Don't use sync/atomic

2 files changed, 23 insertions, 6 deletions

diff --git a/STYLE.md b/STYLE.md
index 3a6ae2bad..d72775073 100644
--- a/STYLE.md
+++ b/STYLE.md
@@ -107,4 +107,15 @@ instead of:
 func (server) GetBlob(_ *pb.GetBlobRequest, _ pb.BlobService_GetBlobServer) error {
     return helper.Unimplemented
 }
-```
\ No newline at end of file
+```
+
+## Concurrency
+
+The [documentation of "sync/atomic"](https://golang.org/pkg/sync/atomic/) says:
+
+> These functions require great care to be used correctly. Except for
+special, low-level applications, synchronization is better done with
+channels or the facilities of the sync package.
+
+Gitaly is not a low-level application so we should avoid "sync/atomic".
+We use channels and [package "sync"](https://golang.org/pkg/sync/).
diff --git a/internal/middleware/limithandler/testhelper_test.go b/internal/middleware/limithandler/testhelper_test.go
index 40eff4f01..e197b18f4 100644
--- a/internal/middleware/limithandler/testhelper_test.go
+++ b/internal/middleware/limithandler/testhelper_test.go
@@ -1,23 +1,29 @@
 package limithandler_test
 
 import (
-	"sync/atomic"
+	"sync"
 
 	pb "gitlab.com/gitlab-org/gitaly/internal/middleware/limithandler/testpb"
 	"golang.org/x/net/context"
 )
 
 type server struct {
-	requestCount uint64
-	blockCh      chan (struct{})
+	requestCount int
+	sync.Mutex
+	blockCh chan (struct{})
 }
 
 func (s *server) registerRequest() {
-	atomic.AddUint64(&s.requestCount, 1)
+	s.Lock()
+	s.requestCount++
+	s.Unlock()
 }
 
 func (s *server) getRequestCount() int {
-	return int(atomic.LoadUint64(&s.requestCount))
+	s.Lock()
+	count := s.requestCount
+	s.Unlock()
+	return count
 }
 
 func (s *server) Unary(ctx context.Context, in *pb.UnaryRequest) (*pb.UnaryResponse, error) {