HDFS-14660. [SBN Read] ObserverNameNode should throw StandbyException for requests not from ObserverProxyProvider. Contributed by Chao Sun.

Author: ayushtkn

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/GlobalStateIdContext.java

@@ -18,6 +18,7 @@
 
 package org.apache.hadoop.hdfs.server.namenode;
 
+import java.io.IOException;
 import java.lang.reflect.Method;
 import java.util.HashSet;
 import java.util.concurrent.TimeUnit;
@@ -26,9 +27,11 @@
 import org.apache.hadoop.classification.InterfaceStability;
 import org.apache.hadoop.ha.HAServiceProtocol.HAServiceState;
 import org.apache.hadoop.hdfs.protocol.ClientProtocol;
+import org.apache.hadoop.hdfs.server.namenode.ha.ObserverReadProxyProvider;
 import org.apache.hadoop.hdfs.server.namenode.ha.ReadOnly;
 import org.apache.hadoop.ipc.AlignmentContext;
 import org.apache.hadoop.ipc.RetriableException;
+import org.apache.hadoop.ipc.StandbyException;
 import org.apache.hadoop.ipc.protobuf.RpcHeaderProtos.RpcRequestHeaderProto;
 import org.apache.hadoop.ipc.protobuf.RpcHeaderProtos.RpcResponseHeaderProto;
 
@@ -123,7 +126,18 @@ public void updateRequestState(RpcRequestHeaderProto.Builder header) {
    */
   @Override
   public long receiveRequestState(RpcRequestHeaderProto header,
-      long clientWaitTime) throws RetriableException {
+      long clientWaitTime) throws IOException {
+    if (!header.hasStateId() &&
+        HAServiceState.OBSERVER.equals(namesystem.getState())) {
+      // This could happen if client configured with non-observer proxy provider
+      // (e.g., ConfiguredFailoverProxyProvider) is accessing a cluster with
+      // observers. In this case, we should let the client failover to the
+      // active node, rather than potentially serving stale result (client
+      // stateId is 0 if not set).
+      throw new StandbyException("Observer Node received request without "
+          + "stateId. This mostly likely is because client is not configured "
+          + "with " + ObserverReadProxyProvider.class.getSimpleName());
+    }
     long serverStateId = getLastSeenStateId();
     long clientStateId = header.getStateId();
     FSNamesystem.LOG.trace("Client State ID= {} and Server State ID= {}",

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestConsistentReadsObserver.java

@@ -22,6 +22,7 @@
 import static org.junit.Assert.fail;
 
 import java.io.IOException;
+import java.util.Collections;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
 import java.util.concurrent.atomic.AtomicInteger;
@@ -33,12 +34,15 @@
 import org.apache.hadoop.fs.permission.FsPermission;
 import org.apache.hadoop.hdfs.DistributedFileSystem;
 import org.apache.hadoop.hdfs.MiniDFSCluster;
+import org.apache.hadoop.hdfs.client.HdfsClientConfigKeys;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants;
 import org.apache.hadoop.hdfs.qjournal.MiniQJMHACluster;
 import org.apache.hadoop.hdfs.server.namenode.NameNode;
 import org.apache.hadoop.hdfs.server.namenode.NameNodeAdapter;
+import org.apache.hadoop.ipc.RemoteException;
 import org.apache.hadoop.ipc.RpcScheduler;
 import org.apache.hadoop.ipc.Schedulable;
+import org.apache.hadoop.ipc.StandbyException;
 import org.apache.hadoop.test.GenericTestUtils;
 import org.apache.hadoop.util.Time;
 import org.junit.After;
@@ -344,6 +348,39 @@ public void testUncoordinatedCall() throws Exception {
     reader.interrupt();
   }
 
+  @Test
+  public void testRequestFromNonObserverProxyProvider() throws Exception {
+    // Create another HDFS client using ConfiguredFailoverProvider
+    Configuration conf2 = new Configuration(conf);
+
+    // Populate the above configuration with only a single observer in the
+    // namenode list. Also reduce retries to make test finish faster.
+    HATestUtil.setFailoverConfigurations(
+        conf2,
+        HATestUtil.getLogicalHostname(dfsCluster),
+        Collections.singletonList(
+            dfsCluster.getNameNode(2).getNameNodeAddress()),
+        ConfiguredFailoverProxyProvider.class);
+    conf2.setBoolean("fs.hdfs.impl.disable.cache", true);
+    conf2.setInt(HdfsClientConfigKeys.Retry.MAX_ATTEMPTS_KEY, 1);
+    conf2.setInt(HdfsClientConfigKeys.Failover.MAX_ATTEMPTS_KEY, 1);
+    FileSystem dfs2 = FileSystem.get(conf2);
+
+    dfs.mkdir(testPath, FsPermission.getDefault());
+    dfsCluster.rollEditLogAndTail(0);
+
+    try {
+      // Request should be rejected by observer and throw StandbyException
+      dfs2.listStatus(testPath);
+      fail("listStatus should have thrown exception");
+    } catch (RemoteException re) {
+      IOException e = re.unwrapRemoteException();
+      assertTrue("should have thrown StandbyException but got "
+              + e.getClass().getSimpleName(),
+          e instanceof StandbyException);
+    }
+  }
+
   private void assertSentTo(int nnIdx) throws IOException {
     assertTrue("Request was not sent to the expected namenode " + nnIdx,
         HATestUtil.isSentToAnyOfNameNodes(dfs, dfsCluster, nnIdx));