HADOOP-7549. Use JDK ServiceLoader mechanism to find FileSystem implementations. (tucu)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1329994 13f79535-47bb-0310-9956-ffa450edef68

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -269,6 +269,8 @@ Release 2.0.0 - UNRELEASED
 
     HADOOP-8152. Expand public APIs for security library classes. (atm via eli)
 
+    HADOOP-7549. Use JDK ServiceLoader mechanism to find FileSystem implementations. (tucu)
+
   OPTIMIZATIONS
 
   BUG FIXES

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

@@ -32,6 +32,7 @@ import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 import java.util.NoSuchElementException;
+import java.util.ServiceLoader;
 import java.util.Set;
 import java.util.Stack;
 import java.util.TreeSet;
@@ -184,6 +185,17 @@ public abstract class FileSystem extends Configured implements Closeable {
     statistics = getStatistics(name.getScheme(), getClass());    
   }
 
+  /**
+   * Return the protocol scheme for the FileSystem.
+   * <p/>
+   * This implementation throws an <code>UnsupportedOperationException</code>.
+   *
+   * @return the protocol scheme for the FileSystem.
+   */
+  public String getScheme() {
+    throw new UnsupportedOperationException("Not implemented by  the FileSystem implementation");
+  }
+
   /** Returns a URI whose scheme and authority identify this FileSystem.*/
   public abstract URI getUri();
   
@@ -2078,9 +2090,45 @@ public abstract class FileSystem extends Configured implements Closeable {
       ) throws IOException {
   }
 
+  // making it volatile to be able to do a double checked locking
+  private volatile static boolean FILE_SYSTEMS_LOADED = false;
+
+  private static final Map<String, Class<? extends FileSystem>>
+    SERVICE_FILE_SYSTEMS = new HashMap<String, Class<? extends FileSystem>>();
+
+  private static void loadFileSystems() {
+    synchronized (FileSystem.class) {
+      if (!FILE_SYSTEMS_LOADED) {
+        ServiceLoader<FileSystem> serviceLoader = ServiceLoader.load(FileSystem.class);
+        for (FileSystem fs : serviceLoader) {
+          SERVICE_FILE_SYSTEMS.put(fs.getScheme(), fs.getClass());
+        }
+        FILE_SYSTEMS_LOADED = true;
+      }
+    }
+  }
+
+  public static Class<? extends FileSystem> getFileSystemClass(String scheme,
+      Configuration conf) throws IOException {
+    if (!FILE_SYSTEMS_LOADED) {
+      loadFileSystems();
+    }
+    Class<? extends FileSystem> clazz = null;
+    if (conf != null) {
+      clazz = (Class<? extends FileSystem>) conf.getClass("fs." + scheme + ".impl", null);
+    }
+    if (clazz == null) {
+      clazz = SERVICE_FILE_SYSTEMS.get(scheme);
+    }
+    if (clazz == null) {
+      throw new IOException("No FileSystem for scheme: " + scheme);
+    }
+    return clazz;
+  }
+
   private static FileSystem createFileSystem(URI uri, Configuration conf
       ) throws IOException {
-    Class<?> clazz = conf.getClass("fs." + uri.getScheme() + ".impl", null);
+    Class<?> clazz = getFileSystemClass(uri.getScheme(), conf);
     if (clazz == null) {
       throw new IOException("No FileSystem for scheme: " + uri.getScheme());
     }

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

@@ -71,7 +71,18 @@ public class HarFileSystem extends FilterFileSystem {
    */
   public HarFileSystem() {
   }
-  
+
+  /**
+   * Return the protocol scheme for the FileSystem.
+   * <p/>
+   *
+   * @return <code>har</code>
+   */
+  @Override
+  public String getScheme() {
+    return "har";
+  }
+
   /**
    * Constructor to create a HarFileSystem with an
    * underlying filesystem.

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

@@ -39,7 +39,18 @@ public class LocalFileSystem extends ChecksumFileSystem {
   public LocalFileSystem() {
     this(new RawLocalFileSystem());
   }
-  
+
+  /**
+   * Return the protocol scheme for the FileSystem.
+   * <p/>
+   *
+   * @return <code>file</code>
+   */
+  @Override
+  public String getScheme() {
+    return "file";
+  }
+
   public FileSystem getRaw() {
     return getRawFileSystem();
   }

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/ftp/FTPFileSystem.java

@@ -59,6 +59,17 @@ public class FTPFileSystem extends FileSystem {
 
   private URI uri;
 
+  /**
+   * Return the protocol scheme for the FileSystem.
+   * <p/>
+   *
+   * @return <code>ftp</code>
+   */
+  @Override
+  public String getScheme() {
+    return "ftp";
+  }
+
   @Override
   public void initialize(URI uri, Configuration conf) throws IOException { // get
     super.initialize(uri, conf);

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/kfs/KosmosFileSystem.java

@@ -57,6 +57,17 @@ public class KosmosFileSystem extends FileSystem {
         this.kfsImpl = fsimpl;
     }
 
+    /**
+     * Return the protocol scheme for the FileSystem.
+     * <p/>
+     *
+     * @return <code>kfs</code>
+     */
+    @Override
+    public String getScheme() {
+      return "kfs";
+    }
+
     @Override
     public URI getUri() {
 	return uri;

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/s3/S3FileSystem.java

@@ -67,6 +67,17 @@ public class S3FileSystem extends FileSystem {
     this.store = store;
   }
 
+  /**
+   * Return the protocol scheme for the FileSystem.
+   * <p/>
+   *
+   * @return <code>s3</code>
+   */
+  @Override
+  public String getScheme() {
+    return "s3";
+  }
+
   @Override
   public URI getUri() {
     return uri;

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/s3native/NativeS3FileSystem.java

@@ -251,7 +251,18 @@ public class NativeS3FileSystem extends FileSystem {
   public NativeS3FileSystem(NativeFileSystemStore store) {
     this.store = store;
   }
-  
+
+  /**
+   * Return the protocol scheme for the FileSystem.
+   * <p/>
+   *
+   * @return <code>s3n</code>
+   */
+  @Override
+  public String getScheme() {
+    return "s3n";
+  }
+
   @Override
   public void initialize(URI uri, Configuration conf) throws IOException {
     super.initialize(uri, conf);

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

@@ -149,6 +149,17 @@ public class ViewFileSystem extends FileSystem {
     creationTime = System.currentTimeMillis();
   }
 
+  /**
+   * Return the protocol scheme for the FileSystem.
+   * <p/>
+   *
+   * @return <code>viewfs</code>
+   */
+  @Override
+  public String getScheme() {
+    return "viewfs";
+  }
+
   /**
    * Called after a new FileSystem instance is constructed.
    * @param theUri a uri whose authority section names the host, port, etc. for

hadoop-common-project/hadoop-common/src/main/resources/META-INF/services/org.apache.hadoop.fs.FileSystem

@@ -0,0 +1,22 @@
+# 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.
+
+org.apache.hadoop.fs.LocalFileSystem
+org.apache.hadoop.fs.viewfs.ViewFileSystem
+org.apache.hadoop.fs.s3.S3FileSystem
+org.apache.hadoop.fs.s3native.NativeS3FileSystem
+org.apache.hadoop.fs.kfs.KosmosFileSystem
+org.apache.hadoop.fs.ftp.FTPFileSystem
+org.apache.hadoop.fs.HarFileSystem

hadoop-common-project/hadoop-common/src/main/resources/core-default.xml

@@ -352,25 +352,6 @@
   </description>
 </property>
 
-<property>
-  <name>fs.file.impl</name>
-  <value>org.apache.hadoop.fs.LocalFileSystem</value>
-  <description>The FileSystem for file: uris.</description>
-</property>
-
-<property>
-  <name>fs.hdfs.impl</name>
-  <value>org.apache.hadoop.hdfs.DistributedFileSystem</value>
-  <description>The FileSystem for hdfs: uris.</description>
-</property>
-
-<property>
-  <name>fs.viewfs.impl</name>
-  <value>org.apache.hadoop.fs.viewfs.ViewFileSystem</value>
-  <description>The FileSystem for view file system for viewfs: uris
-  (ie client side mount table:).</description>
-</property>
-
 <property>
   <name>fs.AbstractFileSystem.file.impl</name>
   <value>org.apache.hadoop.fs.local.LocalFs</value>
@@ -391,45 +372,6 @@
   (ie client side mount table:).</description>
 </property>
 
-<property>
-  <name>fs.s3.impl</name>
-  <value>org.apache.hadoop.fs.s3.S3FileSystem</value>
-  <description>The FileSystem for s3: uris.</description>
-</property>
-
-<property>
-  <name>fs.s3n.impl</name>
-  <value>org.apache.hadoop.fs.s3native.NativeS3FileSystem</value>
-  <description>The FileSystem for s3n: (Native S3) uris.</description>
-</property>
-
-<property>
-  <name>fs.kfs.impl</name>
-  <value>org.apache.hadoop.fs.kfs.KosmosFileSystem</value>
-  <description>The FileSystem for kfs: uris.</description>
-</property>
-
-<property>
-  <name>fs.hftp.impl</name>
-  <value>org.apache.hadoop.hdfs.HftpFileSystem</value>
-</property>
-
-<property>
-  <name>fs.hsftp.impl</name>
-  <value>org.apache.hadoop.hdfs.HsftpFileSystem</value>
-</property>
-
-<property>
-  <name>fs.webhdfs.impl</name>
-  <value>org.apache.hadoop.hdfs.web.WebHdfsFileSystem</value>
-</property>
-
-<property>
-  <name>fs.ftp.impl</name>
-  <value>org.apache.hadoop.fs.ftp.FTPFileSystem</value>
-  <description>The FileSystem for ftp: uris.</description>
-</property>
-
 <property>
   <name>fs.ftp.host</name>
   <value>0.0.0.0</value>
@@ -444,18 +386,6 @@
   </description>
 </property>
 
-<property>
-  <name>fs.har.impl</name>
-  <value>org.apache.hadoop.fs.HarFileSystem</value>
-  <description>The filesystem for Hadoop archives. </description>
-</property>
-
-<property>
-  <name>fs.har.impl.disable.cache</name>
-  <value>true</value>
-  <description>Don't cache 'har' filesystem instances.</description>
-</property>
-
 <property>
   <name>fs.df.interval</name>
   <value>60000</value>

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

@@ -43,7 +43,7 @@ public class TestFileSystemCaching {
   @Test
   public void testCacheEnabled() throws Exception {
     Configuration conf = new Configuration();
-    conf.set("fs.cachedfile.impl", conf.get("fs.file.impl"));
+    conf.set("fs.cachedfile.impl", FileSystem.getFileSystemClass("file", null).getName());
     FileSystem fs1 = FileSystem.get(new URI("cachedfile://a"), conf);
     FileSystem fs2 = FileSystem.get(new URI("cachedfile://a"), conf);
     assertSame(fs1, fs2);
@@ -84,7 +84,7 @@ public class TestFileSystemCaching {
     // wait for InitializeForeverFileSystem to start initialization
     InitializeForeverFileSystem.sem.acquire();
     
-    conf.set("fs.cachedfile.impl", conf.get("fs.file.impl"));
+    conf.set("fs.cachedfile.impl", FileSystem.getFileSystemClass("file", null).getName());
     FileSystem.get(new URI("cachedfile://a"), conf);
     t.interrupt();
     t.join();
@@ -93,7 +93,7 @@ public class TestFileSystemCaching {
   @Test
   public void testCacheDisabled() throws Exception {
     Configuration conf = new Configuration();
-    conf.set("fs.uncachedfile.impl", conf.get("fs.file.impl"));
+    conf.set("fs.uncachedfile.impl", FileSystem.getFileSystemClass("file", null).getName());
     conf.setBoolean("fs.uncachedfile.impl.disable.cache", true);
     FileSystem fs1 = FileSystem.get(new URI("uncachedfile://a"), conf);
     FileSystem fs2 = FileSystem.get(new URI("uncachedfile://a"), conf);
@@ -104,7 +104,7 @@ public class TestFileSystemCaching {
   @Test
   public <T extends TokenIdentifier> void testCacheForUgi() throws Exception {
     final Configuration conf = new Configuration();
-    conf.set("fs.cachedfile.impl", conf.get("fs.file.impl"));
+    conf.set("fs.cachedfile.impl", FileSystem.getFileSystemClass("file", null).getName());
     UserGroupInformation ugiA = UserGroupInformation.createRemoteUser("foo");
     UserGroupInformation ugiB = UserGroupInformation.createRemoteUser("bar");
     FileSystem fsA = ugiA.doAs(new PrivilegedExceptionAction<FileSystem>() {
@@ -156,7 +156,7 @@ public class TestFileSystemCaching {
   @Test
   public void testUserFS() throws Exception {
     final Configuration conf = new Configuration();
-    conf.set("fs.cachedfile.impl", conf.get("fs.file.impl"));
+    conf.set("fs.cachedfile.impl", FileSystem.getFileSystemClass("file", null).getName());
     FileSystem fsU1 = FileSystem.get(new URI("cachedfile://a"), conf, "bar");
     FileSystem fsU2 = FileSystem.get(new URI("cachedfile://a"), conf, "foo");
     
@@ -166,7 +166,7 @@ public class TestFileSystemCaching {
   @Test
   public void testFsUniqueness() throws Exception {
     final Configuration conf = new Configuration();
-    conf.set("fs.cachedfile.impl", conf.get("fs.file.impl"));
+    conf.set("fs.cachedfile.impl", FileSystem.getFileSystemClass("file", null).getName());
     // multiple invocations of FileSystem.get return the same object.
     FileSystem fs1 = FileSystem.get(conf);
     FileSystem fs2 = FileSystem.get(conf);
@@ -183,7 +183,7 @@ public class TestFileSystemCaching {
   @Test
   public void testCloseAllForUGI() throws Exception {
     final Configuration conf = new Configuration();
-    conf.set("fs.cachedfile.impl", conf.get("fs.file.impl"));
+    conf.set("fs.cachedfile.impl", FileSystem.getFileSystemClass("file", null).getName());
     UserGroupInformation ugiA = UserGroupInformation.createRemoteUser("foo");
     FileSystem fsA = ugiA.doAs(new PrivilegedExceptionAction<FileSystem>() {
       public FileSystem run() throws Exception {

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

@@ -165,7 +165,10 @@ public class TestFilterFileSystem {
     public Token<?> getDelegationToken(String renewer) throws IOException {
       return null;
     }
-    
+
+    public String getScheme() {
+      return "dontcheck";
+    }
   }
   
   @Test

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

@@ -89,6 +89,17 @@ public class DistributedFileSystem extends FileSystem {
   public DistributedFileSystem() {
   }
 
+  /**
+   * Return the protocol scheme for the FileSystem.
+   * <p/>
+   *
+   * @return <code>hdfs</code>
+   */
+  @Override
+  public String getScheme() {
+    return "hdfs";
+  }
+
   @Deprecated
   public DistributedFileSystem(InetSocketAddress namenode,
     Configuration conf) throws IOException {

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

@@ -154,6 +154,17 @@ public class HftpFileSystem extends FileSystem
     return SecurityUtil.buildTokenService(nnSecureUri).toString();
   }
 
+  /**
+   * Return the protocol scheme for the FileSystem.
+   * <p/>
+   *
+   * @return <code>hftp</code>
+   */
+  @Override
+  public String getScheme() {
+    return "hftp";
+  }
+
   @Override
   public void initialize(final URI name, final Configuration conf)
   throws IOException {

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

@@ -58,6 +58,17 @@ public class HsftpFileSystem extends HftpFileSystem {
   private static final long MM_SECONDS_PER_DAY = 1000 * 60 * 60 * 24;
   private volatile int ExpWarnDays = 0;
 
+  /**
+   * Return the protocol scheme for the FileSystem.
+   * <p/>
+   *
+   * @return <code>hsftp</code>
+   */
+  @Override
+  public String getScheme() {
+    return "hsftp";
+  }
+
   @Override
   public void initialize(URI name, Configuration conf) throws IOException {
     super.initialize(name, conf);

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/web/WebHdfsFileSystem.java

@@ -155,6 +155,17 @@ public class WebHdfsFileSystem extends FileSystem
     }
   }
 
+  /**
+   * Return the protocol scheme for the FileSystem.
+   * <p/>
+   *
+   * @return <code>webhdfs</code>
+   */
+  @Override
+  public String getScheme() {
+    return "webhdfs";
+  }
+
   @Override
   public synchronized void initialize(URI uri, Configuration conf
       ) throws IOException {

hadoop-hdfs-project/hadoop-hdfs/src/main/resources/META-INF/services/org.apache.hadoop.fs.FileSystem

@@ -0,0 +1,19 @@
+# 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.
+
+org.apache.hadoop.hdfs.DistributedFileSystem
+org.apache.hadoop.hdfs.HftpFileSystem
+org.apache.hadoop.hdfs.HsftpFileSystem
+org.apache.hadoop.hdfs.web.WebHdfsFileSystem