config: guarantee initialize config before use

config.go

@@ -19,6 +19,7 @@ import (
 // (see Config.Set() for available parameters)
 type Config struct {
 	sync.RWMutex
+	initOnce sync.Once
 
 	verbose bool `opt:"verbose"`
 
@@ -62,41 +63,40 @@ type Config struct {
 
 // NewConfig returns a new default configuration
 func NewConfig() *Config {
-	hostname, err := os.Hostname()
-	if err != nil {
-		log.Fatalf("ERROR: unable to get hostname %s", err.Error())
-	}
-	conf := &Config{
-		maxInFlight: 1,
-		maxAttempts: 5,
-
-		lookupdPollInterval: 60 * time.Second,
-		lookupdPollJitter:   0.3,
-
-		lowRdyIdleTimeout: 10 * time.Second,
-
-		defaultRequeueDelay: 90 * time.Second,
-		maxRequeueDelay:     15 * time.Minute,
-
-		backoffMultiplier:  time.Second,
-		maxBackoffDuration: 120 * time.Second,
-
-		readTimeout:  DefaultClientTimeout,
-		writeTimeout: time.Second,
-
-		deflateLevel:        6,
-		outputBufferSize:    16 * 1024,
-		outputBufferTimeout: 250 * time.Millisecond,
-
-		heartbeatInterval: DefaultClientTimeout / 2,
-
-		clientID:  strings.Split(hostname, ".")[0],
-		hostname:  hostname,
-		userAgent: fmt.Sprintf("go-nsq/%s", VERSION),
-	}
+	conf := &Config{}
+	conf.initialize()
 	return conf
 }
 
+// initialize is used to ensure that a Config has a baseline set of defaults
+// despite how it might have been insantiated
+func (c *Config) initialize() {
+	c.initOnce.Do(func() {
+		hostname, err := os.Hostname()
+		if err != nil {
+			log.Fatalf("ERROR: unable to get hostname %s", err.Error())
+		}
+		c.maxInFlight = 1
+		c.maxAttempts = 5
+		c.lookupdPollInterval = 60 * time.Second
+		c.lookupdPollJitter = 0.3
+		c.lowRdyIdleTimeout = 10 * time.Second
+		c.defaultRequeueDelay = 90 * time.Second
+		c.maxRequeueDelay = 15 * time.Minute
+		c.backoffMultiplier = time.Second
+		c.maxBackoffDuration = 120 * time.Second
+		c.readTimeout = DefaultClientTimeout
+		c.writeTimeout = time.Second
+		c.deflateLevel = 6
+		c.outputBufferSize = 16 * 1024
+		c.outputBufferTimeout = 250 * time.Millisecond
+		c.heartbeatInterval = DefaultClientTimeout / 2
+		c.clientID = strings.Split(hostname, ".")[0]
+		c.hostname = hostname
+		c.userAgent = fmt.Sprintf("go-nsq/%s", VERSION)
+	})
+}
+
 // Set takes an option as a string and a value as an interface and
 // attempts to set the appropriate configuration option.
 //
@@ -171,6 +171,8 @@ func (c *Config) Set(option string, value interface{}) error {
 	c.Lock()
 	defer c.Unlock()
 
+	c.initialize()
+
 	val := reflect.ValueOf(c).Elem()
 	typ := val.Type()
 	for i := 0; i < typ.NumField(); i++ {

conn.go

@@ -90,6 +90,7 @@ type Conn struct {
 
 // NewConn returns a new Conn instance
 func NewConn(addr string, config *Config) *Conn {
+	config.initialize()
 	return &Conn{
 		addr: addr,
 

consumer.go

@@ -112,6 +112,8 @@ type Consumer struct {
 // The returned Consumer instance is setup with sane default values.  To modify
 // configuration, update the values on the returned instance before connecting.
 func NewConsumer(topic string, channel string, config *Config) (*Consumer, error) {
+	config.initialize()
+
 	if !IsValidTopicName(topic) {
 		return nil, errors.New("invalid topic name")
 	}

producer.go

@@ -56,6 +56,7 @@ func (t *ProducerTransaction) finish() {
 
 // NewProducer returns an instance of Producer for the specified address
 func NewProducer(addr string, config *Config) *Producer {
+	config.initialize()
 	return &Producer{
 		id: atomic.AddInt64(&instCount, 1),