recovery: change the default behavior (#439)

interceptors/recovery/interceptors.go

@@ -8,10 +8,10 @@ package recovery
 
 import (
 	"context"
+	"fmt"
+	"runtime"
 
 	"google.golang.org/grpc"
-	"google.golang.org/grpc/codes"
-	"google.golang.org/grpc/status"
 )
 
 // RecoveryHandlerFunc is a function that recovers from the panic `p` by returning an `error`.
@@ -50,8 +50,19 @@ func StreamServerInterceptor(opts ...Option) grpc.StreamServerInterceptor {
 }
 
 func recoverFrom(ctx context.Context, p interface{}, r RecoveryHandlerFuncContext) error {
-	if r == nil {
-		return status.Errorf(codes.Internal, "%s", p)
+	if r != nil {
+		return r(ctx, p)
 	}
-	return r(ctx, p)
+	stack := make([]byte, 64<<10)
+	stack = stack[:runtime.Stack(stack, false)]
+	return &PanicError{Panic: p, Stack: stack}
+}
+
+type PanicError struct {
+	Panic interface{}
+	Stack []byte
+}
+
+func (e *PanicError) Error() string {
+	return fmt.Sprintf("panic caught: %v\n\n%s", e.Panic, e.Stack)
 }

interceptors/recovery/interceptors_test.go

@@ -66,8 +66,9 @@ func (s *RecoverySuite) TestUnary_SuccessfulRequest() {
 func (s *RecoverySuite) TestUnary_PanickingRequest() {
 	_, err := s.Client.Ping(s.SimpleCtx(), &testpb.PingRequest{Value: "panic"})
 	require.Error(s.T(), err, "there must be an error")
-	assert.Equal(s.T(), codes.Internal, status.Code(err), "must error with internal")
-	assert.Equal(s.T(), "very bad thing happened", status.Convert(err).Message(), "must error with message")
+	assert.Equal(s.T(), codes.Unknown, status.Code(err), "must error with unknown")
+	assert.Contains(s.T(), status.Convert(err).Message(), "panic caught", "must error with message")
+	assert.Contains(s.T(), status.Convert(err).Message(), "recovery.recoverFrom", "must include stack trace")
 }
 
 func (s *RecoverySuite) TestStream_SuccessfulReceive() {
@@ -83,8 +84,9 @@ func (s *RecoverySuite) TestStream_PanickingReceive() {
 	require.NoError(s.T(), err, "should not fail on establishing the stream")
 	_, err = stream.Recv()
 	require.Error(s.T(), err, "there must be an error")
-	assert.Equal(s.T(), codes.Internal, status.Code(err), "must error with internal")
-	assert.Equal(s.T(), "very bad thing happened", status.Convert(err).Message(), "must error with message")
+	assert.Equal(s.T(), codes.Unknown, status.Code(err), "must error with unknown")
+	assert.Contains(s.T(), status.Convert(err).Message(), "panic caught", "must error with message")
+	assert.Contains(s.T(), status.Convert(err).Message(), "recovery.recoverFrom", "must include stack trace")
 }
 
 func TestRecoveryOverrideSuite(t *testing.T) {