Nits

src/java/org/apache/cassandra/db/compaction/CompactionManager.java

@@ -919,9 +919,6 @@ public UnfilteredRowIterator cleanup(UnfilteredRowIterator partition)
 
                 cfs.invalidateCachedPartition(partition.partitionKey());
 
-                // we need to acquire memtable lock because secondary index deletion may
-                // cause a race (see CASSANDRA-3712). This is done internally by the
-                // index manager (see newCleanupTransaction())
                 cfs.indexManager.deletePartition(partition, nowInSec);
                 return null;
             }

src/java/org/apache/cassandra/db/partitions/AtomicBTreePartition.java

@@ -86,7 +86,7 @@ public class AtomicBTreePartition extends AbstractBTreePartition
 
     public AtomicBTreePartition(CFMetaData metadata, DecoratedKey partitionKey, MemtableAllocator allocator)
     {
-        // TODO: is this a potential bug? partition columns may be a subset if we alter columns while it's in memtable
+        // involved in potential bug? partition columns may be a subset if we alter columns while it's in memtable
         super(metadata, partitionKey, metadata.partitionColumns());
         this.allocator = allocator;
         this.ref = EMPTY;
@@ -149,7 +149,6 @@ public long[] addAllWithSizeDelta(final PartitionUpdate update, OpOrder.Group wr
                     deletionInfo = current.deletionInfo;
                 }
 
-                // todo static rows? anything more to do for indexing
                 Row newStatic = update.staticRow();
                 Row staticRow = newStatic.isEmpty()
                               ? current.staticRow

src/java/org/apache/cassandra/index/Index.java

@@ -27,10 +27,10 @@
  * The main interface defines methods for index management, index selection at both write and query time,
  * as well as validation of values that will ultimately be indexed.
  * Two sub-interfaces are also defined, which represent single use helpers for short lived tasks at read and write time.
- * Indexer: an event listener which receives notifications at particular points duing an update of a single partition
+ * Indexer: an event listener which receives notifications at particular points during an update of a single partition
  * in the base table.
- * IndexSearcher: perform queries against the index based on a predicate defined in a RowFilter.Expression. An instance
- * is expected to be single use, being used by the execution of a single ReadCommand.
+ * Searcher: performs queries against the index based on a predicate defined in a RowFilter. An instance
+ * is expected to be single use, being involved in the execution of a single ReadCommand.
  *
  * The main interface includes factory methods for obtaining instances of both of the sub-interfaces;
  *
@@ -281,21 +281,21 @@ public interface Indexer
          * Notification of the start of a partition update.
          * This event always occurs before any other during the update.
          */
-        default void begin(){}
+        public void begin();
 
         /**
          * Notification of a top level partition delete.
          * @param deletionTime
          */
-        default void partitionDelete(DeletionTime deletionTime){}
+        public void partitionDelete(DeletionTime deletionTime);
 
         /**
          * Notification of a RangeTombstone.
          * An update of a single partition may contain multiple RangeTombstones,
          * and a notification will be passed for each of them.
          * @param tombstone
          */
-        default void rangeTombstone(RangeTombstone tombstone){}
+        public void rangeTombstone(RangeTombstone tombstone);
 
         /**
          * Notification that a new row was inserted into the Memtable holding the partition.
@@ -305,7 +305,7 @@ default void rangeTombstone(RangeTombstone tombstone){}
          *
          * @param row the Row being inserted into the base table's Memtable.
          */
-        default void insertRow(Row row){}
+        public void insertRow(Row row);
 
         /**
          * Notification of a modification to a row in the base table's Memtable.
@@ -326,7 +326,7 @@ default void insertRow(Row row){}
          * @param newRowData data that was not present in the existing row and is being inserted
          *                   into the base table's Memtable
          */
-        default void updateRow(Row oldRowData, Row newRowData){}
+        public void updateRow(Row oldRowData, Row newRowData);
 
         /**
          * Notification that a row was removed from the partition.
@@ -342,18 +342,15 @@ default void updateRow(Row oldRowData, Row newRowData){}
          * have been deleted, so implementations which index primary key columns should not
          * purge those entries from their indexes.
          *
-         * Row deletions via the normal write path do not trigger calls to this method as
-         * they are processed as RangeTombstones.
-         *
          * @param row data being removed from the base table
          */
-        default void removeRow(Row row){}
+        public void removeRow(Row row);
 
         /**
          * Notification of the end of the partition update.
          * This event always occurs after all others for the particular update.
          */
-        default void finish(){}
+        public void finish();
     }
 
     /*
@@ -370,16 +367,16 @@ default void finish(){}
      * transformed in this way but this may change over time as usage is generalized.
      * See CASSANDRA-8717 for further discussion.
      *
-     * The function should takes a PartitionIterator of the results from the replicas which has already been collated
+     * The function takes a PartitionIterator of the results from the replicas which has already been collated
      * & reconciled, along with the command being executed. It returns another PartitionIterator containing the results
-     * of the transformation.
+     * of the transformation (which may be the same as the input if the transformation is a no-op).
      */
     public BiFunction<PartitionIterator, ReadCommand, PartitionIterator> postProcessorFor(ReadCommand command);
 
     /**
      * Factory method for query time search helper.
      * @param command the read command being executed
-     * @return an Optional<IndexSearcher> which should be empty if this index cannot satisfy the
+     * @return an Searcher with which to perform the supplied command
      */
     public Searcher searcherFor(ReadCommand command);
 

src/java/org/apache/cassandra/index/SecondaryIndexManager.java

@@ -428,6 +428,9 @@ public void indexPartition(UnfilteredRowIterator partition, OpOrder.Group opGrou
      */
     public void deletePartition(UnfilteredRowIterator partition, int nowInSec)
     {
+        // we need to acquire memtable lock because secondary index deletion may
+        // cause a race (see CASSANDRA-3712). This is done internally by the
+        // index transaction when it commits
         CleanupTransaction indexTransaction = newCleanupTransaction(partition.partitionKey(),
                                                                     partition.columns(),
                                                                     nowInSec);

src/java/org/apache/cassandra/index/internal/CassandraIndex.java

@@ -196,6 +196,18 @@ public Indexer indexerFor(final DecoratedKey key,
     {
         return new Indexer()
         {
+            public void begin()
+            {
+            }
+
+            public void partitionDelete(DeletionTime deletionTime)
+            {
+            }
+
+            public void rangeTombstone(RangeTombstone tombstone)
+            {
+            }
+
             public void insertRow(Row row)
             {
                 if (isPrimaryKeyIndex())
@@ -224,6 +236,7 @@ public void removeRow(Row row)
                     removeCell(row.clustering(), row.getCell(metadata.indexedColumn));
             }
 
+
             public void updateRow(Row oldRow, Row newRow)
             {
                 if (isPrimaryKeyIndex())
@@ -243,6 +256,10 @@ public void updateRow(Row oldRow, Row newRow)
                 }
             }
 
+            public void finish()
+            {
+            }
+
             private void indexCells(Clustering clustering, Iterable<Cell> cells)
             {
                 if (cells == null)

test/unit/org/apache/cassandra/index/StubIndex.java

@@ -82,6 +82,18 @@ public Indexer indexerFor(DecoratedKey key,
     {
         return new Indexer()
         {
+            public void begin()
+            {
+            }
+
+            public void partitionDelete(DeletionTime deletionTime)
+            {
+            }
+
+            public void rangeTombstone(RangeTombstone tombstone)
+            {
+            }
+
             public void insertRow(Row row)
             {
                 rowsInserted.add(row);
@@ -96,6 +108,10 @@ public void updateRow(Row oldRowData, Row newRowData)
             {
                 rowsUpdated.add(Pair.create(oldRowData, newRowData));
             }
+
+            public void finish()
+            {
+            }
         };
     }