// XXX pulled this out of donut, maybe i should make a zk util lib?
// Watch the children at path until a byte is sent on the returned channel
// Uses the SafeMap more like a set, so you'll have to use Contains() for entries
func watchZKChildren(zk *zookeeper.Conn, path string, children *donut.SafeMap, onChange func(*donut.SafeMap)) (chan byte, error) {
initial, _, watch, err := zk.ChildrenW(path)
if err != nil {
return nil, err
}
m := children.RangeLock()
for _, node := range initial {
m[node] = nil
}
children.RangeUnlock()
kill := make(chan byte, 1)
log.Printf("watching "+path+" len is %d", children.Len())
go func() {
defer close(kill)
var nodes []string
var err error
for {
select {
case <-kill:
// close(watch)
log.Printf("got kill")
return
case event := <-watch:
if !event.Ok() {
continue
}
// close(watch)
nodes, _, watch, err = zk.ChildrenW(path)
if err != nil {
log.Printf("Error in watchZkChildren: %v", err)
// XXX I should really provide some way for the client to find out about this error...
return
}
m := children.RangeLock()
// mark all dead
for k := range m {
m[k] = 0
}
for _, node := range nodes {
m[node] = 1
}
for k, v := range m {
if v.(int) == 0 {
delete(m, k)
}
}
children.RangeUnlock()
onChange(children)
}
}
}()
log.Printf("watcher setup on %s", path)
return kill, nil
}
func (c *Coordinator) onWorkersChange(m *donut.SafeMap) {
log.Println("workers updated")
if atomic.LoadInt32(&c.state) > SetupState {
// invalidate current step
// update partition mapping
// roll back to last checkpoint
} else {
if m.Len() == c.config.InitialWorkers {
// go into prepare state
if !atomic.CompareAndSwapInt32(&c.state, SetupState, PrepareState) {
log.Println("Could not properly move from SetupState to PrepareState")
return
}
log.Printf("InitialWorkers met, preparing node for work")
// everyone is here, create the partition mapping
lm := m.RangeLock()
var workers []string
for k := range lm {
workers = append(workers, k)
}
m.RangeUnlock()
sort.Strings(workers)
for i := 0; i < len(workers); i++ {
c.partitions[i] = workers[i]
if workers[i] == c.config.NodeId {
c.graph.partitionId = i
}
}
// set up connections to all the other nodes
c.cachedWorkerInfo = make(map[string]map[string]interface{})
c.rpcClients = make(map[string]*rpc.Client)
for _, w := range workers {
// pull down worker info for all of the existing workers
c.cachedWorkerInfo[w] = c.workerInfo(w)
c.rpcClients[w], _ = rpc.DialHTTP("tcp", net.JoinHostPort(c.cachedWorkerInfo[w]["host"].(string), c.cachedWorkerInfo[w]["port"].(string)))
}
// go into loadstate
if !atomic.CompareAndSwapInt32(&c.state, PrepareState, LoadState) {
log.Println("Could not properly move from PrepareState to LoadState")
return
}
go c.createLoadWork()
}
}
}