chore: add StateHashedNotification (#15395)

Signed-off-by: Michael Tinker <[email protected]>

platform-sdk/swirlds-platform-core/src/main/java/com/swirlds/platform/components/AppNotifier.java

@@ -21,6 +21,7 @@
 import com.swirlds.platform.listeners.ReconnectCompleteNotification;
 import com.swirlds.platform.listeners.StateWriteToDiskCompleteNotification;
 import com.swirlds.platform.system.state.notifications.IssNotification;
+import com.swirlds.platform.system.state.notifications.StateHashedNotification;
 import com.swirlds.platform.system.status.PlatformStatus;
 import edu.umd.cs.findbugs.annotations.NonNull;
 
@@ -36,6 +37,14 @@ public interface AppNotifier {
     @InputWireLabel("state written notification")
     void sendStateWrittenToDiskNotification(@NonNull final StateWriteToDiskCompleteNotification notification);
 
+    /**
+     * Send a notification to the app that a state has been written to disk.
+     *
+     * @param notification the notification
+     */
+    @InputWireLabel("state hashed notification")
+    void sendStateHashedNotification(@NonNull final StateHashedNotification notification);
+
     /**
      * Send a notification to the app that a reconnect has completed.
      *

platform-sdk/swirlds-platform-core/src/main/java/com/swirlds/platform/components/DefaultAppNotifier.java

@@ -27,6 +27,8 @@
 import com.swirlds.platform.system.state.notifications.IssListener;
 import com.swirlds.platform.system.state.notifications.IssNotification;
 import com.swirlds.platform.system.state.notifications.NewSignedStateListener;
+import com.swirlds.platform.system.state.notifications.StateHashedListener;
+import com.swirlds.platform.system.state.notifications.StateHashedNotification;
 import com.swirlds.platform.system.status.PlatformStatus;
 import edu.umd.cs.findbugs.annotations.NonNull;
 
@@ -42,6 +44,11 @@ public void sendStateWrittenToDiskNotification(@NonNull final StateWriteToDiskCo
         notificationEngine.dispatch(StateWriteToDiskCompleteListener.class, notification);
     }
 
+    @Override
+    public void sendStateHashedNotification(@NonNull final StateHashedNotification notification) {
+        notificationEngine.dispatch(StateHashedListener.class, notification);
+    }
+
     /**
      * {@inheritDoc}
      */

platform-sdk/swirlds-platform-core/src/main/java/com/swirlds/platform/system/state/notifications/StateHashedListener.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright (C) 2024 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.swirlds.platform.system.state.notifications;
+
+import com.swirlds.common.notification.DispatchMode;
+import com.swirlds.common.notification.DispatchModel;
+import com.swirlds.common.notification.DispatchOrder;
+import com.swirlds.common.notification.Listener;
+
+/**
+ * A method that listens for the newly hashed states.
+ */
+@DispatchModel(mode = DispatchMode.SYNC, order = DispatchOrder.UNORDERED)
+public interface StateHashedListener extends Listener<StateHashedNotification> {}

platform-sdk/swirlds-platform-core/src/main/java/com/swirlds/platform/system/state/notifications/StateHashedNotification.java

@@ -0,0 +1,59 @@
+/*
+ * Copyright (C) 2024 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.swirlds.platform.system.state.notifications;
+
+import static java.util.Objects.requireNonNull;
+
+import com.swirlds.common.crypto.Hash;
+import com.swirlds.common.notification.AbstractNotification;
+import com.swirlds.common.notification.Notification;
+import com.swirlds.platform.wiring.components.StateAndRound;
+import edu.umd.cs.findbugs.annotations.NonNull;
+
+/**
+ * A {@link Notification} that a state hash has been computed.
+ */
+public class StateHashedNotification extends AbstractNotification {
+    private final long roundNumber;
+    private final Hash hash;
+
+    /**
+     * Create a notification for a newly hashed state.
+     * @param stateAndRound the state and round that is now hashed
+     * @return a new notification
+     */
+    public static StateHashedNotification from(@NonNull final StateAndRound stateAndRound) {
+        try (final var state = stateAndRound.reservedSignedState()) {
+            return new StateHashedNotification(
+                    stateAndRound.round().getRoundNum(),
+                    requireNonNull(state.get().getState().getHash()));
+        }
+    }
+
+    private StateHashedNotification(final long roundNumber, @NonNull final Hash hash) {
+        this.roundNumber = roundNumber;
+        this.hash = requireNonNull(hash);
+    }
+
+    public long round() {
+        return roundNumber;
+    }
+
+    public @NonNull Hash hash() {
+        return hash;
+    }
+}

platform-sdk/swirlds-platform-core/src/main/java/com/swirlds/platform/wiring/PlatformWiring.java

@@ -99,6 +99,7 @@
 import com.swirlds.platform.system.events.BirthRoundMigrationShim;
 import com.swirlds.platform.system.events.UnsignedEvent;
 import com.swirlds.platform.system.state.notifications.IssNotification;
+import com.swirlds.platform.system.state.notifications.StateHashedNotification;
 import com.swirlds.platform.system.status.PlatformStatus;
 import com.swirlds.platform.system.status.PlatformStatusConfig;
 import com.swirlds.platform.system.status.StatusActionSubmitter;
@@ -665,6 +666,9 @@ private void wire() {
         hashedStateOutputWire.solderTo(hashLoggerWiring.getInputWire(HashLogger::logHashes));
         hashedStateOutputWire.solderTo(stateSignerWiring.getInputWire(StateSigner::signState));
         hashedStateAndRoundOutputWire.solderTo(issDetectorWiring.getInputWire(IssDetector::handleStateAndRound));
+        hashedStateAndRoundOutputWire
+                .buildTransformer("postHasher_notifier", "state and round", StateHashedNotification::from)
+                .solderTo(notifierWiring.getInputWire(AppNotifier::sendStateHashedNotification));
 
         stateSignerWiring
                 .getOutputWire()

platform-sdk/swirlds-platform-core/src/test/java/com/swirlds/platform/system/state/notifications/StateHashedNotificationTest.java

@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) 2024 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.swirlds.platform.system.state.notifications;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.mockito.BDDMockito.given;
+
+import com.swirlds.common.crypto.Hash;
+import com.swirlds.platform.internal.ConsensusRound;
+import com.swirlds.platform.state.MerkleRoot;
+import com.swirlds.platform.state.signed.ReservedSignedState;
+import com.swirlds.platform.state.signed.SignedState;
+import com.swirlds.platform.wiring.components.StateAndRound;
+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 StateHashedNotificationTest {
+    private static final long ROUND = 123L;
+    private static final Hash HASH = new Hash(new byte[48]);
+
+    @Mock
+    private MerkleRoot merkleRoot;
+
+    @Mock
+    private SignedState signedState;
+
+    @Mock
+    private ConsensusRound round;
+
+    @Mock
+    private ReservedSignedState reservedSignedState;
+
+    @Test
+    void factoryWorksAsExpected() {
+        given(round.getRoundNum()).willReturn(ROUND);
+        given(reservedSignedState.get()).willReturn(signedState);
+        given(signedState.getState()).willReturn(merkleRoot);
+        given(merkleRoot.getHash()).willReturn(HASH);
+
+        final var notification = StateHashedNotification.from(new StateAndRound(reservedSignedState, round));
+
+        assertEquals(ROUND, notification.round());
+        assertEquals(HASH, notification.hash());
+    }
+}