Re: [Xen-devel] [PATCH RFC 3/8] golang/xenlight: Add host-related functionality

[George Dunlap <george.dunlap@xxxxxxxxxx>]

On 18/01/17 19:56, Ronald Rojas wrote:
> Add calls for the following host-related functionality:
> - libxl_get_max_cpus
> - libxl_get_online_cpus
> - libxl_get_max_nodes
> - libxl_get_free_memory
> - libxl_get_physinfo
> - libxl_get_version_info
> 
> Include Golang versions of the following structs:
> - libxl_physinfo as Physinfo
> - libxl_version_info as VersionInfo
> - libxl_hwcap as Hwcap
> 
> Signed-off-by: Ronald Rojas <ronladred@xxxxxxxxx>

This looks good, and I think could be checked in once rebased on
previous changes.  One comment for future direction...

> ---
>  tools/golang/xenlight/xenlight.go | 185 
> ++++++++++++++++++++++++++++++++++++++
>  1 file changed, 185 insertions(+)
> 
> diff --git a/tools/golang/xenlight/xenlight.go 
> b/tools/golang/xenlight/xenlight.go
> index d58f8b8..6b04850 100644
> --- a/tools/golang/xenlight/xenlight.go
> +++ b/tools/golang/xenlight/xenlight.go
> @@ -109,6 +109,62 @@ type Context struct {
>       ctx *C.libxl_ctx
>  }
>  
> +type Hwcap []C.uint32_t
> +
> +func hwcapCToGo(chwcap C.libxl_hwcap) (ghwcap Hwcap) {
> +     // Alloc a Go slice for the bytes
> +     size := 8
> +     ghwcap = make([]C.uint32_t, size)
> +
> +     // Make a slice pointing to the C array
> +     mapslice := (*[1 << 
> 30]C.uint32_t)(unsafe.Pointer(&chwcap[0]))[:size:size]
> +
> +     // And copy the C array into the Go array
> +     copy(ghwcap, mapslice)
> +
> +     return
> +}

In my own copy of the library, I was experimenting with using methods to
do this, rather than making standalone functions that embed the name in
the type.  Something like this:

func (c C.libxl_dominfo) toGo() (g Dominfo) {
        g.Uuid = Uuid(c.uuid)
 [etc]
}

That way you can do cdi.toGo() rather than dominfoCToGo(cdi).  The
syntax looks a lot cleaner and more consistent.

What do you think?

 -George


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