HDFS-16861. RBF. Truncate API always fails when dirs use AllResolver oder on Router (#5184)

Co-authored-by: xiezhineng <xiezhineng@corp.netease.com>
Reviewed-by: Inigo Goiri <inigoiri@apache.org>
Signed-off-by: Tao Li <tomscut@apache.org>

hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/router/RouterClientProtocol.java

@@ -702,8 +702,9 @@ public class RouterClientProtocol implements ClientProtocol {
     RemoteMethod method = new RemoteMethod("truncate",
         new Class<?>[] {String.class, long.class, String.class},
         new RemoteParam(), newLength, clientName);
+    // Truncate can return true/false, so don't expect a result
     return rpcClient.invokeSequential(locations, method, Boolean.class,
-        Boolean.TRUE);
+        null);
   }
 
   @Override

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

@@ -33,6 +33,7 @@ import org.apache.hadoop.fs.FSDataOutputStream;
 import org.apache.hadoop.fs.FileStatus;
 import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.hdfs.DistributedFileSystem;
 import org.apache.hadoop.hdfs.server.federation.RouterConfigBuilder;
 import org.apache.hadoop.hdfs.server.federation.MiniRouterDFSCluster.NamenodeContext;
 import org.apache.hadoop.hdfs.server.federation.MiniRouterDFSCluster.RouterContext;
@@ -46,6 +47,7 @@ import org.apache.hadoop.hdfs.server.federation.store.protocol.AddMountTableEntr
 import org.apache.hadoop.hdfs.server.federation.store.protocol.GetMountTableEntriesRequest;
 import org.apache.hadoop.hdfs.server.federation.store.protocol.GetMountTableEntriesResponse;
 import org.apache.hadoop.hdfs.server.federation.store.records.MountTable;
+import org.apache.hadoop.hdfs.server.namenode.TestFileTruncate;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
@@ -191,6 +193,18 @@ public class TestRouterAllResolver {
     assertDirsEverywhere(path, 9);
     assertFilesDistributed(path, 15);
 
+    // Test truncate
+    String testTruncateFile = path + "/dir2/dir22/dir220/file-truncate.txt";
+    createTestFile(routerFs, testTruncateFile);
+    Path testTruncateFilePath = new Path(testTruncateFile);
+    routerFs.truncate(testTruncateFilePath, 10);
+    TestFileTruncate.checkBlockRecovery(testTruncateFilePath,
+        (DistributedFileSystem) routerFs);
+    assertEquals("Truncate file fails", 10,
+        routerFs.getFileStatus(testTruncateFilePath).getLen());
+    assertDirsEverywhere(path, 9);
+    assertFilesDistributed(path, 16);
+
     // Removing a directory should remove it from every subcluster
     routerFs.delete(new Path(path + "/dir2/dir22/dir220"), true);
     assertDirsEverywhere(path, 8);