Bug#35157953 MySQL Router stops accepting connections - 8.0.32

This patch: - adds more logging info to help debug the issue - replaces use of ENOENT with custom error code for scenario when the Router discovers there are no destinations available Change-Id: I544973fdd01d1c8012abc353c5d1214444b1a43d

Author: Andrzej Religa

router/src/routing/src/classic_connect.cc

@@ -153,7 +153,8 @@ ConnectProcessor::init_destination() {
  } else {
  if (!last_ec_) {
  // no backends
- last_ec_ = make_error_code(std::errc::no_such_file_or_directory);
+ log_debug("init_destination(): the destinations list is empty");
+ last_ec_ = make_error_code(DestinationsErrc::kNoDestinations);
  }
 
  stage(Stage::Error);
@@ -194,6 +195,9 @@ stdx::expected<Processor::Result, std::error_code> ConnectProcessor::resolve() {
  destination->hostname(), std::to_string(destination->port()));
 
  if (!resolve_res) {
+ log_debug("resolve(%s,%d) failed: %s:%s", destination->hostname().c_str(),
+ destination->port(), resolve_res.error().category().name(),
+ resolve_res.error().message().c_str());
  destination->connect_status(resolve_res.error());
 
  stage(Stage::NextDestination);
@@ -463,6 +467,10 @@ stdx::expected<Processor::Result, std::error_code> ConnectProcessor::connect() {
 
  return Result::SendableToServer;
  } else {
+ log_debug("connect(%s, %d) failed: %s:%s",
+ server_endpoint_.address().to_string().c_str(),
+ server_endpoint_.port(), connect_res.error().category().name(),
+ connect_res.error().message().c_str());
  connection()->connect_error_code(ec);
 
  stage(Stage::ConnectFinish);
@@ -651,7 +659,10 @@ stdx::expected<Processor::Result, std::error_code> ConnectProcessor::error() {
 
  connection()->connect_error_code(ec);
 
- if (ec == std::errc::no_such_file_or_directory) {
+ log_debug("ConnectProcessor::error(): %s:%s", ec.category().name(),
+ ec.message().c_str());
+
+ if (ec == DestinationsErrc::kNoDestinations) {
  log_error("no backend available to connect to");
  } else {
  log_fatal_error_code("connecting to backend failed", ec);
@@ -664,7 +675,7 @@ stdx::expected<Processor::Result, std::error_code> ConnectProcessor::error() {
  //
  // don't retry as router may run into an infinite loop.
  ConnectionPoolComponent::get_instance().clear();
- } else if (ec == std::errc::no_such_file_or_directory &&
+ } else if (ec == DestinationsErrc::kNoDestinations &&
  connection()->get_destination_id().empty()) {
  // if there are no destinations for a fresh connect, close the
  // acceptor-ports

router/src/routing/src/classic_connect.h

@@ -42,7 +42,14 @@ class ConnectProcessor : public Processor {
  io_ctx_{conn->socket_splicer()->client_conn().connection()->io_ctx()},
  destinations_{conn->current_destinations()},
  destinations_it_{destinations_.begin()},
- on_error_(std::move(on_error)) {}
+ on_error_(std::move(on_error)) {
+ // this is needed to shut down accepting port with next-available strategy
+ // despite there are destinations available
+ if (conn->destinations()->get_strategy() ==
+ routing::RoutingStrategy::kNextAvailable) {
+ last_ec_ = make_error_code(DestinationsErrc::kNoDestinations);
+ }
+ }
 
  using server_protocol_type = net::ip::tcp;
 
@@ -94,8 +101,7 @@ class ConnectProcessor : public Processor {
  net::ip::tcp::resolver::results_type endpoints_;
  net::ip::tcp::resolver::results_type::iterator endpoints_it_;
 
- std::error_code last_ec_{
- make_error_code(std::errc::no_such_file_or_directory)};
+ std::error_code last_ec_{make_error_code(DestinationsErrc::kNotSet)};
 
  std::function<void(const classic_protocol::message::server::Error &err)>
  on_error_;

router/src/routing/src/connection.cc

@@ -47,7 +47,7 @@ stdx::expected<void, std::error_code> ConnectorBase::init_destination() {
  // no backends
  log_warning("%d: no connectable destinations :(", __LINE__);
  return stdx::make_unexpected(
- make_error_code(std::errc::no_such_file_or_directory));
+ make_error_code(DestinationsErrc::kNoDestinations));
  }
 }
 

router/src/routing/src/connection.h

@@ -219,8 +219,7 @@ class ConnectorBase {
  net::ip::tcp::resolver::results_type endpoints_;
  net::ip::tcp::resolver::results_type::iterator endpoints_it_;
 
- std::error_code last_ec_{
- make_error_code(std::errc::no_such_file_or_directory)};
+ std::error_code last_ec_{make_error_code(DestinationsErrc::kNotSet)};
 
  Function func_{Function::kInitDestination};
 

router/src/routing/src/dest_first_available.h

@@ -40,6 +40,10 @@ class DestFirstAvailable final : public RouteDestination {
  // mark index as invalid
  void mark_ndx_invalid(size_t ndx) noexcept { valid_ndx_ = ndx + 1; }
 
+ routing::RoutingStrategy get_strategy() override {
+ return routing::RoutingStrategy::kFirstAvailable;
+ }
+
  private:
  size_t valid_ndx_{};
 };

router/src/routing/src/dest_metadata_cache.cc

@@ -502,8 +502,12 @@ std::optional<Destinations> DestMetadataCacheGroup::refresh_destinations(
  auto const *primary_member = dynamic_cast<MetadataCacheDestination *>(
  previous_dests.begin()->get());
 
- if (primary_member->last_error_code() ==
- make_error_condition(std::errc::timed_out)) {
+ const auto err = primary_member->last_error_code();
+ log_debug("refresh_destinations(): %s:%s", err.category().name(),
+ err.message().c_str());
+
+ if (err == make_error_condition(std::errc::timed_out) ||
+ err == make_error_condition(std::errc::no_such_file_or_directory)) {
  return std::nullopt;
  }
 

router/src/routing/src/dest_metadata_cache.h

@@ -113,6 +113,8 @@ class DestMetadataCacheGroup final
  cache_api()->handle_sockets_acceptors_on_md_refresh();
  }
 
+ routing::RoutingStrategy get_strategy() override { return routing_strategy_; }
+
  private:
  /** @brief The Metadata Cache to use
  *

router/src/routing/src/dest_next_available.h

@@ -44,6 +44,10 @@ class DestNextAvailable final : public RouteDestination {
  }
  }
 
+ routing::RoutingStrategy get_strategy() override {
+ return routing::RoutingStrategy::kNextAvailable;
+ }
+
  private:
  size_t valid_ndx_{};
 };

router/src/routing/src/dest_round_robin.h

@@ -52,6 +52,10 @@ class DestRoundRobin : public RouteDestination {
 
  Destinations destinations() override;
 
+ routing::RoutingStrategy get_strategy() override {
+ return routing::RoutingStrategy::kRoundRobin;
+ }
+
  protected:
  // MUST take the RouteDestination Mutex
  size_t start_pos_{};

router/src/routing/src/destination.cc

@@ -157,3 +157,27 @@ std::optional<Destinations> RouteDestination::refresh_destinations(
  const Destinations &) {
  return std::nullopt;
 }
+
+const std::error_category &destinations_error_category() noexcept {
+ class destinations_category_impl : public std::error_category {
+ public:
+ const char *name() const noexcept override { return "destinations"; }
+ std::string message(int ev) const override {
+ switch (static_cast<DestinationsErrc>(ev)) {
+ case DestinationsErrc::kNotSet:
+ return "not set";
+ case DestinationsErrc::kNoDestinations:
+ return "no destinations";
+ default:
+ return "(unrecognized error)";
+ }
+ }
+ };
+
+ static destinations_category_impl instance;
+ return instance;
+}
+
+std::error_code make_error_code(DestinationsErrc e) {
+ return {static_cast<int>(e), destinations_error_category()};
+}