[PATCH] [RFC] KVM test: Create a remote session cleaning thread

[Lucas Meneghel Rodrigues <lmr@redhat.com>]

In some occasions even though a VM has terminated,
some remote shell sessions will take a long time
before giving up on the host. This situation is
happening frequently on subtests such as autotest:
The VM shuts down, but the session will be alive
for a long time after the VM died.

So let's keep track of all sessions stablished to
a VM object, and create a remote session cleaning
thread, very much similar to the screendumps thread
recently introduced. This thread would go over all
dead VMs in the environment, and kill any remote
sessions associated to them that might still be alive.

This way we can save some good time in tests where
the VM was terminated due to some weird reason.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
---
 client/tests/kvm/kvm_preprocessing.py |   33 ++++++++++++++++++++++++++++++++-
 client/tests/kvm/kvm_vm.py            |    7 +++++++
 2 files changed, 39 insertions(+), 1 deletions(-)

diff --git a/client/tests/kvm/kvm_preprocessing.py b/client/tests/kvm/kvm_preprocessing.py
index 50db65c..707565d 100644
--- a/client/tests/kvm/kvm_preprocessing.py
+++ b/client/tests/kvm/kvm_preprocessing.py
@@ -13,7 +13,8 @@ except ImportError:
 
 _screendump_thread = None
 _screendump_thread_termination_event = None
-
+_session_cleaning_thread = None
+_session_cleaning_thread_termination_event = None
 
 def preprocess_image(test, params):
     """
@@ -267,6 +268,14 @@ def preprocess(test, params, env):
                                               args=(test, params, env))
         _screendump_thread.start()
 
+    # Start the session cleaning thread
+    logging.debug("Starting remote session cleaning thread")
+    global _session_cleaning_thread, _session_cleaning_thread_termination_event
+    _session_cleaning_thread_termination_event = threading.Event()
+    _session_cleaning_thread = threading.Thread(target=_clean_remote_sessions,
+                                          args=(test, params, env))
+    _session_cleaning_thread.start()
+
 
 def postprocess(test, params, env):
     """
@@ -442,3 +451,25 @@ def _take_screendumps(test, params, env):
         if _screendump_thread_termination_event.isSet():
             break
         _screendump_thread_termination_event.wait(delay)
+
+
+def _clean_remote_sessions(test, params, env):
+    """
+    Some remote shell servers such as SSH can be very slow on giving up of a
+    connection, which is fair. However, if the VM is known to be dead, we
+    can speed up this process reaping the remote sessions stablished to it.
+
+    @param test: KVM test object.
+    @param params: Dictionary with test parameters.
+    @param env: KVM test environment.
+    """
+    global _session_cleaning_termination_event
+    delay = float(params.get("session_cleaning_delay", 30))
+    while True:
+        for vm in kvm_utils.env_get_all_vms(env):
+            if vm.is_dead():
+                for session in vm.get_remote_session_list():
+                    session.close()
+        if _session_cleaning_thread_termination_event.isSet():
+            break
+        _session_cleaning_thread_termination_event.wait(delay)
diff --git a/client/tests/kvm/kvm_vm.py b/client/tests/kvm/kvm_vm.py
index 047505a..82ef3cf 100755
--- a/client/tests/kvm/kvm_vm.py
+++ b/client/tests/kvm/kvm_vm.py
@@ -115,6 +115,7 @@ class VM:
         self.root_dir = root_dir
         self.address_cache = address_cache
         self.pci_assignable = None
+        self.remote_session_list = []
 
         # Find available monitor filename
         while True:
@@ -749,6 +750,10 @@ class VM:
         return self.process.get_pid()
 
 
+    def get_remote_session_list(self):
+        return self.remote_session_list
+
+
     def get_shared_meminfo(self):
         """
         Returns the VM's shared memory information.
@@ -802,6 +807,8 @@ class VM:
         if session:
             session.set_status_test_command(self.params.get("status_test_"
                                                             "command", ""))
+            self.remote_session_list.append(session)
+
         return session
 
 
-- 
1.6.6.1