package tracer import ( cryptorand "crypto/rand" "math" "math/big" "math/rand" "sync" "time" "gopkg.in/DataDog/dd-trace-go.v1/internal/log" ) // random holds a thread-safe source of random numbers. var random *rand.Rand func init() { var seed int64 n, err := cryptorand.Int(cryptorand.Reader, big.NewInt(math.MaxInt64)) if err == nil { seed = n.Int64() } else { log.Warn("cannot generate random seed: %v; using current time", err) seed = time.Now().UnixNano() } random = rand.New(&safeSource{ source: rand.NewSource(seed), }) } // safeSource holds a thread-safe implementation of rand.Source64. type safeSource struct { source rand.Source sync.Mutex } func (rs *safeSource) Int63() int64 { rs.Lock() n := rs.source.Int63() rs.Unlock() return n } func (rs *safeSource) Uint64() uint64 { return uint64(rs.Int63()) } func (rs *safeSource) Seed(seed int64) { rs.Lock() rs.Seed(seed) rs.Unlock() }