HDFS-328. Improve fs -setrep error message for invalid replication factors. Contributed by Daniel Templeton.

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -877,6 +877,9 @@ Release 2.8.0 - UNRELEASED
     HDFS-2070. Add more unit tests for FsShell getmerge (Daniel Templeton via
     Colin P. McCabe)
 
+    HDFS-328. Improve fs -setrep error message for invalid replication factors.
+    (Daniel Templeton via wang)
+
   OPTIMIZATIONS
 
     HDFS-8026. Trace FSOutputSummer#writeChecksumChunks rather than

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockManager.java

@@ -953,28 +953,39 @@ public short adjustReplication(short replication) {
 
   /**
    * Check whether the replication parameter is within the range
-   * determined by system configuration.
+   * determined by system configuration and throw an exception if it's not.
+   *
+   * @param src the path to the target file
+   * @param replication the requested replication factor
+   * @param clientName the name of the client node making the request
+   * @throws java.io.IOException thrown if the requested replication factor
+   * is out of bounds
    */
    public void verifyReplication(String src,
                           short replication,
                           String clientName) throws IOException {
 
-    if (replication >= minReplication && replication <= maxReplication) {
-      //common case. avoid building 'text'
-      return;
+    if (replication < minReplication || replication > maxReplication) {
+      StringBuilder msg = new StringBuilder("Requested replication factor of ");
+
+      msg.append(replication);
+
+      if (replication > maxReplication) {
+        msg.append(" exceeds maximum of ");
+        msg.append(maxReplication);
+      } else {
+        msg.append(" is less than the required minimum of ");
+        msg.append(minReplication);
       }
 
-    String text = "file " + src 
-      + ((clientName != null) ? " on client " + clientName : "")
-      + ".\n"
-      + "Requested replication " + replication;
+      msg.append(" for ").append(src);
 
-    if (replication > maxReplication)
-      throw new IOException(text + " exceeds maximum " + maxReplication);
+      if (clientName != null) {
+        msg.append(" from ").append(clientName);
+      }
 
-    if (replication < minReplication)
-      throw new IOException(text + " is less than the required minimum " +
-                            minReplication);
+      throw new IOException(msg.toString());
+    }
   }
 
   /**

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

@@ -2412,7 +2412,63 @@ public void testCopyFromLocalWithPermissionDenied() throws Exception {
     }
   }
 
+  /**
+   * Test -setrep with a replication factor that is too low.  We have to test
+   * this here because the mini-cluster used with testHDFSConf.xml uses a
+   * replication factor of 1 (for good reason).
+   */
+  @Test (timeout = 30000)
+  public void testSetrepLow() throws Exception {
+    Configuration conf = new Configuration();
 
+    conf.setInt(DFSConfigKeys.DFS_NAMENODE_REPLICATION_MIN_KEY, 2);
+
+    MiniDFSCluster.Builder builder = new MiniDFSCluster.Builder(conf);
+    MiniDFSCluster cluster = builder.numDataNodes(2).format(true).build();
+    FsShell shell = new FsShell(conf);
+
+    cluster.waitActive();
+
+    final String testdir = "/tmp/TestDFSShell-testSetrepLow";
+    final Path hdfsFile = new Path(testdir, "testFileForSetrepLow");
+    final PrintStream origOut = System.out;
+    final PrintStream origErr = System.err;
+
+    try {
+      final FileSystem fs = cluster.getFileSystem();
+
+      assertTrue("Unable to create test directory",
+          fs.mkdirs(new Path(testdir)));
+
+      fs.create(hdfsFile, true).close();
+
+      // Capture the command output so we can examine it
+      final ByteArrayOutputStream bao = new ByteArrayOutputStream();
+      final PrintStream capture = new PrintStream(bao);
+
+      System.setOut(capture);
+      System.setErr(capture);
+
+      final String[] argv = new String[] { "-setrep", "1", hdfsFile.toString() };
+
+      try {
+        assertEquals("Command did not return the expected exit code",
+            1, shell.run(argv));
+      } finally {
+        System.setOut(origOut);
+        System.setErr(origErr);
+      }
+
+      assertEquals("Error message is not the expected error message",
+          "setrep: Requested replication factor of 1 is less than "
+              + "the required minimum of 2 for /tmp/TestDFSShell-"
+              + "testSetrepLow/testFileForSetrepLow\n",
+          bao.toString());
+    } finally {
+      shell.close();
+      cluster.shutdown();
+    }
+  }
 
   // setrep for file and directory.
   @Test (timeout = 30000)

hadoop-hdfs-project/hadoop-hdfs/src/test/resources/testHDFSConf.xml

@@ -6472,6 +6472,60 @@
       </comparators>
     </test>
 
+    <test> <!-- TESTED -->
+      <description>setrep: invalid replication factor -- too high</description>
+      <test-commands>
+        <command>-fs NAMENODE -mkdir -p /dir0</command>
+        <command>-fs NAMENODE -touchz /dir0/file0</command>
+        <command>-fs NAMENODE -setrep 1025 /dir0/file0</command>
+      </test-commands>
+      <cleanup-commands>
+        <command>-fs NAMENODE -rm -r /user</command>
+      </cleanup-commands>
+      <comparators>
+        <comparator>
+          <type>RegexpComparator</type>
+          <expected-output>^setrep: Requested replication factor of 1025 exceeds maximum of [0-9]+ for /dir0/file0</expected-output>
+        </comparator>
+      </comparators>
+    </test>
+
+    <test> <!-- TESTED -->
+      <description>setrep: invalid replication factor -- 0</description>
+      <test-commands>
+        <command>-fs NAMENODE -mkdir -p dir0</command>
+        <command>-fs NAMENODE -touchz dir0/file0</command>
+        <command>-fs NAMENODE -setrep 0 dir0/file0</command>
+      </test-commands>
+      <cleanup-commands>
+        <command>-fs NAMENODE -rm -r /user</command>
+      </cleanup-commands>
+      <comparators>
+        <comparator>
+          <type>RegexpComparator</type>
+          <expected-output>^-setrep: replication must be >= 1</expected-output>
+        </comparator>
+      </comparators>
+    </test>
+
+    <test> <!-- TESTED -->
+      <description>setrep: invalid replication factor -- NaN</description>
+      <test-commands>
+        <command>-fs NAMENODE -mkdir -p dir0</command>
+        <command>-fs NAMENODE -touchz dir0/file0</command>
+        <command>-fs NAMENODE -setrep three dir0/file0</command>
+      </test-commands>
+      <cleanup-commands>
+        <command>-fs NAMENODE -rm -r /user</command>
+      </cleanup-commands>
+      <comparators>
+        <comparator>
+          <type>RegexpComparator</type>
+          <expected-output>^setrep: Illegal replication, a positive integer expected</expected-output>
+        </comparator>
+      </comparators>
+    </test>
+
     <!-- Tests for touchz-->
     <test> <!-- TESTED -->
       <description>touchz: touching file (absolute path) </description>