Optimize conversion to a cacheable DocIdSet

Author: imotov

src/main/java/org/elasticsearch/common/lucene/docset/DocIdSets.java

@@ -82,7 +82,12 @@ public static DocIdSet toCacheable(AtomicReader reader, @Nullable DocIdSet set)
  if (set instanceof FixedBitSet) {
  return set;
  }
- return toFixedBitSet(set.iterator(), reader.maxDoc());
+ FixedBitSet fixedBitSet = new FixedBitSet(reader.maxDoc());
+ do {
+ fixedBitSet.set(doc);
+ doc = it.nextDoc();
+ } while (doc != DocIdSetIterator.NO_MORE_DOCS);
+ return fixedBitSet;
  }
 
  /**
@@ -100,16 +105,16 @@ public static Bits toSafeBits(AtomicReader reader, @Nullable DocIdSet set) throw
  if (iterator == null) {
  return new Bits.MatchNoBits(reader.maxDoc());
  }
- return new FixedBitSet(toFixedBitSet(iterator, reader.maxDoc()));
+ return toFixedBitSet(iterator, reader.maxDoc());
  }
 
  /**
  * Creates a {@link FixedBitSet} from an iterator.
  */
- public static FixedBitSet toFixedBitSet(DocIdSetIterator iteartor, int numBits) throws IOException {
+ public static FixedBitSet toFixedBitSet(DocIdSetIterator iterator, int numBits) throws IOException {
  FixedBitSet set = new FixedBitSet(numBits);
  int doc;
- while ((doc = iteartor.nextDoc()) != DocIdSetIterator.NO_MORE_DOCS) {
+ while ((doc = iterator.nextDoc()) != DocIdSetIterator.NO_MORE_DOCS) {
  set.set(doc);
  }
  return set;