Fix race in QEMU shutdown

1 files changed, 14 insertions, 4 deletions

diff --git a/bbot/agent/machine.cxx b/bbot/agent/machine.cxx
index 69ef3c7..fdc11c0 100644
--- a/bbot/agent/machine.cxx
+++ b/bbot/agent/machine.cxx
@@ -378,8 +378,16 @@ namespace bbot
     }
     catch (const system_error& e)
     {
-      size_t t (0);
-      if (wait (t))
+      // There is a window between QEMU closing the monitor socket and exiting
+      // so we wait but only briefly.
+      //
+      size_t t (seconds > 0 ? 1 : 0);
+
+      seconds -= t;
+      bool r (wait (t));
+      seconds += t;
+
+      if (r)
         return true;
 
       fail << "unable to communicate with qemu monitor: " << e;
@@ -391,13 +399,15 @@ namespace bbot
   void kvm_machine::
   forcedown (bool fh)
   {
+    // Similar logic to shutdown().
+    //
     try
     {
       monitor_command ("system_reset");
     }
     catch (const system_error& e)
     {
-      size_t t (0);
+      size_t t (1);
       if (wait (t, fh))
         return;
 
@@ -450,7 +460,7 @@ namespace bbot
     }
     catch (const process_error& e)
     {
-      fail (fh) << "unable to execute " << kvm << ": " << e << endf;
+      fail (fh) << "unable to wait for " << kvm << ": " << e << endf;
     }
   }