(self.originator, log))
+        SMlog("APISession [{}] {}".format(self.originator, log), priority=LOG_DEBUG)
         self.session = None
 
     def logout(self, log="logout"):
@@ -807,9 +808,13 @@ def __del__(self):
     def atexit(self):
         self._logout(log="logout atexit")
 
+    @override
     def __enter__(self):
+        if not self.session:
+            raise SyntaxError("Session is already closed: wrong usage of context.")
         return self.session
 
+    @override
     def __exit__(self, _type, _value, _traceback):
         self.logout(log=f"logout exception[{_type}] {_value}" if _type else "logout context")