Add prototype nexter.

commands/pilosa-nexter/nexter.go

@@ -0,0 +1,125 @@
+package main
+
+import (
+	"github.com/coreos/go-etcd/etcd"
+	"log"
+	"net/http"
+	"encoding/json"
+	"strings"
+	"strconv"
+	"time"
+)
+
+type Command struct {
+	property int
+	retchan chan int
+}
+
+type Property struct {
+	id int
+	current int
+	max int
+}
+
+func (p *Property) Increment() int {
+	p.current += 1
+	if p.current < p.max {
+		return p.current
+	} else {
+		p.Sync()
+		p.current += 1
+		return p.current
+	}
+}
+
+func (p *Property) Sync() {
+	path := "nexter/" + strconv.Itoa(p.id)
+	max := 0
+	key, err := client.Get(path)
+	if err != nil {
+		ee, ok := err.(etcd.EtcdError)
+		if ok {
+			if ee.ErrorCode == 100 {
+				client.Set(path, "0", 0)
+			}
+		} else {
+			log.Fatal(err)
+		}
+	} else {
+		max, err = strconv.Atoi(key[0].Value)
+		if err != nil {
+			log.Fatal(err)
+		}
+	}
+	for {
+		newval, ok, err := client.TestAndSet(path, strconv.Itoa(max), strconv.Itoa(max+5), 0)
+		if err != nil {
+			log.Fatal(err)
+		}
+		if ok {
+			break
+		} else {
+			time.Sleep(time.Second)
+			max, err = strconv.Atoi(newval.Value)
+			if err != nil {
+				log.Fatal(err)
+			}
+		}
+	}
+	p.max = max
+	p.current = max - 5
+}
+
+func NewProperty(id int) *Property {
+	prop := &Property{id:id}
+	prop.Sync()
+	return prop
+}
+
+var commandchan chan *Command
+var client *etcd.Client
+
+func Nextifier() {
+	prop_map := make(map[int]*Property)
+	for {
+		select {
+		case c := <-commandchan:
+			log.Println(prop_map)
+			prop, ok := prop_map[c.property]
+			if !ok {
+				prop = NewProperty(c.property)
+				prop_map[c.property] = prop
+			}
+			c.retchan <- prop.Increment()
+		}
+	}
+}
+
+func Nexter(w http.ResponseWriter, r *http.Request) {
+	url := r.URL.Path
+	splits := strings.Split(url, "/")
+	if len(splits) < 3 {
+		http.Error(w, "Missing property id", http.StatusBadRequest)
+		return
+	}
+	id_string := splits[2]
+	id, err := strconv.Atoi(id_string)
+	if err != nil {
+		http.Error(w, "Property id is not a number", http.StatusBadRequest)
+		return
+	}
+	retchan := make(chan int)
+	commandchan <- &Command{id, retchan}
+	num := <-retchan
+	dec := json.NewEncoder(w)
+	dec.Encode(num)
+}
+
+func main() {
+	client = etcd.NewClient(nil)
+	commandchan = make(chan *Command)
+	go Nextifier()
+	log.Println("Starting Nexter...")
+	http.HandleFunc("/nexter/", Nexter)
+	http.ListenAndServe(":9000", nil)
+}