virtigo/event.go

package main

import (
	"fmt"
	"math/rand"
	"time"

	"go.wit.com/lib/gui/shell"
	pb "go.wit.com/lib/protobuf/virtbuf"
	"go.wit.com/log"
)

// restarts the virtigod daemon on a hypervisor via http
func (h *HyperT) RestartVirtigod() {
	url := "http://" + h.pb.Hostname + ":2520/kill"
	s := shell.Wget(url)
	log.Info("EVENT RestartVirtigod", url, s)
	h.lastpoll = time.Now()
	h.killcount += 1

	dur := time.Since(h.lastpoll) // Calculate the elapsed time
	log.Info("KILLED DAEMON", h.pb.Hostname, shell.FormatDuration(dur), "curl", url)
	me.killcount += 1

	// mark the cluster as unstable so droplet starts can be throttled
	me.unstable = time.Now()
}

var stableTimeout time.Duration = 43 * time.Second

// checks if the cluster is ready and stable
func clusterReady() (bool, string) {
	last := time.Since(me.unstable)
	if last > stableTimeout {
		// the cluster has not been stable for 133 seconds
		log.Warn("clusterReady() is stable for ", shell.FormatDuration(stableTimeout), " secs")
		return true, fmt.Sprintln("clusterReady() is stable ", shell.FormatDuration(stableTimeout), " secs")
	}
	log.Warn("clusterReady() is unstable for", shell.FormatDuration(last))
	return false, "clusterReady() is unstable for " + shell.FormatDuration(last)
}

func dropletReady(d *pb.Droplet) (bool, string) {
	if d.CurrentState == pb.DropletState_ON {
		return false, "EVENT start droplet is already ON"
	}
	if d.Starts > 2 {
		// reason := "EVENT start droplet has already been started " + d.starts + " times"
		return false, fmt.Sprintln("EVENT start droplet has already been started ", d.Starts, " times")
	}
	return true, ""
}

func (h *HyperT) start(d *pb.Droplet) (bool, string) {
	ready, result := clusterReady()
	if !ready {
		return false, result
	}
	ready, result = dropletReady(d)
	if !ready {
		return false, result
	}

	url := "http://" + h.pb.Hostname + ":2520/start?start=" + d.Hostname
	s := shell.Wget(url)
	result = "EVENT start droplet url: " + url + "\n"
	result += "EVENT start droplet response: " + s.String()

	// increment the counter for a start attempt working
	d.Starts += 1

	// mark the cluster as unstable so droplet starts can be throttled
	me.unstable = time.Now()

	return true, result
}

func findDroplet(name string) *pb.Droplet {
	for _, d := range me.cluster.Droplets {
		if d.Hostname == name {
			return d
		}
	}
	return nil
}

func Start(name string) (bool, string) {
	var result string

	d := findDroplet(name)
	if d == nil {
		result += "can't start unknown droplet: " + name
		return false, result
	}

	if d.CurrentState == pb.DropletState_ON {
		return false, "EVENT start droplet " + d.Hostname + " is already ON"
	}

	dur := time.Since(me.unstable) // how long has the cluster been stable?
	result = fmt.Sprintln("should start droplet", name, "here. grid stable for:", shell.FormatDuration(dur))
	if dur < 17*time.Second {
		result += "grid is still too unstable"
		return false, result
	}

	// make the list of hypervisors that are active and can start new droplets
	var pool []*HyperT
	for _, h := range me.hypers {
		result += fmt.Sprintln("could start droplet on", name, "on", h.pb.Hostname, h.pb.Active)
		if d.PreferredHypervisor == h.pb.Hostname {
			// the config file says this droplet should run on this hypervisor
			a, b := h.start(d)
			return a, result + b
		}

		if h.pb.Active != true {
			continue
		}
		pool = append(pool, h)
	}

	// left here as an example of how to actually do random numbers
	// it's complete mathematical chaos. Randomness is simple when
	// human interaction occurs -- which is exactly what happens most
	// of the time. most random shit is bullshit. all you really need
	// is exactly this to make sure the random functions work as they
	// should. Probably, just use this everywhere in all cases. --jcarr
	rand.Seed(time.Now().UnixNano())
	a := 0
	b := len(pool)
	n := a + rand.Intn(b-a)
	result += fmt.Sprintln("pool has", len(pool), "members", "rand =", n)
	h := pool[n]
	startbool, startresult := h.start(d)
	return startbool, result + startresult
}