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UpgradeIndexMergePolicy.cs
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UpgradeIndexMergePolicy.cs
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using System;
using System.Collections.Generic;
namespace Lucene.Net.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.
*/
using Constants = Lucene.Net.Util.Constants;
/// <summary>
/// This <see cref="MergePolicy"/> is used for upgrading all existing segments of
/// an index when calling <see cref="IndexWriter.ForceMerge(int)"/>.
/// All other methods delegate to the base <see cref="MergePolicy"/> given to the constructor.
/// This allows for an as-cheap-as possible upgrade of an older index by only upgrading segments that
/// are created by previous Lucene versions. ForceMerge does no longer really merge;
/// it is just used to "ForceMerge" older segment versions away.
/// <para/>In general one would use <see cref="IndexUpgrader"/>, but for a fully customizeable upgrade,
/// you can use this like any other <see cref="MergePolicy"/> and call <see cref="IndexWriter.ForceMerge(int)"/>:
/// <code>
/// IndexWriterConfig iwc = new IndexWriterConfig(LuceneVersion.LUCENE_XX, new KeywordAnalyzer());
/// iwc.MergePolicy = new UpgradeIndexMergePolicy(iwc.MergePolicy);
/// using (IndexWriter w = new IndexWriter(dir, iwc))
/// {
/// w.ForceMerge(1);
/// }
/// </code>
/// <para/><b>Warning:</b> this merge policy may reorder documents if the index was partially
/// upgraded before calling <see cref="IndexWriter.ForceMerge(int)"/> (e.g., documents were added). If your application relies
/// on "monotonicity" of doc IDs (which means that the order in which the documents
/// were added to the index is preserved), do a <c>ForceMerge(1)</c> instead. Please note, the
/// delegate <see cref="MergePolicy"/> may also reorder documents.
/// <para/>
/// @lucene.experimental
/// </summary>
/// <seealso cref="IndexUpgrader"/>
public class UpgradeIndexMergePolicy : MergePolicy
{
/// <summary>
/// Wrapped <see cref="MergePolicy"/>. </summary>
protected readonly MergePolicy m_base;
/// <summary>
/// Wrap the given <see cref="MergePolicy"/> and intercept <see cref="IndexWriter.ForceMerge(int)"/> requests to
/// only upgrade segments written with previous Lucene versions.
/// </summary>
public UpgradeIndexMergePolicy(MergePolicy @base)
{
this.m_base = @base;
}
/// <summary>
/// Returns <c>true</c> if the given segment should be upgraded. The default implementation
/// will return <c>!Constants.LUCENE_MAIN_VERSION.Equals(si.Info.Version, StringComparison.Ordinal)</c>,
/// so all segments created with a different version number than this Lucene version will
/// get upgraded.
/// </summary>
protected virtual bool ShouldUpgradeSegment(SegmentCommitInfo si)
{
return !Constants.LUCENE_MAIN_VERSION.Equals(si.Info.Version, StringComparison.Ordinal);
}
public override void SetIndexWriter(IndexWriter writer)
{
base.SetIndexWriter(writer);
m_base.SetIndexWriter(writer);
}
public override MergeSpecification FindMerges(MergeTrigger mergeTrigger, SegmentInfos segmentInfos)
{
// LUCENENET specific - just use min value to indicate "null" for merge trigger
return m_base.FindMerges((MergeTrigger)int.MinValue, segmentInfos);
}
public override MergeSpecification FindForcedMerges(SegmentInfos segmentInfos, int maxSegmentCount, IDictionary<SegmentCommitInfo, bool?> segmentsToMerge)
{
// first find all old segments
IDictionary<SegmentCommitInfo, bool?> oldSegments = new Dictionary<SegmentCommitInfo, bool?>();
foreach (SegmentCommitInfo si in segmentInfos.Segments)
{
bool? v = segmentsToMerge[si];
if (v != null && ShouldUpgradeSegment(si))
{
oldSegments[si] = v;
}
}
if (Verbose())
{
Message("findForcedMerges: segmentsToUpgrade=" + oldSegments);
}
if (oldSegments.Count == 0)
{
return null;
}
MergeSpecification spec = m_base.FindForcedMerges(segmentInfos, maxSegmentCount, oldSegments);
if (spec != null)
{
// remove all segments that are in merge specification from oldSegments,
// the resulting set contains all segments that are left over
// and will be merged to one additional segment:
foreach (OneMerge om in spec.Merges)
{
foreach (SegmentCommitInfo sipc in om.Segments)
{
oldSegments.Remove(sipc);
}
}
}
if (oldSegments.Count > 0)
{
if (Verbose())
{
Message("findForcedMerges: " + m_base.GetType().Name + " does not want to merge all old segments, merge remaining ones into new segment: " + oldSegments);
}
IList<SegmentCommitInfo> newInfos = new List<SegmentCommitInfo>();
foreach (SegmentCommitInfo si in segmentInfos.Segments)
{
if (oldSegments.ContainsKey(si))
{
newInfos.Add(si);
}
}
// add the final merge
if (spec == null)
{
spec = new MergeSpecification();
}
spec.Add(new OneMerge(newInfos));
}
return spec;
}
public override MergeSpecification FindForcedDeletesMerges(SegmentInfos segmentInfos)
{
return m_base.FindForcedDeletesMerges(segmentInfos);
}
public override bool UseCompoundFile(SegmentInfos segments, SegmentCommitInfo newSegment)
{
return m_base.UseCompoundFile(segments, newSegment);
}
protected override void Dispose(bool disposing)
{
if (disposing)
{
m_base.Dispose();
}
}
public override string ToString()
{
return "[" + this.GetType().Name + "->" + m_base + "]";
}
private bool Verbose()
{
IndexWriter w = m_writer.Get();
return w != null && w.infoStream.IsEnabled("UPGMP");
}
private void Message(string message)
{
m_writer.Get().infoStream.Message("UPGMP", message);
}
}
}