HDFS-10651. Clean up some configuration related codes about legacy block reader. Contributed by Youwei Wang

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

@@ -97,9 +97,6 @@ public interface HdfsClientConfigKeys {
   int     DFS_CLIENT_CACHED_CONN_RETRY_DEFAULT = 3;
   String  DFS_CLIENT_CONTEXT = "dfs.client.context";
   String  DFS_CLIENT_CONTEXT_DEFAULT = "default";
-  String  DFS_CLIENT_USE_LEGACY_BLOCKREADER =
-      "dfs.client.use.legacy.blockreader";
-  boolean DFS_CLIENT_USE_LEGACY_BLOCKREADER_DEFAULT = false;
   String  DFS_CLIENT_USE_LEGACY_BLOCKREADERLOCAL =
       "dfs.client.use.legacy.blockreader.local";
   boolean DFS_CLIENT_USE_LEGACY_BLOCKREADERLOCAL_DEFAULT = false;

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

@@ -1275,12 +1275,6 @@ public class DFSConfigKeys extends CommonConfigurationKeys {
       HdfsClientConfigKeys.DFS_CLIENT_MAX_BLOCK_ACQUIRE_FAILURES_DEFAULT;
 
   @Deprecated
-  public static final String  DFS_CLIENT_USE_LEGACY_BLOCKREADER =
-      HdfsClientConfigKeys.DFS_CLIENT_USE_LEGACY_BLOCKREADER;
-  @Deprecated
-  public static final boolean DFS_CLIENT_USE_LEGACY_BLOCKREADER_DEFAULT =
-      HdfsClientConfigKeys.DFS_CLIENT_USE_LEGACY_BLOCKREADER_DEFAULT;
-  @Deprecated
   public static final String  DFS_CLIENT_USE_LEGACY_BLOCKREADERLOCAL =
       HdfsClientConfigKeys.DFS_CLIENT_USE_LEGACY_BLOCKREADERLOCAL;
   @Deprecated

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

@@ -3376,15 +3376,6 @@
   </description>
 </property>
 
-<property>
-  <name>dfs.client.use.legacy.blockreader</name>
-  <value>false</value>
-  <description>
-    If true, use the RemoteBlockReader class for local read short circuit.  If false, use
-    the newer RemoteBlockReader2 class.
-  </description>
-</property>
-
 <property>
   <name>dfs.client.write.byte-array-manager.count-limit</name>
   <value>2048</value>

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

@@ -73,7 +73,6 @@ public class TestDFSInputStream {
   @Test(timeout=60000)
   public void testSkipWithRemoteBlockReader() throws IOException {
     Configuration conf = new Configuration();
-    conf.setBoolean(HdfsClientConfigKeys.DFS_CLIENT_USE_LEGACY_BLOCKREADER, true);
     MiniDFSCluster cluster = new MiniDFSCluster.Builder(conf).build();
     try {
       testSkipInner(cluster);