Fix: Added locks around counter (#4)

benchmark_test.go

@@ -0,0 +1,55 @@
+package tsid
+
+import (
+	"fmt"
+	"sync"
+	"testing"
+)
+
+func BenchmarkGenerate(b *testing.B) {
+
+	b.Run("one goroutine", func(b *testing.B) {
+
+		tsidFactory, err := TsidFactoryBuilder().
+			WithNode(1).
+			Build()
+
+		if err != nil {
+			b.FailNow()
+		}
+
+		for i := 0; i < b.N; i++ {
+			tsidFactory.Generate()
+		}
+	})
+
+	b.Run("multiple goroutines", func(b *testing.B) {
+
+		goroutineCount := 10
+		wg := &sync.WaitGroup{}
+
+		for i := 0; i < goroutineCount; i++ {
+
+			wg.Add(1)
+			go func(iterationCount int, wg *sync.WaitGroup) {
+				defer wg.Done()
+				tsidFactory, err := TsidFactoryBuilder().
+					WithNode(1).
+					Build()
+
+				if err != nil {
+					fmt.Errorf("Failed to instantiate tsid factory with error: %s", err)
+					return
+				}
+
+				for i := 0; i < b.N; i++ {
+					tsidFactory.Generate()
+				}
+
+			}(b.N, wg)
+		}
+
+		wg.Wait()
+	})
+
+}

tsid_factory.go

@@ -109,17 +109,21 @@ func (factory *tsidFactory) Generate() (*tsid, error) {
 func (factory *tsidFactory) getTime() (int64, error) {
 	time := factory.clock.UnixMilli()
 	if time <= factory.lastTime {
+		lock.Lock()
 		factory.counter++
 		carry := uint32(factory.counter) >> factory.counterBits
 		factory.counter = factory.counter & factory.counterMask
 		time = factory.lastTime + int64(carry)
+		lock.Unlock()
 
 	} else {
 		value, err := factory.getRandomValue()
 		if err != nil {
 			return 0, err
 		}
+		lock.Lock()
 		factory.counter = value
+		lock.Unlock()
 	}
 	factory.lastTime = time
 	return (time - factory.customEpoch), nil