Added integration support for DataDog APM Tracing

vendor/gopkg.in/DataDog/dd-trace-go.v1/ddtrace/tracer/rand.go

@@ -0,0 +1,50 @@
+package tracer
+
+import (
+	cryptorand "crypto/rand"
+	"log"
+	"math"
+	"math/big"
+	"math/rand"
+	"sync"
+	"time"
+)
+
+// 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.Printf("%scannot generate random seed: %v; using current time\n", errorPrefix, 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()
+}