HDFS-4296. Reserve layout version for release 1.2.0. Contributed by Suresh Srinivas.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1420700 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -20,6 +20,8 @@ Trunk (Unreleased)
     HDFS-3495. Update Balancer to support new NetworkTopology with NodeGroup.
     (Junping Du via szetszwo)
 
+    HDFS-4296. Reserve layout version for release 1.2.0. (suresh)
+
   IMPROVEMENTS
 
     HDFS-1620. Rename HdfsConstants -> HdfsServerConstants, FSConstants ->

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

@@ -82,10 +82,11 @@ public class LayoutVersion {
     EDITS_CHESKUM(-28, "Support checksum for editlog"),
     UNUSED(-29, "Skipped version"),
     FSIMAGE_NAME_OPTIMIZATION(-30, "Store only last part of path in fsimage"),
-    RESERVED_REL20_203(-31, -19, "Reserved for release 0.20.203"),
-    RESERVED_REL20_204(-32, "Reserved for release 0.20.204"),
-    RESERVED_REL22(-33, -27, "Reserved for release 0.22"),
-    RESERVED_REL23(-34, -30, "Reserved for release 0.23"),
+    RESERVED_REL20_203(-31, -19, "Reserved for release 0.20.203", true,
+        DELEGATION_TOKEN),
+    RESERVED_REL20_204(-32, -31, "Reserved for release 0.20.204", true),
+    RESERVED_REL22(-33, -27, "Reserved for release 0.22", true),
+    RESERVED_REL23(-34, -30, "Reserved for release 0.23", true),
     FEDERATION(-35, "Support for namenode federation"),
     LEASE_REASSIGNMENT(-36, "Support for persisting lease holder reassignment"),
     STORED_TXIDS(-37, "Transaction IDs are stored in edits log and image files"),
@@ -94,33 +95,40 @@ public class LayoutVersion {
         "Use LongWritable and ShortWritable directly instead of ArrayWritable of UTF8"),
     OPTIMIZE_PERSIST_BLOCKS(-40,
         "Serialize block lists with delta-encoded variable length ints, " +
-        "add OP_UPDATE_BLOCKS");
+        "add OP_UPDATE_BLOCKS"),
+    RESERVED_REL1_2_0(-41, -32, "Reserved for release 1.2.0", true, CONCAT);
     
     final int lv;
     final int ancestorLV;
     final String description;
+    final boolean reserved;
+    final Feature[] specialFeatures;
     
     /**
-     * Feature that is added at {@code currentLV}. 
+     * Feature that is added at layout version {@code lv} - 1. 
      * @param lv new layout version with the addition of this feature
      * @param description description of the feature
      */
     Feature(final int lv, final String description) {
-      this(lv, lv + 1, description);
+      this(lv, lv + 1, description, false);
     }
 
     /**
-     * Feature that is added at {@code currentLV}.
+     * Feature that is added at layout version {@code ancestoryLV}.
      * @param lv new layout version with the addition of this feature
-     * @param ancestorLV layout version from which the new lv is derived
-     *          from.
+     * @param ancestorLV layout version from which the new lv is derived from.
      * @param description description of the feature
+     * @param reserved true when this is a layout version reserved for previous
+     *          verions
+     * @param features set of features that are to be enabled for this version
      */
-    Feature(final int lv, final int ancestorLV,
-        final String description) {
+    Feature(final int lv, final int ancestorLV, final String description,
+        boolean reserved, Feature... features) {
       this.lv = lv;
       this.ancestorLV = ancestorLV;
       this.description = description;
+      this.reserved = reserved;
+      specialFeatures = features;
     }
     
     /** 
@@ -146,6 +154,10 @@ public class LayoutVersion {
     public String getDescription() {
       return description;
     }
+    
+    public boolean isReservedForOldRelease() {
+      return reserved;
+    }
   }
   
   // Build layout version and corresponding feature matrix
@@ -171,19 +183,14 @@ public class LayoutVersion {
         map.put(f.ancestorLV, ancestorSet);
       }
       EnumSet<Feature> featureSet = EnumSet.copyOf(ancestorSet);
+      if (f.specialFeatures != null) {
+        for (Feature specialFeature : f.specialFeatures) {
+          featureSet.add(specialFeature);
+        }
+      }
       featureSet.add(f);
       map.put(f.lv, featureSet);
     }
-    
-    // Special initialization for 0.20.203 and 0.20.204
-    // to add Feature#DELEGATION_TOKEN
-    specialInit(Feature.RESERVED_REL20_203.lv, Feature.DELEGATION_TOKEN);
-    specialInit(Feature.RESERVED_REL20_204.lv, Feature.DELEGATION_TOKEN);
-  }
-  
-  private static void specialInit(int lv, Feature f) {
-    EnumSet<Feature> set = map.get(lv);
-    set.add(f);
   }
   
   /**
@@ -222,6 +229,11 @@ public class LayoutVersion {
    */
   public static int getCurrentLayoutVersion() {
     Feature[] values = Feature.values();
-    return values[values.length - 1].lv;
+    for (int i = values.length -1; i >= 0; i--) {
+      if (!values[i].isReservedForOldRelease()) {
+        return values[i].lv;
+      }
+    }
+    throw new AssertionError("All layout versions are reserved.");
   }
 }

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/protocol/TestLayoutVersion.java

@@ -59,6 +59,15 @@ public class TestLayoutVersion {
         Feature.RESERVED_REL20_204.lv));
   }
   
+  /**
+   * Test to make sure release 1.2.0 support CONCAT
+   */
+  @Test
+  public void testRelease1_2_0() {
+    assertTrue(LayoutVersion.supports(Feature.CONCAT, 
+        Feature.RESERVED_REL1_2_0.lv));
+  }
+  
   /**
    * Given feature {@code f}, ensures the layout version of that feature
    * supports all the features supported by it's ancestor.
@@ -69,7 +78,9 @@ public class TestLayoutVersion {
     EnumSet<Feature> ancestorSet = LayoutVersion.map.get(ancestorLV);
     assertNotNull(ancestorSet);
     for (Feature  feature : ancestorSet) {
-      assertTrue(LayoutVersion.supports(feature, lv));
+      assertTrue("LV " + lv + " does nto support " + feature
+          + " supported by the ancestor LV " + f.ancestorLV,
+          LayoutVersion.supports(feature, lv));
     }
   }
 }