HDFS-15322. Make NflyFS to work when ViewFsOverloadScheme's scheme and target uris schemes are same.

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/viewfs/ConfigUtil.java

@@ -135,6 +135,17 @@ public static void addLinkMerge(Configuration conf, final URI[] targets) {
     addLinkMerge(conf, Constants.CONFIG_VIEWFS_DEFAULT_MOUNT_TABLE, targets);
   }
 
+  /**
+   * Add nfly link to configuration for the given mount table.
+   */
+  public static void addLinkNfly(Configuration conf, String mountTableName,
+      String src, String settings, final String targets) {
+    conf.set(
+        getConfigViewFsPrefix(mountTableName) + "."
+            + Constants.CONFIG_VIEWFS_LINK_NFLY + "." + settings + "." + src,
+        targets);
+  }
+
   /**
    *
    * @param conf
@@ -149,9 +160,7 @@ public static void addLinkNfly(Configuration conf, String mountTableName,
     settings = settings == null
         ? "minReplication=2,repairOnRead=true"
         : settings;
-
-    conf.set(getConfigViewFsPrefix(mountTableName) + "." +
-            Constants.CONFIG_VIEWFS_LINK_NFLY + "." + settings + "." + src,
+    addLinkNfly(conf, mountTableName, src, settings,
         StringUtils.uriToString(targets));
   }
 

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/viewfs/FsGetter.java

@@ -0,0 +1,47 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.fs.viewfs;
+
+import java.io.IOException;
+import java.net.URI;
+
+import org.apache.hadoop.classification.InterfaceAudience.Private;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.FileSystem;
+
+/**
+ * File system instance getter.
+ */
+@Private
+class FsGetter {
+
+  /**
+   * Gets new file system instance of given uri.
+   */
+  public FileSystem getNewInstance(URI uri, Configuration conf)
+      throws IOException {
+    return FileSystem.newInstance(uri, conf);
+  }
+
+  /**
+   * Gets file system instance of given uri.
+   */
+  public FileSystem get(URI uri, Configuration conf) throws IOException {
+    return FileSystem.get(uri, conf);
+  }
+}

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/viewfs/HCFSMountTableConfigLoader.java

@@ -59,8 +59,7 @@ public void load(String mountTableConfigPath, Configuration conf)
       throws IOException {
     this.mountTable = new Path(mountTableConfigPath);
     String scheme = mountTable.toUri().getScheme();
-    ViewFileSystem.FsGetter fsGetter =
-        new ViewFileSystemOverloadScheme.ChildFsGetter(scheme);
+    FsGetter fsGetter = new ViewFileSystemOverloadScheme.ChildFsGetter(scheme);
     try (FileSystem fs = fsGetter.getNewInstance(mountTable.toUri(), conf)) {
       RemoteIterator<LocatedFileStatus> listFiles =
           fs.listFiles(mountTable, false);

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/viewfs/NflyFSystem.java

@@ -212,6 +212,21 @@ private static String getRack(String rackString) {
    */
   private NflyFSystem(URI[] uris, Configuration conf, int minReplication,
       EnumSet<NflyKey> nflyFlags) throws IOException {
+    this(uris, conf, minReplication, nflyFlags, null);
+  }
+
+  /**
+   * Creates a new Nfly instance.
+   *
+   * @param uris the list of uris in the mount point
+   * @param conf configuration object
+   * @param minReplication minimum copies to commit a write op
+   * @param nflyFlags modes such readMostRecent
+   * @param fsGetter to get the file system instance with the given uri
+   * @throws IOException
+   */
+  private NflyFSystem(URI[] uris, Configuration conf, int minReplication,
+      EnumSet<NflyKey> nflyFlags, FsGetter fsGetter) throws IOException {
     if (uris.length < minReplication) {
       throw new IOException(minReplication + " < " + uris.length
           + ": Minimum replication < #destinations");
@@ -238,8 +253,14 @@ private NflyFSystem(URI[] uris, Configuration conf, int minReplication,
     nodes = new NflyNode[uris.length];
     final Iterator<String> rackIter = rackStrings.iterator();
     for (int i = 0; i < nodes.length; i++) {
-      nodes[i] = new NflyNode(hostStrings.get(i), rackIter.next(), uris[i],
-          conf);
+      if (fsGetter != null) {
+        nodes[i] = new NflyNode(hostStrings.get(i), rackIter.next(),
+            new ChRootedFileSystem(fsGetter.getNewInstance(uris[i], conf),
+                uris[i]));
+      } else {
+        nodes[i] =
+            new NflyNode(hostStrings.get(i), rackIter.next(), uris[i], conf);
+      }
     }
     // sort all the uri's by distance from myNode, the local file system will
     // automatically be the the first one.
@@ -921,7 +942,7 @@ private static void processThrowable(NflyNode nflyNode, String op,
    * @throws IOException
    */
   static FileSystem createFileSystem(URI[] uris, Configuration conf,
-      String settings) throws IOException {
+      String settings, FsGetter fsGetter) throws IOException {
     // assert settings != null
     int minRepl = DEFAULT_MIN_REPLICATION;
     EnumSet<NflyKey> nflyFlags = EnumSet.noneOf(NflyKey.class);
@@ -946,6 +967,6 @@ static FileSystem createFileSystem(URI[] uris, Configuration conf,
         throw new IllegalArgumentException(nflyKey + ": Infeasible");
       }
     }
-    return new NflyFSystem(uris, conf, minRepl, nflyFlags);
+    return new NflyFSystem(uris, conf, minRepl, nflyFlags, fsGetter);
   }
 }

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/viewfs/ViewFileSystem.java

@@ -96,27 +96,6 @@ static AccessControlException readOnlyMountTable(final String operation,
     return readOnlyMountTable(operation, p.toString());
   }
 
-  /**
-   * File system instance getter.
-   */
-  static class FsGetter {
-
-    /**
-     * Gets new file system instance of given uri.
-     */
-    public FileSystem getNewInstance(URI uri, Configuration conf)
-        throws IOException {
-      return FileSystem.newInstance(uri, conf);
-    }
-
-    /**
-     * Gets file system instance of given uri.
-     */
-    public FileSystem get(URI uri, Configuration conf) throws IOException {
-      return FileSystem.get(uri, conf);
-    }
-  }
-
   /**
    * Gets file system creator instance.
    */
@@ -316,7 +295,8 @@ protected FileSystem getTargetFileSystem(final INodeDir<FileSystem> dir)
         @Override
         protected FileSystem getTargetFileSystem(final String settings,
             final URI[] uris) throws URISyntaxException, IOException {
-          return NflyFSystem.createFileSystem(uris, config, settings);
+          return NflyFSystem.createFileSystem(uris, config, settings,
+              fsGetter);
         }
       };
       workingDir = this.getHomeDirectory();

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/viewfs/ViewFileSystemBaseTest.java

@@ -50,7 +50,6 @@
 import org.apache.hadoop.fs.permission.AclUtil;
 import org.apache.hadoop.fs.permission.FsAction;
 import org.apache.hadoop.fs.permission.FsPermission;
-import org.apache.hadoop.fs.viewfs.ViewFileSystem.FsGetter;
 import org.apache.hadoop.fs.viewfs.ViewFileSystem.MountPoint;
 import org.apache.hadoop.security.AccessControlException;
 import org.apache.hadoop.security.Credentials;

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/viewfs/ViewFsTestSetup.java

@@ -31,6 +31,7 @@
 import org.apache.hadoop.fs.viewfs.ViewFileSystemOverloadScheme.ChildFsGetter;
 import org.apache.hadoop.util.Shell;
 import org.eclipse.jetty.util.log.Log;
+import org.junit.Assert;
 
 
 /**
@@ -146,7 +147,8 @@ static void addMountLinksToFile(String mountTable, String[] sources,
       throws IOException, URISyntaxException {
     ChildFsGetter cfs = new ViewFileSystemOverloadScheme.ChildFsGetter(
         mountTableConfPath.toUri().getScheme());
-    try (FileSystem fs = cfs.getNewInstance(mountTableConfPath.toUri(), conf)) {
+    try (FileSystem fs = cfs.getNewInstance(mountTableConfPath.toUri(),
+        conf)) {
       try (FSDataOutputStream out = fs.create(mountTableConfPath)) {
         String prefix =
             new StringBuilder(Constants.CONFIG_VIEWFS_PREFIX).append(".")
@@ -158,17 +160,23 @@ static void addMountLinksToFile(String mountTable, String[] sources,
         for (int i = 0; i < sources.length; i++) {
           String src = sources[i];
           String target = targets[i];
+          boolean isNfly = src.startsWith(Constants.CONFIG_VIEWFS_LINK_NFLY);
           out.writeBytes("<property><name>");
-          if (Constants.CONFIG_VIEWFS_LINK_FALLBACK.equals(src)) {
+          if (isNfly) {
+            String[] srcParts = src.split("[.]");
+            Assert.assertEquals("Invalid NFlyLink format", 3, srcParts.length);
+            String actualSrc = srcParts[srcParts.length - 1];
+            String params = srcParts[srcParts.length - 2];
+            out.writeBytes(prefix + Constants.CONFIG_VIEWFS_LINK_NFLY + "."
+                + params + "." + actualSrc);
+          } else if (Constants.CONFIG_VIEWFS_LINK_FALLBACK.equals(src)) {
             out.writeBytes(prefix + Constants.CONFIG_VIEWFS_LINK_FALLBACK);
-            out.writeBytes("</name>");
           } else if (Constants.CONFIG_VIEWFS_LINK_MERGE_SLASH.equals(src)) {
             out.writeBytes(prefix + Constants.CONFIG_VIEWFS_LINK_MERGE_SLASH);
-            out.writeBytes("</name>");
           } else {
             out.writeBytes(prefix + Constants.CONFIG_VIEWFS_LINK + "." + src);
-            out.writeBytes("</name>");
           }
+          out.writeBytes("</name>");
           out.writeBytes("<value>");
           out.writeBytes(target);
           out.writeBytes("</value></property>");
@@ -191,7 +199,15 @@ static void addMountLinksToConf(String mountTable, String[] sources,
       String target = targets[i];
       String mountTableName = mountTable == null ?
           Constants.CONFIG_VIEWFS_DEFAULT_MOUNT_TABLE : mountTable;
-      if (src.equals(Constants.CONFIG_VIEWFS_LINK_FALLBACK)) {
+      boolean isNfly = src.startsWith(Constants.CONFIG_VIEWFS_LINK_NFLY);
+      if (isNfly) {
+        String[] srcParts = src.split("[.]");
+        Assert.assertEquals("Invalid NFlyLink format", 3, srcParts.length);
+        String actualSrc = srcParts[srcParts.length - 1];
+        String params = srcParts[srcParts.length - 2];
+        ConfigUtil.addLinkNfly(config, mountTableName, actualSrc, params,
+            target);
+      } else if (src.equals(Constants.CONFIG_VIEWFS_LINK_FALLBACK)) {
         ConfigUtil.addLinkFallback(config, mountTableName, new URI(target));
       } else if (src.equals(Constants.CONFIG_VIEWFS_LINK_MERGE_SLASH)) {
         ConfigUtil.addLinkMergeSlash(config, mountTableName, new URI(target));