ARROW-10250: [C++][FlightRPC] Consistently use FlightClientOptions::Defaults

cpp/src/arrow/flight/client.cc

@@ -90,9 +90,6 @@ std::shared_ptr<FlightWriteSizeStatusDetail> FlightWriteSizeStatusDetail::Unwrap
   return std::dynamic_pointer_cast<FlightWriteSizeStatusDetail>(status.detail());
 }
 
-FlightClientOptions::FlightClientOptions()
-    : write_size_limit_bytes(0), disable_server_verification(false) {}
-
 FlightClientOptions FlightClientOptions::Defaults() { return FlightClientOptions(); }
 
 struct ClientRpc {
@@ -1240,7 +1237,7 @@ FlightClient::~FlightClient() {}
 
 Status FlightClient::Connect(const Location& location,
                              std::unique_ptr<FlightClient>* client) {
-  return Connect(location, {}, client);
+  return Connect(location, FlightClientOptions::Defaults(), client);
 }
 
 Status FlightClient::Connect(const Location& location, const FlightClientOptions& options,

cpp/src/arrow/flight/client.h

@@ -92,10 +92,7 @@ class ARROW_FLIGHT_EXPORT FlightWriteSizeStatusDetail : public arrow::StatusDeta
   int64_t actual_;
 };
 
-class ARROW_FLIGHT_EXPORT FlightClientOptions {
- public:
-  FlightClientOptions();
-
+struct ARROW_FLIGHT_EXPORT FlightClientOptions {
   /// \brief Root certificates to use for validating server
   /// certificates.
   std::string tls_root_certs;
@@ -113,14 +110,14 @@ class ARROW_FLIGHT_EXPORT FlightClientOptions {
   /// Used to help limit server memory consumption. Only enabled if
   /// positive. When enabled, FlightStreamWriter.Write* may yield a
   /// IOError with error detail FlightWriteSizeStatusDetail.
-  int64_t write_size_limit_bytes;
+  int64_t write_size_limit_bytes = 0;
 
   /// \brief Generic connection options, passed to the underlying
   ///     transport; interpretation is implementation-dependent.
   std::vector<std::pair<std::string, util::Variant<int, std::string>>> generic_options;
 
   /// \brief Use TLS without validating the server certificate. Use with caution.
-  bool disable_server_verification;
+  bool disable_server_verification = false;
 
   /// \brief Get default options.
   static FlightClientOptions Defaults();

cpp/src/arrow/flight/flight_test.cc

@@ -740,7 +740,7 @@ class TestTls : public ::testing::Test {
   }
 
   Status ConnectClient() {
-    auto options = FlightClientOptions();
+    auto options = FlightClientOptions::Defaults();
     CertKeyPair root_cert;
     RETURN_NOT_OK(ExampleTlsCertificateRoot(&root_cert));
     options.tls_root_certs = root_cert.pem_cert;
@@ -1891,7 +1891,7 @@ TEST_F(TestDoPut, DoPutSizeLimit) {
   const int64_t size_limit = 4096;
   Location location;
   ASSERT_OK(Location::ForGrpcTcp("localhost", server_->port(), &location));
-  FlightClientOptions client_options;
+  auto client_options = FlightClientOptions::Defaults();
   client_options.write_size_limit_bytes = size_limit;
   std::unique_ptr<FlightClient> client;
   ASSERT_OK(FlightClient::Connect(location, client_options, &client));
@@ -2155,7 +2155,7 @@ TEST_F(TestTls, DoAction) {
 #if defined(GRPC_NAMESPACE_FOR_TLS_CREDENTIALS_OPTIONS)
 TEST_F(TestTls, DisableServerVerification) {
   std::unique_ptr<FlightClient> client;
-  auto client_options = FlightClientOptions();
+  auto client_options = FlightClientOptions::Defaults();
   // For security reasons, if encryption is being used,
   // the client should be configured to verify the server by default.
   ASSERT_EQ(client_options.disable_server_verification, false);
@@ -2180,7 +2180,7 @@ TEST_F(TestTls, DisableServerVerification) {
 
 TEST_F(TestTls, OverrideHostname) {
   std::unique_ptr<FlightClient> client;
-  auto client_options = FlightClientOptions();
+  auto client_options = FlightClientOptions::Defaults();
   client_options.override_hostname = "fakehostname";
   CertKeyPair root_cert;
   ASSERT_OK(ExampleTlsCertificateRoot(&root_cert));
@@ -2199,7 +2199,7 @@ TEST_F(TestTls, OverrideHostname) {
 // Test the facility for setting generic transport options.
 TEST_F(TestTls, OverrideHostnameGeneric) {
   std::unique_ptr<FlightClient> client;
-  auto client_options = FlightClientOptions();
+  auto client_options = FlightClientOptions::Defaults();
   client_options.generic_options.emplace_back(GRPC_SSL_TARGET_NAME_OVERRIDE_ARG,
                                               "fakehostname");
   CertKeyPair root_cert;

python/pyarrow/_flight.pyx

@@ -1055,7 +1055,7 @@ cdef class FlightClient(_Weakrefable):
         cdef:
             int c_port = 0
             CLocation c_location = Location.unwrap(location)
-            CFlightClientOptions c_options
+            CFlightClientOptions c_options = CFlightClientOptions.Defaults()
             function[cb_client_middleware_start_call] start_call = \
                 &_client_middleware_start_call
             CIntStringVariant variant

python/pyarrow/includes/libarrow_flight.pxd

@@ -289,7 +289,6 @@ cdef extern from "arrow/flight/api.h" namespace "arrow" nogil:
         vector[pair[c_string, shared_ptr[CServerMiddlewareFactory]]] middleware
 
     cdef cppclass CFlightClientOptions" arrow::flight::FlightClientOptions":
-        CFlightClientOptions()
         c_string tls_root_certs
         c_string cert_chain
         c_string private_key
@@ -299,6 +298,9 @@ cdef extern from "arrow/flight/api.h" namespace "arrow" nogil:
         vector[pair[c_string, CIntStringVariant]] generic_options
         c_bool disable_server_verification
 
+        @staticmethod
+        CFlightClientOptions Defaults()
+
     cdef cppclass CFlightClient" arrow::flight::FlightClient":
         @staticmethod
         CStatus Connect(const CLocation& location,