[Libvirt-cim] [PATCH] Avoid connection to libvirt if previous attempt fails

[Chip Vincent]

Very nice! This should keep things must simpler and quiet, especially 
with brute force clients.

Thanks.

BTW - I ran tests before and after this patch with no diff in results:

# diff 01_run_report.txt 02_run_report.txt
9,10c9,10
< Libvirt-cim revision: 1156
< Libvirt-cim changeset: 555e122
---
 > Libvirt-cim revision: 1158
 > Libvirt-cim changeset: d0c6a89

So, +1 and pushed. Thanks!!!

On 10/28/2011 04:03 PM, Eduardo Lima (Etrunko) wrote:
> From: Eduardo Lima (Etrunko)<eblima at br.ibm.com>
>
> This is a workaround to avoid libvirt flooding error messages in syslog. This
> happens often if a client submits queries for CIM_ superclasses, which then will
> translate to a query for each registered class. In our case KVM_, LXC_ and XEN_.
>
> Ideally, there should be a way to ask libvirt if a given URI or hypervisor is
> enabled/supported. A patch for that feature is on the works, and as soon as it
> is integrated to libvirt tree this feature will be updated.
>
> Signed-off-by: Eduardo Lima (Etrunko)<eblima at br.ibm.com>
> ---
>   libxkutil/misc_util.c |   48 ++++++++++++++++++++++++++++++++++++++++++++++++
>   1 files changed, 48 insertions(+), 0 deletions(-)
>
> diff --git a/libxkutil/misc_util.c b/libxkutil/misc_util.c
> index c2cc204..61893c3 100644
> --- a/libxkutil/misc_util.c
> +++ b/libxkutil/misc_util.c
> @@ -24,6 +24,7 @@
>
>   #include<stdio.h>
>   #include<string.h>
> +#include<strings.h>
>   #include<stdlib.h>
>   #include<stdbool.h>
>   #include<stdarg.h>
> @@ -53,6 +54,46 @@ static int libvirt_initialized = 0;
>
>   #define URI_ENV "HYPURI"
>
> +struct _hypervisor_status_t {
> +        const char *name;
> +        bool enabled;
> +};
> +
> +typedef struct _hypervisor_status_t hypervisor_status_t;
> +
> +static hypervisor_status_t hypervisor_list[] = {
> +        { "xen", true },
> +        { "kvm", true },
> +        { "lxc", true },
> +        { NULL },
> +};
> +
> +static bool get_hypervisor_enabled(const char *hypervisor)
> +{
> +        hypervisor_status_t *h;
> +
> +        for (h =&hypervisor_list[0]; h != NULL; h++) {
> +                if (strncasecmp(hypervisor, h->name, strlen(h->name)) == 0) {
> +                        return h->enabled;
> +                }
> +        }
> +
> +        return false;
> +}
> +
> +static void set_hypervisor_disabled(const char *hypervisor)
> +{
> +        hypervisor_status_t *h;
> +
> +        for (h =&hypervisor_list[0]; h != NULL; h++) {
> +                if (strncasecmp(hypervisor, h->name, strlen(h->name)) == 0) {
> +                        CU_DEBUG("Setting '%s' hypervisor as DISABLED", h->name);
> +                        h->enabled = false;
> +                        return;
> +                }
> +        }
> +}
> +
>   static const char *cn_to_uri(const char *classname)
>   {
>           if (STARTS_WITH(classname, "Xen"))
> @@ -117,6 +158,9 @@ virConnectPtr connect_by_classname(const CMPIBroker *broker,
>                   return NULL;
>           }
>
> +        if (!get_hypervisor_enabled(classname))
> +                return NULL;
> +
>           CU_DEBUG("Connecting to libvirt with uri `%s'", uri);
>
>           pthread_mutex_lock(&libvirt_mutex);
> @@ -129,6 +173,10 @@ virConnectPtr connect_by_classname(const CMPIBroker *broker,
>           pthread_mutex_unlock(&libvirt_mutex);
>
>           if (!conn) {
> +                virErrorPtr error = virGetLastError();
> +                if (error->code == VIR_ERR_NO_CONNECT)
> +                        set_hypervisor_disabled(classname);
> +
>                   CU_DEBUG("Unable to connect to `%s'", uri);
>                   return NULL;
>           }


-- 
Chip Vincent
Open Virtualization
IBM Linux Technology Center
cvincent at linux.vnet.ibm.com