feat: add congestion multiplier metric

hedera-node/hedera-app/src/main/java/com/hedera/node/app/throttle/CongestionMetrics.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright (C) 2025 Hedera Hashgraph, LLC
+ *
+ * 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.
+ */
+
+package com.hedera.node.app.throttle;
+
+import static java.util.Objects.requireNonNull;
+
+import com.hedera.node.app.fees.congestion.CongestionMultipliers;
+import com.hedera.node.app.store.ReadableStoreFactory;
+import com.hedera.node.app.workflows.TransactionInfo;
+import com.swirlds.metrics.api.LongGauge;
+import com.swirlds.metrics.api.Metrics;
+import edu.umd.cs.findbugs.annotations.NonNull;
+import javax.inject.Inject;
+import javax.inject.Singleton;
+
+@Singleton
+public class CongestionMetrics {
+    private final CongestionMultipliers congestionMultipliers;
+    private final LongGauge congestionMultiplierGauge;
+
+    @Inject
+    public CongestionMetrics(
+            @NonNull final Metrics metrics, @NonNull final CongestionMultipliers congestionMultipliers) {
+        requireNonNull(metrics);
+        this.congestionMultipliers = requireNonNull(congestionMultipliers);
+
+        final var config =
+                new LongGauge.Config("app", "congestionMultiplier").withDescription("Current congestion multiplier");
+        this.congestionMultiplierGauge = metrics.getOrCreate(config);
+    }
+
+    public void updateMultiplier(
+            @NonNull final TransactionInfo txnInfo, @NonNull final ReadableStoreFactory storeFactory) {
+        congestionMultiplierGauge.set(congestionMultipliers.maxCurrentMultiplier(txnInfo, storeFactory));
+    }
+}

hedera-node/hedera-app/src/main/java/com/hedera/node/app/workflows/handle/HandleWorkflow.java

@@ -82,6 +82,7 @@
 import com.hedera.node.app.state.recordcache.LegacyListRecordSource;
 import com.hedera.node.app.store.StoreFactoryImpl;
 import com.hedera.node.app.store.WritableStoreFactory;
+import com.hedera.node.app.throttle.CongestionMetrics;
 import com.hedera.node.app.throttle.ThrottleServiceManager;
 import com.hedera.node.app.workflows.OpWorkflowMetrics;
 import com.hedera.node.app.workflows.TransactionInfo;
@@ -153,6 +154,7 @@ public class HandleWorkflow {
     private final KVStateChangeListener kvStateChangeListener;
     private final BoundaryStateChangeListener boundaryStateChangeListener;
     private final ScheduleService scheduleService;
+    private final CongestionMetrics congestionMetrics;
 
     // The last second since the epoch at which the metrics were updated; this does not affect transaction handling
     private long lastMetricUpdateSecond;
@@ -184,7 +186,8 @@ public HandleWorkflow(
             @NonNull final AddressBookHelper addressBookHelper,
             @NonNull final KVStateChangeListener kvStateChangeListener,
             @NonNull final BoundaryStateChangeListener boundaryStateChangeListener,
-            @NonNull final ScheduleService scheduleService) {
+            @NonNull final ScheduleService scheduleService,
+            @NonNull final CongestionMetrics congestionMetrics) {
         this.networkInfo = requireNonNull(networkInfo);
         this.stakePeriodChanges = requireNonNull(stakePeriodChanges);
         this.dispatchProcessor = requireNonNull(dispatchProcessor);
@@ -209,6 +212,7 @@ public HandleWorkflow(
         this.kvStateChangeListener = requireNonNull(kvStateChangeListener);
         this.boundaryStateChangeListener = requireNonNull(boundaryStateChangeListener);
         this.scheduleService = requireNonNull(scheduleService);
+        this.congestionMetrics = requireNonNull(congestionMetrics);
         this.streamMode = configProvider
                 .getConfiguration()
                 .getConfigData(BlockStreamConfig.class)
@@ -319,7 +323,7 @@ private void handleEvents(
             }
         }
         // Update all throttle metrics once per round
-        throttleServiceManager.updateAllMetrics();
+        throttleServiceManager.updateAllMetrics(); // TODO: update congestion multiplier metrics here?
         // Inform the BlockRecordManager that the round is complete, so it can update running-hashes in state
         // that have been being computed in background threads. The running hash has to be included in
         // state, but we want to synchronize with background threads as infrequently as possible. So once per
@@ -384,6 +388,7 @@ private boolean handlePlatformTransaction(
         }
 
         opWorkflowMetrics.updateDuration(userTxn.functionality(), (int) (System.nanoTime() - handleStart));
+        congestionMetrics.updateMultiplier(userTxn.txnInfo(), userTxn.readableStoreFactory());
 
         if (streamMode == RECORDS) {
             // We don't support long-term scheduled transactions if only producing records

hedera-node/hedera-app/src/test/java/com/hedera/node/app/throttle/CongestionMetricsTest.java

@@ -0,0 +1,68 @@
+/*
+ * Copyright (C) 2025 Hedera Hashgraph, LLC
+ *
+ * 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.
+ */
+
+package com.hedera.node.app.throttle;
+
+import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import com.hedera.node.app.fees.congestion.CongestionMultipliers;
+import com.hedera.node.app.store.ReadableStoreFactory;
+import com.hedera.node.app.workflows.TransactionInfo;
+import com.swirlds.metrics.api.LongGauge;
+import com.swirlds.metrics.api.Metrics;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+@ExtendWith(MockitoExtension.class)
+class CongestionMetricsTest {
+    @Mock
+    private Metrics metrics;
+
+    @Mock
+    private CongestionMultipliers congestionMultipliers;
+
+    @Mock
+    private LongGauge longGauge;
+
+    @Mock
+    private TransactionInfo txnInfo;
+
+    @Mock
+    private ReadableStoreFactory storeFactory;
+
+    private CongestionMetrics congestionMetrics;
+
+    @BeforeEach
+    void setUp() {
+        when(metrics.getOrCreate(any(LongGauge.Config.class))).thenReturn(longGauge);
+        congestionMetrics = new CongestionMetrics(metrics, congestionMultipliers);
+    }
+
+    @Test
+    void testUpdateMultiplier() {
+        when(congestionMultipliers.maxCurrentMultiplier(txnInfo, storeFactory)).thenReturn(5L);
+
+        congestionMetrics.updateMultiplier(txnInfo, storeFactory);
+
+        verify(longGauge).set(5L);
+    }
+}

hedera-node/hedera-app/src/test/java/com/hedera/node/app/workflows/handle/HandleWorkflowTest.java

@@ -41,6 +41,7 @@
 import com.hedera.node.app.service.token.impl.handlers.staking.StakePeriodManager;
 import com.hedera.node.app.spi.metrics.StoreMetricsService;
 import com.hedera.node.app.state.HederaRecordCache;
+import com.hedera.node.app.throttle.CongestionMetrics;
 import com.hedera.node.app.throttle.ThrottleServiceManager;
 import com.hedera.node.app.workflows.OpWorkflowMetrics;
 import com.hedera.node.app.workflows.handle.cache.CacheWarmer;
@@ -144,6 +145,9 @@ class HandleWorkflowTest {
     @Mock
     private UserTxnFactory userTxnFactory;
 
+    @Mock
+    private CongestionMetrics congestionMetrics;
+
     private HandleWorkflow subject;
 
     @BeforeEach
@@ -222,6 +226,7 @@ private void givenSubjectWith(
                 new AddressBookHelper(),
                 kvStateChangeListener,
                 boundaryStateChangeListener,
-                scheduleService);
+                scheduleService,
+                congestionMetrics);
     }
 }