Let a session serve several callers without one closing it

One session is now routinely handed to a console and a command at once, and
logout closed it for both, leaving whoever was left holding one that
answered as though it had been lost.  Count the holders and give up a claim
instead, unless the session is no longer usable, which logout is told by
sessionok.

A console had no way to give a claim back: close deactivated its sol payload
and left the session alone, which was right when closing meant closing it
for everybody and is a leak now.  Both of its exits release it.

confluent_server/aiohmi/ipmi/console.py

@@ -204,6 +204,21 @@ class Console(object):
         if not self.awaitingack:
             await self._sendpendingoutput()
 
+    async def _release_session(self):
+        """Give up this console's claim on the ipmi session
+
+        A console can be sharing one with whatever else is talking to the same
+        bmc, so let go of it rather than closing it.  Clearing the reference
+        first means it does not matter how many exits end up here.
+        """
+        sess = self.ipmi_session
+        if sess is None:
+            return
+        self.ipmi_session = None
+        if sess.sol_handler is not None and sess.sol_handler.__self__ is self:
+            sess.sol_handler = None
+        await sess.logout()
+
     async def close(self):
         """Shut down an SOL session"""
 
@@ -217,6 +232,7 @@ class Console(object):
                 # if underlying ipmi session is not working, then
                 # run with the implicit success
                 pass
+        await self._release_session()
 
     async def send_data(self, data):
         if self.broken:
@@ -320,10 +336,8 @@ class Console(object):
         self.broken = True
         if self.ipmi_session:
             self.ipmi_session.unregister_keepalive(self.keepaliveid)
-            if (self.ipmi_session.sol_handler
-                    and self.ipmi_session.sol_handler.__self__ is self):
-                self.ipmi_session.sol_handler = None
-            self.ipmi_session = None
+            # A console that has given up is finished with the session too
+            await self._release_session()
         if type(error) == dict:
             await self._print_data(error)
         else:

confluent_server/aiohmi/ipmi/private/session.py

@@ -479,10 +479,15 @@ class Session(object):
                     # id, however it's easier this way
                     forbidsock.append(self.socket)
             if trueself:
-                return await cls._await_login(trueself)
+                await cls._await_login(trueself)
+                # Count the caller only once it is really getting the session
+                trueself.users += 1
+                return trueself
             i = cls.initting_sessions.get(sesskey, False)
             if i:
-                return await cls._await_login(i)
+                await cls._await_login(i)
+                i.users += 1
+                return i
             self = super().__new__(cls)
             self.forbidsock = forbidsock
             # Register before establishing, not after: this is where a caller
@@ -531,6 +536,8 @@ class Session(object):
         # Whether this session still holds the socket pool count it took.
         # Set before anything can fail, so releasing is safe either way.
         self._socketclaimed = False
+        # How many callers hold this session; the last one out closes it
+        self.users = 1
         self.lastpayload = None
         self._customkeepalives = None
         # queue of events denoting line to run a cmd
@@ -1936,7 +1943,15 @@ class Session(object):
                 WAITING_SESSIONS.release()
 
     async def logout(self, sessionok=True):
-
+        if (sessionok and self.users > 1
+                and not self.broken and not self.cleaningup):
+            # A caller finished with a working session gives up its claim and
+            # leaves it to whoever else holds it; closing it here would hand
+            # them one that answers as though it had been lost.  sessionok is
+            # false when it is no longer usable, and then it comes down anyway.
+            self.users -= 1
+            return {'success': True}
+        self.users = 0
         if self.cleaningup:
             self.nowait = True
         if self.logged: