/// <summary>Carefully merges deletes for the segments we just
/// merged. This is tricky because, although merging will
/// clear all deletes (compacts the documents), new
/// deletes may have been flushed to the segments since
/// the merge was started. This method "carries over"
/// such new deletes onto the newly merged segment, and
/// saves the resulting deletes file (incrementing the
/// delete generation for merge.info). If no deletes were
/// flushed, no new deletes file is saved.
/// </summary>
private void CommitMergedDeletes(MergePolicy.OneMerge merge, SegmentReader mergeReader)
{
lock (this)
{
System.Diagnostics.Debug.Assert(TestPoint("startCommitMergeDeletes"));
SegmentInfos sourceSegments = merge.segments;
if (infoStream != null)
Message("commitMergeDeletes " + merge.SegString(directory));
// Carefully merge deletes that occurred after we
// started merging:
int docUpto = 0;
int delCount = 0;
for (int i = 0; i < sourceSegments.Count; i++)
{
SegmentInfo info = sourceSegments.Info(i);
int docCount = info.docCount;
SegmentReader previousReader = merge.readersClone[i];
SegmentReader currentReader = merge.readers[i];
if (previousReader.HasDeletions())
{
// There were deletes on this segment when the merge
// started. The merge has collapsed away those
// deletes, but, if new deletes were flushed since
// the merge started, we must now carefully keep any
// newly flushed deletes but mapping them to the new
// docIDs.
if (currentReader.NumDeletedDocs() > previousReader.NumDeletedDocs())
{
// This means this segment has had new deletes
// committed since we started the merge, so we
// must merge them:
for (int j = 0; j < docCount; j++)
{
if (previousReader.IsDeleted(j))
{
System.Diagnostics.Debug.Assert(currentReader.IsDeleted(j));
}
else
{
if (currentReader.IsDeleted(j))
{
mergeReader.DoDelete(docUpto);
delCount++;
}
docUpto++;
}
}
}
else
{
docUpto += docCount - previousReader.NumDeletedDocs();
}
}
else if (currentReader.HasDeletions())
{
// This segment had no deletes before but now it
// does:
for (int j = 0; j < docCount; j++)
{
if (currentReader.IsDeleted(j))
{
mergeReader.DoDelete(docUpto);
delCount++;
}
docUpto++;
}
}
// No deletes before or after
else
docUpto += info.docCount;
}
System.Diagnostics.Debug.Assert(mergeReader.NumDeletedDocs() == delCount);
mergeReader.hasChanges = delCount > 0;
}
}
