Re: New Outreachy Applicant

[Ronald Rojas <ronladred@gmail.com>]

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On Tue, Sep 20, 2016 at 04:24:47PM +0100, George Dunlap wrote:
> Thanks for your interest in the Xen Project!  Sorry for the delay in
> responding -- somehow your mail either never made it to my personal
> inbox or I accidentally deleted it instead of filing it properly.  I
> saw your question on IRC and now found your mail here on xen-devel.
> 
> First, I want to emphasize that Outreachy internships should be
> considered a full-time job.  As part of the application process you
> will be asked to confirm that you will not be taking any classes, nor
> have any other significant commitments (such as another job) during
> the period of the internship.

I'll confirm now that won't be taking any classes or working during the
majority of the program, however the fall semester for my college will
end around the 20th of December. 
> 
> Now on to the bite-sized task.  We've actually found that one of the
> difficult parts of getting going with our project is making sure that
> you understand how to get your whole system and environment set up.
> And another thing we want to see is to what degree you can balance
> figuring things out, finding the answers on the web, and asking for
> help when you need it.
> 
> So with that in mind, we've started experimenting with tasks which
> don't contribute very much to the project directly, but provide a
> really solid base of knowledge to do further contributions.
> 
> So here's my challenge for you.
> 
> -------
> OUTCOME
> 
> Write a simple go program that will list the current cpu pools,
> similar to the output of "xl cpupool-list".  No need to handle extra
> arguments or modify libxl.go (beyond what may be needed to compile it).

RESULTS:
I've managed to get xen running on my local machine. I am running linux natively
on ubuntu with xen 4.8-unstable and it is running reasonable well.
There are two VM's running on my computer, one is named tutorial-pv-guest that I
created by following the xen beginners guide. The other is called ubuntu1 and
was created through a custom configuration file that I created. I wasn't having
much luck with the outreachy tutorial provided so after some googling the link 
below really helped me get through the process.

http://www.virtuatopia.com/index.php/Building_a_Xen_Guest_Domain_using_Xen-Tools

> 
> Please post a copy of your .go program, along with the results of
> output *when more than one VM is running*.

The output when I run "sudo go run libxl.go" is pasted below. The output was made 
when the two VM's mentioned above were running. It prints out the appropiate 
output for Pool Name, Scheduler, and Domain Count. 
All the changes in libxl.go are contained within the main() method and the libxl.go
file is pasted below as well.


CONCERNS/QUESTIONS:
I believe I was only able to print out the information for Name, Sched, and Domain 
count because the other information such as Active and CPU's are not stored within
CpupoolInfo. Was there a way I could obtain that information? I don't think the 
code privided had that functionality. Maybe the next task could be to add that 
functionality?
It also seems that Domain Count is off. The command "xl cpupool-list" lists 3 domains
(which are Dom0, tutorial-pv-guest, and ubuntu1) but my program returns 11 domains. 
Would you like me to look into the issue? I'm using the information called from 
Ctx.ListCpupool() so I may have to take a closer look at that code. 

Thank You!
Ronald Rojas

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Name		Sched		Domain count
Pool-0		credit		11

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/*
 * Copyright (C) 2016 George W. Dunlap, Citrix Systems UK Ltd
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; version 2 of the
 * License only.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 */
package main

/*
#cgo LDFLAGS: -lyajl -lxenlight
#include <libxl.h>
#include <stdlib.h>
*/
import "C"

import (
	"unsafe"
	"fmt"
	"time"
)

type Context struct {
	ctx *C.libxl_ctx
}

var Ctx Context

func (Ctx *Context) IsOpen() bool {
	return Ctx.ctx != nil
}

func (Ctx *Context) Open() (err error) {
	if Ctx.ctx != nil {
		return
	}
	
	ret := C.libxl_ctx_alloc(unsafe.Pointer(&Ctx.ctx), C.LIBXL_VERSION, 0, nil)

	if ret != 0 {
		err = fmt.Errorf("Allocating libxl context: %d", ret)
	}
	return
}

func (Ctx *Context) Close() (err error) {
	ret := C.libxl_ctx_free(unsafe.Pointer(Ctx.ctx))
	Ctx.ctx = nil

	if ret != 0 {
		err = fmt.Errorf("Freeing libxl context: %d", ret)
	}
	return
}

type Domid uint32

type MemKB uint64

// FIXME: Use the idl to generate types
type Dominfo struct {
	// FIXME: uuid
	Domid             Domid
	Running           bool
	Blocked           bool
	Paused            bool
	Shutdown          bool
	Dying             bool
	Never_stop        bool
	
	Shutdown_reason   int32 // FIXME shutdown_reason enumeration
	Outstanding_memkb MemKB
	Current_memkb     MemKB
	Shared_memkb      MemKB
	Paged_memkb       MemKB
	Max_memkb         MemKB
	Cpu_time          time.Duration
	Vcpu_max_id       uint32
	Vcpu_online       uint32
	Cpupool           uint32
	Domain_type       int32 //FIXME libxl_domain_type enumeration

}

func (Ctx *Context) DomainInfo(Id Domid) (di *Dominfo, err error) {
	if Ctx.ctx == nil {
		err = fmt.Errorf("Context not opened")
		return
	}

		
	var cdi C.libxl_dominfo

	ret := C.libxl_domain_info(Ctx.ctx, unsafe.Pointer(&cdi), C.uint32_t(Id))

	// FIXME: IsDomainNotPresentError
	if ret != 0 {
		err = fmt.Errorf("libxl_domain_info failed: %d", ret)
		return
	}

	// FIXME -- use introspection to make this more robust
	di = &Dominfo{}
	di.Domid = Domid(cdi.domid)
	di.Running = bool(cdi.running)
	di.Blocked = bool(cdi.blocked)
	di.Paused = bool(cdi.paused)
	di.Shutdown = bool(cdi.shutdown)
	di.Dying = bool(cdi.dying)
	di.Never_stop = bool(cdi.never_stop)
	di.Shutdown_reason = int32(cdi.shutdown_reason)
	di.Outstanding_memkb = MemKB(cdi.outstanding_memkb)
	di.Current_memkb = MemKB(cdi.current_memkb)
	di.Shared_memkb = MemKB(cdi.shared_memkb)
	di.Paged_memkb = MemKB(cdi.paged_memkb)
	di.Max_memkb = MemKB(cdi.max_memkb)
	di.Cpu_time = time.Duration(cdi.cpu_time)
	di.Vcpu_max_id = uint32(cdi.vcpu_max_id)
	di.Vcpu_online = uint32(cdi.vcpu_online)
	di.Cpupool = uint32(cdi.cpupool)
	di.Domain_type = int32(cdi.domain_type)
	return
}

func (Ctx *Context) DomainUnpause(Id Domid) (err error) {
	if Ctx.ctx == nil {
		err = fmt.Errorf("Context not opened")
		return
	}

	ret := C.libxl_domain_unpause(Ctx.ctx, C.uint32_t(Id))

	if ret != 0 {
		err = fmt.Errorf("libxl_domain_unpause failed: %d", ret)
	}
	return
}


// typedef struct {
//     uint32_t size;          /* number of bytes in map */
//     uint8_t *map;
// } libxl_bitmap;
// void libxl_bitmap_init(libxl_bitmap *map);
// void libxl_bitmap_dispose(libxl_bitmap *map);

// # Consistent with values defined in domctl.h
// # Except unknown which we have made up
// libxl_scheduler = Enumeration("scheduler", [
//     (0, "unknown"),
//     (4, "sedf"),
//     (5, "credit"),
//     (6, "credit2"),
//     (7, "arinc653"),
//     (8, "rtds"),
//     ])
type Scheduler int
var (
	SchedulerUnknown  Scheduler = 0
	SchedulerSedf     Scheduler = 4
	SchedulerCredit   Scheduler = 5
	SchedulerCredit2  Scheduler = 6
	SchedulerArinc653 Scheduler = 7
	SchedulerRTDS     Scheduler = 8
)

// const char *libxl_scheduler_to_string(libxl_scheduler p);
// int libxl_scheduler_from_string(const char *s, libxl_scheduler *e);
func (s Scheduler) String() (string) {
	cs := C.libxl_scheduler_to_string(C.libxl_scheduler(s))
	// No need to free const return value

	return C.GoString(cs)
}

func SchedulerFromString(name string) (s Scheduler, err error) {
	cname := C.CString(name)
	defer C.free(unsafe.Pointer(cname))

	var cs C.libxl_scheduler

	ret := C.libxl_scheduler_from_string(cname, &cs)
	if ret != 0 {
		err = fmt.Errorf("libxl_scheduler_from_string failed: %d", ret)
		return
	}

	s = Scheduler(cs)

	return
}

// libxl_cpupoolinfo = Struct("cpupoolinfo", [
//     ("poolid",      uint32),
//     ("pool_name",   string),
//     ("sched",       libxl_scheduler),
//     ("n_dom",       uint32),
//     ("cpumap",      libxl_bitmap)
//     ], dir=DIR_OUT)

type CpupoolInfo struct {
	PoolId uint32
	PoolName string
	Scheduler Scheduler
	DomainCount int
	// Punt on cpumap for now
}

// libxl_cpupoolinfo * libxl_list_cpupool(libxl_ctx*, int *nb_pool_out);
// void libxl_cpupoolinfo_list_free(libxl_cpupoolinfo *list, int nb_pool);
func (Ctx *Context) ListCpupool() (list []CpupoolInfo) {
	var nbPool C.int

	c_cpupool_list := C.libxl_list_cpupool(Ctx.ctx, &nbPool)

	defer C.libxl_cpupoolinfo_list_free(c_cpupool_list, nbPool)

	if int(nbPool) == 0 {
		return
	}

	// Magic
	cpupoolListSlice := (*[1 << 30]C.libxl_cpupoolinfo)(unsafe.Pointer(c_cpupool_list))[:nbPool:nbPool]

	for i := range cpupoolListSlice {
		var info CpupoolInfo
		
		info.PoolId = uint32(cpupoolListSlice[i].poolid)
		info.PoolName = C.GoString(cpupoolListSlice[i].pool_name)
		info.Scheduler = Scheduler(cpupoolListSlice[i].sched)
		info.DomainCount = int(cpupoolListSlice[i].n_dom)

		list = append(list, info)
	}

	return
}

func (Ctx *Context) CpupoolFindByName(name string) (info CpupoolInfo, found bool) {
	plist := Ctx.ListCpupool()

	for i := range plist {
		if plist[i].PoolName == name {
			found = true
			info = plist[i]
			return
		}
	}
	return
}




func main() {
    err := Ctx.Open()
    if err != nil{
        fmt.Print(err)
        return
    }
    var list []CpupoolInfo = Ctx.ListCpupool()

    fmt.Print("Name\t\tSched\t\tDomain count\n")
    for _, info := range list {
        fmt.Printf("%s\t\t%s\t\t%b\n", info.PoolName, info.Scheduler, info.DomainCount)
    }



}

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