P0 discovery: zero-traffic wire budget for exact Smart Discovery baselines

include/ariec61850/mms/association_runtime.hpp

@@ -172,7 +172,11 @@ class MmsAssociationRuntime final {
     [[nodiscard]] MmsConfirmedExchangeResult exchange_confirmed(
         std::span<const std::uint8_t> presentation_payload,
         std::uint32_t expected_invoke_id,
-        std::stop_token stop_token = {});
+        std::stop_token stop_token = {},
+        // Optional per-call receipt, independent of the bounded event log.
+        // True only when the complete confirmed request was sent to transport.
+        // A response timeout after a successful send still leaves this true.
+        bool* request_sent = nullptr);
 
     [[nodiscard]] MmsPduEnvelope poll_once(
         std::stop_token stop_token = {});

include/ariec61850/mms/live_discovery.hpp

@@ -72,10 +72,26 @@ struct MmsReportControlEvidence final {
     [[nodiscard]] bool success() const noexcept { return state.has_value(); }
 };
 
+// Completed outbound confirmed MMS request sends (including responses that
+// later fail or time out). Pre-send failures and post-disconnect probes do not
+// count. Pure accounting: no extra MMS service or scheduling side effects.
+struct MmsLiveDiscoveryWireBudget final {
+    std::size_t get_name_list{};
+    std::size_t get_variable_access_attributes{};
+    std::size_t get_named_variable_list_attributes{};
+    std::size_t read_report_controls{};
+
+    [[nodiscard]] std::size_t total() const noexcept {
+        return get_name_list + get_variable_access_attributes +
+            get_named_variable_list_attributes + read_report_controls;
+    }
+};
+
 struct MmsLiveDiscoveryResult final {
     MmsEndpoint endpoint;
     std::string association_profile;
     std::vector<MmsAssociationAttemptEvidence> association_attempts;
+    MmsLiveDiscoveryWireBudget wire_budget;
     MmsDiscoverySnapshot names;
     MmsReportInventory report_inventory;
     std::vector<MmsVariableTypeEvidence> variable_types;
@@ -116,6 +132,7 @@ class MmsLiveDiscoveryClient final {
         MmsGetNameListObjectClass object_class,
         const std::string& domain,
         const MmsLiveDiscoveryOptions& options,
+        MmsLiveDiscoveryWireBudget& wire_budget,
         std::stop_token stop_token);
 
     MmsAssociationRuntime& association_;

src/mms/association_runtime.cpp

@@ -668,7 +668,9 @@ void MmsAssociationRuntime::disconnect(const std::stop_token stop_token) noexcep
 MmsConfirmedExchangeResult MmsAssociationRuntime::exchange_confirmed(
     const std::span<const std::uint8_t> presentation_payload,
     const std::uint32_t expected_invoke_id,
-    const std::stop_token stop_token) {
+    const std::stop_token stop_token,
+    bool* const request_sent) {
+    if (request_sent != nullptr) *request_sent = false;
     require_associated();
     if (expected_invoke_id == 0U ||
         expected_invoke_id > MmsPduCodec::maximum_invoke_id) {
@@ -689,6 +691,7 @@ MmsConfirmedExchangeResult MmsAssociationRuntime::exchange_confirmed(
     const auto deadline = deadline_after(options_.request_timeout);
     try {
         send_application_payload(presentation_payload, deadline, stop_token);
+        if (request_sent != nullptr) *request_sent = true;
         add_event(MmsAssociationEventKind::confirmed_request_sent,
                   "Confirmed MMS request sent.", expected_invoke_id);
 

src/mms/live_discovery.cpp

@@ -266,13 +266,39 @@ std::string MmsLiveDiscoveryResult::summary() const {
     return stream.str();
 }
 
+namespace {
+
+// Capture the per-exchange send receipt even when the response times out.
+// This scoped counter is independent of shared event history and keeps the
+// correct service category if a later optional probe fails before sending.
+struct ConfirmedSendCount final {
+    std::size_t& service_count;
+    bool sent{};
+    ~ConfirmedSendCount() {
+        if (sent) ++service_count;
+    }
+};
+
+[[nodiscard]] MmsConfirmedExchangeResult exchange_counted(
+    MmsAssociationRuntime& association,
+    const std::span<const std::uint8_t> request,
+    const std::uint32_t invoke_id,
+    const std::stop_token stop_token,
+    std::size_t& service_count) {
+    ConfirmedSendCount receipt{service_count};
+    return association.exchange_confirmed(request, invoke_id, stop_token, &receipt.sent);
+}
+
+} // namespace
+
 MmsLiveDiscoveryClient::MmsLiveDiscoveryClient(MmsAssociationRuntime& association)
     : association_{association} {}
 
 std::vector<std::string> MmsLiveDiscoveryClient::get_name_list(
     const MmsGetNameListObjectClass object_class,
     const std::string& domain,
     const MmsLiveDiscoveryOptions& options,
+    MmsLiveDiscoveryWireBudget& wire_budget,
     const std::stop_token stop_token) {
     std::vector<std::string> names;
     std::set<std::string, std::less<>> seen;
@@ -290,8 +316,9 @@ std::vector<std::string> MmsLiveDiscoveryClient::get_name_list(
 
         const auto encoded = MmsServiceCodec::encode_get_name_list_request_p_data(
             request, association_.negotiated().presentation_context_id);
-        const auto exchange = association_.exchange_confirmed(
-            encoded, request.invoke_id, stop_token);
+        const auto exchange = exchange_counted(
+            association_, encoded, request.invoke_id, stop_token,
+            wire_budget.get_name_list);
         const auto payload = response_payload(exchange, "GetNameList");
         const auto response = MmsServiceCodec::decode_get_name_list_response(
             payload, request.invoke_id);
@@ -342,7 +369,7 @@ MmsLiveDiscoveryResult MmsLiveDiscoveryClient::discover(
     result.association_attempts = association_.association_attempts();
 
     const auto domains = get_name_list(
-        MmsGetNameListObjectClass::domain, {}, options, stop_token);
+        MmsGetNameListObjectClass::domain, {}, options, result.wire_budget, stop_token);
     if (domains.size() > options.maximum_domains) {
         throw MmsLiveDiscoveryError(
             "Domain discovery exceeded the configured domain bound.");
@@ -356,6 +383,7 @@ MmsLiveDiscoveryResult MmsLiveDiscoveryClient::discover(
                     MmsGetNameListObjectClass::named_variable,
                     domain,
                     options,
+                    result.wire_budget,
                     stop_token));
         } catch (const std::exception& exception) {
             if (!options.continue_on_optional_probe_error) {
@@ -373,6 +401,7 @@ MmsLiveDiscoveryResult MmsLiveDiscoveryClient::discover(
                     MmsGetNameListObjectClass::named_variable_list,
                     domain,
                     options,
+                    result.wire_budget,
                     stop_token));
         } catch (const std::exception& exception) {
             if (!options.continue_on_optional_probe_error) {
@@ -403,8 +432,9 @@ MmsLiveDiscoveryResult MmsLiveDiscoveryClient::discover(
                     evidence.candidate.reference);
                 const auto encoded = MmsDataSetDirectoryCodec::encode_request_p_data(
                     request, association_.negotiated().presentation_context_id);
-                const auto exchange = association_.exchange_confirmed(
-                    encoded, request.invoke_id, stop_token);
+                const auto exchange = exchange_counted(
+                    association_, encoded, request.invoke_id, stop_token,
+                    result.wire_budget.get_named_variable_list_attributes);
                 const auto payload = response_payload(
                     exchange, "GetNamedVariableListAttributes");
                 evidence.directory = MmsDataSetDirectoryCodec::decode_response(
@@ -452,8 +482,9 @@ MmsLiveDiscoveryResult MmsLiveDiscoveryClient::discover(
                     encode_variable_access_attributes_request_p_data(
                         request,
                         association_.negotiated().presentation_context_id);
-                const auto exchange = association_.exchange_confirmed(
-                    encoded, request.invoke_id, stop_token);
+                const auto exchange = exchange_counted(
+                    association_, encoded, request.invoke_id, stop_token,
+                    result.wire_budget.get_variable_access_attributes);
                 const auto payload = response_payload(
                     exchange, "GetVariableAccessAttributes");
                 evidence.attributes = MmsServiceCodec::
@@ -509,8 +540,9 @@ MmsLiveDiscoveryResult MmsLiveDiscoveryClient::discover(
                     evidence.requested_attributes);
                 const auto encoded = MmsServiceCodec::encode_read_request_p_data(
                     request, association_.negotiated().presentation_context_id);
-                const auto exchange = association_.exchange_confirmed(
-                    encoded, invoke_id, stop_token);
+                const auto exchange = exchange_counted(
+                    association_, encoded, invoke_id, stop_token,
+                    result.wire_budget.read_report_controls);
                 const auto payload = response_payload(
                     exchange, "Read RCB attributes");
                 const auto response = MmsServiceCodec::decode_read_response(

tests/test_live_discovery.cpp

@@ -480,6 +480,11 @@ void live_discovery_builds_csharp_compatible_read_only_model() {
         ++read_only_requests;
     }
     CHECK(read_only_requests == 6U);
+    CHECK(result.wire_budget.get_name_list == 3U);
+    CHECK(result.wire_budget.get_variable_access_attributes == 1U);
+    CHECK(result.wire_budget.get_named_variable_list_attributes == 1U);
+    CHECK(result.wire_budget.read_report_controls == 1U);
+    CHECK(result.wire_budget.total() == read_only_requests);
 }
 
 
@@ -628,6 +633,55 @@ void verified_data_set_hints_restore_late_ln_type_schema() {
     }
     CHECK(found_cswi);
     CHECK(transport.sent().size() == 8U); // association (2) + 6 reads
+    CHECK(result.wire_budget.get_name_list == 3U);
+    CHECK(result.wire_budget.get_named_variable_list_attributes == 1U);
+    CHECK(result.wire_budget.get_variable_access_attributes == 2U);
+    CHECK(result.wire_budget.read_report_controls == 0U);
+    CHECK(result.wire_budget.total() == 6U);
+}
+
+void disconnected_optional_probes_do_not_inflate_wire_budget() {
+    ScriptedTransport transport;
+    queue_handshake(transport);
+    transport.push_receive(wrap_application(
+        mms::MmsServiceCodec::encode_get_name_list_response_p_data(
+            {1U, {"OLS501LD0"}, false})));
+    transport.push_receive(wrap_application(
+        mms::MmsServiceCodec::encode_get_name_list_response_p_data(
+            {2U, {"LLN0$ST$Mod$stVal", "LLN0$RP$urcbA01$RptEna"}, false})));
+    transport.push_receive(wrap_application(
+        mms::MmsServiceCodec::encode_get_name_list_response_p_data(
+            {3U, {"LLN0$DataSetA"}, false})));
+    // Do not enqueue an answer to the GVA request: the exchange sends one
+    // confirmed request, then times out and closes this association.
+    // DataSet and RCB optional phases continue but can no longer send.
+    mms::MmsAssociationOptions transportOptions;
+    transportOptions.maximum_events = 1U; // Bounded events must not affect accounting.
+    mms::MmsAssociationRuntime association{transport, transportOptions};
+    association.connect({"127.0.0.1", 102U});
+
+    mms::MmsLiveDiscoveryOptions options;
+    options.maximum_variable_type_probes = 1U;
+    options.maximum_data_set_directories = 1U;
+    options.maximum_report_control_probes = 1U;
+    options.continue_on_optional_probe_error = true;
+    const auto result = mms::MmsLiveDiscoveryClient{association}.discover(options);
+
+    CHECK(!association.associated());
+    CHECK(result.partial());
+    CHECK(result.domain_count() == 1U);
+    CHECK(result.wire_budget.get_name_list == 3U);
+    CHECK(result.wire_budget.get_variable_access_attributes == 1U);
+    CHECK(result.wire_budget.get_named_variable_list_attributes == 0U);
+    CHECK(result.wire_budget.read_report_controls == 0U);
+    CHECK(result.wire_budget.total() == 4U);
+    CHECK(transport.sent().size() == 6U); // 2 handshake + 4 actual requests
+    CHECK(result.variable_types.size() == 1U);
+    CHECK(!result.variable_types.front().success());
+    CHECK(result.data_set_directories.size() == 1U);
+    CHECK(!result.data_set_directories.front().success());
+    CHECK(result.report_controls.size() == 1U);
+    CHECK(!result.report_controls.front().success());
 }
 
 void pagination_without_forward_progress_is_rejected() {
@@ -661,6 +715,7 @@ int main() {
         case_distinct_references_are_not_deduplicated();
         case_distinct_ln_type_probes_are_preserved();
         verified_data_set_hints_restore_late_ln_type_schema();
+        disconnected_optional_probes_do_not_inflate_wire_budget();
         pagination_without_forward_progress_is_rejected();
         std::cout << "Live MMS discovery and model parity tests passed.\n";
         return 0;