software: fixed possible deadlock in session manager

* peak() method used to lock wrong mutex, which could cause a deadlock.

* pop_reply() method could block if non-blocking access had been requested.

1 files changed, 20 insertions, 10 deletions

diff --git a/src/software/lmi/software/yumdb/sessionmanager.py b/src/software/lmi/software/yumdb/sessionmanager.py
index 8bc0474..07450ac 100644
--- a/src/software/lmi/software/yumdb/sessionmanager.py
+++ b/src/software/lmi/software/yumdb/sessionmanager.py
@@ -208,7 +208,7 @@ class SessionManager(threading.Thread):
 
         :rtype: tuple
         """
-        with self._busy_lock:
+        with self._reply_cond:
             return self._reply
 
     @property
@@ -223,7 +223,7 @@ class SessionManager(threading.Thread):
     @property
     def is_busy(self):
         """
-        :returns: Whether there is job being processed.
+        :returns: Whether there is a job being processed.
         :type: boolean
         """
         if self._busy_lock.acquire(False):
@@ -243,14 +243,24 @@ class SessionManager(threading.Thread):
         :returns: Received reply in form ``(jobid, result_code, result_data)``.
         :rtype: tuple
         """
-        with self._busy_lock:
-            reply = self._reply
-            if reply is None and no_wait:
-                raise TQueue.Empty("reply has been not received yet")
-            while reply is None:
-                self._busy_cond.wait()
-                reply = self._reply
-            self._reply = None
+        reply = None
+        if self._busy_lock.acquire(not no_wait):
+            try:
+                with self._reply_cond:
+                    reply = self._reply
+                    self._reply = None
+                if not no_wait:
+                    while reply is None:
+                        self._busy_cond.wait()
+                        with self._reply_cond:
+                            reply = self._reply
+                            self._reply = None
+            finally:
+                self._busy_lock.release()
+
+        if reply is None:   # this is possible only if no_wait=True
+            raise TQueue.Empty("reply has not been received yet")
+
         return reply
 
     @cmpi_logging.trace_method