HDFS-10544. Balancer doesn't work with IPFailoverProxyProvider.

(cherry picked from commit 087290e6b1cb1082646d966b65494082712ebe3e)
(cherry picked from commit 5b4e916b3cae2540267d48716fd9240dfc055288)

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSUtil.java

@@ -719,10 +719,11 @@ public class DFSUtil {
 
   /**
    * Get a URI for each internal nameservice. If a nameservice is
-   * HA-enabled, then the logical URI of the nameservice is returned. If the
-   * nameservice is not HA-enabled, then a URI corresponding to an RPC address
-   * of the single NN for that nameservice is returned, preferring the service
-   * RPC address over the client RPC address.
+   * HA-enabled, and the configured failover proxy provider supports logical
+   * URIs, then the logical URI of the nameservice is returned.
+   * Otherwise, a URI corresponding to an RPC address of the single NN for that
+   * nameservice is returned, preferring the service RPC address over the
+   * client RPC address.
    * 
    * @param conf configuration
    * @return a collection of all configured NN URIs, preferring service
@@ -736,9 +737,10 @@ public class DFSUtil {
 
   /**
    * Get a URI for each configured nameservice. If a nameservice is
-   * HA-enabled, then the logical URI of the nameservice is returned. If the
-   * nameservice is not HA-enabled, then a URI corresponding to the address of
-   * the single NN for that nameservice is returned.
+   * HA-enabled, and the configured failover proxy provider supports logical
+   * URIs, then the logical URI of the nameservice is returned.
+   * Otherwise, a URI corresponding to the address of the single NN for that
+   * nameservice is returned.
    * 
    * @param conf configuration
    * @param keys configuration keys to try in order to get the URI for non-HA
@@ -757,13 +759,27 @@ public class DFSUtil {
     Set<URI> nonPreferredUris = new HashSet<URI>();
     
     for (String nsId : nameServices) {
-      if (HAUtil.isHAEnabled(conf, nsId)) {
+      URI nsUri;
+      try {
+        nsUri = new URI(HdfsConstants.HDFS_URI_SCHEME + "://" + nsId);
+      } catch (URISyntaxException ue) {
+        throw new IllegalArgumentException(ue);
+      }
+      /**
+       * Determine whether the logical URI of the name service can be resolved
+       * by the configured failover proxy provider. If not, we should try to
+       * resolve the URI here
+       */
+      boolean useLogicalUri = false;
+      try {
+        useLogicalUri = HAUtil.useLogicalUri(conf, nsUri);
+      } catch (IOException e){
+        LOG.warn("Getting exception  while trying to determine if nameservice "
+            + nsId + " can use logical URI: " + e);
+      }
+      if (HAUtil.isHAEnabled(conf, nsId) && useLogicalUri) {
         // Add the logical URI of the nameservice.
-        try {
-          ret.add(new URI(HdfsConstants.HDFS_URI_SCHEME + "://" + nsId));
-        } catch (URISyntaxException ue) {
-          throw new IllegalArgumentException(ue);
-        }
+        ret.add(nsUri);
       } else {
         // Add the URI corresponding to the address of the NN.
         boolean uriFound = false;

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSUtil.java

@@ -62,6 +62,7 @@ import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.hdfs.client.HdfsClientConfigKeys;
 import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
 import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
+import org.apache.hadoop.hdfs.protocol.HdfsConstants;
 import org.apache.hadoop.hdfs.protocol.LocatedBlock;
 import org.apache.hadoop.hdfs.protocol.LocatedBlocks;
 import org.apache.hadoop.hdfs.server.namenode.NameNode;
@@ -533,7 +534,11 @@ public class TestDFSUtil {
     // Ditto for nameservice IDs, if multiple are defined
     assertEquals(null, DFSUtil.getNamenodeNameServiceId(conf));
     assertEquals(null, DFSUtil.getSecondaryNameServiceId(conf));
-    
+
+    String proxyProviderKey = HdfsClientConfigKeys.Failover.
+        PROXY_PROVIDER_KEY_PREFIX + ".ns2";
+    conf.set(proxyProviderKey, "org.apache.hadoop.hdfs.server.namenode.ha."
+        + "ConfiguredFailoverProxyProvider");
     Collection<URI> uris = getInternalNameServiceUris(conf, DFS_NAMENODE_RPC_ADDRESS_KEY);
     assertEquals(2, uris.size());
     assertTrue(uris.contains(new URI("hdfs://ns1")));
@@ -633,6 +638,7 @@ public class TestDFSUtil {
   public void testGetNNUris() throws Exception {
     HdfsConfiguration conf = new HdfsConfiguration();
 
+    final String NS1_NN_ADDR   = "ns1-nn.example.com:8020";
     final String NS1_NN1_ADDR   = "ns1-nn1.example.com:8020";
     final String NS1_NN2_ADDR   = "ns1-nn2.example.com:8020";
     final String NS2_NN_ADDR    = "ns2-nn.example.com:8020";
@@ -664,6 +670,9 @@ public class TestDFSUtil {
     conf.set(DFSUtil.addKeySuffixes(
         DFS_NAMENODE_RPC_ADDRESS_KEY, "ns1", "nn2"), NS1_NN2_ADDR);
 
+    conf.set(DFSUtil.addKeySuffixes(
+        DFS_NAMENODE_SERVICE_RPC_ADDRESS_KEY, "ns1"), NS1_NN_ADDR);
+
     conf.set(DFSUtil.addKeySuffixes(
         DFS_NAMENODE_SERVICE_RPC_ADDRESS_KEY, "ns2"), NS2_NN_ADDR);
 
@@ -671,6 +680,40 @@ public class TestDFSUtil {
 
     conf.set(CommonConfigurationKeys.FS_DEFAULT_NAME_KEY, "hdfs://" + NN2_ADDR);
 
+    /**
+     * {@link DFSUtil#getInternalNsRpcUris} decides whether to resolve a logical
+     * URI based on whether the failover proxy provider supports logical URIs.
+     * We will test both cases.
+     *
+     * First configure ns1 to use {@link IPFailoverProxyProvider} which doesn't
+     * support logical Uris. So {@link DFSUtil#getInternalNsRpcUris} will
+     * resolve the logical URI of ns1 based on the configured value at
+     * dfs.namenode.servicerpc-address.ns1, which is {@link NS1_NN_ADDR}
+     */
+    String proxyProviderKey = HdfsClientConfigKeys.Failover.
+        PROXY_PROVIDER_KEY_PREFIX + ".ns1";
+    conf.set(proxyProviderKey, "org.apache.hadoop.hdfs.server.namenode.ha."
+        + "IPFailoverProxyProvider");
+
+    uris = DFSUtil.getInternalNsRpcUris(conf);
+    assertEquals("Incorrect number of URIs returned", 3, uris.size());
+    assertTrue("Missing URI for RPC address",
+        uris.contains(new URI("hdfs://" + NN1_ADDR)));
+    assertTrue("Missing URI for name service ns2",
+        uris.contains(new URI(HdfsConstants.HDFS_URI_SCHEME + "://" +
+            NS1_NN_ADDR)));
+    assertTrue("Missing URI for name service ns2",
+        uris.contains(new URI(HdfsConstants.HDFS_URI_SCHEME + "://" +
+            NS2_NN_ADDR)));
+
+    /**
+     * Second, test ns1 with {@link ConfiguredFailoverProxyProvider} which does
+     * support logical URIs. So instead of {@link NS1_NN_ADDR}, the logical URI
+     * of ns1, hdfs://ns1, will be returned.
+     */
+    conf.set(proxyProviderKey, "org.apache.hadoop.hdfs.server.namenode.ha."
+        + "ConfiguredFailoverProxyProvider");
+
     uris = DFSUtil.getInternalNsRpcUris(conf);
 
     assertEquals("Incorrect number of URIs returned", 3, uris.size());