HADOOP-11658. Externalize io.compression.codecs property. Contributed by Kai Zheng.

(cherry picked from commit 0650e1c56f2d87ca9bdc51d7d4678895f494464a)

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

@@ -224,6 +224,9 @@ Release 2.7.0 - UNRELEASED
     HADOOP-10976. moving the source code of hadoop-tools docs to the
     directory under hadoop-tools (Masatake Iwasaki via aw)
 
+    HADOOP-11658. Externalize io.compression.codecs property.
+    (Kai Zheng via aajisaka)
+
   OPTIMIZATIONS
 
     HADOOP-11323. WritableComparator#compare keeps reference to byte array.

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

@@ -91,17 +91,24 @@ public class CommonConfigurationKeys extends CommonConfigurationKeysPublic {
   public static final String IPC_CALLQUEUE_IMPL_KEY = "callqueue.impl";
   public static final String IPC_CALLQUEUE_IDENTITY_PROVIDER_KEY = "identity-provider.impl";
 
+  /** This is for specifying the implementation for the mappings from
+   * hostnames to the racks they belong to
+   */
+  public static final String  NET_TOPOLOGY_CONFIGURED_NODE_MAPPING_KEY =
+      "net.topology.configured.node.mapping";
+
+  /**
+   * Supported compression codec classes
+   */
+  public static final String IO_COMPRESSION_CODECS_KEY = "io.compression.codecs";
+
   /** Internal buffer size for Lzo compressor/decompressors */
   public static final String  IO_COMPRESSION_CODEC_LZO_BUFFERSIZE_KEY =
     "io.compression.codec.lzo.buffersize";
+
   /** Default value for IO_COMPRESSION_CODEC_LZO_BUFFERSIZE_KEY */
   public static final int     IO_COMPRESSION_CODEC_LZO_BUFFERSIZE_DEFAULT =
     64*1024;
-  /** This is for specifying the implementation for the mappings from
-   * hostnames to the racks they belong to
-   */
-  public static final String  NET_TOPOLOGY_CONFIGURED_NODE_MAPPING_KEY =
-    "net.topology.configured.node.mapping";
 
   /** Internal buffer size for Snappy compressor/decompressors */
   public static final String IO_COMPRESSION_CODEC_SNAPPY_BUFFERSIZE_KEY =

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/compress/CompressionCodecFactory.java

@@ -24,6 +24,7 @@ import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.classification.InterfaceStability;
 import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.CommonConfigurationKeys;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.util.ReflectionUtils;
 
@@ -106,7 +107,8 @@ public class CompressionCodecFactory {
    * @param conf the configuration to look in
    * @return a list of the {@link CompressionCodec} classes
    */
-  public static List<Class<? extends CompressionCodec>> getCodecClasses(Configuration conf) {
+  public static List<Class<? extends CompressionCodec>> getCodecClasses(
+      Configuration conf) {
     List<Class<? extends CompressionCodec>> result
       = new ArrayList<Class<? extends CompressionCodec>>();
     // Add codec classes discovered via service loading
@@ -118,7 +120,8 @@ public class CompressionCodecFactory {
       }
     }
     // Add codec classes from configuration
-    String codecsString = conf.get("io.compression.codecs");
+    String codecsString = conf.get(
+        CommonConfigurationKeys.IO_COMPRESSION_CODECS_KEY);
     if (codecsString != null) {
       StringTokenizer codecSplit = new StringTokenizer(codecsString, ",");
       while (codecSplit.hasMoreElements()) {
@@ -161,7 +164,7 @@ public class CompressionCodecFactory {
         buf.append(itr.next().getName());
       }
     }
-    conf.set("io.compression.codecs", buf.toString());   
+    conf.set(CommonConfigurationKeys.IO_COMPRESSION_CODECS_KEY, buf.toString());
   }
   
   /**
@@ -172,7 +175,8 @@ public class CompressionCodecFactory {
     codecs = new TreeMap<String, CompressionCodec>();
     codecsByClassName = new HashMap<String, CompressionCodec>();
     codecsByName = new HashMap<String, CompressionCodec>();
-    List<Class<? extends CompressionCodec>> codecClasses = getCodecClasses(conf);
+    List<Class<? extends CompressionCodec>> codecClasses =
+        getCodecClasses(conf);
     if (codecClasses == null || codecClasses.isEmpty()) {
       addCodec(new GzipCodec());
       addCodec(new DefaultCodec());      
@@ -193,7 +197,8 @@ public class CompressionCodecFactory {
     CompressionCodec result = null;
     if (codecs != null) {
       String filename = file.getName();
-      String reversedFilename = new StringBuilder(filename).reverse().toString();
+      String reversedFilename =
+          new StringBuilder(filename).reverse().toString();
       SortedMap<String, CompressionCodec> subMap = 
         codecs.headMap(reversedFilename);
       if (!subMap.isEmpty()) {
@@ -239,7 +244,8 @@ public class CompressionCodecFactory {
       }
       CompressionCodec codec = getCodecByClassName(codecName);
       if (codec == null) {
-        // trying to get the codec by name in case the name was specified instead a class
+        // trying to get the codec by name in case the name was specified
+        // instead a class
         codec = codecsByName.get(codecName.toLowerCase());
       }
       return codec;
@@ -260,7 +266,8 @@ public class CompressionCodecFactory {
      * @param codecName the canonical class name of the codec
      * @return the codec class
      */
-    public Class<? extends CompressionCodec> getCodecClassByName(String codecName) {
+    public Class<? extends CompressionCodec> getCodecClassByName(
+        String codecName) {
       CompressionCodec codec = getCodecByName(codecName);
       if (codec == null) {
         return null;

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/io/compress/TestCodecFactory.java

@@ -24,6 +24,7 @@ import java.io.OutputStream;
 import java.util.*;
 
 import junit.framework.TestCase;
+import org.apache.hadoop.fs.CommonConfigurationKeys;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.conf.Configuration;
 
@@ -258,7 +259,7 @@ public class TestCodecFactory extends TestCase {
     checkCodec("overridden factory for gzip codec", NewGzipCodec.class, codec);
     
     Configuration conf = new Configuration();
-    conf.set("io.compression.codecs", 
+    conf.set(CommonConfigurationKeys.IO_COMPRESSION_CODECS_KEY,
         "   org.apache.hadoop.io.compress.GzipCodec   , " +
         "    org.apache.hadoop.io.compress.DefaultCodec  , " +
         " org.apache.hadoop.io.compress.BZip2Codec   ");