[libvirt] [PATCHv5 14/19] Util: Add function for checking if monitor is running

[John Ferlan]

On 10/9/18 6:30 AM, Wang Huaqiang wrote:
> Check monitor status by checking the PIDs are in file 'task'
> or not.
> 
> Signed-off-by: Wang Huaqiang <huaqiang.wang at intel.com>
> ---
>  src/libvirt_private.syms |  1 +
>  src/util/virresctrl.c    | 84 +++++++++++++++++++++++++++++++++++++++++++++++-
>  src/util/virresctrl.h    |  4 +++
>  3 files changed, 88 insertions(+), 1 deletion(-)
> 
> diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
> index 4b22ed4..c90e48a 100644
> --- a/src/libvirt_private.syms
> +++ b/src/libvirt_private.syms
> @@ -2686,6 +2686,7 @@ virResctrlMonitorDeterminePath;
>  virResctrlMonitorGetCacheLevel;
>  virResctrlMonitorGetCacheOccupancy;
>  virResctrlMonitorGetID;
> +virResctrlMonitorIsRunning;
>  virResctrlMonitorNew;
>  virResctrlMonitorRemove;
>  virResctrlMonitorSetCacheLevel;
> diff --git a/src/util/virresctrl.c b/src/util/virresctrl.c
> index 41e8d48..67dfbb8 100644
> --- a/src/util/virresctrl.c
> +++ b/src/util/virresctrl.c
> @@ -364,6 +364,9 @@ struct _virResctrlMonitor {
>      char *path;
>      /* Boolean flag for default monitor */
>      bool default_monitor;
> +    /* Tracking the tasks' PID associated with this monitor */
> +    pid_t *pids;
> +    size_t npids;
>      /* The cache 'level', special for cache monitor */
>      unsigned int cache_level;
>  };
> @@ -425,6 +428,7 @@ virResctrlMonitorDispose(void *obj)
>      virObjectUnref(monitor->alloc);
>      VIR_FREE(monitor->id);
>      VIR_FREE(monitor->path);
> +    VIR_FREE(monitor->pids);
>  }
>  
>  
> @@ -2491,7 +2495,13 @@ int
>  virResctrlMonitorAddPID(virResctrlMonitorPtr monitor,
>                          pid_t pid)
>  {
> -    return virResctrlAddPID(monitor->path, pid);
> +    if (virResctrlAddPID(monitor->path, pid) < 0)
> +        return -1;
> +
> +    if (VIR_APPEND_ELEMENT(monitor->pids, monitor->npids, pid) < 0)
> +        return -1;
> +
> +    return 0;
>  }
>  
>  
> @@ -2762,3 +2772,75 @@ virResctrlMonitorSetDefault(virResctrlMonitorPtr monitor)
>  {
>      monitor->default_monitor = true;
>  }
> +
> +
> +static int
> +virResctrlPIDCompare(const void *pida, const void *pidb)
> +{
> +    return *(pid_t*)pida - *(pid_t*)pidb;
> +}
> +
> +
> +bool
> +virResctrlMonitorIsRunning(virResctrlMonitorPtr monitor)
> +{
> +    char *pidstr = NULL;
> +    char **spids = NULL;
> +    size_t nspids = 0;
> +    pid_t *pids = NULL;
> +    size_t npids = 0;
> +    size_t i = 0;
> +    int rv = -1;
> +    bool ret = false;
> +
> +    if (!monitor->path)
> +        return false;
> +
> +    if (monitor->npids == 0)
> +        return false;
> +
> +    rv = virFileReadValueString(&pidstr, "%s/tasks", monitor->path);
> +    if (rv == -2)
> +        virReportError(VIR_ERR_INTERNAL_ERROR,
> +                       _("Task file '%s/tasks' does not exist"),
> +                       monitor->path);
> +    if (rv < 0)
> +        goto cleanup;
> +
> +    /* no PID in task file */
> +    if (!*pidstr)
> +        goto cleanup;
> +
> +    spids = virStringSplitCount(pidstr, "\n", 0, &nspids);
> +    if (nspids != monitor->npids)
> +        return false;

This will cause a leak...  "goto cleanup;"

> +
> +    for (i = 0; i < nspids; i++) {
> +        unsigned int val = 0;
> +        pid_t pid = 0;
> +
> +        if (virStrToLong_uip(spids[i], NULL, 0, &val) < 0)
> +            goto cleanup;
> +
> +        pid = (pid_t)val;
> +
> +        if (VIR_APPEND_ELEMENT(pids, npids, pid) < 0)
> +            goto cleanup;
> +    }
> +
> +    qsort(pids, npids, sizeof(pid_t), virResctrlPIDCompare);
> +    qsort(monitor->pids, monitor->npids, sizeof(pid_t), virResctrlPIDCompare);
> +
> +    for (i = 0; i < monitor->npids; i++) {
> +        if (monitor->pids[i] != pids[i])
> +            goto cleanup;
> +    }
> +
> +    ret = true;
> + cleanup:

NB: Any place where you get here without an error message, but w/ ret =
false may cause "issues" for the caller especially since some of the
ways to get here w/ @false do set an error message.

John

> +    virStringListFree(spids);
> +    VIR_FREE(pids);
> +    VIR_FREE(pidstr);
> +
> +    return ret;
> +}
> diff --git a/src/util/virresctrl.h b/src/util/virresctrl.h
> index 371df8a..c5794cb 100644
> --- a/src/util/virresctrl.h
> +++ b/src/util/virresctrl.h
> @@ -230,4 +230,8 @@ virResctrlMonitorGetCacheOccupancy(virResctrlMonitorPtr monitor,
>                                     unsigned int **bankcaches);
>  void
>  virResctrlMonitorSetDefault(virResctrlMonitorPtr monitor);
> +
> +bool
> +virResctrlMonitorIsRunning(virResctrlMonitorPtr monitor);
> +
>  #endif /*  __VIR_RESCTRL_H__ */
>