[GitHub] [zookeeper] ztzg commented on a change in pull request #1664: ZOOKEEPER-4269: acceptedEpoch.tmp rename failure will cause server startup error

[GitBox <gi...@apache.org>]

ztzg commented on a change in pull request #1664:
URL: https://github.com/apache/zookeeper/pull/1664#discussion_r604419892



##########
File path: zookeeper-server/src/test/java/org/apache/zookeeper/server/quorum/CurrentEpochWriteFailureTest.java
##########
@@ -0,0 +1,129 @@
+/*
+ * 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.zookeeper.server.quorum;
+
+import static org.apache.zookeeper.test.ClientBase.CONNECTION_TIMEOUT;
+import static org.junit.Assert.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import java.io.File;
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.Map;
+import org.apache.commons.io.FileUtils;
+import org.apache.zookeeper.CreateMode;
+import org.apache.zookeeper.ZooDefs.Ids;
+import org.apache.zookeeper.ZooKeeper;
+import org.apache.zookeeper.common.AtomicFileOutputStream;
+import org.apache.zookeeper.test.ClientBase;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class CurrentEpochWriteFailureTest extends QuorumPeerTestBase {
+    protected static final Logger LOG = LoggerFactory.getLogger(CurrentEpochWriteFailureTest.class);
+    private Servers servers;
+    private int clientPort;
+    private Map<String, String> additionalProp;
+
+    @Before
+    public void setUp() {
+        additionalProp = new HashMap<>();
+        additionalProp.put("admin.enableServer", "true");
+        additionalProp.put("4lw.commands.whitelist", "*");

Review comment:
       I was wondering why these two were necessary—but the test seems to run fine without them.  Did you add them for a specific purpose, or did you simply inherit them?  (Not that I expect them to hurt.)

##########
File path: zookeeper-server/src/test/java/org/apache/zookeeper/server/quorum/CurrentEpochWriteFailureTest.java
##########
@@ -0,0 +1,129 @@
+/*
+ * 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.zookeeper.server.quorum;
+
+import static org.apache.zookeeper.test.ClientBase.CONNECTION_TIMEOUT;
+import static org.junit.Assert.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import java.io.File;
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.Map;
+import org.apache.commons.io.FileUtils;
+import org.apache.zookeeper.CreateMode;
+import org.apache.zookeeper.ZooDefs.Ids;
+import org.apache.zookeeper.ZooKeeper;
+import org.apache.zookeeper.common.AtomicFileOutputStream;
+import org.apache.zookeeper.test.ClientBase;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;

Review comment:
       This compiles, but causes the test not to run when selected with `-Dtest=CurrentEpochWriteFailureTest`!  (I don't know if it runs when the full test suite is active.)
   
   I believe you want this:
   
   ```diff
   --- a/zookeeper-server/src/test/java/org/apache/zookeeper/server/quorum/CurrentEpochWriteFailureTest.java
   +++ b/zookeeper-server/src/test/java/org/apache/zookeeper/server/quorum/CurrentEpochWriteFailureTest.java
   @@ -30,9 +30,9 @@
    import org.apache.zookeeper.ZooKeeper;
    import org.apache.zookeeper.common.AtomicFileOutputStream;
    import org.apache.zookeeper.test.ClientBase;
   -import org.junit.After;
   -import org.junit.Before;
   -import org.junit.Test;
   +import org.junit.jupiter.api.AfterEach;
   +import org.junit.jupiter.api.BeforeEach;
   +import org.junit.jupiter.api.Test;
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    
   @@ -42,14 +42,14 @@
        private int clientPort;
        private Map<String, String> additionalProp;
    
   -    @Before
   +    @BeforeEach
        public void setUp() {
            additionalProp = new HashMap<>();
            additionalProp.put("admin.enableServer", "true");
            additionalProp.put("4lw.commands.whitelist", "*");
        }
    
   -    @After
   +    @AfterEach
        public void tearDown() throws InterruptedException {
            if (servers != null) {
                servers.shutDownAllServers();
   ```

##########
File path: zookeeper-server/src/test/java/org/apache/zookeeper/server/quorum/CurrentEpochWriteFailureTest.java
##########
@@ -0,0 +1,129 @@
+/*
+ * 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.zookeeper.server.quorum;
+
+import static org.apache.zookeeper.test.ClientBase.CONNECTION_TIMEOUT;
+import static org.junit.Assert.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import java.io.File;
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.Map;
+import org.apache.commons.io.FileUtils;
+import org.apache.zookeeper.CreateMode;
+import org.apache.zookeeper.ZooDefs.Ids;
+import org.apache.zookeeper.ZooKeeper;
+import org.apache.zookeeper.common.AtomicFileOutputStream;
+import org.apache.zookeeper.test.ClientBase;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class CurrentEpochWriteFailureTest extends QuorumPeerTestBase {
+    protected static final Logger LOG = LoggerFactory.getLogger(CurrentEpochWriteFailureTest.class);
+    private Servers servers;
+    private int clientPort;
+    private Map<String, String> additionalProp;
+
+    @Before
+    public void setUp() {
+        additionalProp = new HashMap<>();
+        additionalProp.put("admin.enableServer", "true");
+        additionalProp.put("4lw.commands.whitelist", "*");
+    }
+
+    @After
+    public void tearDown() throws InterruptedException {
+        if (servers != null) {
+            servers.shutDownAllServers();
+        }
+    }
+
+    /*
+     * ZOOKEEPER-4269:
+     * accepted epoch is first written to temporary file acceptedEpoch.tmp then this file is
+     * renamed to acceptedEpoch.
+     * Failure, either because of exception or power-off, in renaming the acceptedEpoch.tmp file
+     * will cause server startup error with message "The current epoch, x, is older than the last
+     * zxid y"
+     * To handle this scenario we should read accepted epoch from this temp file as well.
+     */
+    @Test
+    public void testReadCurrentEpochFromAcceptedEpochTmpFile() throws Exception {
+        startServers(additionalProp);
+        writSomeData();
+
+        restartServers();
+        writSomeData();
+
+        MainThread firstServer = servers.mt[0];
+
+        // As started servers two times, current epoch must be two
+        long currentEpoch = firstServer.getQuorumPeer().getCurrentEpoch();
+        assertEquals(2, currentEpoch);
+
+        // Initialize files for later use
+        File snapDir = firstServer.getQuorumPeer().getTxnFactory().getSnapDir();
+        File currentEpochFile = new File(snapDir, QuorumPeer.CURRENT_EPOCH_FILENAME);
+        File currentEpochTempFile = new File(snapDir,
+            QuorumPeer.CURRENT_EPOCH_FILENAME + AtomicFileOutputStream.TMP_EXTENSION);
+
+        // Shutdown servers
+        servers.shutDownAllServers();
+        waitForAll(servers, ZooKeeper.States.CONNECTING);
+
+        // Create scenario of file currentEpoch.tmp rename to currentEpoch failure.
+        // In this case currentEpoch file will have old epoch and currentEpoch.tmp will have the latest epoch
+        FileUtils.write(currentEpochFile, Long.toString(currentEpoch - 1), "UTF-8");
+        FileUtils.write(currentEpochTempFile, Long.toString(currentEpoch), "UTF-8");
+
+        // Restart the serves, all serves should restart successfully.
+        servers.restartAllServersAndClients(this);
+
+        // Check the first server where problem was injected.
+        assertTrue(ClientBase
+                .waitForServerUp("127.0.0.1:" + firstServer.getClientPort(), CONNECTION_TIMEOUT),
+            "server " + firstServer.getMyid()
+                + " is not up as file currentEpoch.tmp rename to currentEpoch file was failed"
+                + " which lead current epoch inconsistent state.");
+    }
+
+    private void restartServers() throws InterruptedException, IOException {
+        servers.shutDownAllServers();
+        waitForAll(servers, ZooKeeper.States.CONNECTING);
+        servers.restartAllServersAndClients(this);
+        waitForAll(servers, ZooKeeper.States.CONNECTED);
+    }
+
+    private void writSomeData() throws Exception {

Review comment:
       Nit: `writeSomeData`?




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