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The following commit(s) were added to refs/heads/main by this push:
new 0f8d5779a88 NIFI-16120 Added caching for Kubernetes Leader Election
Manager (#11445)
0f8d5779a88 is described below
commit 0f8d5779a8863951fc0f3e0b0ae9b4e559a0d701
Author: David Handermann <[email protected]>
AuthorDate: Mon Jul 20 13:28:44 2026 -0500
NIFI-16120 Added caching for Kubernetes Leader Election Manager (#11445)
- Configured cache with timeout of 5 seconds for leader status following
the pattern of the ZooKeeper implementation
---
.../election/KubernetesLeaderElectionManager.java | 4 +-
.../CachingLeaderElectionCommandProvider.java | 96 +++++++++++++++++
.../CachingLeaderElectionCommandProviderTest.java | 113 +++++++++++++++++++++
3 files changed, 212 insertions(+), 1 deletion(-)
diff --git
a/nifi-framework-bundle/nifi-framework-extensions/nifi-framework-kubernetes-bundle/nifi-framework-kubernetes-leader-election/src/main/java/org/apache/nifi/kubernetes/leader/election/KubernetesLeaderElectionManager.java
b/nifi-framework-bundle/nifi-framework-extensions/nifi-framework-kubernetes-bundle/nifi-framework-kubernetes-leader-election/src/main/java/org/apache/nifi/kubernetes/leader/election/KubernetesLeaderElectionManager.java
index 02721494705..4d84c7785bc 100644
---
a/nifi-framework-bundle/nifi-framework-extensions/nifi-framework-kubernetes-bundle/nifi-framework-kubernetes-leader-election/src/main/java/org/apache/nifi/kubernetes/leader/election/KubernetesLeaderElectionManager.java
+++
b/nifi-framework-bundle/nifi-framework-extensions/nifi-framework-kubernetes-bundle/nifi-framework-kubernetes-leader-election/src/main/java/org/apache/nifi/kubernetes/leader/election/KubernetesLeaderElectionManager.java
@@ -23,6 +23,7 @@ import
org.apache.nifi.kubernetes.client.KubernetesClientProvider;
import org.apache.nifi.kubernetes.client.NamespaceProvider;
import org.apache.nifi.kubernetes.client.ServiceAccountNamespaceProvider;
import org.apache.nifi.kubernetes.client.StandardKubernetesClientProvider;
+import
org.apache.nifi.kubernetes.leader.election.command.CachingLeaderElectionCommandProvider;
import
org.apache.nifi.kubernetes.leader.election.command.LeaderElectionCommandProvider;
import
org.apache.nifi.kubernetes.leader.election.command.StandardLeaderElectionCommandProvider;
import org.apache.nifi.util.NiFiProperties;
@@ -243,7 +244,8 @@ public class KubernetesLeaderElectionManager extends
TrackedLeaderElectionManage
final NamespaceProvider namespaceProvider = new
ServiceAccountNamespaceProvider();
final String namespace = namespaceProvider.getNamespace();
final KubernetesClientProvider kubernetesClientProvider = new
StandardKubernetesClientProvider();
- return new
StandardLeaderElectionCommandProvider(kubernetesClientProvider, namespace);
+ final LeaderElectionCommandProvider standardProvider = new
StandardLeaderElectionCommandProvider(kubernetesClientProvider, namespace);
+ return new CachingLeaderElectionCommandProvider(standardProvider);
}
private synchronized void registerLeaderElectionCommand(final String
roleName, final LeaderElectionStateChangeListener listener, final String
participantId) {
diff --git
a/nifi-framework-bundle/nifi-framework-extensions/nifi-framework-kubernetes-bundle/nifi-framework-kubernetes-leader-election/src/main/java/org/apache/nifi/kubernetes/leader/election/command/CachingLeaderElectionCommandProvider.java
b/nifi-framework-bundle/nifi-framework-extensions/nifi-framework-kubernetes-bundle/nifi-framework-kubernetes-leader-election/src/main/java/org/apache/nifi/kubernetes/leader/election/command/CachingLeaderElectionCommandProvider.java
new file mode 100644
index 00000000000..378a56005d5
--- /dev/null
+++
b/nifi-framework-bundle/nifi-framework-extensions/nifi-framework-kubernetes-bundle/nifi-framework-kubernetes-leader-election/src/main/java/org/apache/nifi/kubernetes/leader/election/command/CachingLeaderElectionCommandProvider.java
@@ -0,0 +1,96 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.nifi.kubernetes.leader.election.command;
+
+import java.io.IOException;
+import java.time.Duration;
+import java.time.Instant;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.function.Consumer;
+
+/**
+ * Leader Election Command Provider implementing caching of Leader status
minimizing requests to Kubernetes
+ */
+public class CachingLeaderElectionCommandProvider implements
LeaderElectionCommandProvider {
+ /** Expiration for cached Leader Identifiers shorter than the Lease
Duration */
+ private static final Duration DEFAULT_CACHE_EXPIRATION =
Duration.ofSeconds(5);
+
+ private final LeaderElectionCommandProvider provider;
+
+ private final Duration cacheExpiration;
+
+ private final Map<String, CachedLeader> cachedLeaders = new
ConcurrentHashMap<>();
+
+ public CachingLeaderElectionCommandProvider(final
LeaderElectionCommandProvider provider) {
+ this(provider, DEFAULT_CACHE_EXPIRATION);
+ }
+
+ CachingLeaderElectionCommandProvider(final LeaderElectionCommandProvider
provider, final Duration cacheExpiration) {
+ this.provider = Objects.requireNonNull(provider, "Provider required");
+ this.cacheExpiration = Objects.requireNonNull(cacheExpiration, "Cache
Expiration required");
+ }
+
+ @Override
+ public Runnable getCommand(
+ final String name,
+ final String identity,
+ final Runnable onStartLeading,
+ final Runnable onStopLeading,
+ final Consumer<String> onNewLeader
+ ) {
+ return provider.getCommand(name, identity, onStartLeading,
onStopLeading, onNewLeader);
+ }
+
+ /**
+ * Find Leader Identifier for specified Election Name returning a cached
result when available and not expired
+ *
+ * @param name Election Name
+ * @return Leader Identifier or empty when not found
+ */
+ @Override
+ public Optional<String> findLeader(final String name) {
+ final Optional<String> leader;
+
+ // Concurrent requests handled without locking
+ final CachedLeader cachedLeader = cachedLeaders.get(name);
+ if (cachedLeader == null || cachedLeader.isExpired()) {
+ leader = provider.findLeader(name);
+ final Instant expiration = Instant.now().plus(cacheExpiration);
+ cachedLeaders.put(name, new CachedLeader(leader.orElse(null),
expiration));
+ } else {
+ leader = Optional.ofNullable(cachedLeader.leader);
+ }
+
+ return leader;
+ }
+
+ @Override
+ public void close() throws IOException {
+ cachedLeaders.clear();
+ provider.close();
+ }
+
+ private record CachedLeader(String leader, Instant expiration) {
+
+ private boolean isExpired() {
+ return Instant.now().isAfter(expiration);
+ }
+ }
+}
diff --git
a/nifi-framework-bundle/nifi-framework-extensions/nifi-framework-kubernetes-bundle/nifi-framework-kubernetes-leader-election/src/test/java/org/apache/nifi/kubernetes/leader/election/command/CachingLeaderElectionCommandProviderTest.java
b/nifi-framework-bundle/nifi-framework-extensions/nifi-framework-kubernetes-bundle/nifi-framework-kubernetes-leader-election/src/test/java/org/apache/nifi/kubernetes/leader/election/command/CachingLeaderElectionCommandProviderTest.java
new file mode 100644
index 00000000000..398907a7fe2
--- /dev/null
+++
b/nifi-framework-bundle/nifi-framework-extensions/nifi-framework-kubernetes-bundle/nifi-framework-kubernetes-leader-election/src/test/java/org/apache/nifi/kubernetes/leader/election/command/CachingLeaderElectionCommandProviderTest.java
@@ -0,0 +1,113 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.nifi.kubernetes.leader.election.command;
+
+import org.apache.nifi.controller.leader.election.LeaderElectionRole;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+import java.io.IOException;
+import java.time.Duration;
+import java.util.Optional;
+import java.util.function.Consumer;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertSame;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+@ExtendWith(MockitoExtension.class)
+class CachingLeaderElectionCommandProviderTest {
+
+ private static final String CLUSTER_COORDINATOR =
LeaderElectionRole.CLUSTER_COORDINATOR.getRoleName();
+
+ private static final String PRIMARY_NODE =
LeaderElectionRole.PRIMARY_NODE.getRoleName();
+
+ private static final String LEADER = "Node-0";
+
+ @Mock
+ LeaderElectionCommandProvider mockProvider;
+
+ @Test
+ void testFindLeaderCachedWithinExpiration() {
+
when(mockProvider.findLeader(CLUSTER_COORDINATOR)).thenReturn(Optional.of(LEADER));
+ final CachingLeaderElectionCommandProvider provider = new
CachingLeaderElectionCommandProvider(mockProvider);
+
+ final Optional<String> first =
provider.findLeader(CLUSTER_COORDINATOR);
+ final Optional<String> second =
provider.findLeader(CLUSTER_COORDINATOR);
+
+ assertEquals(Optional.of(LEADER), first);
+ assertEquals(Optional.of(LEADER), second);
+ verify(mockProvider, times(1)).findLeader(CLUSTER_COORDINATOR);
+ }
+
+ @Test
+ void testFindLeaderRefreshedAfterExpiration() {
+
when(mockProvider.findLeader(CLUSTER_COORDINATOR)).thenReturn(Optional.of(LEADER));
+ final Duration negativeExpiration = Duration.ofSeconds(-5);
+ final CachingLeaderElectionCommandProvider provider = new
CachingLeaderElectionCommandProvider(mockProvider, negativeExpiration);
+
+ provider.findLeader(CLUSTER_COORDINATOR);
+ provider.findLeader(CLUSTER_COORDINATOR);
+
+ verify(mockProvider, times(2)).findLeader(CLUSTER_COORDINATOR);
+ }
+
+ @Test
+ void testFindLeaderCachedPerName() {
+
when(mockProvider.findLeader(CLUSTER_COORDINATOR)).thenReturn(Optional.of(LEADER));
+
when(mockProvider.findLeader(PRIMARY_NODE)).thenReturn(Optional.empty());
+ final CachingLeaderElectionCommandProvider provider = new
CachingLeaderElectionCommandProvider(mockProvider);
+
+ assertEquals(Optional.of(LEADER),
provider.findLeader(CLUSTER_COORDINATOR));
+ assertEquals(Optional.empty(), provider.findLeader(PRIMARY_NODE));
+ assertEquals(Optional.of(LEADER),
provider.findLeader(CLUSTER_COORDINATOR));
+
+ verify(mockProvider, times(1)).findLeader(CLUSTER_COORDINATOR);
+ verify(mockProvider, times(1)).findLeader(PRIMARY_NODE);
+ }
+
+ @Test
+ void testGetCommandDelegates() {
+ final Runnable command = () -> { };
+ final Runnable onStartLeading = () -> { };
+ final Runnable onStopLeading = () -> { };
+ final Consumer<String> onNewLeader = leader -> { };
+ when(mockProvider.getCommand(CLUSTER_COORDINATOR, LEADER,
onStartLeading, onStopLeading, onNewLeader)).thenReturn(command);
+ final CachingLeaderElectionCommandProvider provider = new
CachingLeaderElectionCommandProvider(mockProvider);
+
+ final Runnable returned = provider.getCommand(CLUSTER_COORDINATOR,
LEADER, onStartLeading, onStopLeading, onNewLeader);
+
+ assertSame(command, returned);
+ }
+
+ @Test
+ void testCloseClearsCacheAndClosesDelegatedProvider() throws IOException {
+
when(mockProvider.findLeader(CLUSTER_COORDINATOR)).thenReturn(Optional.of(LEADER));
+ final CachingLeaderElectionCommandProvider provider = new
CachingLeaderElectionCommandProvider(mockProvider);
+
+ provider.findLeader(CLUSTER_COORDINATOR);
+ provider.close();
+ provider.findLeader(CLUSTER_COORDINATOR);
+
+ verify(mockProvider).close();
+ verify(mockProvider, times(2)).findLeader(CLUSTER_COORDINATOR);
+ }
+}
