HDFS-16845: Adds configuration flag to allow clients to use router observer reads without using the ObserverReadProxyProvider.

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/NameNodeProxiesClient.java

@@ -349,6 +349,12 @@ public static ClientProtocol createProxyWithAlignmentContext(
       boolean withRetries, AtomicBoolean fallbackToSimpleAuth,
       AlignmentContext alignmentContext)
       throws IOException {
+    if (alignmentContext == null &&
+        conf.getBoolean(HdfsClientConfigKeys.DFS_RBF_OBSERVER_READ_ENABLE,
+            HdfsClientConfigKeys.DFS_RBF_OBSERVER_READ_ENABLE_DEFAULT)) {
+      alignmentContext = new ClientGSIContext();
+    }
+
     RPC.setProtocolEngine(conf, ClientNamenodeProtocolPB.class,
         ProtobufRpcEngine2.class);
 

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/client/HdfsClientConfigKeys.java

@@ -78,6 +78,8 @@ public interface HdfsClientConfigKeys {
   int     DFS_NAMENODE_HTTPS_PORT_DEFAULT = 9871;
   String  DFS_NAMENODE_HTTPS_ADDRESS_KEY = "dfs.namenode.https-address";
   String DFS_HA_NAMENODES_KEY_PREFIX = "dfs.ha.namenodes";
+  String DFS_RBF_OBSERVER_READ_ENABLE = "dfs.client.rbf.observer.read.enable";
+  boolean DFS_RBF_OBSERVER_READ_ENABLE_DEFAULT = false;
   int DFS_NAMENODE_RPC_PORT_DEFAULT = 8020;
   String DFS_NAMENODE_KERBEROS_PRINCIPAL_KEY =
       "dfs.namenode.kerberos.principal";

hadoop-hdfs-project/hadoop-hdfs-rbf/src/test/java/org/apache/hadoop/hdfs/server/federation/MiniRouterDFSCluster.java

@@ -234,7 +234,12 @@ public FileSystem getFileSystem() throws IOException {
       return DistributedFileSystem.get(conf);
     }
 
-    public FileSystem getFileSystemWithObserverReadsEnabled() throws IOException {
+    public FileSystem getFileSystem(Configuration configuration) throws  IOException {
+      configuration.addResource(conf);
+      return DistributedFileSystem.get(configuration);
+    }
+
+    public FileSystem getFileSystemWithObserverReadProxyProvider() throws IOException {
       Configuration observerReadConf = new Configuration(conf);
       observerReadConf.set(DFS_NAMESERVICES,
           observerReadConf.get(DFS_NAMESERVICES)+ ",router-service");

hadoop-hdfs-project/hadoop-hdfs-rbf/src/test/java/org/apache/hadoop/hdfs/server/federation/router/TestObserverWithRouter.java

@@ -34,6 +34,7 @@
 import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.hdfs.DFSConfigKeys;
+import org.apache.hadoop.hdfs.client.HdfsClientConfigKeys;
 import org.apache.hadoop.hdfs.server.federation.MiniRouterDFSCluster;
 import org.apache.hadoop.hdfs.server.federation.MiniRouterDFSCluster.RouterContext;
 import org.apache.hadoop.hdfs.server.federation.RouterConfigBuilder;
@@ -122,11 +123,17 @@ public void startUpCluster(int numberOfObserver, Configuration confOverrides) th
 
     cluster.waitActiveNamespaces();
     routerContext  = cluster.getRandomRouter();
-    fileSystem = routerContext.getFileSystemWithObserverReadsEnabled();
+  }
+
+  private static Configuration getConfToEnableObserverReads() {
+    Configuration conf = new Configuration();
+    conf.setBoolean(HdfsClientConfigKeys.DFS_RBF_OBSERVER_READ_ENABLE, true);
+    return conf;
   }
 
   @Test
   public void testObserverRead() throws Exception {
+    fileSystem = routerContext.getFileSystem(getConfToEnableObserverReads());
     internalTestObserverRead();
   }
 
@@ -137,7 +144,6 @@ public void testObserverRead() throws Exception {
    */
   @Test
   public void testReadWithoutObserverClientConfigurations() throws Exception {
-    fileSystem.close();
     fileSystem = routerContext.getFileSystem();
     assertThrows(AssertionError.class, this::internalTestObserverRead);
   }
@@ -173,6 +179,7 @@ public void testObserverReadWithoutFederatedStatePropagation() throws Exception
     Configuration confOverrides = new Configuration(false);
     confOverrides.setInt(RBFConfigKeys.DFS_ROUTER_OBSERVER_FEDERATED_STATE_PROPAGATION_MAXSIZE, 0);
     startUpCluster(2, confOverrides);
+    fileSystem = routerContext.getFileSystem(getConfToEnableObserverReads());
     List<? extends FederationNamenodeContext> namenodes = routerContext
         .getRouter().getNamenodeResolver()
         .getNamenodesForNameserviceId(cluster.getNameservices().get(0), true);
@@ -202,6 +209,7 @@ public void testDisablingObserverReadUsingNameserviceOverride() throws Exception
     Configuration confOverrides = new Configuration(false);
     confOverrides.set(RBFConfigKeys.DFS_ROUTER_OBSERVER_READ_OVERRIDES, "ns0");
     startUpCluster(2, confOverrides);
+    fileSystem = routerContext.getFileSystem(getConfToEnableObserverReads());
 
     Path path = new Path("/testFile");
     fileSystem.create(path).close();
@@ -219,6 +227,7 @@ public void testDisablingObserverReadUsingNameserviceOverride() throws Exception
 
   @Test
   public void testReadWhenObserverIsDown() throws Exception {
+    fileSystem = routerContext.getFileSystem(getConfToEnableObserverReads());
     Path path = new Path("/testFile1");
     // Send Create call to active
     fileSystem.create(path).close();
@@ -246,6 +255,7 @@ public void testReadWhenObserverIsDown() throws Exception {
 
   @Test
   public void testMultipleObserver() throws Exception {
+    fileSystem = routerContext.getFileSystem(getConfToEnableObserverReads());
     Path path = new Path("/testFile1");
     // Send Create call to active
     fileSystem.create(path).close();
@@ -384,6 +394,7 @@ public void testMultipleObserverRouter() throws Exception {
 
   @Test
   public void testUnavailableObserverNN() throws Exception {
+    fileSystem = routerContext.getFileSystem(getConfToEnableObserverReads());
     stopObserver(2);
 
     Path path = new Path("/testFile");
@@ -417,10 +428,9 @@ public void testUnavailableObserverNN() throws Exception {
     assertTrue("There must be unavailable namenodes", hasUnavailable);
   }
 
-
-
   @Test
   public void testRouterMsync() throws Exception {
+    fileSystem = routerContext.getFileSystem(getConfToEnableObserverReads());
     Path path = new Path("/testFile");
 
     // Send Create call to active
@@ -439,4 +449,60 @@ public void testRouterMsync() throws Exception {
     assertEquals("Four calls should be sent to active", 4,
         rpcCountForActive);
   }
+
+  @Test
+  public void testSingleRead() throws Exception {
+    fileSystem = routerContext.getFileSystem(getConfToEnableObserverReads());
+    List<? extends FederationNamenodeContext> namenodes = routerContext
+        .getRouter().getNamenodeResolver()
+        .getNamenodesForNameserviceId(cluster.getNameservices().get(0), true);
+    assertEquals("First namenode should be observer", namenodes.get(0).getState(),
+        FederationNamenodeServiceState.OBSERVER);
+    Path path = new Path("/");
+
+    long rpcCountForActive;
+    long rpcCountForObserver;
+
+    // Send read request
+    fileSystem.listFiles(path, false);
+    fileSystem.close();
+
+    rpcCountForActive = routerContext.getRouter().getRpcServer()
+        .getRPCMetrics().getActiveProxyOps();
+    // getListingCall sent to active.
+    assertEquals("Only one call should be sent to active", 1, rpcCountForActive);
+
+    rpcCountForObserver = routerContext.getRouter().getRpcServer()
+        .getRPCMetrics().getObserverProxyOps();
+    // getList call should be sent to observer
+    assertEquals("No calls should be sent to observer", 0, rpcCountForObserver);
+  }
+
+  @Test
+  public void testSingleReadUsingObserverReadProxyProvider() throws Exception {
+    fileSystem = routerContext.getFileSystemWithObserverReadProxyProvider();
+    List<? extends FederationNamenodeContext> namenodes = routerContext
+        .getRouter().getNamenodeResolver()
+        .getNamenodesForNameserviceId(cluster.getNameservices().get(0), true);
+    assertEquals("First namenode should be observer", namenodes.get(0).getState(),
+        FederationNamenodeServiceState.OBSERVER);
+    Path path = new Path("/");
+
+    long rpcCountForActive;
+    long rpcCountForObserver;
+
+    // Send read request
+    fileSystem.listFiles(path, false);
+    fileSystem.close();
+
+    rpcCountForActive = routerContext.getRouter().getRpcServer()
+        .getRPCMetrics().getActiveProxyOps();
+    // Two msync calls to the active namenodes.
+    assertEquals("Two calls should be sent to active", 2, rpcCountForActive);
+
+    rpcCountForObserver = routerContext.getRouter().getRpcServer()
+        .getRPCMetrics().getObserverProxyOps();
+    // getList call should be sent to observer
+    assertEquals("One call should be sent to observer", 1, rpcCountForObserver);
+  }
 }

hadoop-hdfs-project/hadoop-hdfs/src/main/resources/hdfs-default.xml

@@ -6442,4 +6442,11 @@
       If the namespace is DEFAULT, it's best to change this conf to other value.
     </description>
   </property>
+  <property>
+    <name>dfs.client.rbf.observer.read.enable</name>
+    <value>false</value>
+    <description>
+      Enables observer reads for clients. This should only be enabled when clients are using routers.
+    </description>
+  </property>
 </configuration>