Introduce the MemberSuspectEvent class extends MembershipEvent to signal when a peer member of the distributd system (cluster) becomes suspect.

A peer member of the distributed system (cluster) becomse suspect when it is no longer responsive to other peer members in the cluster.

apache-geode-extensions/src/main/java/org/springframework/geode/distributed/event/support/MemberSuspectEvent.java

@@ -0,0 +1,113 @@
+/*
+ * Copyright 2020 the original author or authors.
+ *
+ * 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
+ *
+ *     https://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 org.springframework.geode.distributed.event.support;
+
+import java.util.Optional;
+
+import org.apache.geode.distributed.DistributedMember;
+import org.apache.geode.distributed.DistributedSystem;
+import org.apache.geode.distributed.internal.DistributionManager;
+
+import org.springframework.geode.distributed.event.MembershipEvent;
+
+/**
+ * {@link MembershipEvent} fired when a {@link DistributedMember} of the {@link DistributedSystem} is suspected
+ * of being unresponsive to other {@link DistributedMember peer members} in the cluster.
+ *
+ * @author John Blum
+ * @see org.apache.geode.distributed.DistributedMember
+ * @see org.apache.geode.distributed.DistributedSystem
+ * @see org.springframework.geode.distributed.event.MembershipEvent
+ * @since 1.3.0
+ */
+public class MemberSuspectEvent extends MembershipEvent<MemberSuspectEvent> {
+
+	private DistributedMember suspectMember;
+
+	private String reason;
+
+	/**
+	 * Constructs a new instance of {@link MemberSuspectEvent} initialized with the given {@link DistributionManager}.
+	 *
+	 * @param distributionManager {@link DistributionManager} used as the {@link #getSource() source} of this event;
+	 * must not be {@literal null}.
+	 * @throws IllegalArgumentException if {@link DistributionManager} is {@literal null}.
+	 * @see org.apache.geode.distributed.internal.DistributionManager
+	 */
+	public MemberSuspectEvent(DistributionManager distributionManager) {
+		super(distributionManager);
+	}
+
+	/**
+	 * Returns an {@link Optional} {@link String reason} describing the suspicion of the peer member.
+	 *
+	 * @return an {@link Optional} {@link String reason} describing the suspicion of the peer member.
+	 * @see java.util.Optional
+	 */
+	public Optional<String> getReason() {
+		return Optional.ofNullable(this.reason);
+	}
+
+	/**
+	 * Returns an {@link Optional} {@link DistributedMember} identified as the suspect in the {@link MembershipEvent}.
+	 *
+	 * @return an {@link Optional} {@link DistributedMember} identified as the suspect in the {@link MembershipEvent}.
+	 * @see org.apache.geode.distributed.DistributedMember
+	 * @see java.util.Optional
+	 */
+	public Optional<DistributedMember> getSuspectMember() {
+		return Optional.ofNullable(this.suspectMember);
+	}
+
+	/**
+	 * Builder method used to configure the {@link String reason} describing the suspicion of
+	 * the {@link DistributedMember suspect member}.
+	 *
+	 * @param reason {@link String} describing the suspicion of the {@link DistributedMember peer member};
+	 * may be {@literal null}.
+	 * @return this {@link MemberSuspectEvent}.
+	 * @see #getReason()
+	 */
+	public MemberSuspectEvent withReason(String reason) {
+
+		this.reason = reason;
+
+		return this;
+	}
+
+	/**
+	 * Builder method used to configure the {@link DistributedMember peer member} that is the subject of the suspicion
+	 * {@link MembershipEvent}.
+	 *
+	 * @param suspectMember {@link DistributedMember peer member} that is being suspected; may be {@literal null}.
+	 * @return this {@link MemberSuspectEvent}.
+	 * @see #getSuspectMember()
+	 */
+	public MemberSuspectEvent withSuspect(DistributedMember suspectMember) {
+
+		this.suspectMember = suspectMember;
+
+		return this;
+	}
+
+	/**
+	 * @inheritDoc
+	 */
+	@Override
+	public final Type getType() {
+		return Type.MEMBER_SUSPECT;
+	}
+}

apache-geode-extensions/src/test/java/org/springframework/geode/distributed/event/support/MemberSuspectEventUnitTests.java

@@ -0,0 +1,95 @@
+/*
+ * Copyright 2020 the original author or authors.
+ *
+ * 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
+ *
+ *     https://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 org.springframework.geode.distributed.event.support;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verifyNoInteractions;
+
+import org.junit.Test;
+
+import org.apache.geode.distributed.DistributedMember;
+import org.apache.geode.distributed.internal.DistributionManager;
+
+import org.springframework.geode.distributed.event.MembershipEvent;
+
+/**
+ * Unit Tests for {@link MemberSuspectEvent}.
+ *
+ * @author John Blum
+ * @see org.junit.Test
+ * @see org.mockito.Mockito
+ * @see org.apache.geode.distributed.DistributedMember
+ * @see org.springframework.geode.distributed.event.MembershipEvent
+ * @see org.springframework.geode.distributed.event.support.MemberSuspectEvent
+ * @since 1.3.0
+ */
+public class MemberSuspectEventUnitTests {
+
+	@Test
+	public void constructsMemberSuspectEvent() {
+
+		DistributionManager mockDistributionManager = mock(DistributionManager.class);
+
+		MemberSuspectEvent event = new MemberSuspectEvent(mockDistributionManager);
+
+		assertThat(event).isNotNull();
+		assertThat(event.getDistributionManager()).isEqualTo(mockDistributionManager);
+		assertThat(event.getReason().orElse(null)).isNull();
+		assertThat(event.getSuspectMember().orElse(null)).isNull();
+		assertThat(event.getType()).isEqualTo(MembershipEvent.Type.MEMBER_SUSPECT);
+
+		verifyNoInteractions(mockDistributionManager);
+	}
+
+	@Test
+	public void setAndGetReason() {
+
+		DistributionManager mockDistributionManager = mock(DistributionManager.class);
+
+		MemberSuspectEvent event = new MemberSuspectEvent(mockDistributionManager);
+
+		assertThat(event).isNotNull();
+		assertThat(event.getReason().orElse(null)).isNull();
+		assertThat(event.withReason("TEST")).isSameAs(event);
+		assertThat(event.getReason().orElse(null)).isEqualTo("TEST");
+		assertThat(event.withReason(null)).isSameAs(event);
+		assertThat(event.getReason().orElse(null)).isNull();
+		assertThat(event.withReason("  ")).isSameAs(event);
+		assertThat(event.getReason().orElse(null)).isEqualTo("  ");
+		assertThat(event.withReason(null)).isSameAs(event);
+		assertThat(event.getReason().orElse(null)).isNull();
+		assertThat(event.withReason("")).isSameAs(event);
+		assertThat(event.getReason().orElse(null)).isEqualTo("");
+	}
+
+	@Test
+	public void setAndGetSuspectMember() {
+
+		DistributedMember mockDistributedMember = mock(DistributedMember.class);
+
+		DistributionManager mockDistributionManager = mock(DistributionManager.class);
+
+		MemberSuspectEvent event = new MemberSuspectEvent(mockDistributionManager);
+
+		assertThat(event).isNotNull();
+		assertThat(event.getSuspectMember().orElse(null)).isNull();
+		assertThat(event.withSuspect(mockDistributedMember)).isSameAs(event);
+		assertThat(event.getSuspectMember().orElse(null)).isEqualTo(mockDistributedMember);
+		assertThat(event.withSuspect(null)).isSameAs(event);
+		assertThat(event.getSuspectMember().orElse(null)).isNull();
+	}
+}