Filter out leaderPaxos from list of namespaces

changelog/@unreleased/pr-4760.v2.yml

@@ -0,0 +1,6 @@
+type: fix
+fix:
+  description: '`leaderPaxos` will not be returned as a namespace. Previously, `leaderPaxos`
+    was incorrectly considered as a namespace.'
+  links:
+  - https://github.com/palantir/atlasdb/pull/4760

timelock-impl/src/main/java/com/palantir/atlasdb/timelock/management/DiskNamespaceLoader.java

@@ -26,6 +26,7 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import com.palantir.atlasdb.timelock.paxos.PaxosTimeLockConstants;
 import com.palantir.atlasdb.timelock.paxos.PaxosUseCase;
 import com.palantir.logsafe.SafeArg;
 import com.palantir.paxos.Client;
@@ -44,6 +45,7 @@ public Set<Client> getAllPersistedNamespaces() {
                 .filter(useCase -> useCase != PaxosUseCase.LEADER_FOR_ALL_CLIENTS)
                 .map(useCase -> useCase.logDirectoryRelativeToDataDirectory(rootDataDirectory))
                 .flatMap(DiskNamespaceLoader::getNamespacesFromUseCaseResolvedDirectory)
+                .filter(namespace -> !namespace.equals(PaxosTimeLockConstants.LEADER_PAXOS_NAMESPACE))
                 .map(Client::of)
                 .collect(Collectors.toSet());
     }

timelock-impl/src/test/java/com/palantir/atlasdb/timelock/management/DiskNamespaceLoaderTest.java

@@ -0,0 +1,71 @@
+/*
+ * (c) Copyright 2020 Palantir Technologies Inc. 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.
+ */
+
+package com.palantir.atlasdb.timelock.management;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.nio.file.Paths;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+
+import com.palantir.atlasdb.timelock.paxos.PaxosTimeLockConstants;
+
+public class DiskNamespaceLoaderTest {
+    private static final String NAMESPACE_1 = "namespace_1";
+    private static final String NAMESPACE_2 = "namespace_2";
+
+
+    public final @Rule TemporaryFolder tempFolder = new TemporaryFolder();
+
+    public DiskNamespaceLoader diskNamespaceLoader;
+
+    @Before
+    public void setup() {
+        diskNamespaceLoader = new DiskNamespaceLoader(tempFolder.getRoot().toPath());
+        createDirectoryForLeaderForEachClientUseCase(NAMESPACE_1);
+        createDirectoryInRootDataDirectory(NAMESPACE_2);
+    }
+
+    @Test
+    public void doesNotLoadLeaderPaxosAsNamespace() {
+        Set<String> namespaces = diskNamespaceLoader.getAllPersistedNamespaces().stream().map(client -> client.value()).collect(
+                Collectors.toSet());
+        assertThat(namespaces).containsExactlyInAnyOrder(NAMESPACE_1, NAMESPACE_2);
+    }
+
+    private void createDirectoryForLeaderForEachClientUseCase(String namespace) {
+        if (Paths.get(tempFolder.getRoot().toPath().toString(),
+                PaxosTimeLockConstants.LEADER_PAXOS_NAMESPACE,
+                PaxosTimeLockConstants.MULTI_LEADER_PAXOS_NAMESPACE,
+                namespace).toFile().mkdirs()) {
+            return;
+        }
+        throw new RuntimeException("Unexpected error when creating a subdirectory");
+    }
+
+    private void createDirectoryInRootDataDirectory(String namespace) {
+        if (Paths.get(tempFolder.getRoot().toPath().toString(), namespace).toFile().mkdirs()) {
+            return;
+        }
+        throw new RuntimeException("Unexpected error when creating a subdirectory");
+    }
+}