org.apache.lucene.index.SegmentReadState.java Source code

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Here is the source code for org.apache.lucene.index.SegmentReadState.java

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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.
 */
package org.apache.lucene.index;

import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

import org.apache.lucene.codecs.PostingsFormat; // javadocs
import org.apache.lucene.codecs.perfield.PerFieldPostingsFormat; // javadocs
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.IOContext;

/**
 * Holder class for common parameters used during read.
 * @lucene.experimental
 */
public class SegmentReadState {
    /** {@link Directory} where this segment is read from. */
    public final Directory directory;

    /** {@link SegmentInfo} describing this segment. */
    public final SegmentInfo segmentInfo;

    /** {@link FieldInfos} describing all fields in this
     *  segment. */
    public final FieldInfos fieldInfos;

    /** {@link IOContext} to pass to {@link
     *  Directory#openInput(String,IOContext)}. */
    public final IOContext context;

    /** Unique suffix for any postings files read for this
     *  segment.  {@link PerFieldPostingsFormat} sets this for
     *  each of the postings formats it wraps.  If you create
     *  a new {@link PostingsFormat} then any files you
     *  write/read must be derived using this suffix (use
     *  {@link IndexFileNames#segmentFileName(String,String,String)}). */
    public final String segmentSuffix;

    /**
     * True iff this SegmentReadState is opened from an IndexWriter.
     */
    public final boolean openedFromWriter;

    /**
     * The reader attributes for this reader. This is used to configure low level options on the codec layer.
     * This attribute map is user supplied at reader creation time.
     */
    public final Map<String, String> readerAttributes;

    /** Create a {@code SegmentReadState}. */
    public SegmentReadState(Directory dir, SegmentInfo info, FieldInfos fieldInfos, boolean openedFromWriter,
            IOContext context, Map<String, String> readerAttributes) {
        this(dir, info, fieldInfos, openedFromWriter, context, "", readerAttributes);
    }

    /** Create a {@code SegmentReadState}. */
    public SegmentReadState(Directory dir, SegmentInfo info, FieldInfos fieldInfos, boolean openedFromWriter,
            IOContext context, String segmentSuffix, Map<String, String> readerAttributes) {
        this.directory = dir;
        this.segmentInfo = info;
        this.fieldInfos = fieldInfos;
        this.context = context;
        this.segmentSuffix = segmentSuffix;
        this.openedFromWriter = openedFromWriter;
        this.readerAttributes = Collections.unmodifiableMap(new HashMap<>(readerAttributes));
    }

    /** Create a {@code SegmentReadState}. */
    public SegmentReadState(SegmentReadState other, String newSegmentSuffix) {
        this.directory = other.directory;
        this.segmentInfo = other.segmentInfo;
        this.fieldInfos = other.fieldInfos;
        this.context = other.context;
        this.openedFromWriter = other.openedFromWriter;
        this.segmentSuffix = newSegmentSuffix;
        this.readerAttributes = other.readerAttributes;
    }
}