HADOOP-12924. Configure raw erasure coders for supported codecs. Contributed by Rui Li.

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

@@ -21,6 +21,9 @@
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.classification.InterfaceStability;
 import org.apache.hadoop.http.lib.StaticUserWebFilter;
+import org.apache.hadoop.io.erasurecode.rawcoder.RSRawErasureCoderFactory;
+import org.apache.hadoop.io.erasurecode.rawcoder.RSRawErasureCoderFactoryLegacy;
+import org.apache.hadoop.io.erasurecode.rawcoder.XORRawErasureCoderFactory;
 
 /** 
  * This class contains constants for configuration keys used
@@ -156,13 +159,23 @@ public class CommonConfigurationKeys extends CommonConfigurationKeysPublic {
   /** Supported erasure codec classes */
   public static final String IO_ERASURECODE_CODECS_KEY = "io.erasurecode.codecs";
 
-  /** Raw coder factory for the RS codec. */
+  /** Raw coder factory for the RS default codec. */
-  public static final String IO_ERASURECODE_CODEC_RS_RAWCODER_KEY =
+  public static final String IO_ERASURECODE_CODEC_RS_DEFAULT_RAWCODER_KEY =
-      "io.erasurecode.codec.rs.rawcoder";
+      "io.erasurecode.codec.rs-default.rawcoder";
+  public static final String IO_ERASURECODE_CODEC_RS_DEFAULT_RAWCODER_DEFAULT =
+      RSRawErasureCoderFactory.class.getCanonicalName();
+
+  /** Raw coder factory for the RS legacy codec. */
+  public static final String IO_ERASURECODE_CODEC_RS_LEGACY_RAWCODER_KEY =
+      "io.erasurecode.codec.rs-legacy.rawcoder";
+  public static final String IO_ERASURECODE_CODEC_RS_LEGACY_RAWCODER_DEFAULT =
+      RSRawErasureCoderFactoryLegacy.class.getCanonicalName();
 
   /** Raw coder factory for the XOR codec. */
   public static final String IO_ERASURECODE_CODEC_XOR_RAWCODER_KEY =
       "io.erasurecode.codec.xor.rawcoder";
+  public static final String IO_ERASURECODE_CODEC_XOR_RAWCODER_DEFAULT =
+      XORRawErasureCoderFactory.class.getCanonicalName();
 
   /**
    * Service Authorization

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/erasurecode/CodecUtil.java

@@ -17,17 +17,14 @@
  */
 package org.apache.hadoop.io.erasurecode;
 
+import com.google.common.base.Preconditions;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.CommonConfigurationKeys;
-import org.apache.hadoop.io.erasurecode.rawcoder.RSRawDecoder;
-import org.apache.hadoop.io.erasurecode.rawcoder.RSRawEncoder;
 import org.apache.hadoop.io.erasurecode.rawcoder.RawErasureCoder;
 import org.apache.hadoop.io.erasurecode.rawcoder.RawErasureCoderFactory;
 import org.apache.hadoop.io.erasurecode.rawcoder.RawErasureDecoder;
 import org.apache.hadoop.io.erasurecode.rawcoder.RawErasureEncoder;
-import org.apache.hadoop.io.erasurecode.rawcoder.XORRawDecoder;
-import org.apache.hadoop.io.erasurecode.rawcoder.XORRawEncoder;
 
 /**
  * A codec & coder utility to help create raw coders conveniently.
@@ -42,39 +39,55 @@ private CodecUtil() { }
    * @param conf configuration possibly with some items to configure the coder
    * @param numDataUnits number of data units in a coding group
    * @param numParityUnits number of parity units in a coding group
+   * @param codec the codec to use. If null, will use the default codec
    * @return raw encoder
    */
   public static RawErasureEncoder createRSRawEncoder(
-      Configuration conf, int numDataUnits, int numParityUnits) {
+      Configuration conf, int numDataUnits, int numParityUnits, String codec) {
-    RawErasureCoder rawCoder = createRawCoder(conf,
+    Preconditions.checkNotNull(conf);
-        CommonConfigurationKeys.IO_ERASURECODE_CODEC_RS_RAWCODER_KEY,
+    if (codec == null) {
-        true, numDataUnits, numParityUnits);
+      codec = ErasureCodeConstants.RS_DEFAULT_CODEC_NAME;
-    if (rawCoder == null) {
-      rawCoder = new RSRawEncoder(numDataUnits, numParityUnits);
     }
-
+    RawErasureCoder rawCoder = createRawCoder(conf,
+        getFactNameFromCodec(conf, codec), true, numDataUnits, numParityUnits);
     return (RawErasureEncoder) rawCoder;
   }
 
+  /**
+   * Create RS raw encoder using the default codec.
+   */
+  public static RawErasureEncoder createRSRawEncoder(
+      Configuration conf, int numDataUnits, int numParityUnits) {
+    return createRSRawEncoder(conf, numDataUnits, numParityUnits, null);
+  }
+
   /**
    * Create RS raw decoder according to configuration.
    * @param conf configuration possibly with some items to configure the coder
    * @param numDataUnits number of data units in a coding group
    * @param numParityUnits number of parity units in a coding group
+   * @param codec the codec to use. If null, will use the default codec
    * @return raw decoder
    */
   public static RawErasureDecoder createRSRawDecoder(
-      Configuration conf, int numDataUnits, int numParityUnits) {
+      Configuration conf, int numDataUnits, int numParityUnits, String codec) {
-    RawErasureCoder rawCoder = createRawCoder(conf,
+    Preconditions.checkNotNull(conf);
-        CommonConfigurationKeys.IO_ERASURECODE_CODEC_RS_RAWCODER_KEY,
+    if (codec == null) {
-        false, numDataUnits, numParityUnits);
+      codec = ErasureCodeConstants.RS_DEFAULT_CODEC_NAME;
-    if (rawCoder == null) {
-      rawCoder = new RSRawDecoder(numDataUnits, numParityUnits);
     }
-
+    RawErasureCoder rawCoder = createRawCoder(conf,
+        getFactNameFromCodec(conf, codec), false, numDataUnits, numParityUnits);
     return (RawErasureDecoder) rawCoder;
   }
 
+  /**
+   * Create RS raw decoder using the default codec.
+   */
+  public static RawErasureDecoder createRSRawDecoder(
+      Configuration conf, int numDataUnits, int numParityUnits) {
+    return createRSRawDecoder(conf, numDataUnits, numParityUnits, null);
+  }
+
   /**
    * Create XOR raw encoder according to configuration.
    * @param conf configuration possibly with some items to configure the coder
@@ -84,13 +97,10 @@ public static RawErasureDecoder createRSRawDecoder(
    */
   public static RawErasureEncoder createXORRawEncoder(
       Configuration conf, int numDataUnits, int numParityUnits) {
+    Preconditions.checkNotNull(conf);
     RawErasureCoder rawCoder = createRawCoder(conf,
-        CommonConfigurationKeys.IO_ERASURECODE_CODEC_XOR_RAWCODER_KEY,
+        getFactNameFromCodec(conf, ErasureCodeConstants.XOR_CODEC_NAME),
         true, numDataUnits, numParityUnits);
-    if (rawCoder == null) {
-      rawCoder = new XORRawEncoder(numDataUnits, numParityUnits);
-    }
-
     return (RawErasureEncoder) rawCoder;
   }
 
@@ -103,51 +113,65 @@ public static RawErasureEncoder createXORRawEncoder(
    */
   public static RawErasureDecoder createXORRawDecoder(
       Configuration conf, int numDataUnits, int numParityUnits) {
+    Preconditions.checkNotNull(conf);
     RawErasureCoder rawCoder = createRawCoder(conf,
-        CommonConfigurationKeys.IO_ERASURECODE_CODEC_XOR_RAWCODER_KEY,
+        getFactNameFromCodec(conf, ErasureCodeConstants.XOR_CODEC_NAME),
         false, numDataUnits, numParityUnits);
-    if (rawCoder == null) {
-      rawCoder = new XORRawDecoder(numDataUnits, numParityUnits);
-    }
-
     return (RawErasureDecoder) rawCoder;
   }
 
   /**
    * Create raw coder using specified conf and raw coder factory key.
    * @param conf configuration possibly with some items to configure the coder
-   * @param rawCoderFactoryKey configuration key to find the raw coder factory
+   * @param rawCoderFactory name of the raw coder factory
    * @param isEncoder is encoder or not we're going to create
    * @param numDataUnits number of data units in a coding group
    * @param numParityUnits number of parity units in a coding group
    * @return raw coder
    */
   public static RawErasureCoder createRawCoder(Configuration conf,
-      String rawCoderFactoryKey, boolean isEncoder, int numDataUnits,
+      String rawCoderFactory, boolean isEncoder, int numDataUnits,
                                                int numParityUnits) {
 
-    if (conf == null) {
-      return null;
-    }
-
-    Class<? extends RawErasureCoderFactory> factClass = null;
-    factClass = conf.getClass(rawCoderFactoryKey,
-        factClass, RawErasureCoderFactory.class);
-
-    if (factClass == null) {
-      return null;
-    }
-
     RawErasureCoderFactory fact;
     try {
+      Class<? extends RawErasureCoderFactory> factClass = conf.getClassByName(
+          rawCoderFactory).asSubclass(RawErasureCoderFactory.class);
       fact = factClass.newInstance();
-    } catch (InstantiationException e) {
+    } catch (ClassNotFoundException | InstantiationException |
-      throw new RuntimeException("Failed to create raw coder", e);
+        IllegalAccessException e) {
-    } catch (IllegalAccessException e) {
       throw new RuntimeException("Failed to create raw coder", e);
     }
 
     return isEncoder ? fact.createEncoder(numDataUnits, numParityUnits) :
             fact.createDecoder(numDataUnits, numParityUnits);
   }
+
+  private static String getFactNameFromCodec(Configuration conf, String codec) {
+    switch (codec) {
+    case ErasureCodeConstants.RS_DEFAULT_CODEC_NAME:
+      return conf.get(
+          CommonConfigurationKeys.IO_ERASURECODE_CODEC_RS_DEFAULT_RAWCODER_KEY,
+          CommonConfigurationKeys.
+              IO_ERASURECODE_CODEC_RS_DEFAULT_RAWCODER_DEFAULT);
+    case ErasureCodeConstants.RS_LEGACY_CODEC_NAME:
+      return conf.get(
+          CommonConfigurationKeys.IO_ERASURECODE_CODEC_RS_LEGACY_RAWCODER_KEY,
+          CommonConfigurationKeys.
+              IO_ERASURECODE_CODEC_RS_LEGACY_RAWCODER_DEFAULT);
+    case ErasureCodeConstants.XOR_CODEC_NAME:
+      return conf.get(
+          CommonConfigurationKeys.IO_ERASURECODE_CODEC_XOR_RAWCODER_KEY,
+          CommonConfigurationKeys.IO_ERASURECODE_CODEC_XOR_RAWCODER_DEFAULT);
+    default:
+      // For custom codec, we throw exception if the factory is not configured
+      String rawCoderKey = "io.erasurecode.codec." + codec + ".rawcoder";
+      String factName = conf.get(rawCoderKey);
+      if (factName == null) {
+        throw new IllegalArgumentException("Raw coder factory not configured " +
+            "for custom codec " + codec);
+      }
+      return factName;
+    }
+  }
 }

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/erasurecode/ErasureCodeConstants.java

@@ -0,0 +1,40 @@
+/**
+ * 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.io.erasurecode;
+
+/**
+ * Constants related to the erasure code feature.
+ */
+public final class ErasureCodeConstants {
+
+  private ErasureCodeConstants(){
+  }
+
+  public static final String RS_DEFAULT_CODEC_NAME = "rs-default";
+  public static final String RS_LEGACY_CODEC_NAME = "rs-legacy";
+  public static final String XOR_CODEC_NAME = "xor";
+
+  public static final ECSchema RS_6_3_SCHEMA = new ECSchema(
+      RS_DEFAULT_CODEC_NAME, 6, 3);
+
+  public static final ECSchema RS_3_2_SCHEMA = new ECSchema(
+      RS_DEFAULT_CODEC_NAME, 3, 2);
+
+  public static final ECSchema RS_6_3_LEGACY_SCHEMA = new ECSchema(
+      RS_LEGACY_CODEC_NAME, 6, 3);
+}

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/erasurecode/coder/HHXORErasureEncoder.java

@@ -65,7 +65,7 @@ protected ErasureCodingStep prepareEncodingStep(
   private RawErasureEncoder checkCreateRSRawEncoder() {
     if (rsRawEncoder == null) {
       rsRawEncoder = CodecUtil.createRSRawEncoder(getConf(),
-              getNumDataUnits(), getNumParityUnits());
+          getNumDataUnits(), getNumParityUnits());
     }
     return rsRawEncoder;
   }

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/erasurecode/coder/RSErasureDecoder.java

@@ -54,6 +54,7 @@ protected ErasureCodingStep prepareDecodingStep(final ECBlockGroup blockGroup) {
 
   private RawErasureDecoder checkCreateRSRawDecoder() {
     if (rsRawDecoder == null) {
+      // TODO: we should create the raw coder according to codec.
       rsRawDecoder = CodecUtil.createRSRawDecoder(getConf(),
           getNumDataUnits(), getNumParityUnits());
     }

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/erasurecode/coder/RSErasureEncoder.java

@@ -54,8 +54,9 @@ protected ErasureCodingStep prepareEncodingStep(final ECBlockGroup blockGroup) {
 
   private RawErasureEncoder checkCreateRSRawEncoder() {
     if (rawEncoder == null) {
+      // TODO: we should create the raw coder according to codec.
       rawEncoder = CodecUtil.createRSRawEncoder(getConf(),
-              getNumDataUnits(), getNumParityUnits());
+          getNumDataUnits(), getNumParityUnits());
     }
     return rawEncoder;
   }

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

@@ -506,6 +506,14 @@
   </description>
 </property>
 
+<property>
+  <name>io.erasurecode.codec.rs-default.rawcoder</name>
+  <value>org.apache.hadoop.io.erasurecode.rawcoder.RSRawErasureCoderFactory</value>
+  <description>
+    Raw coder implementation for the rs-default codec.
+  </description>
+</property>
+
 <!-- file system properties -->
 
 <property>

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/io/erasurecode/TestCodecRawCoderMapping.java

@@ -0,0 +1,85 @@
+/**
+ * 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
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.io.erasurecode;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.CommonConfigurationKeys;
+import org.apache.hadoop.io.erasurecode.rawcoder.RSRawDecoder;
+import org.apache.hadoop.io.erasurecode.rawcoder.RSRawDecoderLegacy;
+import org.apache.hadoop.io.erasurecode.rawcoder.RSRawEncoder;
+import org.apache.hadoop.io.erasurecode.rawcoder.RSRawEncoderLegacy;
+import org.apache.hadoop.io.erasurecode.rawcoder.RawErasureDecoder;
+import org.apache.hadoop.io.erasurecode.rawcoder.RawErasureEncoder;
+import org.apache.hadoop.test.GenericTestUtils;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+/**
+ * Test the codec to raw coder mapping.
+ */
+public class TestCodecRawCoderMapping {
+
+  private static Configuration conf;
+  private static final int numDataUnit = 6;
+  private static final int numParityUnit = 3;
+
+  @Before
+  public void setup() {
+    conf = new Configuration();
+  }
+
+  @Test
+  public void testRSDefaultRawCoder() {
+    // should return default raw coder of rs-default codec
+    RawErasureEncoder encoder = CodecUtil.createRSRawEncoder(
+        conf, numDataUnit, numParityUnit);
+    Assert.assertTrue(encoder instanceof RSRawEncoder);
+    RawErasureDecoder decoder = CodecUtil.createRSRawDecoder(
+        conf, numDataUnit, numParityUnit);
+    Assert.assertTrue(decoder instanceof RSRawDecoder);
+
+    // should return default raw coder of rs-legacy codec
+    encoder = CodecUtil.createRSRawEncoder(conf, numDataUnit, numParityUnit,
+        ErasureCodeConstants.RS_LEGACY_CODEC_NAME);
+    Assert.assertTrue(encoder instanceof RSRawEncoderLegacy);
+    decoder = CodecUtil.createRSRawDecoder(conf, numDataUnit, numParityUnit,
+        ErasureCodeConstants.RS_LEGACY_CODEC_NAME);
+    Assert.assertTrue(decoder instanceof RSRawDecoderLegacy);
+  }
+
+  @Test
+  public void testDedicatedRawCoderKey() {
+    String dummyFactName = "DummyNoneExistingFactory";
+    // set the dummy factory to rs-legacy and create a raw coder
+    // with rs-default, which is OK as the raw coder key is not used
+    conf.set(CommonConfigurationKeys.
+        IO_ERASURECODE_CODEC_RS_LEGACY_RAWCODER_KEY, dummyFactName);
+    RawErasureEncoder encoder = CodecUtil.createRSRawEncoder(conf, numDataUnit,
+        numParityUnit, ErasureCodeConstants.RS_DEFAULT_CODEC_NAME);
+    Assert.assertTrue(encoder instanceof RSRawEncoder);
+    // now create the raw coder with rs-legacy, which should throw exception
+    try {
+      CodecUtil.createRSRawEncoder(conf, numDataUnit, numParityUnit,
+          ErasureCodeConstants.RS_LEGACY_CODEC_NAME);
+      Assert.fail();
+    } catch (Exception e) {
+      GenericTestUtils.assertExceptionContains("Failed to create raw coder", e);
+    }
+  }
+}

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/io/erasurecode/TestCoderBase.java

@@ -112,7 +112,7 @@ protected void setAllowDump(boolean allowDump) {
   protected void prepare(Configuration conf, int numDataUnits,
                          int numParityUnits, int[] erasedDataIndexes,
                          int[] erasedParityIndexes, boolean usingFixedData) {
-    this.conf = conf;
+    this.conf = conf != null ? conf : new Configuration();
     this.numDataUnits = numDataUnits;
     this.numParityUnits = numParityUnits;
     this.erasedDataIndexes = erasedDataIndexes != null ?

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/io/erasurecode/coder/TestHHXORErasureCoder.java

@@ -50,7 +50,7 @@ public void testCodingDirectBufferWithConf_10x4_erasing_d0() {
      * This tests if the configuration items work or not.
      */
     Configuration conf = new Configuration();
-    conf.set(CommonConfigurationKeys.IO_ERASURECODE_CODEC_RS_RAWCODER_KEY,
+    conf.set(CommonConfigurationKeys.IO_ERASURECODE_CODEC_RS_DEFAULT_RAWCODER_KEY,
         RSRawErasureCoderFactory.class.getCanonicalName());
     prepare(conf, 10, 4, new int[]{0}, new int[0]);
 

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/io/erasurecode/coder/TestRSErasureCoder.java

@@ -57,7 +57,7 @@ public void testCodingDirectBufferWithConf_10x4_erasing_d0() {
      * This tests if the configuration items work or not.
      */
     Configuration conf = new Configuration();
-    conf.set(CommonConfigurationKeys.IO_ERASURECODE_CODEC_RS_RAWCODER_KEY,
+    conf.set(CommonConfigurationKeys.IO_ERASURECODE_CODEC_RS_DEFAULT_RAWCODER_KEY,
         RSRawErasureCoderFactory.class.getCanonicalName());
     prepare(conf, 10, 4, new int[]{0}, new int[0]);
 

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

@@ -185,7 +185,7 @@ void skip() {
     readingService =
         new ExecutorCompletionService<>(dfsClient.getStripedReadsThreadPool());
     decoder = CodecUtil.createRSRawDecoder(dfsClient.getConfiguration(),
-        dataBlkNum, parityBlkNum);
+        dataBlkNum, parityBlkNum, ecPolicy.getCodecName());
     if (DFSClient.LOG.isDebugEnabled()) {
       DFSClient.LOG.debug("Creating an striped input stream for file " + src);
     }

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

@@ -287,7 +287,7 @@ private void flipDataBuffers() {
         ExecutorCompletionService<>(flushAllExecutor);
 
     encoder = CodecUtil.createRSRawEncoder(dfsClient.getConfiguration(),
-        numDataBlocks, numParityBlocks);
+        numDataBlocks, numParityBlocks, ecPolicy.getCodecName());
 
     coordinator = new Coordinator(numAllBlocks);
     try {

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

@@ -72,6 +72,10 @@ public int getNumParityUnits() {
     return schema.getNumParityUnits();
   }
 
+  public String getCodecName() {
+    return schema.getCodecName();
+  }
+
   public byte getId() {
     return id;
   }

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

@@ -22,7 +22,6 @@
 
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.fs.Path;
-import org.apache.hadoop.io.erasurecode.ECSchema;
 import org.apache.hadoop.util.StringUtils;
 
 @InterfaceAudience.Private
@@ -145,11 +144,9 @@ public enum DatanodeReportType {
     ALL, LIVE, DEAD, DECOMMISSIONING
   }
 
-  public static final ECSchema RS_6_3_SCHEMA = new ECSchema("rs", 6, 3);
   public static final byte RS_6_3_POLICY_ID = 0;
-
-  public static final ECSchema RS_3_2_SCHEMA = new ECSchema("rs", 3, 2);
   public static final byte RS_3_2_POLICY_ID = 1;
+  public static final byte RS_6_3_LEGACY_POLICY_ID = 2;
 
   /* Hidden constructor */
   protected HdfsConstants() {

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/erasurecode/StripedReconstructor.java

@@ -216,7 +216,7 @@ void reconstructAndTransfer() throws IOException {
   private void initDecoderIfNecessary() {
     if (decoder == null) {
       decoder = CodecUtil.createRSRawDecoder(conf, ecPolicy.getNumDataUnits(),
-          ecPolicy.getNumParityUnits());
+          ecPolicy.getNumParityUnits(), ecPolicy.getCodecName());
     }
   }
 

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

@@ -20,6 +20,7 @@
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.hdfs.protocol.ErasureCodingPolicy;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants;
+import org.apache.hadoop.io.erasurecode.ErasureCodeConstants;
 
 import java.util.Map;
 import java.util.TreeMap;
@@ -39,15 +40,18 @@ public final class ErasureCodingPolicyManager {
    */
   private static final int DEFAULT_CELLSIZE = 64 * 1024;
   private static final ErasureCodingPolicy SYS_POLICY1 =
-      new ErasureCodingPolicy(HdfsConstants.RS_6_3_SCHEMA, DEFAULT_CELLSIZE,
+      new ErasureCodingPolicy(ErasureCodeConstants.RS_6_3_SCHEMA,
-          HdfsConstants.RS_6_3_POLICY_ID);
+          DEFAULT_CELLSIZE, HdfsConstants.RS_6_3_POLICY_ID);
   private static final ErasureCodingPolicy SYS_POLICY2 =
-      new ErasureCodingPolicy(HdfsConstants.RS_3_2_SCHEMA, DEFAULT_CELLSIZE,
+      new ErasureCodingPolicy(ErasureCodeConstants.RS_3_2_SCHEMA,
-          HdfsConstants.RS_3_2_POLICY_ID);
+          DEFAULT_CELLSIZE, HdfsConstants.RS_3_2_POLICY_ID);
+  private static final ErasureCodingPolicy SYS_POLICY3 =
+      new ErasureCodingPolicy(ErasureCodeConstants.RS_6_3_LEGACY_SCHEMA,
+          DEFAULT_CELLSIZE, HdfsConstants.RS_6_3_LEGACY_POLICY_ID);
 
   //We may add more later.
   private static final ErasureCodingPolicy[] SYS_POLICIES =
-      new ErasureCodingPolicy[]{SYS_POLICY1, SYS_POLICY2};
+      new ErasureCodingPolicy[]{SYS_POLICY1, SYS_POLICY2, SYS_POLICY3};
 
   /**
    * All active policies maintained in NN memory for fast querying,

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

@@ -96,8 +96,10 @@ Deployment
 ### Configuration keys
 
   The codec implementation for Reed-Solomon and XOR can be configured with the following client and DataNode configuration keys:
-  `io.erasurecode.codec.rs.rawcoder` and `io.erasurecode.codec.xor.rawcoder`.
+  `io.erasurecode.codec.rs-default.rawcoder` for the default RS codec,
-  The default implementations for both of these codecs are pure Java.
+  `io.erasurecode.codec.rs-legacy.rawcoder` for the legacy RS codec,
+  `io.erasurecode.codec.xor.rawcoder` for the XOR codec.
+  The default implementations for all of these codecs are pure Java.
 
   Erasure coding background recovery work on the DataNodes can also be tuned via the following configuration parameters:
 

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

@@ -491,7 +491,8 @@ static void verifyParityBlocks(Configuration conf, final long size,
       }
     }
     final RawErasureEncoder encoder =
-        CodecUtil.createRSRawEncoder(conf, dataBytes.length, parityBytes.length);
+        CodecUtil.createRSRawEncoder(conf, dataBytes.length, parityBytes.length,
+            TEST_EC_POLICY.getCodecName());
     encoder.encode(dataBytes, expectedParityBytes);
     for (int i = 0; i < parityBytes.length; i++) {
       if (checkSet.contains(i + dataBytes.length)){

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

@@ -218,7 +218,7 @@ public void testPreadWithDNFailure() throws Exception {
     }
 
     RawErasureDecoder rawDecoder = CodecUtil.createRSRawDecoder(conf,
-        DATA_BLK_NUM, PARITY_BLK_NUM);
+        DATA_BLK_NUM, PARITY_BLK_NUM, ecPolicy.getCodecName());
 
     // Update the expected content for decoded data
     int[] missingBlkIdx = new int[PARITY_BLK_NUM];

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

@@ -109,7 +109,7 @@
       <description>setPolicy : set erasure coding policy on a directory to encode files</description>
       <test-commands>
         <command>-fs NAMENODE -mkdir /ecdir</command>
-        <ec-admin-command>-fs NAMENODE -setPolicy -p RS-6-3-64k /ecdir</ec-admin-command>
+        <ec-admin-command>-fs NAMENODE -setPolicy -p RS-DEFAULT-6-3-64k /ecdir</ec-admin-command>
       </test-commands>
       <cleanup-commands>
         <command>-fs NAMENODE -rmdir /ecdir</command>
@@ -179,7 +179,7 @@
       <description>getPolicy : get EC policy information at specified path, which doesn't have an EC policy</description>
       <test-commands>
         <command>-fs NAMENODE -mkdir /ecdir</command>
-        <ec-admin-command>-fs NAMENODE -setPolicy -p RS-6-3-64k /ecdir</ec-admin-command>
+        <ec-admin-command>-fs NAMENODE -setPolicy -p RS-DEFAULT-6-3-64k /ecdir</ec-admin-command>
         <ec-admin-command>-fs NAMENODE -getPolicy /ecdir</ec-admin-command>
       </test-commands>
       <cleanup-commands>
@@ -188,7 +188,7 @@
       <comparators>
         <comparator>
           <type>SubstringComparator</type>
-          <expected-output>ErasureCodingPolicy=[Name=RS-6-3-64k</expected-output>
+          <expected-output>ErasureCodingPolicy=[Name=RS-DEFAULT-6-3-64k</expected-output>
         </comparator>
       </comparators>
     </test>
@@ -197,7 +197,7 @@
       <description>getPolicy : get EC policy information at specified path, which doesn't have an EC policy</description>
       <test-commands>
         <command>-fs NAMENODE -mkdir /ecdir</command>
-        <ec-admin-command>-fs NAMENODE -setPolicy -p RS-6-3-64k /ecdir</ec-admin-command>
+        <ec-admin-command>-fs NAMENODE -setPolicy -p RS-DEFAULT-6-3-64k /ecdir</ec-admin-command>
         <command>-fs NAMENODE -touchz /ecdir/ecfile</command>
         <ec-admin-command>-fs NAMENODE -getPolicy /ecdir/ecfile</ec-admin-command>
       </test-commands>
@@ -208,7 +208,7 @@
       <comparators>
         <comparator>
           <type>SubstringComparator</type>
-          <expected-output>ErasureCodingPolicy=[Name=RS-6-3-64k</expected-output>
+          <expected-output>ErasureCodingPolicy=[Name=RS-DEFAULT-6-3-64k</expected-output>
         </comparator>
       </comparators>
     </test>
@@ -223,7 +223,7 @@
       <comparators>
         <comparator>
           <type>SubstringComparator</type>
-          <expected-output>RS-6-3</expected-output>
+          <expected-output>RS-DEFAULT-6-3</expected-output>
         </comparator>
       </comparators>
     </test>