LogDocMergePolicy.cs

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/* 
 * 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 System;

namespace Lucene.Net.Index
{
    
    /// <summary>This is a <see cref="LogMergePolicy" /> that measures size of a
    /// segment as the number of documents (not taking deletions
    /// into account). 
    /// </summary>
    
    public class LogDocMergePolicy : LogMergePolicy
    {
        
        /// <seealso cref="MinMergeDocs">
        /// </seealso>
        public const int DEFAULT_MIN_MERGE_DOCS = 1000;
        
        public LogDocMergePolicy(IndexWriter writer):base(writer)
        {
            minMergeSize = DEFAULT_MIN_MERGE_DOCS;
            
            // maxMergeSize is never used by LogDocMergePolicy; set
            // it to Long.MAX_VALUE to disable it
            maxMergeSize = System.Int64.MaxValue;
        }
        protected internal override long Size(SegmentInfo info)
        {
            return SizeDocs(info);
        }

        protected override void Dispose(bool disposing)
        {
            // Do nothing.
        }

        /// <summary>Gets or sets the minimum size for the lowest level segments.
        /// Any segments below this size are considered to be on
        /// the same level (even if they vary drastically in size)
        /// and will be merged whenever there are mergeFactor of
        /// them.  This effectively truncates the "long tail" of
        /// small segments that would otherwise be created into a
        /// single level.  If you set this too large, it could
        /// greatly increase the merging cost during indexing (if
        /// you flush many small segments). 
        /// </summary>
        public virtual int MinMergeDocs
        {
            get { return (int) minMergeSize; }
            set { minMergeSize = value; }
        }
    }
}