Bug 1109749

Description of problem:
Engine validator canRunVm cannot handle situation of messages parameter being Null. This, under certain circumstances, blocks users from being attached to a pool VM and as a result of that they're not able to get a VM from Pool.

Version-Release number of selected component (if applicable):
3.3.3

How reproducible:
Not sure of the reproducer. In customer's usecase any pool created under 3.3 Compatibility mode exhibits this behavior.

Additional info:

014-06-02 09:05:51,603 INFO  [org.ovirt.engine.core.bll.AttachUserToVmFromPoolAndRunCommand] (ajp-/127.0.0.1:8702-41) [343c44e3] Lock freed to object EngineLock [exclusiveLocks= key: 2ce9ba7c-bc2c-4b36-afdd-44122092b16d value: USER_VM_POOL
, sharedLocks= ]
2014-06-02 09:05:51,687 INFO  [org.ovirt.engine.core.bll.AttachUserToVmFromPoolAndRunCommand] (ajp-/127.0.0.1:8702-16) [4aa9b181] Lock Acquired to object EngineLock [exclusiveLocks= key: 3486bf14-1e2a-49d8-a3b8-53e4edee3f0e value: USER_VM_POOL
, sharedLocks= ]
2014-06-02 09:05:51,932 ERROR [org.ovirt.engine.core.bll.AttachUserToVmFromPoolAndRunCommand] (ajp-/127.0.0.1:8702-16) [4aa9b181] Error during CanDoActionFailure.: java.lang.NullPointerException
        at org.ovirt.engine.core.bll.VmPoolCommandBase.canRunPoolVm(VmPoolCommandBase.java:229) [bll.jar:]
        at org.ovirt.engine.core.bll.VmPoolCommandBase.isVmFree(VmPoolCommandBase.java:139) [bll.jar:]
        at org.ovirt.engine.core.bll.VmPoolCommandBase.canAttachNonPrestartedVmToUser(VmPoolCommandBase.java:105) [bll.jar:]
        at org.ovirt.engine.core.bll.AttachUserToVmFromPoolAndRunCommand.getNonPrestartedVmToAttach(AttachUserToVmFromPoolAndRunCommand.java:127) [bll.jar:]
        at org.ovirt.engine.core.bll.AttachUserToVmFromPoolAndRunCommand.getVmToAttach(AttachUserToVmFromPoolAndRunCommand.java:104) [bll.jar:]
        at org.ovirt.engine.core.bll.AttachUserToVmFromPoolAndRunCommand.canDoAction(AttachUserToVmFromPoolAndRunCommand.java:64) [bll.jar:]
        at org.ovirt.engine.core.bll.CommandBase.internalCanDoAction(CommandBase.java:741) [bll.jar:]
        at org.ovirt.engine.core.bll.CommandBase.executeAction(CommandBase.java:356) [bll.jar:]
        at org.ovirt.engine.core.bll.Backend.runAction(Backend.java:416) [bll.jar:]
        at org.ovirt.engine.core.bll.Backend.runActionImpl(Backend.java:395) [bll.jar:]
        at org.ovirt.engine.core.bll.Backend.RunAction(Backend.java:353) [bll.jar:]
        at sun.reflect.GeneratedMethodAccessor187.invoke(Unknown Source) [:1.7.0_51]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) [rt.jar:1.7.0_51]
        at java.lang.reflect.Method.invoke(Method.java:606) [rt.jar:1.7.0_51]
        at org.jboss.as.ee.component.ManagedReferenceMethodInterceptorFactory$ManagedReferenceMethodInterceptor.processInvocation(ManagedReferenceMethodInterceptorFactory.java:72) [jboss-as-ee.jar:7.3.1.Final-redhat-3]


Taking a look into the code the NullPointer Exception is thrown from CanDoAction method which checks availability of Pool VM in AttachUserToVmFromPoolAndRunCommand.java class

    protected boolean canDoAction() {
        boolean returnValue = true;

        synchronized (_lockObject) {
            // no available VMs:
            if (Guid.Empty.equals(getVmToAttach(getParameters().getVmPoolId())))
            {
                addCanDoActionMessage(VdcBllMessages.ACTION_TYPE_FAILED_NO_AVAILABLE_POOL_VMS);
                returnValue = false;
            }
        }

This means NPE has to be thrown out by following clause:
if (Guid.Empty.equals(getVmToAttach(getParameters().getVmPoolId())))

Following code is the one throwing NPE:

    protected static boolean canRunPoolVm(Guid vmId, ArrayList<String> messages) {
        VM vm = DbFacade.getInstance().getVmDao().get(vmId);
        if (vm == null) {
            messages.add(VdcBllMessages.ACTION_TYPE_FAILED_VM_NOT_FOUND.name());
            return false;
        }

        // TODO: This is done to keep consistency with VmDAO.getById.
        // It can probably be removed, but that requires some more research
        VmHandler.updateNetworkInterfacesFromDb(vm);

        RunVmParams runVmParams = new RunVmParams(vmId);
        runVmParams.setUseVnc(osRepository.isLinux(vm.getVmOsId()) || vm.getVmType() == VmType.Server);

        return new RunVmValidator(vm, runVmParams, false, findActiveISODomain(vm.getStoragePoolId()))
                .canRunVm(
   --------->           messages,
                        fetchStoragePool(vm.getStoragePoolId()),
                        Collections.<Guid> emptyList(),
                        null,
                        null,
                        DbFacade.getInstance().getVdsGroupDao().get(vm.getVdsGroupId()));
    }

    ---------> It looks like the messages parameter of canRunVm is null

Checking lower level code it looks like the validator expects the messages to be a list,
but does not anyhow handle if the list is null and no messages are populated in it:

    public boolean canRunVm(List<String> messages, StoragePool storagePool, List<Guid> vdsBlackList,
            List<Guid> vdsWhiteList, Guid destVds, VDSGroup vdsGroup) {

        if (vm.getStatus() == VMStatus.Paused) {
            // if the VM is paused, we should only check the VDS status
            // as the rest of the checks were already checked before
            return validate(validateVdsStatus(vm), messages);
        }

        return
                validateVmProperties(vm, runVmParam.getCustomProperties(), messages) &&
                validate(validateBootSequence(vm, runVmParam.getBootSequence(), getVmDisks(), activeIsoDomainId), messages) &&
                validate(validateDisplayType(), messages) &&
                validate(new VmValidator(vm).vmNotLocked(), messages) &&
                validate(getSnapshotValidator().vmNotDuringSnapshot(vm.getId()), messages) &&
                validate(validateVmStatusUsingMatrix(vm), messages) &&
                validate(validateStoragePoolUp(vm, storagePool, getVmImageDisks()), messages) &&
                validate(validateIsoPath(vm, runVmParam.getDiskPath(), runVmParam.getFloppyPath(), activeIsoDomainId), messages)  &&
                validate(vmDuringInitialization(vm), messages) &&
                validate(validateStatelessVm(vm, getVmDisks(), runVmParam.getRunAsStateless()), messages) &&
                validate(validateStorageDomains(vm, isInternalExecution, getVmImageDisks()), messages) &&
                validate(validateImagesForRunVm(vm, getVmImageDisks()), messages) &&
                SchedulingManager.getInstance().canSchedule(
                        vdsGroup, vm, vdsBlackList, vdsWhiteList, destVds, messages);
    }