Re: [PATCH] libxenlight: fix multiple xenstore watches problem

[Andres Lagar-Cavilla <andres@lagarcavilla.com>]

mmm,
most likely the first two patches in my latest resend clash against 
this. Yikes
Andres
> Message: 3
> Date: Wed, 2 Dec 2009 15:01:32 +0000
> From: Stefano Stabellini<stefano.stabellini@eu.citrix.com>
> Subject: [Xen-devel] [PATCH] libxenlight: fix multiple xenstore
> 	watches	problem
> To: xen-devel@lists.xensource.com
> Message-ID:<alpine.DEB.2.00.0912021455450.26846@kaball-desktop>
> Content-Type: text/plain; charset="US-ASCII"
>
> Hi all,
> this patch fixes the multiple xenstore watches problem in libxenlight
> opening a new xenstore connection to set and read temporary watches on
> the device state nodes.
> This way they don't interfere with other long running watches.
>
> Signed-off-by: Stefano Stabellini<stefano.stabellini@eu.citrix.com>
>
> ---
>
> diff -r 96a9740f4f33 tools/libxl/libxl_device.c
> --- a/tools/libxl/libxl_device.c	Wed Dec 02 14:29:24 2009 +0000
> +++ b/tools/libxl/libxl_device.c	Wed Dec 02 14:43:06 2009 +0000
> @@ -212,47 +212,50 @@
>       fd_set rfds;
>       struct timeval tv;
>       flexarray_t *toremove;
> +    struct libxl_ctx clone = *ctx;
>
> +    clone.xsh = xs_daemon_open();
>       toremove = flexarray_make(16, 1);
> -    path = libxl_sprintf(ctx, "/local/domain/%d/device", domid);
> -    l1 = libxl_xs_directory(ctx, XBT_NULL, path,&num1);
> +    path = libxl_sprintf(&clone, "/local/domain/%d/device", domid);
> +    l1 = libxl_xs_directory(&clone, XBT_NULL, path,&num1);
>       if (!l1) {
> -        XL_LOG(ctx, XL_LOG_ERROR, "%s is empty", path);
> +        XL_LOG(&clone, XL_LOG_ERROR, "%s is empty", path);
> +        xs_daemon_close(clone.xsh);
>           return -1;
>       }
>       for (i = 0; i<  num1; i++) {
> -        path = libxl_sprintf(ctx, "/local/domain/%d/device/%s", domid, l1[i]);
> -        l2 = libxl_xs_directory(ctx, XBT_NULL, path,&num2);
> +        path = libxl_sprintf(&clone, "/local/domain/%d/device/%s", domid, l1[i]);
> +        l2 = libxl_xs_directory(&clone, XBT_NULL, path,&num2);
>           if (!l2)
>               continue;
>           for (j = 0; j<  num2; j++) {
> -            fe_path = libxl_sprintf(ctx, "/local/domain/%d/device/%s/%s", domid, l1[i], l2[j]);
> -            be_path = libxl_xs_read(ctx, XBT_NULL, libxl_sprintf(ctx, "%s/backend", fe_path));
> +            fe_path = libxl_sprintf(&clone, "/local/domain/%d/device/%s/%s", domid, l1[i], l2[j]);
> +            be_path = libxl_xs_read(&clone, XBT_NULL, libxl_sprintf(&clone, "%s/backend", fe_path));
>               if (be_path != NULL) {
> -                if (libxl_device_destroy(ctx, be_path, force)>  0)
> +                if (libxl_device_destroy(&clone, be_path, force)>  0)
>                       n_watches++;
> -                flexarray_set(toremove, n++, libxl_dirname(ctx, be_path));
> +                flexarray_set(toremove, n++, libxl_dirname(&clone, be_path));
>               } else {
> -                xs_rm(ctx->xsh, XBT_NULL, path);
> +                xs_rm(clone.xsh, XBT_NULL, path);
>               }
>           }
>       }
>       if (!force) {
> -        nfds = xs_fileno(ctx->xsh) + 1;
> +        nfds = xs_fileno(clone.xsh) + 1;
>           /* Linux-ism */
>           tv.tv_sec = LIBXL_DESTROY_TIMEOUT;
>           tv.tv_usec = 0;
>           while (n_watches>  0&&  tv.tv_sec>  0) {
>               FD_ZERO(&rfds);
> -            FD_SET(xs_fileno(ctx->xsh),&rfds);
> +            FD_SET(xs_fileno(clone.xsh),&rfds);
>               if (select(nfds,&rfds, NULL, NULL,&tv)>  0) {
> -                l1 = xs_read_watch(ctx->xsh,&num1);
> +                l1 = xs_read_watch(clone.xsh,&num1);
>                   if (l1 != NULL) {
> -                    char *state = libxl_xs_read(ctx, XBT_NULL, l1[0]);
> +                    char *state = libxl_xs_read(&clone, XBT_NULL, l1[0]);
>                       if (!state || atoi(state) == 6) {
> -                        xs_unwatch(ctx->xsh, l1[0], l1[1]);
> -                        xs_rm(ctx->xsh, XBT_NULL, l1[1]);
> -                        XL_LOG(ctx, XL_LOG_DEBUG, "Destroyed device backend at %s", l1[1]);
> +                        xs_unwatch(clone.xsh, l1[0], l1[1]);
> +                        xs_rm(clone.xsh, XBT_NULL, l1[1]);
> +                        XL_LOG(&clone, XL_LOG_DEBUG, "Destroyed device backend at %s", l1[1]);
>                           n_watches--;
>                       }
>                       free(l1);
> @@ -263,9 +266,10 @@
>       }
>       for (i = 0; i<  n; i++) {
>           flexarray_get(toremove, i, (void**)&path);
> -        xs_rm(ctx->xsh, XBT_NULL, path);
> +        xs_rm(clone.xsh, XBT_NULL, path);
>       }
>       flexarray_free(toremove);
> +    xs_daemon_close(clone.xsh);
>       return 0;
>   }
>
>