HDFS-2752. HA: exit if multiple shared dirs are configured. Contributed by Eli Collins

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-1623@1240916 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/CHANGES.HDFS-1623.txt

@@ -170,3 +170,5 @@ HDFS-2792. Make fsck work. (atm)
 HDFS-2808. HA: haadmin should use namenode ids. (eli)
 
 HDFS-2819. Document new HA-related configs in hdfs-default.xml. (eli)
+
+HDFS-2752. HA: exit if multiple shared dirs are configured. (eli)

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java

@@ -683,17 +683,28 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
    * are ordered before non-shared directories, and any duplicates
    * are removed. The order they are specified in the configuration
    * is retained.
+   * @return Collection of shared edits directories.
+   * @throws IOException if multiple shared edits directories are configured
    */
-  public static List<URI> getNamespaceEditsDirs(Configuration conf) {
+  public static List<URI> getNamespaceEditsDirs(Configuration conf)
+      throws IOException {
     // Use a LinkedHashSet so that order is maintained while we de-dup
     // the entries.
     LinkedHashSet<URI> editsDirs = new LinkedHashSet<URI>();
     
+    List<URI> sharedDirs = getSharedEditsDirs(conf);
+
+    // Fail until multiple shared edits directories are supported (HDFS-2782)
+    if (sharedDirs.size() > 1) {
+      throw new IOException(
+          "Multiple shared edits directories are not yet supported");
+    }
+
     // First add the shared edits dirs. It's critical that the shared dirs
     // are added first, since JournalSet syncs them in the order they are listed,
     // and we need to make sure all edits are in place in the shared storage
     // before they are replicated locally. See HDFS-2874.
-    for (URI dir : getSharedEditsDirs(conf)) {
+    for (URI dir : sharedDirs) {
       if (!editsDirs.add(dir)) {
         LOG.warn("Edits URI " + dir + " listed multiple times in " + 
             DFS_NAMENODE_SHARED_EDITS_DIR_KEY + ". Ignoring duplicates.");

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

@@ -1594,7 +1594,7 @@ public class MiniDFSCluster {
   /**
    * Get the directories where the namenode stores its edits.
    */
-  public Collection<URI> getNameEditsDirs(int nnIndex) {
+  public Collection<URI> getNameEditsDirs(int nnIndex) throws IOException {
     return FSNamesystem.getNamespaceEditsDirs(nameNodes[nnIndex].conf);
   }
   

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestFSNamesystem.java

@@ -21,6 +21,7 @@ package org.apache.hadoop.hdfs.server.namenode;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.*;
 import static org.junit.Assert.*;
 
+import java.io.IOException;
 import java.net.URI;
 import java.util.Collection;
 
@@ -33,7 +34,7 @@ public class TestFSNamesystem {
    * Tests that the namenode edits dirs are gotten with duplicates removed
    */
   @Test
-  public void testUniqueEditDirs() {
+  public void testUniqueEditDirs() throws IOException {
     Configuration config = new Configuration();
 
     config.set(DFS_NAMENODE_EDITS_DIR_KEY, "file://edits/dir, "

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestFailureOfSharedDir.java

@@ -68,6 +68,29 @@ public class TestFailureOfSharedDir {
         requiredEditsDirs.contains(bar));
   }
 
+  /**
+   * Multiple shared edits directories is an invalid configuration.
+   */
+  @Test
+  public void testMultipleSharedDirsFails() throws Exception {
+    Configuration conf = new Configuration();
+    URI sharedA = new URI("file:///shared-A");
+    URI sharedB = new URI("file:///shared-B");
+    URI localA = new URI("file:///local-A");
+
+    conf.set(DFSConfigKeys.DFS_NAMENODE_SHARED_EDITS_DIR_KEY,
+        Joiner.on(",").join(sharedA,sharedB));
+    conf.set(DFSConfigKeys.DFS_NAMENODE_EDITS_DIR_KEY,
+        localA.toString());
+
+    try {
+      FSNamesystem.getNamespaceEditsDirs(conf);
+      fail("Allowed multiple shared edits directories");
+    } catch (IOException ioe) {
+      assertEquals("Multiple shared edits directories are not yet supported",
+          ioe.getMessage());
+    }
+  }
   
   /**
    * Make sure that the shared edits dirs are listed before non-shared dirs
@@ -78,13 +101,12 @@ public class TestFailureOfSharedDir {
   public void testSharedDirsComeFirstInEditsList() throws Exception {
     Configuration conf = new Configuration();
     URI sharedA = new URI("file:///shared-A");
-    URI sharedB = new URI("file:///shared-B");
     URI localA = new URI("file:///local-A");
     URI localB = new URI("file:///local-B");
     URI localC = new URI("file:///local-C");
     
     conf.set(DFSConfigKeys.DFS_NAMENODE_SHARED_EDITS_DIR_KEY,
-        Joiner.on(",").join(sharedA,sharedB));
+        sharedA.toString());
     // List them in reverse order, to make sure they show up in
     // the order listed, regardless of lexical sort order.
     conf.set(DFSConfigKeys.DFS_NAMENODE_EDITS_DIR_KEY,
@@ -93,7 +115,7 @@ public class TestFailureOfSharedDir {
     assertEquals(
         "Shared dirs should come first, then local dirs, in the order " +
         "they were listed in the configuration.",
-        Joiner.on(",").join(sharedA, sharedB, localC, localB, localA),
+        Joiner.on(",").join(sharedA, localC, localB, localA),
         Joiner.on(",").join(dirs));
   }
   

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestHAConfiguration.java

@@ -20,6 +20,7 @@ package org.apache.hadoop.hdfs.server.namenode.ha;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.*;
 import static org.junit.Assert.*;
 
+import java.io.IOException;
 import java.net.URI;
 import java.util.Collection;
 
@@ -87,7 +88,7 @@ public class TestHAConfiguration {
    * duplicates removed
    */
   @Test
-  public void testHAUniqueEditDirs() {
+  public void testHAUniqueEditDirs() throws IOException {
     Configuration config = new Configuration();
 
     config.set(DFS_NAMENODE_EDITS_DIR_KEY, "file://edits/dir, "