// Find possible addresses for cluster named name.
func lookup(b *doozer.Conn, name string) (as []string) {
rev, err := b.Rev()
if err != nil {
panic(err)
}
path := "/ctl/ns/" + name
names, err := b.Getdir(path, rev, 0, -1)
if err == doozer.ErrNoEnt {
return nil
} else if err, ok := err.(*doozer.Error); ok && err.Err == doozer.ErrNoEnt {
return nil
} else if err != nil {
panic(err)
}
path += "/"
for _, name := range names {
body, _, err := b.Get(path+name, &rev)
if err != nil {
panic(err)
}
as = append(as, string(body))
}
return as
}
// 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...)
}
}
}