// GetTopic performs a thread safe operation
// to return a pointer to a Topic object (potentially new)
func (n *NSQd) GetTopic(topicName string) *Topic {
n.Lock()
t, ok := n.topicMap[topicName]
if ok {
n.Unlock()
return t
} else {
t = NewTopic(topicName, &Context{n})
n.topicMap[topicName] = t
log.Printf("TOPIC(%s): created", t.name)
// release our global nsqd lock, and switch to a more granular topic lock while we init our
// channels from lookupd. This blocks concurrent PutMessages to this topic.
t.Lock()
n.Unlock()
// if using lookupd, make a blocking call to get the topics, and immediately create them.
// this makes sure that any message received is buffered to the right channels
if len(n.lookupPeers) > 0 {
channelNames, _ := lookupd.GetLookupdTopicChannels(t.name, n.lookupHttpAddrs())
for _, channelName := range channelNames {
t.getOrCreateChannel(channelName)
}
}
t.Unlock()
// NOTE: I would prefer for this to only happen in topic.GetChannel() but we're special
// casing the code above so that we can control the locks such that it is impossible
// for a message to be written to a (new) topic while we're looking up channels
// from lookupd...
//
// update messagePump state
select {
case t.channelUpdateChan <- 1:
case <-t.exitChan:
}
}
return t
}
func lookupHandler(w http.ResponseWriter, req *http.Request) {
reqParams, err := util.NewReqParams(req)
if err != nil {
log.Printf("ERROR: failed to parse request params - %s", err.Error())
http.Error(w, "INVALID_REQUEST", 500)
return
}
channels := make(map[string][]string)
allTopics, _ := lookupd.GetLookupdTopics(lookupdHTTPAddrs)
for _, topicName := range allTopics {
var producers []string
producers, _ = lookupd.GetLookupdTopicProducers(topicName, lookupdHTTPAddrs)
if len(producers) == 0 {
topicChannels, _ := lookupd.GetLookupdTopicChannels(topicName, lookupdHTTPAddrs)
channels[topicName] = topicChannels
}
}
p := struct {
Title string
GraphOptions *GraphOptions
TopicMap map[string][]string
Lookupd []string
Version string
}{
Title: "NSQ Lookup",
GraphOptions: NewGraphOptions(w, req, reqParams),
TopicMap: channels,
Lookupd: lookupdHTTPAddrs,
Version: util.BINARY_VERSION,
}
err = templates.ExecuteTemplate(w, "lookup.html", p)
if err != nil {
log.Printf("Template Error %s", err.Error())
http.Error(w, "Template Error", 500)
}
}