package org.apache.lucene.index;
/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/** Remaps docIDs after a merge has completed, where the
* merged segments had at least one deletion. This is used
* to renumber the buffered deletes in IndexWriter when a
* merge of segments with deletions commits. */
final class MergeDocIDRemapper {
int[] starts; // used for binary search of mapped docID
int[] newStarts; // starts, minus the deletes
int[][] docMaps; // maps docIDs in the merged set
int minDocID; // minimum docID that needs renumbering
int maxDocID; // 1+ the max docID that needs renumbering
int docShift; // total # deleted docs that were compacted by this merge
public MergeDocIDRemapper(SegmentInfos infos, int[][] docMaps, int[] delCounts, MergePolicy.OneMerge merge, int mergedDocCount) {
this.docMaps = docMaps;
SegmentInfo firstSegment = merge.segments.info(0);
int i = 0;
while(true) {
SegmentInfo info = infos.info(i);
if (info.equals(firstSegment))
break;
minDocID += info.docCount;
i++;
}
int numDocs = 0;
for(int j=0;j<docMaps.length;i++,j++) {
numDocs += infos.info(i).docCount;
assert infos.info(i).equals(merge.segments.info(j));
}
maxDocID = minDocID + numDocs;
starts = new int[docMaps.length];
newStarts = new int[docMaps.length];
starts[0] = minDocID;
newStarts[0] = minDocID;
for(i=1;i<docMaps.length;i++) {
final int lastDocCount = merge.segments.info(i-1).docCount;
starts[i] = starts[i-1] + lastDocCount;
newStarts[i] = newStarts[i-1] + lastDocCount - delCounts[i-1];
}
docShift = numDocs - mergedDocCount;
// There are rare cases when docShift is 0. It happens
// if you try to delete a docID that's out of bounds,
// because the SegmentReader still allocates deletedDocs
// and pretends it has deletions ... so we can't make
// this assert here
// assert docShift > 0;
// Make sure it all adds up:
assert docShift == maxDocID - (newStarts[docMaps.length-1] + merge.segments.info(docMaps.length-1).docCount - delCounts[docMaps.length-1]);
}
public int remap(int oldDocID) {
if (oldDocID < minDocID)
// Unaffected by merge
return oldDocID;
else if (oldDocID >= maxDocID)
// This doc was "after" the merge, so simple shift
return oldDocID - docShift;
else {
// Binary search to locate this document & find its new docID
int lo = 0; // search starts array
int hi = docMaps.length - 1; // for first element less
while (hi >= lo) {
int mid = (lo + hi) >>> 1;
int midValue = starts[mid];
if (oldDocID < midValue)
hi = mid - 1;
else if (oldDocID > midValue)
lo = mid + 1;
else { // found a match
while (mid+1 < docMaps.length && starts[mid+1] == midValue) {
mid++; // scan to last match
}
if (docMaps[mid] != null)
return newStarts[mid] + docMaps[mid][oldDocID-starts[mid]];
else
return newStarts[mid] + oldDocID-starts[mid];
}
}
if (docMaps[hi] != null)
return newStarts[hi] + docMaps[hi][oldDocID-starts[hi]];
else
return newStarts[hi] + oldDocID-starts[hi];
}
}
}