// Elect chooses a seed node, and returns a connection to a cal.
// If this process is the seed, returns nil.
func elect(name, id, laddr string, b *doozer.Conn) *doozer.Conn {
// advertise our presence, since we might become a cal
nspath := "/ctl/ns/" + name + "/" + id
r, err := b.Set(nspath, 0, []byte(laddr))
if err != nil {
panic(err)
}
// fight to be the seed
_, err = b.Set("/ctl/boot/"+name, 0, []byte(id))
if err, ok := err.(*doozer.Error); ok && err.Err == doozer.ErrOldRev {
// we lost, lookup addresses again
cl := lookupAndAttach(b, name)
if cl == nil {
panic("failed to attach after losing election")
}
// also delete our entry, since we're not officially a cal yet.
// it gets set again in peer.Main when we become a cal.
err := b.Del(nspath, r)
if err != nil {
panic(err)
}
return cl
} else if err != nil {
panic(err)
}
return nil // we are the seed node -- don't attach
}
// watch updates the peer list of servers based on changes to the
// doozer configuration or signals from the OS.
func watch(d *doozer.Conn) {
peerFile := "/peers"
var peers []string
var rev int64
// Run the initial get.
data, rev, err := d.Get(peerFile, nil)
if err != nil {
log.Println("initial peer list get:", err)
log.Println("using empty set to start")
peers = []string{}
} else {
peers = strings.Split(string(data), " ")
}
// Add myself to the list.
peers = append(peers, "http://"+addr)
rev, err = d.Set(peerFile, rev,
[]byte(strings.Join(peers, " ")))
if err != nil {
log.Println("unable to add myself to the peer list (no longer watching).")
return
}
pool.Set(peers...)
log.Println("added myself to the peer list.")
// Setup signal handling to deal with ^C and others.
sigs := make(chan os.Signal, 1)
signal.Notify(sigs, os.Interrupt, os.Kill)
// Get the channel that's listening for changes.
updates := wait(d, peerFile, &rev)
for {
select {
case <-sigs:
// Remove ourselves from the peer list and exit.
for i, peer := range peers {
if peer == "http://"+addr {
peers = append(peers[:i], peers[i+1:]...)
d.Set(peerFile, rev, []byte(strings.Join(peers, " ")))
log.Println("removed myself from peer list before exiting.")
}
}
os.Exit(1)
case update, ok := <-updates:
// If the channel was closed, we should stop selecting on it.
if !ok {
updates = nil
continue
}
// Otherwise, update the peer list.
peers = update
log.Println("got new peer list:", strings.Join(peers, " "))
pool.Set(peers...)
}
}
}
func set(cl *doozer.Conn, id, iter int, path string, value []byte, f cb) {
for i := 0; i < iter; i++ {
s := time.Nanoseconds()
rev, err := cl.Set(path, math.MaxInt64, value)
e := time.Nanoseconds()
f(id, i, rev, s, e, err)
}
}
func activate(st *store.Store, self string, c *doozer.Conn) int64 {
rev, _ := st.Snap()
entries := store.Getdir(st, calDir)
base := entries[len(entries)-1]
index, _ := strconv.ParseInt(base, 10, 32)
index += 1
p := calDir + "/" + strconv.Itoa(int(index))
seqn, err := c.Set(p, rev, []byte(self))
if err != nil {
panic(err)
}
// for _, base := range store.Getdir(st, calDir) {
// p := calDir + "/" + base
// v, rev := st.Get(p)
// if rev != store.Dir && v[0] == "" {
// seqn, err := c.Set(p, rev, []byte(self))
// if err != nil {
// log.Println(err)
// continue
// }
// return seqn
// }
// }
// for {
// ch, err := st.Wait(calGlob, rev+1)
// if err != nil {
// panic(err)
// }
// ev, ok := <-ch
// if !ok {
// panic(io.EOF)
// }
// rev = ev.Rev
// // TODO ev.IsEmpty()
// if ev.IsSet() && ev.Body == "" {
// seqn, err := c.Set(ev.Path, ev.Rev, []byte(self))
// if err != nil {
// log.Println(err)
// continue
// }
// return seqn
// } else if ev.IsSet() && ev.Body == self {
// return ev.Seqn
// }
// }
return seqn
}
func activate(st *store.Store, self string, c *doozer.Conn) int64 {
rev, _ := st.Snap()
for _, base := range store.Getdir(st, calDir) {
p := calDir + "/" + base
v, rev := st.Get(p)
if rev != store.Dir && v[0] == "" {
seqn, err := c.Set(p, rev, []byte(self))
if err != nil {
log.Println(err)
continue
}
return seqn
}
}
for {
ch, err := st.Wait(calGlob, rev+1)
if err != nil {
panic(err)
}
ev, ok := <-ch
if !ok {
panic(io.EOF)
}
rev = ev.Rev
// TODO ev.IsEmpty()
if ev.IsSet() && ev.Body == "" {
seqn, err := c.Set(ev.Path, ev.Rev, []byte(self))
if err != nil {
log.Println(err)
continue
}
return seqn
} else if ev.IsSet() && ev.Body == self {
return ev.Seqn
}
}
return 0
}
func setC(cl *doozer.Conn, path, body string, rev int64) {
_, err := cl.Set(path, rev, []byte(body))
if err != nil {
panic(err)
}
}