Add a new xs_watch_depth() function to libxenstore allowing to limit
the scope of a Xenstore watch. It can be used only in case Xenstore is
supporting the XENSTORE_SERVER_FEATURE_WATCHDEPTH feature.
For convenience add a xs_watch_try_depth() wrapper, which will call
xs_watch_depth() if supported and xs_watch() otherwise.
Cache the supported features of Xenstore in order not having to get
them from Xenstore for each call of one of the new functions.
While touching xs.c fix a whitespace issue there.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jason Andryuk <jason.andryuk@amd.com>
Juergen Gross
27d908e74e