CA-233915 turn post-op assertions that VM is "Running" into warnings

Most VM operations that change the power state of a VM include
assertions that the power state is indeed as expected after that
operation. Such a check can issue a false alarm in some cases and this
commit removes it from operations that change the power state to
"running" but still logs any unexpected power state:

    start
    unpause
    reboot
    resume

The problem was that the assertion was too naive when changing the
state into running: when a VM quickly changes its state once it is
running (e.g., by rebooting) the assertion can fail because it can be
too late and would find the VM not running as expected.

Assertions after operations that change the state not to running are
kept by this commit.

Signed-off-by: Christian Lindig <[email protected]>

Author: lindig

ocaml/xapi/xapi_xenops.ml

@@ -28,6 +28,20 @@ module Rrdd = Rrd_client.Client
 open Xenops_interface
 open Xapi_xenops_queue
 
+let check_power_state_is ~__context ~self ~expected =
+  if expected <> `Running then
+    Xapi_vm_lifecycle.assert_power_state_is ~__context ~self ~expected
+  else
+    (* CA-233915: only warn about unexpected power state - the check
+     * is too naive to make it an assertion
+     *)
+    let actual = Db.VM.get_power_state ~__context ~self in
+    if actual <> expected then
+      warn "Potential problem: VM %s in power state '%s' when expecting '%s'"
+        (Db.VM.get_uuid ~__context ~self)
+        (Record_util.power_to_string expected)
+        (Record_util.power_to_string actual)
+
 let event_wait queue_name dbg ?from p =
   let finished = ref false in
   let event_id = ref from in
@@ -2292,7 +2306,7 @@ let unpause ~__context ~self =
        let module Client = (val make_client queue_name : XENOPS) in
        Client.VM.unpause dbg id |> sync_with_task __context queue_name;
        Events_from_xenopsd.wait queue_name dbg id ();
-       Xapi_vm_lifecycle.assert_power_state_is ~__context ~self ~expected:`Running
+       check_power_state_is ~__context ~self ~expected:`Running
     )
 
 let request_rdp ~__context ~self enabled =
@@ -2452,7 +2466,7 @@ let start ~__context ~self paused force =
 
         set_resident_on ~__context ~self;
         (* set_resident_on syncs both xenopsd and with the xapi event mechanism *)
-        Xapi_vm_lifecycle.assert_power_state_is ~__context ~self ~expected:(if paused then `Paused else `Running)
+        check_power_state_is ~__context ~self ~expected:(if paused then `Paused else `Running)
       with e ->
         error "Caught exception starting VM: %s" (string_of_exn e);
         set_resident_on ~__context ~self;
@@ -2498,7 +2512,7 @@ let reboot ~__context ~self timeout =
            (fun () ->
               Events_from_xenopsd.wait queue_name dbg id ())
        in
-       Xapi_vm_lifecycle.assert_power_state_is ~__context ~self ~expected:`Running
+       check_power_state_is ~__context ~self ~expected:`Running
     )
 
 let shutdown ~__context ~self timeout =
@@ -2626,7 +2640,7 @@ let resume ~__context ~self ~start_paused ~force =
          (fun rpc session_id ->
             XenAPI.VDI.destroy rpc session_id vdi
          );
-       Xapi_vm_lifecycle.assert_power_state_is ~__context ~self ~expected:(if start_paused then `Paused else `Running)
+       check_power_state_is ~__context ~self ~expected:(if start_paused then `Paused else `Running)
     )
 
 let s3suspend ~__context ~self =