Fix race referencing config

Three data races existed referencing the Config item - these
can be detected by running after building with 'go build -race'
on go 1.4.2. This fixes them by adding an RWMutex to protect
the config structure.

config.go

@@ -4,6 +4,7 @@ import (
  "fmt"
  "log"
  "os"
+ "sync"
  "time"
 
  "github.com/abh/geodns/Godeps/_workspace/src/code.google.com/p/gcfg"
@@ -23,6 +24,25 @@ type AppConfig struct {
 }
 
 var Config = new(AppConfig)
+var cfgMutex sync.RWMutex
+
+func (conf *AppConfig) HasStatHat() bool {
+ cfgMutex.RLock()
+ defer cfgMutex.RUnlock()
+ return conf.Flags.HasStatHat
+}
+
+func (conf *AppConfig) StatHatApiKey() string {
+ cfgMutex.RLock()
+ defer cfgMutex.RUnlock()
+ return conf.StatHat.ApiKey
+}
+
+func (conf *AppConfig) GeoIPDirectory() string {
+ cfgMutex.RLock()
+ defer cfgMutex.RUnlock()
+ return conf.GeoIP.Directory
+}
 
 func configWatcher(fileName string) {
 
@@ -91,7 +111,9 @@ func configReader(fileName string) error {
  // log.Println("STATHAT APIKEY:", cfg.StatHat.ApiKey)
  // log.Println("STATHAT FLAG :", cfg.Flags.HasStatHat)
 
- Config = cfg
+ cfgMutex.Lock()
+ *Config = *cfg // shallow copy to prevent race conditions in referring to Config.foo()
+ cfgMutex.Unlock()
 
  return nil
 }

geodns.go

@@ -141,8 +141,6 @@ func main() {
  metrics := NewMetrics()
  go metrics.Updater()
 
- go statHatPoster()
-
  if *flaginter == "*" {
  addrs, _ := net.InterfaceAddrs()
  ips := make([]string, 0)
@@ -161,6 +159,8 @@ func main() {
 
  inter := getInterfaces()
 
+ go statHatPoster()
+
  Zones := make(Zones)
 
  go monitor(Zones)

geoip.go

@@ -81,8 +81,9 @@ func (g *GeoIP) GetASN(ip net.IP) (asn string, netmask int) {
 }
 
 func (g *GeoIP) setDirectory() {
- if len(Config.GeoIP.Directory) > 0 {
- geoip.SetCustomDirectory(Config.GeoIP.Directory)
+ directory := Config.GeoIPDirectory()
+ if len(directory) > 0 {
+ geoip.SetCustomDirectory(directory)
  }
 }
 

stathat.go

@@ -12,7 +12,7 @@ import (
 
 func (zs *Zones) statHatPoster() {
 
- if len(Config.StatHat.ApiKey) == 0 {
+ if !Config.HasStatHat() {
  return
  }
 
@@ -40,17 +40,17 @@ func (zs *Zones) statHatPoster() {
 
  apiKey := zone.Logging.StatHatAPI
  if len(apiKey) == 0 {
- apiKey = Config.StatHat.ApiKey
+ apiKey = Config.StatHatApiKey()
  }
  if len(apiKey) == 0 {
  continue
  }
- stathat.PostEZCount("zone "+name+" queries~"+suffix, Config.StatHat.ApiKey, int(newCount))
+ stathat.PostEZCount("zone "+name+" queries~"+suffix, Config.StatHatApiKey(), int(newCount))
 
  ednsCount := zone.Metrics.EdnsQueries.Count()
  newEdnsCount := ednsCount - lastEdnsCounts[name]
  lastEdnsCounts[name] = ednsCount
- stathat.PostEZCount("zone "+name+" edns queries~"+suffix, Config.StatHat.ApiKey, int(newEdnsCount))
+ stathat.PostEZCount("zone "+name+" edns queries~"+suffix, Config.StatHatApiKey(), int(newEdnsCount))
 
  }
  }
@@ -68,7 +68,7 @@ func statHatPoster() {
  for {
  time.Sleep(60 * time.Second)
 
- if !Config.Flags.HasStatHat {
+ if !Config.HasStatHat() {
  log.Println("No stathat configuration")
  continue
  }
@@ -79,8 +79,8 @@ func statHatPoster() {
  newQueries := current - lastQueryCount
  lastQueryCount = current
 
- stathat.PostEZCount("queries~"+suffix, Config.StatHat.ApiKey, int(newQueries))
- stathat.PostEZValue("goroutines "+serverID, Config.StatHat.ApiKey, float64(runtime.NumGoroutine()))
+ stathat.PostEZCount("queries~"+suffix, Config.StatHatApiKey(), int(newQueries))
+ stathat.PostEZValue("goroutines "+serverID, Config.StatHatApiKey(), float64(runtime.NumGoroutine()))
 
  }
 }