Fix bug in clustering key read (block header shift)

Author: Nitsan Wakart

src/java/org/apache/cassandra/io/sstable/SSTableCursorReader.java

@@ -543,11 +543,8 @@ static void readUnfilteredClustering(RandomAccessReader dataReader, AbstractType
                 clusteringBlockHeader = dataReader.readUnsignedVInt();
                 clustering.writeUnsignedVInt(clusteringBlockHeader);
             }
-            clusteringBlockHeader = clusteringBlockHeader >>> 2;
-            // struct clustering_block {
-            //    varint clustering_block_header;
-            //    simple_cell[] clustering_cells;
-            // };
+
+            // load value if present
             if ((clusteringBlockHeader & 0b11) == 0)
             {
                 AbstractType<?> type = types[clusteringIndex];
@@ -566,6 +563,7 @@ static void readUnfilteredClustering(RandomAccessReader dataReader, AbstractType
                     clustering.loadPart(dataReader, varLength);
                 }
             }
+            clusteringBlockHeader = clusteringBlockHeader >>> 2;
         }
         if (fixedLengthClusteringLength != 0) clustering.loadPart(dataReader, fixedLengthClusteringLength);
     }
@@ -583,17 +581,14 @@ private static void skipClustering(RandomAccessReader dataReader, AbstractType<?
             {
                 clusteringBlockHeader = dataReader.readUnsignedVInt();
             }
-            clusteringBlockHeader = clusteringBlockHeader >>> 2;
-            // struct clustering_block {
-            //    varint clustering_block_header;
-            //    simple_cell[] clustering_cells;
-            // };
+            // skip value if present
             if ((clusteringBlockHeader & 0b11) == 0)
             {
                 AbstractType<?> type = types[clusteringIndex];
                 int len = type.isValueLengthFixed() ? type.valueLengthIfFixed() : dataReader.readUnsignedVInt32();
                 dataReader.skipBytes(len);
             }
+            clusteringBlockHeader = clusteringBlockHeader >>> 2;
         }
     }