[PATCH v1 3/7] tools/kvm_stat: fix updates for dead guests

[Stefan Raspl <raspl@xxxxxxxxxxxxx>]

From: Stefan Raspl <stefan.raspl@xxxxxxxxxx>

With pid filtering active, when a guest is removed e.g. via virsh shutdown,
successive updates produce garbage.
Therefore, we add code to detect this case and prevent further body updates.
Note that when displaying the help dialog via 'h' in this case, once we exit
we're stuck with the 'Collecting data...' message till we remove the filter.

Signed-off-by: Stefan Raspl <raspl@xxxxxxxxxxxxx>
---
 tools/kvm/kvm_stat/kvm_stat | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/tools/kvm/kvm_stat/kvm_stat b/tools/kvm/kvm_stat/kvm_stat
index b9e8d0def1ab..7c92545931e3 100755
--- a/tools/kvm/kvm_stat/kvm_stat
+++ b/tools/kvm/kvm_stat/kvm_stat
@@ -1170,6 +1170,9 @@ class Tui(object):
 
             return sorted_items
 
+        if not self._is_running_guest(self.stats.pid_filter):
+            # leave final data on screen
+            return
         row = 3
         self.screen.move(row, 0)
         self.screen.clrtobot()
@@ -1327,6 +1330,12 @@ class Tui(object):
                 msg = '"' + str(val) + '": Invalid value'
         self._refresh_header()
 
+    def _is_running_guest(self, pid):
+        """Check if pid is still a running process."""
+        if not pid:
+            return True
+        return os.path.isdir(os.path.join('/proc/', str(pid)))
+
     def _show_vm_selection_by_guest(self):
         """Draws guest selection mask.
 
@@ -1354,7 +1363,7 @@ class Tui(object):
             if not guest or guest == '0':
                 break
             if guest.isdigit():
-                if not os.path.isdir(os.path.join('/proc/', guest)):
+                if not self._is_running_guest(guest):
                     msg = '"' + guest + '": Not a running process'
                     continue
                 pid = int(guest)
-- 
2.16.4