go vendor

vendor/github.com/revel/log15/ext/id.go

@@ -0,0 +1,47 @@
+package ext
+
+import (
+	"fmt"
+	"math/rand"
+	"sync"
+	"time"
+)
+
+var r = rand.New(&lockedSource{src: rand.NewSource(time.Now().Unix())})
+
+// RandId creates a random identifier of the requested length.
+// Useful for assigning mostly-unique identifiers for logging
+// and identification that are unlikely to collide because of
+// short lifespan or low set cardinality
+func RandId(idlen int) string {
+	b := make([]byte, idlen)
+	var randVal uint32
+	for i := 0; i < idlen; i++ {
+		byteIdx := i % 4
+		if byteIdx == 0 {
+			randVal = r.Uint32()
+		}
+		b[i] = byte((randVal >> (8 * uint(byteIdx))) & 0xFF)
+	}
+	return fmt.Sprintf("%x", b)
+}
+
+// lockedSource is a wrapper to allow a rand.Source to be used
+// concurrently (same type as the one used internally in math/rand).
+type lockedSource struct {
+	lk  sync.Mutex
+	src rand.Source
+}
+
+func (r *lockedSource) Int63() (n int64) {
+	r.lk.Lock()
+	n = r.src.Int63()
+	r.lk.Unlock()
+	return
+}
+
+func (r *lockedSource) Seed(seed int64) {
+	r.lk.Lock()
+	r.src.Seed(seed)
+	r.lk.Unlock()
+}