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Lucene example source code file (BufferedDeletes.java)

This example Lucene source code file (BufferedDeletes.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Lucene tags/keywords

atomicinteger, atomiclong, hashmap, integer, integer, iterable, iterable, iterator, iterator, map, max_int, max_int, string, util, verbose_deletes

The Lucene BufferedDeletes.java source code

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.
 */

import java.util.ArrayList;
import java.util.Iterator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.atomic.AtomicInteger;

import org.apache.lucene.search.Query;
import org.apache.lucene.util.RamUsageEstimator;
import org.apache.lucene.index.BufferedDeletesStream.QueryAndLimit;

/* Holds buffered deletes, by docID, term or query for a
 * single segment. This is used to hold buffered pending
 * deletes against the to-be-flushed segment.  Once the
 * deletes are pushed (on flush in DocumentsWriter), these
 * deletes are converted to a FrozenDeletes instance. */

// NOTE: we are sync'd by BufferedDeletes, ie, all access to
// instances of this class is via sync'd methods on
// BufferedDeletes
class BufferedDeletes {

  /* Rough logic: HashMap has an array[Entry] w/ varying
     load factor (say 2 * POINTER).  Entry is object w/ Term
     key, Integer val, int hash, Entry next
     (OBJ_HEADER + 3*POINTER + INT).  Term is object w/
     String field and String text (OBJ_HEADER + 2*POINTER).
     We don't count Term's field since it's interned.
     Term's text is String (OBJ_HEADER + 4*INT + POINTER +
     OBJ_HEADER + string.length*CHAR).  Integer is
     OBJ_HEADER + INT. */
  final static int BYTES_PER_DEL_TERM = 8*RamUsageEstimator.NUM_BYTES_OBJECT_REF + 5*RamUsageEstimator.NUM_BYTES_OBJECT_HEADER + 6*RamUsageEstimator.NUM_BYTES_INT;

  /* Rough logic: del docIDs are List<Integer>.  Say list
     allocates ~2X size (2*POINTER).  Integer is OBJ_HEADER
     + int */
  final static int BYTES_PER_DEL_DOCID = 2*RamUsageEstimator.NUM_BYTES_OBJECT_REF + RamUsageEstimator.NUM_BYTES_OBJECT_HEADER + RamUsageEstimator.NUM_BYTES_INT;

  /* Rough logic: HashMap has an array[Entry] w/ varying
     load factor (say 2 * POINTER).  Entry is object w/
     Query key, Integer val, int hash, Entry next
     (OBJ_HEADER + 3*POINTER + INT).  Query we often
     undercount (say 24 bytes).  Integer is OBJ_HEADER + INT. */
  final static int BYTES_PER_DEL_QUERY = 5*RamUsageEstimator.NUM_BYTES_OBJECT_REF + 2*RamUsageEstimator.NUM_BYTES_OBJECT_HEADER + 2*RamUsageEstimator.NUM_BYTES_INT + 24;

  final AtomicInteger numTermDeletes = new AtomicInteger();
  final Map<Term,Integer> terms;
  final Map<Query,Integer> queries = new HashMap();
  final List<Integer> docIDs = new ArrayList();

  public static final Integer MAX_INT = Integer.valueOf(Integer.MAX_VALUE);

  final AtomicLong bytesUsed = new AtomicLong();

  private final static boolean VERBOSE_DELETES = false;

  long gen;

  public BufferedDeletes(boolean sortTerms) {
    if (sortTerms) {
      terms = new TreeMap<Term,Integer>();
    } else {
      terms = new HashMap<Term,Integer>();
    }
  }

  @Override
  public String toString() {
    if (VERBOSE_DELETES) {
      return "gen=" + gen + " numTerms=" + numTermDeletes + ", terms=" + terms
        + ", queries=" + queries + ", docIDs=" + docIDs + ", bytesUsed="
        + bytesUsed;
    } else {
      String s = "gen=" + gen;
      if (numTermDeletes.get() != 0) {
        s += " " + numTermDeletes.get() + " deleted terms (unique count=" + terms.size() + ")";
      }
      if (queries.size() != 0) {
        s += " " + queries.size() + " deleted queries";
      }
      if (docIDs.size() != 0) {
        s += " " + docIDs.size() + " deleted docIDs";
      }
      if (bytesUsed.get() != 0) {
        s += " bytesUsed=" + bytesUsed.get();
      }

      return s;
    }
  }
  
  void update(BufferedDeletes in) {
    numTermDeletes.addAndGet(in.numTermDeletes.get());
    for (Map.Entry<Term,Integer> ent : in.terms.entrySet()) {
      final Term term = ent.getKey();
      if (!terms.containsKey(term)) {
        // only incr bytesUsed if this term wasn't already buffered:
        bytesUsed.addAndGet(BYTES_PER_DEL_TERM);
      }
      terms.put(term, MAX_INT);
    }

    for (Map.Entry<Query,Integer> ent : in.queries.entrySet()) {
      final Query query = ent.getKey();
      if (!queries.containsKey(query)) {
        // only incr bytesUsed if this query wasn't already buffered:
        bytesUsed.addAndGet(BYTES_PER_DEL_QUERY);
      }
      queries.put(query, MAX_INT);
    }

    // docIDs never move across segments and the docIDs
    // should already be cleared
  }

  void update(FrozenBufferedDeletes in) {
    numTermDeletes.addAndGet(in.numTermDeletes);
    for(Term term : in.terms) {
      if (!terms.containsKey(term)) {
        // only incr bytesUsed if this term wasn't already buffered:
        bytesUsed.addAndGet(BYTES_PER_DEL_TERM);
      }
      terms.put(term, MAX_INT);
    }

    for(int queryIdx=0;queryIdx<in.queries.length;queryIdx++) {
      final Query query = in.queries[queryIdx];
      if (!queries.containsKey(query)) {
        // only incr bytesUsed if this query wasn't already buffered:
        bytesUsed.addAndGet(BYTES_PER_DEL_QUERY);
      }
      queries.put(query, MAX_INT);
    }
  }

  public void addQuery(Query query, int docIDUpto) {
    Integer current = queries.put(query, docIDUpto);
    // increment bytes used only if the query wasn't added so far.
    if (current == null) {
      bytesUsed.addAndGet(BYTES_PER_DEL_QUERY);
    }
  }

  public void addDocID(int docID) {
    docIDs.add(Integer.valueOf(docID));
    bytesUsed.addAndGet(BYTES_PER_DEL_DOCID);
  }

  public void addTerm(Term term, int docIDUpto) {
    Integer current = terms.get(term);
    if (current != null && docIDUpto < current) {
      // Only record the new number if it's greater than the
      // current one.  This is important because if multiple
      // threads are replacing the same doc at nearly the
      // same time, it's possible that one thread that got a
      // higher docID is scheduled before the other
      // threads.  If we blindly replace then we can
      // incorrectly get both docs indexed.
      return;
    }

    terms.put(term, Integer.valueOf(docIDUpto));
    numTermDeletes.incrementAndGet();
    if (current == null) {
      bytesUsed.addAndGet(BYTES_PER_DEL_TERM + term.text.length() * RamUsageEstimator.NUM_BYTES_CHAR);
    }
  }

  public Iterable<Term> termsIterable() {
    return new Iterable<Term>() {
      // @Override -- not until Java 1.6
      public Iterator<Term> iterator() {
        return terms.keySet().iterator();
      }
    };
  }

  public Iterable<QueryAndLimit> queriesIterable() {
    return new Iterable<QueryAndLimit>() {
      
      // @Override -- not until Java 1.6
      public Iterator<QueryAndLimit> iterator() {
        return new Iterator<QueryAndLimit>() {
          private final Iterator<Map.Entry iter = queries.entrySet().iterator();

          // @Override -- not until Java 1.6
          public boolean hasNext() {
            return iter.hasNext();
          }

          // @Override -- not until Java 1.6
          public QueryAndLimit next() {
            final Map.Entry<Query,Integer> ent = iter.next();
            return new QueryAndLimit(ent.getKey(), ent.getValue());
          }

          // @Override -- not until Java 1.6
          public void remove() {
            throw new UnsupportedOperationException();
          }
        };
      }
    };
  }    
    
  void clear() {
    terms.clear();
    queries.clear();
    docIDs.clear();
    numTermDeletes.set(0);
    bytesUsed.set(0);
  }
  
  void clearDocIDs() {
    bytesUsed.addAndGet(-docIDs.size()*BYTES_PER_DEL_DOCID);
    docIDs.clear();
  }
  
  boolean any() {
    return terms.size() > 0 || docIDs.size() > 0 || queries.size() > 0;
  }
}

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