Add better error messaging and tests for memdb serialization error

internal/datastore/memdb/errors.go

@@ -0,0 +1,37 @@
+package memdb
+
+import (
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+
+	v1 "github.com/authzed/authzed-go/proto/authzed/api/v1"
+
+	"github.com/authzed/spicedb/pkg/spiceerrors"
+)
+
+// ErrSerializationMaxRetriesReached occurs when a write request has reached its maximum number
+// of retries due to serialization errors.
+type ErrSerializationMaxRetriesReached struct {
+	error
+}
+
+// NewSerializationMaxRetriesReachedErr constructs a new max retries reached error.
+func NewSerializationMaxRetriesReachedErr(baseErr error) error {
+	return ErrSerializationMaxRetriesReached{
+		error: baseErr,
+	}
+}
+
+// GRPCStatus implements retrieving the gRPC status for the error.
+func (err ErrSerializationMaxRetriesReached) GRPCStatus() *status.Status {
+	return spiceerrors.WithCodeAndDetails(
+		err,
+		codes.DeadlineExceeded,
+		spiceerrors.ForReason(
+			v1.ErrorReason_ERROR_REASON_UNSPECIFIED,
+			map[string]string{
+				"details": "too many updates were made to the in-memory datastore at once; this datastore has limited write throughput capability",
+			},
+		),
+	)
+}

internal/datastore/memdb/memdb.go

@@ -248,7 +248,7 @@ func (mdb *memdbDatastore) ReadWriteTx(
 		return newRevision, nil
 	}
 
-	return datastore.NoRevision, errors.New("serialization max retries exceeded")
+	return datastore.NoRevision, NewSerializationMaxRetriesReachedErr(errors.New("serialization max retries exceeded; please reduce your parallel writes"))
 }
 
 func (mdb *memdbDatastore) ReadyState(_ context.Context) (datastore.ReadyState, error) {

internal/datastore/memdb/memdb_test.go

@@ -12,9 +12,11 @@ import (
 	"golang.org/x/sync/errgroup"
 
 	"github.com/authzed/spicedb/pkg/datastore"
+	"github.com/authzed/spicedb/pkg/datastore/options"
 	test "github.com/authzed/spicedb/pkg/datastore/test"
 	ns "github.com/authzed/spicedb/pkg/namespace"
 	corev1 "github.com/authzed/spicedb/pkg/proto/core/v1"
+	"github.com/authzed/spicedb/pkg/tuple"
 )
 
 type memDBTest struct{}
@@ -77,3 +79,37 @@ func TestConcurrentWritePanic(t *testing.T) {
 	}, 1*time.Second, 10*time.Millisecond)
 	require.ErrorIs(err, recoverErr)
 }
+
+func TestConcurrentWriteRelsError(t *testing.T) {
+	require := require.New(t)
+
+	ds, err := NewMemdbDatastore(0, 1*time.Hour, 1*time.Hour)
+	require.NoError(err)
+
+	ctx := context.Background()
+
+	// Kick off a number of writes to ensure at least one hits an error.
+	g := errgroup.Group{}
+
+	for i := 0; i < 50; i++ {
+		i := i
+		g.Go(func() error {
+			_, err = ds.ReadWriteTx(ctx, func(rwt datastore.ReadWriteTransaction) error {
+				updates := []*corev1.RelationTupleUpdate{}
+				for j := 0; j < 500; j++ {
+					updates = append(updates, &corev1.RelationTupleUpdate{
+						Operation: corev1.RelationTupleUpdate_TOUCH,
+						Tuple:     tuple.MustParse(fmt.Sprintf("document:doc-%d-%d#viewer@user:tom", i, j)),
+					})
+				}
+
+				return rwt.WriteRelationships(ctx, updates)
+			}, options.WithDisableRetries(true))
+			return err
+		})
+	}
+
+	werr := g.Wait()
+	require.Error(werr)
+	require.ErrorContains(werr, "serialization max retries exceeded")
+}

internal/services/v1/relationships_test.go

@@ -12,6 +12,7 @@ import (
 	v1 "github.com/authzed/authzed-go/proto/authzed/api/v1"
 	"github.com/authzed/grpcutil"
 	"github.com/stretchr/testify/require"
+	"golang.org/x/sync/errgroup"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/status"
 	"google.golang.org/protobuf/proto"
@@ -1462,3 +1463,38 @@ func standardTuplesWithout(without map[string]struct{}) map[string]struct{} {
 	}
 	return out
 }
+
+func TestManyConcurrentWriteRelationshipsReturnsSerializationErrorOnMemdb(t *testing.T) {
+	require := require.New(t)
+
+	conn, cleanup, _, _ := testserver.NewTestServer(require, 0, memdb.DisableGC, true, tf.StandardDatastoreWithData)
+	client := v1.NewPermissionsServiceClient(conn)
+	t.Cleanup(cleanup)
+
+	// Kick off a number of writes to ensure at least one hits an error, as memdb's write throughput
+	// is limited.
+	g := errgroup.Group{}
+
+	for i := 0; i < 50; i++ {
+		i := i
+		g.Go(func() error {
+			updates := []*v1.RelationshipUpdate{}
+			for j := 0; j < 500; j++ {
+				updates = append(updates, &v1.RelationshipUpdate{
+					Operation:    v1.RelationshipUpdate_OPERATION_CREATE,
+					Relationship: tuple.MustToRelationship(tuple.MustParse(fmt.Sprintf("document:doc-%d-%d#viewer@user:tom", i, j))),
+				})
+			}
+
+			_, err := client.WriteRelationships(context.Background(), &v1.WriteRelationshipsRequest{
+				Updates: updates,
+			})
+			return err
+		})
+	}
+
+	werr := g.Wait()
+	require.Error(werr)
+	require.ErrorContains(werr, "serialization max retries exceeded")
+	grpcutil.RequireStatus(t, codes.DeadlineExceeded, werr)
+}