fix NaN too null conversion and restore duration

README.md

@@ -129,7 +129,7 @@ JWT="eyJ0eXAiOiJKV1QiLCJhbGciOiJFZERTQSJ9.eyJ1c2VyIjoiYWRtaW4iLCJyb2xlcyI6WyJST0
 # If the collector and store and nats-server have been running for at least 60 seconds on the same host, you may run:
 curl -H "Authorization: Bearer $JWT" -D - "http://localhost:8080/api/query" -d "{ \"cluster\": \"testcluster\", \"from\": $(expr $(date +%s) - 60), \"to\": $(date +%s), \"queries\": [{
   \"metric\": \"load_one\",
-  \"hostname\": \"$(hostname)\"
+  \"host\": \"$(hostname)\"
 }] }"
 
 # ...

float.go

@@ -46,11 +46,16 @@ type FloatArray []Float
 func (fa FloatArray) MarshalJSON() ([]byte, error) {
 	buf := make([]byte, 0, 2+len(fa)*8)
 	buf = append(buf, '[')
-	if len(fa) > 0 {
-		buf = strconv.AppendFloat(buf, float64(fa[0]), 'f', 1, 32)
-		for i := 1; i < len(fa); i++ {
+	for i := 0; i < len(fa); i++ {
+		if i != 0 {
 			buf = append(buf, ',')
+		}
+
+		if fa[i].IsNaN() {
+			buf = append(buf, `null`...)
+		} else {
 			buf = strconv.AppendFloat(buf, float64(fa[i]), 'f', 1, 32)
+
 		}
 	}
 	buf = append(buf, ']')

metric-store.go

@@ -157,7 +157,7 @@ func main() {
 		log.Fatal(err)
 	}
 
-	restoreFrom := startupTime.Add(d)
+	restoreFrom := startupTime.Add(-d)
 	log.Printf("Loading checkpoints newer than %s\n", restoreFrom.Format(time.RFC3339))
 	files, err := memoryStore.FromCheckpoint(conf.Checkpoints.RootDir, restoreFrom.Unix())
 	if err != nil {

selector.go

@@ -114,5 +114,5 @@ func (l *level) findBuffers(selector Selector, offset int, f func(b *buffer) err
 		return nil
 	}
 
-	panic("impossible")
+	return nil
 }