public virtual ICollection <SearchGroup <T> > Merge(IList <IEnumerable <ISearchGroup <T> > > shards, int offset, int topN)
{
int maxQueueSize = offset + topN;
//System.out.println("merge");
// Init queue:
for (int shardIDX = 0; shardIDX < shards.Count; shardIDX++)
{
IEnumerable <ISearchGroup <T> > shard = shards[shardIDX];
if (shard.Any())
{
//System.out.println(" insert shard=" + shardIDX);
UpdateNextGroup(maxQueueSize, new ShardIter <T>(shard, shardIDX));
}
}
// Pull merged topN groups:
List <SearchGroup <T> > newTopGroups = new List <SearchGroup <T> >();
int count = 0;
while (queue.Count != 0)
{
MergedGroup <T> group = queue.First();
queue.Remove(group);
group.IsProcessed = true;
//System.out.println(" pop: shards=" + group.shards + " group=" + (group.groupValue == null ? "null" : (((BytesRef) group.groupValue).utf8ToString())) + " sortValues=" + Arrays.toString(group.topValues));
if (count++ >= offset)
{
SearchGroup <T> newGroup = new SearchGroup <T>();
newGroup.GroupValue = group.GroupValue;
newGroup.SortValues = group.TopValues;
newTopGroups.Add(newGroup);
if (newTopGroups.Count == topN)
{
break;
}
//} else {
// System.out.println(" skip < offset");
}
// Advance all iters in this group:
foreach (ShardIter <T> shardIter in group.Shards)
{
UpdateNextGroup(maxQueueSize, shardIter);
}
}
if (newTopGroups.Count == 0)
{
return(null);
}
else
{
return(newTopGroups);
}
}