[fetcher] Optionally Force Retry

fetcher/configuration.go

@@ -84,3 +84,18 @@ func WithMaxConnections(connections int) Option {
 		f.maxConnections = connections
 	}
 }
+
+// WithForceRetry overrides the default
+// retry handling logic and treats every error
+// as retriable.
+//
+// This is particularly useful when accessing a Rosetta
+// implementation via a load balancer where there may be
+// periods of inconsistency (i.e. we get a network status
+// from one implementation and query another that has not
+// yet synced the most recent block).
+func WithForceRetry() Option {
+	return func(f *Fetcher) {
+		f.forceRetry = true
+	}
+}

fetcher/errors.go

@@ -57,7 +57,7 @@ func (f *Fetcher) RequestFailedError(
 	return &Error{
 		Err:       fmt.Errorf("%w: %s %s", ErrRequestFailed, message, err.Error()),
 		ClientErr: rosettaErr,
-		Retry: ((rosettaErr != nil && rosettaErr.Retriable) || transientError(err)) &&
+		Retry: ((rosettaErr != nil && rosettaErr.Retriable) || transientError(err) || f.forceRetry) &&
 			!errors.Is(err, context.Canceled),
 	}
 }

fetcher/fetcher.go

@@ -73,6 +73,7 @@ type Fetcher struct {
 	maxRetries       uint64
 	retryElapsedTime time.Duration
 	insecureTLS      bool
+	forceRetry       bool
 
 	// connectionSemaphore is used to limit the
 	// number of concurrent requests we make.

fetcher/network_test.go

@@ -70,6 +70,7 @@ func TestNetworkStatusRetry(t *testing.T) {
 		expectedError       error
 		retriableError      bool
 
+		fetcherForceRetry bool
 		fetcherMaxRetries uint64
 		shouldCancel      bool
 	}{
@@ -91,6 +92,13 @@ func TestNetworkStatusRetry(t *testing.T) {
 			expectedError:       ErrRequestFailed,
 			fetcherMaxRetries:   5,
 		},
+		"non-retriable failure (with force)": {
+			network:             basicNetwork,
+			errorsBeforeSuccess: 2,
+			expectedStatus:      basicNetworkStatus,
+			fetcherMaxRetries:   5,
+			fetcherForceRetry:   true,
+		},
 		"exhausted retries": {
 			network:             basicNetwork,
 			errorsBeforeSuccess: 2,
@@ -148,10 +156,17 @@ func TestNetworkStatusRetry(t *testing.T) {
 
 			defer ts.Close()
 
+			opts := []Option{
+				WithRetryElapsedTime(5 * time.Second),
+				WithMaxRetries(test.fetcherMaxRetries),
+			}
+			if test.fetcherForceRetry {
+				opts = append(opts, WithForceRetry())
+			}
+
 			f := New(
 				ts.URL,
-				WithRetryElapsedTime(5*time.Second),
-				WithMaxRetries(test.fetcherMaxRetries),
+				opts...,
 			)
 			status, err := f.NetworkStatusRetry(
 				ctx,