Add DeviceLoadStatus Support to General Diagnostics Cluster

examples/all-devices-app/all-devices-common/devices/root-node/RootNodeDevice.cpp

@@ -18,6 +18,7 @@
 
 #include <app-common/zap-generated/ids/Attributes.h>
 #include <app-common/zap-generated/ids/Clusters.h>
+#include <app/InteractionModelEngine.h>
 #include <lib/support/CHIPMem.h>
 #include <lib/support/CodeUtils.h>
 #include <platform/CHIPDeviceLayer.h>
@@ -68,7 +69,8 @@ CHIP_ERROR RootNodeDevice::Register(EndpointId endpointId, CodeDrivenDataModelPr
     mAdministratorCommissioningCluster.Create(endpointId, BitFlags<AdministratorCommissioning::Feature>{});
     ReturnErrorOnFailure(provider.AddCluster(mAdministratorCommissioningCluster.Registration()));
 
-    mGeneralDiagnosticsCluster.Create(GeneralDiagnosticsCluster::OptionalAttributeSet{}, BitFlags<GeneralDiagnostics::Feature>{});
+    mGeneralDiagnosticsCluster.Create(GeneralDiagnosticsCluster::OptionalAttributeSet{}, BitFlags<GeneralDiagnostics::Feature>{},
+                                      InteractionModelEngine::GetInstance());
     ReturnErrorOnFailure(provider.AddCluster(mGeneralDiagnosticsCluster.Registration()));
 
     mGroupKeyManagementCluster.Create();

src/app/BUILD.gn

@@ -175,6 +175,7 @@ static_library("interaction-model") {
     "CASESessionManager.h",
     "CommandSender.cpp",
     "CommandSender.h",
+    "DeviceLoadStatusProvider.h",
     "DeviceProxy.cpp",
     "DeviceProxy.h",
     "InteractionModelDelegatePointers.cpp",
@@ -192,6 +193,7 @@ static_library("interaction-model") {
                      # fixing
     "ReadPrepareParams.h",
     "SubscriptionResumptionStorage.h",
+    "SubscriptionStats.h",
     "TimedHandler.cpp",
     "TimedHandler.h",
     "TimedRequest.cpp",
@@ -236,6 +238,7 @@ static_library("interaction-model") {
     "${chip_root}/src/protocols/interaction_model",
     "${chip_root}/src/protocols/secure_channel",
     "${chip_root}/src/system",
+    "${chip_root}/src/transport",
   ]
 
   if (chip_enable_icd_server) {

src/app/DeviceLoadStatusProvider.h

@@ -0,0 +1,41 @@
+/*
+ *
+ *    Copyright (c) 2025 Project CHIP Authors
+ *    All rights reserved.
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ */
+#pragma once
+
+#include <cstdint>
+
+#include <app/SubscriptionStats.h>
+#include <lib/core/DataModelTypes.h>
+#include <transport/MessageStats.h>
+#include <utility>
+
+namespace chip {
+namespace app {
+
+class DeviceLoadStatusProvider
+{
+public:
+    virtual ~DeviceLoadStatusProvider() = default;
+
+    virtual MessageStats GetMessageStats() = 0;
+
+    virtual SubscriptionStats GetSubscriptionStats(FabricIndex fabric) = 0;
+};
+
+} // namespace app
+} // namespace chip

src/app/InteractionModelEngine.cpp

@@ -2269,5 +2269,20 @@ void InteractionModelEngine::ResetNumSubscriptionsRetries()
     }
 }
 #endif // CHIP_CONFIG_PERSIST_SUBSCRIPTIONS && CHIP_CONFIG_SUBSCRIPTION_TIMEOUT_RESUMPTION
+
+MessageStats InteractionModelEngine::GetMessageStats()
+{
+    return GetExchangeManager()->GetSessionManager()->GetMessageStats();
+}
+
+SubscriptionStats InteractionModelEngine::GetSubscriptionStats(FabricIndex fabric)
+{
+    return SubscriptionStats{ .numTotalSubscriptions = GetReportScheduler()->GetTotalSubscriptionsEstablished(),
+                              .numCurrentSubscriptions =
+                                  static_cast<uint16_t>(GetNumActiveReadHandlers(ReadHandler::InteractionType::Subscribe)),
+                              .numCurrentSubscriptionsForFabric = static_cast<uint16_t>(
+                                  GetNumActiveReadHandlers(ReadHandler::InteractionType::Subscribe, fabric)) };
+}
+
 } // namespace app
 } // namespace chip

src/app/InteractionModelEngine.h

@@ -28,20 +28,23 @@
 #include <access/AccessControl.h>
 #include <app/AppConfig.h>
 #include <app/AttributePathParams.h>
+#include <app/CASESessionManager.h>
 #include <app/CommandHandlerImpl.h>
 #include <app/CommandResponseSender.h>
 #include <app/CommandSender.h>
 #include <app/ConcreteAttributePath.h>
 #include <app/ConcreteCommandPath.h>
 #include <app/ConcreteEventPath.h>
 #include <app/DataVersionFilter.h>
+#include <app/DeviceLoadStatusProvider.h>
 #include <app/EventPathParams.h>
 #include <app/MessageDef/AttributeReportIBs.h>
 #include <app/MessageDef/ReportDataMessage.h>
 #include <app/ReadClient.h>
 #include <app/ReadHandler.h>
 #include <app/StatusResponse.h>
 #include <app/SubscriptionResumptionSessionEstablisher.h>
+#include <app/SubscriptionStats.h>
 #include <app/SubscriptionsInfoProvider.h>
 #include <app/TimedHandler.h>
 #include <app/WriteClient.h>
@@ -66,8 +69,7 @@
 #include <protocols/Protocols.h>
 #include <protocols/interaction_model/Constants.h>
 #include <system/SystemPacketBuffer.h>
-
-#include <app/CASESessionManager.h>
+#include <transport/MessageStats.h>
 
 #if CHIP_CONFIG_ENABLE_ICD_SERVER
 #include <app/icd/server/ICDManager.h> // nogncheck
@@ -92,7 +94,8 @@ class InteractionModelEngine : public Messaging::UnsolicitedMessageHandler,
                                public FabricTable::Delegate,
                                public SubscriptionsInfoProvider,
                                public TimedHandlerDelegate,
-                               public WriteHandlerDelegate
+                               public WriteHandlerDelegate,
+                               public DeviceLoadStatusProvider
 {
 public:
     /**
@@ -429,6 +432,11 @@ class InteractionModelEngine : public Messaging::UnsolicitedMessageHandler,
     // Returns the old data model provider value.
     DataModel::Provider * SetDataModelProvider(DataModel::Provider * model);
 
+    // DeviceLoadStatusProvider functions implementation
+    MessageStats GetMessageStats() override;
+
+    SubscriptionStats GetSubscriptionStats(FabricIndex fabric) override;
+
 private:
     /* DataModel::ActionContext implementation */
     Messaging::ExchangeContext * CurrentExchange() override { return mCurrentExchange; }

src/app/SubscriptionStats.h

@@ -0,0 +1,33 @@
+/*
+ *
+ *    Copyright (c) 2025 Project CHIP Authors
+ *    All rights reserved.
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ */
+#pragma once
+
+#include <cstdint>
+
+namespace chip {
+namespace app {
+
+struct SubscriptionStats
+{
+    uint32_t numTotalSubscriptions            = 0;
+    uint16_t numCurrentSubscriptions          = 0;
+    uint16_t numCurrentSubscriptionsForFabric = 0;
+};
+
+} // namespace app
+} // namespace chip

src/app/clusters/general-diagnostics-server/BUILD.gn

@@ -22,6 +22,7 @@ source_set("general-diagnostics-server") {
 
   public_deps = [
     "${chip_root}/src/app:attribute-access",
+    "${chip_root}/src/app:interaction-model",
     "${chip_root}/src/app:test-event-trigger",
     "${chip_root}/src/app/data-model-provider:metadata",
     "${chip_root}/src/app/server",

src/app/clusters/general-diagnostics-server/CodegenIntegration.cpp

@@ -15,6 +15,7 @@
  *    limitations under the License.
  */
 
+#include <app/InteractionModelEngine.h>
 #include <app/clusters/general-diagnostics-server/CodegenIntegration.h>
 #include <app/clusters/general-diagnostics-server/GeneralDiagnosticsCluster.h>
 #include <app/static-cluster-config/GeneralDiagnostics.h>
@@ -50,6 +51,7 @@ class IntegrationDelegate : public CodegenClusterIntegration::Delegate
                                                    uint32_t optionalAttributeBits, uint32_t featureMap) override
     {
         GeneralDiagnosticsCluster::OptionalAttributeSet optionalAttributeSet(optionalAttributeBits);
+        InteractionModelEngine * interactionModel = InteractionModelEngine::GetInstance();
 
 #if defined(ZCL_USING_TIME_SYNCHRONIZATION_CLUSTER_SERVER) || defined(GENERAL_DIAGNOSTICS_ENABLE_PAYLOAD_TEST_REQUEST_CMD)
         const GeneralDiagnosticsFunctionsConfig functionsConfig
@@ -69,9 +71,9 @@ class IntegrationDelegate : public CodegenClusterIntegration::Delegate
             .enablePayloadSnapshot = false,
 #endif
         };
-        gServer.Create(optionalAttributeSet, BitFlags<GeneralDiagnostics::Feature>(featureMap), functionsConfig);
+        gServer.Create(optionalAttributeSet, BitFlags<GeneralDiagnostics::Feature>(featureMap), interactionModel, functionsConfig);
 #else
-        gServer.Create(optionalAttributeSet, BitFlags<GeneralDiagnostics::Feature>(featureMap));
+        gServer.Create(optionalAttributeSet, BitFlags<GeneralDiagnostics::Feature>(featureMap), interactionModel);
 #endif
         return gServer.Registration();
     }

src/app/clusters/general-diagnostics-server/GeneralDiagnosticsCluster.cpp

@@ -16,12 +16,15 @@
  */
 
 #include <app-common/zap-generated/cluster-objects.h>
+#include <app/InteractionModelEngine.h>
+#include <app/SubscriptionStats.h>
 #include <app/clusters/general-diagnostics-server/GeneralDiagnosticsCluster.h>
 #include <app/server-cluster/AttributeListBuilder.h>
 #include <app/server-cluster/DefaultServerCluster.h>
 #include <app/server/Server.h>
 #include <clusters/GeneralDiagnostics/ClusterId.h>
 #include <clusters/GeneralDiagnostics/Metadata.h>
+#include <transport/MessageStats.h>
 
 using namespace chip;
 using namespace chip::app;
@@ -274,6 +277,21 @@ DataModel::ActionReturnStatus GeneralDiagnosticsCluster::ReadAttribute(const Dat
     case GeneralDiagnostics::Attributes::TestEventTriggersEnabled::Id: {
         bool isTestEventTriggersEnabled = IsTestEventTriggerEnabled();
         return encoder.Encode(isTestEventTriggersEnabled);
+    }
+    case GeneralDiagnostics::Attributes::DeviceLoadStatus::Id: {
+        static_assert(CHIP_IM_MAX_NUM_SUBSCRIPTIONS <= UINT16_MAX,
+                      "The maximum number of IM subscriptions is larger than expected (should fit within a 16 bit unsigned int)");
+        const SubscriptionStats subscriptionStats = mDeviceLoadStatusProvider->GetSubscriptionStats(encoder.AccessingFabricIndex());
+        const MessageStats messageStatistics      = mDeviceLoadStatusProvider->GetMessageStats();
+
+        GeneralDiagnostics::Structs::DeviceLoadStruct::Type load = {
+            .currentSubscriptions                  = subscriptionStats.numCurrentSubscriptions,
+            .currentSubscriptionsForFabric         = subscriptionStats.numCurrentSubscriptionsForFabric,
+            .totalSubscriptionsEstablished         = subscriptionStats.numTotalSubscriptions,
+            .totalInteractionModelMessagesSent     = messageStatistics.interactionModelMessagesSent,
+            .totalInteractionModelMessagesReceived = messageStatistics.interactionModelMessagesReceived,
+        };
+        return encoder.Encode(load);
     }
         // Note: Attribute ID 0x0009 was removed (#30002).
 
@@ -328,6 +346,11 @@ CHIP_ERROR GeneralDiagnosticsCluster::Attributes(const ConcreteClusterPath & pat
         GeneralDiagnostics::Attributes::DeviceLoadStatus::kMetadataEntry,
     };
 
+    if (mFeatureFlags.Has(GeneralDiagnostics::Feature::kDeviceLoad))
+    {
+        mOptionalAttributeSet.Set<GeneralDiagnostics::Attributes::DeviceLoadStatus::Id>();
+    }
+
     return listBuilder.Append(Span(GeneralDiagnostics::Attributes::kMandatoryMetadata), Span(optionalAttributeEntries),
                               mOptionalAttributeSet);
 }

src/app/clusters/general-diagnostics-server/GeneralDiagnosticsCluster.h

@@ -17,6 +17,7 @@
 #pragma once
 
 #include <app-common/zap-generated/cluster-objects.h>
+#include <app/DeviceLoadStatusProvider.h>
 #include <app/server-cluster/DefaultServerCluster.h>
 #include <app/server-cluster/OptionalAttributeSet.h>
 #include <app/server/Server.h>
@@ -49,10 +50,11 @@ class GeneralDiagnosticsCluster : public DefaultServerCluster
                                         //       it will be forced as mandatory by the cluster constructor
                                         >;
 
-    GeneralDiagnosticsCluster(OptionalAttributeSet optionalAttributeSet, BitFlags<GeneralDiagnostics::Feature> featureFlags) :
+    GeneralDiagnosticsCluster(OptionalAttributeSet optionalAttributeSet, BitFlags<GeneralDiagnostics::Feature> featureFlags,
+                              DeviceLoadStatusProvider * deviceLoadStatusProvider) :
         DefaultServerCluster({ kRootEndpointId, GeneralDiagnostics::Id }),
         mOptionalAttributeSet(optionalAttributeSet.ForceSet<GeneralDiagnostics::Attributes::UpTime::Id>()),
-        mFeatureFlags(featureFlags)
+        mFeatureFlags(featureFlags), mDeviceLoadStatusProvider(deviceLoadStatusProvider)
     {}
 
     CHIP_ERROR Startup(ServerClusterContext & context) override;
@@ -126,15 +128,17 @@ class GeneralDiagnosticsCluster : public DefaultServerCluster
     OptionalAttributeSet mOptionalAttributeSet;
     CHIP_ERROR ReadNetworkInterfaces(AttributeValueEncoder & aEncoder);
     BitFlags<GeneralDiagnostics::Feature> mFeatureFlags;
+    DeviceLoadStatusProvider * mDeviceLoadStatusProvider;
 };
 
 class GeneralDiagnosticsClusterFullConfigurable : public GeneralDiagnosticsCluster
 {
 public:
     GeneralDiagnosticsClusterFullConfigurable(const GeneralDiagnosticsCluster::OptionalAttributeSet & optionalAttributeSet,
                                               const BitFlags<GeneralDiagnostics::Feature> featureFlags,
+                                              DeviceLoadStatusProvider * deviceLoadStatusProvider,
                                               const GeneralDiagnosticsFunctionsConfig & functionsConfig) :
-        GeneralDiagnosticsCluster(optionalAttributeSet, featureFlags),
+        GeneralDiagnosticsCluster(optionalAttributeSet, featureFlags, deviceLoadStatusProvider),
         mFunctionConfig(functionsConfig)
     {}