1 files changed, 98 insertions, 0 deletions
diff --git a/internal/middleware/errorhandler/errorhandler.go b/internal/middleware/errorhandler/errorhandler.go
new file mode 100644
index 000000000..ea00510d0
--- /dev/null
+++ b/internal/middleware/errorhandler/errorhandler.go
@@ -0,0 +1,98 @@
+package errorhandler
+
+import (
+	"context"
+	"fmt"
+	"sync"
+	"time"
+
+	"gitlab.com/gitlab-org/gitaly/internal/praefect/protoregistry"
+
+	"google.golang.org/grpc"
+)
+
+func UnaryErrorHandler(errorTracker *Errors, registry *protoregistry.Registry) grpc.UnaryServerInterceptor {
+	return func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
+		resp, err := handler(ctx, req)
+		if err != nil {
+			mi, lookupErr := registry.LookupMethod(info.FullMethod)
+			if err != nil {
+				return resp, fmt.Errorf("error when looking up method :%w %w", err, lookupErr)
+			}
+			switch mi.Operation {
+			case protoregistry.OpAccessor:
+				errorTracker.IncrReadErr()
+			case protoregistry.OpMutator:
+				errorTracker.IncrWriteErr()
+			}
+		}
+		return resp, err
+	}
+}
+
+func StreamErrorHandler(errorTracker *Errors, registry *protoregistry.Registry) grpc.StreamServerInterceptor {
+	return func(srv interface{}, stream grpc.ServerStream, info *grpc.StreamServerInfo, handler grpc.StreamHandler) error {
+		err := handler(srv, stream)
+		if err != nil {
+			mi, lookupErr := registry.LookupMethod(info.FullMethod)
+			if err != nil {
+				return fmt.Errorf("error when looking up method :%w %w", err, lookupErr)
+			}
+			switch mi.Operation {
+			case protoregistry.OpAccessor:
+				errorTracker.IncrReadErr()
+			case protoregistry.OpMutator:
+				errorTracker.IncrWriteErr()
+			}
+		}
+
+		return err
+	}
+}
+
+type Errors struct {
+	m                       sync.RWMutex
+	readErrors, writeErrors int64
+}
+
+func (e *Errors) IncrReadErr() {
+	e.m.Lock()
+	defer e.m.Unlock()
+
+	e.readErrors++
+}
+
+func (e *Errors) IncrWriteErr() {
+	e.m.Lock()
+	defer e.m.Unlock()
+
+	e.writeErrors++
+}
+
+func (e *Errors) ReadErrs() int64 {
+	e.m.RLock()
+	defer e.m.RUnlock()
+
+	return e.readErrors
+}
+
+func (e *Errors) WriteErrs() int64 {
+	e.m.RLock()
+	defer e.m.RUnlock()
+
+	return e.writeErrors
+}
+
+func (e *Errors) PeriodicallyClear() {
+	ticker := time.NewTicker(10 * time.Second)
+	for {
+		<-ticker.C
+	}
+}
+
+func (e *Errors) clear() {
+	e.m.Lock()
+	defer e.m.Unlock()
+	e.readErrors = 0
+	e.writeErrors = 0
+}