HDFS-11975. Provide a system-default EC policy. Contributed by Huichun Lu

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

@@ -2515,8 +2515,6 @@ public DFSInotifyEventInputStream getInotifyEventStream(long lastReadTxid)
   public void setErasureCodingPolicy(final Path path,
       final String ecPolicyName) throws IOException {
     Path absF = fixRelativePart(path);
-    Preconditions.checkNotNull(ecPolicyName, "Erasure coding policy cannot be" +
-        " null.");
     new FileSystemLinkResolver<Void>() {
       @Override
       public Void doCall(final Path p) throws IOException {

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocolPB/ClientNamenodeProtocolTranslatorPB.java

@@ -1518,7 +1518,9 @@ public void setErasureCodingPolicy(String src, String ecPolicyName)
     final SetErasureCodingPolicyRequestProto.Builder builder =
         SetErasureCodingPolicyRequestProto.newBuilder();
     builder.setSrc(src);
+    if (ecPolicyName != null) {
       builder.setEcPolicyName(ecPolicyName);
+    }
     SetErasureCodingPolicyRequestProto req = builder.build();
     try {
       rpcProxy.setErasureCodingPolicy(null, req);

hadoop-hdfs-project/hadoop-hdfs-client/src/main/proto/erasurecoding.proto

@@ -25,7 +25,7 @@ import "hdfs.proto";
 
 message SetErasureCodingPolicyRequestProto {
   required string src = 1;
-  required string ecPolicyName = 2;
+  optional string ecPolicyName = 2;
 }
 
 message SetErasureCodingPolicyResponseProto {

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

@@ -564,6 +564,10 @@ public class DFSConfigKeys extends CommonConfigurationKeys {
   public static final String  DFS_NAMENODE_EC_POLICIES_ENABLED_DEFAULT = "";
   public static final String  DFS_NAMENODE_EC_POLICIES_MAX_CELLSIZE_KEY = "dfs.namenode.ec.policies.max.cellsize";
   public static final int     DFS_NAMENODE_EC_POLICIES_MAX_CELLSIZE_DEFAULT = 4 * 1024 * 1024;
+  public static final String  DFS_NAMENODE_EC_SYSTEM_DEFAULT_POLICY =
+      "dfs.namenode.ec.system.default.policy";
+  public static final String  DFS_NAMENODE_EC_SYSTEM_DEFAULT_POLICY_DEFAULT =
+      "RS-6-3-64k";
   public static final String  DFS_DN_EC_RECONSTRUCTION_STRIPED_READ_THREADS_KEY = "dfs.datanode.ec.reconstruction.stripedread.threads";
   public static final int     DFS_DN_EC_RECONSTRUCTION_STRIPED_READ_THREADS_DEFAULT = 20;
   public static final String  DFS_DN_EC_RECONSTRUCTION_STRIPED_READ_BUFFER_SIZE_KEY = "dfs.datanode.ec.reconstruction.stripedread.buffer.size";

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolPB/ClientNamenodeProtocolServerSideTranslatorPB.java

@@ -1488,7 +1488,9 @@ public SetErasureCodingPolicyResponseProto setErasureCodingPolicy(
       RpcController controller, SetErasureCodingPolicyRequestProto req)
       throws ServiceException {
     try {
-      server.setErasureCodingPolicy(req.getSrc(), req.getEcPolicyName());
+      String ecPolicyName = req.hasEcPolicyName() ?
+          req.getEcPolicyName() : null;
+      server.setErasureCodingPolicy(req.getSrc(), ecPolicyName);
       return SetErasureCodingPolicyResponseProto.newBuilder().build();
     } catch (IOException e) {
       throw new ServiceException(e);

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

@@ -17,6 +17,7 @@
  */
 package org.apache.hadoop.hdfs.server.namenode;
 
+import org.apache.commons.lang.ArrayUtils;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.hdfs.DFSConfigKeys;
@@ -92,9 +93,14 @@ private ErasureCodingPolicyManager() {}
 
   public void init(Configuration conf) {
     // Populate the list of enabled policies from configuration
-    final String[] policyNames = conf.getTrimmedStrings(
+    final String[] enablePolicyNames = conf.getTrimmedStrings(
             DFSConfigKeys.DFS_NAMENODE_EC_POLICIES_ENABLED_KEY,
             DFSConfigKeys.DFS_NAMENODE_EC_POLICIES_ENABLED_DEFAULT);
+    final String defaultPolicyName = conf.getTrimmed(
+            DFSConfigKeys.DFS_NAMENODE_EC_SYSTEM_DEFAULT_POLICY,
+            DFSConfigKeys.DFS_NAMENODE_EC_SYSTEM_DEFAULT_POLICY_DEFAULT);
+    final String[] policyNames =
+            (String[]) ArrayUtils.add(enablePolicyNames, defaultPolicyName);
     this.userPoliciesByID = new TreeMap<>();
     this.userPoliciesByName = new TreeMap<>();
     this.removedPoliciesByName = new TreeMap<>();

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

@@ -251,6 +251,8 @@ public class NameNodeRpcServer implements NamenodeProtocols {
   
   private final String minimumDataNodeVersion;
 
+  private final String defaultECPolicyName;
+
   public NameNodeRpcServer(Configuration conf, NameNode nn)
       throws IOException {
     this.nn = nn;
@@ -490,6 +492,10 @@ public NameNodeRpcServer(Configuration conf, NameNode nn)
         DFSConfigKeys.DFS_NAMENODE_MIN_SUPPORTED_DATANODE_VERSION_KEY,
         DFSConfigKeys.DFS_NAMENODE_MIN_SUPPORTED_DATANODE_VERSION_DEFAULT);
 
+    defaultECPolicyName = conf.get(
+        DFSConfigKeys.DFS_NAMENODE_EC_SYSTEM_DEFAULT_POLICY,
+        DFSConfigKeys.DFS_NAMENODE_EC_SYSTEM_DEFAULT_POLICY_DEFAULT);
+
     // Set terse exception whose stack trace won't be logged
     clientRpcServer.addTerseExceptions(SafeModeException.class,
         FileNotFoundException.class,
@@ -2055,6 +2061,12 @@ public void setErasureCodingPolicy(String src, String ecPolicyName)
     }
     boolean success = false;
     try {
+      if (ecPolicyName == null) {
+        ecPolicyName = defaultECPolicyName;
+        LOG.trace("No policy name is specified, " +
+            "set the default policy name instead");
+      }
+      LOG.trace("Set erasure coding policy " + ecPolicyName + " on " + src);
       namesystem.setErasureCodingPolicy(src, ecPolicyName, cacheEntry != null);
       success = true;
     } finally {

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/ECAdmin.java

@@ -335,11 +335,6 @@ public int run(Configuration conf, List<String> args) throws IOException {
 
       final String ecPolicyName = StringUtils.popOptionWithArgument("-policy",
           args);
-      if (ecPolicyName == null) {
-        System.err.println("Please specify the policy name.\nUsage: " +
-            getLongUsage());
-        return 1;
-      }
 
       if (args.size() > 0) {
         System.err.println(getName() + ": Too many arguments");
@@ -350,8 +345,13 @@ public int run(Configuration conf, List<String> args) throws IOException {
       final DistributedFileSystem dfs = AdminHelper.getDFS(p.toUri(), conf);
       try {
         dfs.setErasureCodingPolicy(p, ecPolicyName);
+        if (ecPolicyName == null){
+          System.out.println("Set default erasure coding policy" +
+              " on " + path);
+        } else {
           System.out.println("Set erasure coding policy " + ecPolicyName +
               " on " + path);
+        }
       } catch (Exception e) {
         System.err.println(AdminHelper.prettifyException(e));
         return 2;

hadoop-hdfs-project/hadoop-hdfs/src/main/resources/hdfs-default.xml

@@ -2975,6 +2975,14 @@
   </description>
 </property>
 
+<property>
+  <name>dfs.namenode.ec.system.default.policy</name>
+  <value>RS-6-3-64k</value>
+  <description>The default erasure coding policy name will be used
+    on the path if no policy name is passed.
+  </description>
+</property>
+
 <property>
   <name>dfs.namenode.ec.policies.max.cellsize</name>
   <value>4194304</value>

hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HDFSErasureCoding.md

@@ -117,6 +117,11 @@ Deployment
   be more appropriate. If the administrator only cares about node-level fault-tolerance, `RS-10-4-64k` would still be appropriate as long as
   there are at least 14 DataNodes in the cluster.
 
+  A system default EC policy can be configured via 'dfs.namenode.ec.system.default.policy' configuration. With this configuration,
+  the default EC policy will be used when no policy name is passed as an argument in the '-setPolicy' command.
+
+  By default, the 'dfs.namenode.ec.system.default.policy' is "RS-6-3-64k".
+
   The codec implementations for Reed-Solomon and XOR can be configured with the following client and DataNode configuration keys:
   `io.erasurecode.codec.rs.rawcoders` for the default RS codec,
   `io.erasurecode.codec.rs-legacy.rawcoders` for the legacy RS codec,
@@ -167,6 +172,9 @@ Below are the details about each command.
       `path`: An directory in HDFS. This is a mandatory parameter. Setting a policy only affects newly created files, and does not affect existing files.
 
       `policyName`: The erasure coding policy to be used for files under this directory.
+      This parameter can be omitted if a 'dfs.namenode.ec.system.default.policy' configuration is set.
+      The EC policy of the path will be set with the default value in configuration.
+
 
  *  `[-getPolicy -path <path>]`
 

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

@@ -209,9 +209,9 @@ public void testBasicSetECPolicy()
     cluster.restartNameNodes();
     cluster.waitActive();
 
-    // No policies should be enabled after restart
+    // Only default policy should be enabled after restart
-    Assert.assertTrue("No policies should be enabled after restart",
+    Assert.assertEquals("Only default policy should be enabled after restart",
-        fs.getAllErasureCodingPolicies().isEmpty());
+        1, fs.getAllErasureCodingPolicies().size());
 
     // Already set directory-level policies should still be in effect
     Path disabledPolicy = new Path(dir1, "afterDisabled");
@@ -359,6 +359,24 @@ public void testSetInvalidPolicy()
     }
   }
 
+  @Test
+  public void testSetDefaultPolicy()
+          throws IOException {
+    String src = "/ecDir";
+    final Path ecDir = new Path(src);
+    try {
+      fs.mkdir(ecDir, FsPermission.getDirDefault());
+      fs.getClient().setErasureCodingPolicy(src, null);
+      String actualECPolicyName = fs.getClient().
+          getErasureCodingPolicy(src).getName();
+      String expectedECPolicyName =
+          conf.get(DFSConfigKeys.DFS_NAMENODE_EC_SYSTEM_DEFAULT_POLICY,
+          DFSConfigKeys.DFS_NAMENODE_EC_SYSTEM_DEFAULT_POLICY_DEFAULT);
+      assertEquals(expectedECPolicyName, actualECPolicyName);
+    } catch (Exception e) {
+    }
+  }
+
   @Test
   public void testGetAllErasureCodingPolicies() throws Exception {
     Collection<ErasureCodingPolicy> allECPolicies = fs

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

@@ -75,7 +75,7 @@ public void testDefaultPolicy() throws Exception {
     String defaultECPolicies = conf.get(
         DFSConfigKeys.DFS_NAMENODE_EC_POLICIES_ENABLED_KEY,
         DFSConfigKeys.DFS_NAMENODE_EC_POLICIES_ENABLED_DEFAULT);
-    expectValidPolicy(defaultECPolicies, 0);
+    expectValidPolicy(defaultECPolicies, 1);
   }
 
   @Test
@@ -98,10 +98,10 @@ public void testValid() throws Exception {
     String ecPolicyName = StripedFileTestUtil.getDefaultECPolicy().getName();
     expectValidPolicy(ecPolicyName, 1);
     expectValidPolicy(ecPolicyName + ", ", 1);
-    expectValidPolicy(",", 0);
+    expectValidPolicy(",", 1);
     expectValidPolicy(", " + ecPolicyName, 1);
-    expectValidPolicy(" ", 0);
+    expectValidPolicy(" ", 1);
-    expectValidPolicy(" , ", 0);
+    expectValidPolicy(" , ", 1);
   }
 
   @Test
@@ -147,7 +147,7 @@ private void testGetPolicies(ErasureCodingPolicy[] enabledPolicies)
       Assert.assertTrue("Did not find specified EC policy " + p.getName(),
           found.contains(p.getName()));
     }
-    Assert.assertEquals(enabledPolicies.length, found.size());
+    Assert.assertEquals(enabledPolicies.length, found.size()-1);
     // Check that getEnabledPolicyByName only returns enabled policies
     for (ErasureCodingPolicy p: SystemErasureCodingPolicies.getPolicies()) {
       if (found.contains(p.getName())) {

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

@@ -552,6 +552,41 @@
       </comparators>
     </test>
 
+    <test>
+      <description>setPolicy : set erasure coding policy without given a specific policy name</description>
+      <test-commands>
+        <command>-fs NAMENODE -mkdir /ecdir</command>
+        <ec-admin-command>-fs NAMENODE -setPolicy -path /ecdir</ec-admin-command>
+      </test-commands>
+      <cleanup-commands>
+        <command>-fs NAMENODE -rmdir /ecdir</command>
+      </cleanup-commands>
+      <comparators>
+        <comparator>
+          <type>SubstringComparator</type>
+          <expected-output>Set default erasure coding policy on /ecdir</expected-output>
+        </comparator>
+      </comparators>
+    </test>
+
+    <test>
+      <description>getPolicy: get the default policy after setPolicy without given a specific policy name</description>
+      <test-commands>
+        <command>-fs NAMENODE -mkdir /ecdir</command>
+        <ec-admin-command>-fs NAMENODE -setPolicy -path /ecdir</ec-admin-command>
+        <ec-admin-command>-fs NAMENODE -getPolicy -path /ecdir</ec-admin-command>
+      </test-commands>
+      <cleanup-commands>
+        <command>-fs NAMENODE -rmdir /ecdir</command>
+      </cleanup-commands>
+      <comparators>
+        <comparator>
+          <type>SubstringComparator</type>
+          <expected-output>RS-6-3-64k</expected-output>
+        </comparator>
+      </comparators>
+    </test>
+
     <test>
       <description>getPolicy : illegal parameters - path is missing</description>
       <test-commands>