SearchIndexManager.java

package proj.zoie.impl.indexing.internal;

/**
 * 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.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;

import org.apache.log4j.Logger;
import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.index.IndexReader;

import proj.zoie.api.DirectoryManager;
import proj.zoie.api.DocIDMapperFactory;
import proj.zoie.api.IndexReaderFactory;
import proj.zoie.api.ZoieHealth;
import proj.zoie.api.ZoieMultiReader;
import proj.zoie.api.indexing.IndexReaderDecorator;

public class SearchIndexManager<R extends IndexReader> implements IndexReaderFactory<R> {
  private static final Logger log = Logger.getLogger(SearchIndexManager.class);

  public static enum Status {
    Sleep, Working
  }

  private DirectoryManager _dirMgr;
  private final IndexReaderDecorator<R> _indexReaderDecorator;

  final DocIDMapperFactory _docIDMapperFactory;
  private final DiskSearchIndex<R> _diskIndex;

  private volatile Status _diskIndexerStatus;
  private volatile Mem<R> _mem;
  /**
   * the access lock for _mem for the purpose of proper reference counting
   * for disk IndexReader
   */
  private final Object _memLock = new Object();
  private final RAMIndexFactory<R> _ramIndexFactory;

  private volatile String _memAVersion = null;
  private volatile String _memBVersion = null;
  private volatile String _diskVersion = null;

  private final Comparator<String> _versionComparator;

  public SearchIndexManager(DirectoryManager dirMgr, Comparator<String> versionComparator,
      IndexReaderDecorator<R> indexReaderDecorator, DocIDMapperFactory docIDMapperFactory,
      RAMIndexFactory<R> ramIndexFactory) {
    _dirMgr = dirMgr;
    _versionComparator = versionComparator;
    _docIDMapperFactory = docIDMapperFactory;
    _ramIndexFactory = ramIndexFactory;
    if (indexReaderDecorator != null) {
      _indexReaderDecorator = indexReaderDecorator;
    } else {
      throw new IllegalArgumentException("indexReaderDecorator cannot be null");
    }
    _diskIndexerStatus = Status.Sleep;
    _diskIndex = new DiskSearchIndex<R>(_dirMgr, _indexReaderDecorator, this);
    ZoieMultiReader<R> diskIndexReader = null;

    try {
      diskIndexReader = _diskIndex.getNewReader();
    } catch (IOException e) {
      log.error(e.getMessage(), e);
      return;
    }
    String version = _diskIndex.getVersion();
    RAMSearchIndex<R> memIndexA = _ramIndexFactory
        .newInstance(version, _indexReaderDecorator, this);
    Mem<R> mem = new Mem<R>(memIndexA, null, memIndexA, null, diskIndexReader);
    if (diskIndexReader != null) {
      diskIndexReader.incZoieRef();
    }
    _mem = mem;
  }

  public DocIDMapperFactory getDocIDMapperFactory() {
    return _docIDMapperFactory;
  }

  public int getDiskSegmentCount() throws IOException {
    return _diskIndex.getSegmentCount();
  }

  public String getDiskSegmentInfo() {
    return _diskIndex.getSegmentInfo();
  }

  public int getRAMASegmentCount() {
    Mem<R> mem = _mem;
    if (mem.get_memIndexA() == null) return -1;
    int ret;
    try {
      ret = mem.get_memIndexA().getSegmentCount();
    } catch (IOException e) {
      ret = -1;
    }
    return ret;
  }

  public int getRAMBSegmentCount() {
    Mem<R> mem = _mem;
    if (mem.get_memIndexB() == null) return -1;
    int ret;
    try {
      ret = mem.get_memIndexB().getSegmentCount();
    } catch (IOException e) {
      ret = -1;
    }
    return ret;
  }

  public void setNumLargeSegments(int numLargeSegments) {
    _diskIndex._mergePolicyParams.setNumLargeSegments(numLargeSegments);
  }

  public int getNumLargeSegments() {
    return _diskIndex._mergePolicyParams.getNumLargeSegments();
  }

  public void setMaxSmallSegments(int maxSmallSegments) {
    _diskIndex._mergePolicyParams.setMaxSmallSegments(maxSmallSegments);
  }

  public int getMaxSmallSegments() {
    return _diskIndex._mergePolicyParams.getMaxSmallSegments();
  }

  public void setPartialExpunge(boolean doPartialExpunge) {
    _diskIndex._mergePolicyParams.setPartialExpunge(doPartialExpunge);
  }

  public boolean getPartialExpunge() {
    return _diskIndex._mergePolicyParams.getPartialExpunge();
  }

  public void setMergeFactor(int mergeFactor) {
    _diskIndex._mergePolicyParams.setMergeFactor(mergeFactor);
  }

  public int getMergeFactor() {
    return _diskIndex._mergePolicyParams.getMergeFactor();
  }

  public void setMaxMergeDocs(int maxMergeDocs) {
    _diskIndex._mergePolicyParams.setMaxMergeDocs(maxMergeDocs);
  }

  public int getMaxMergeDocs() {
    return _diskIndex._mergePolicyParams.getMaxMergeDocs();
  }

  public void setUseCompoundFile(boolean useCompoundFile) {
    _diskIndex._mergePolicyParams.setUseCompoundFile(useCompoundFile);
  }

  public boolean isUseCompoundFile() {
    return _diskIndex._mergePolicyParams.isUseCompoundFile();
  }

  /**
   * Gets the current disk indexer status
   */
  public Status getDiskIndexerStatus() {
    return _diskIndexerStatus;
  }

  @Override
  public List<ZoieMultiReader<R>> getIndexReaders() throws IOException {
    ArrayList<ZoieMultiReader<R>> readers = new ArrayList<ZoieMultiReader<R>>();
    ZoieMultiReader<R> reader = null;

    synchronized (this) {
      synchronized (_memLock) {
        Mem<R> mem = _mem;
        RAMSearchIndex<R> memIndexB = mem.get_memIndexB();
        RAMSearchIndex<R> memIndexA = mem.get_memIndexA();

        // the following order, e.g. B,A,Disk matters, see ZoieMultiReader.getSubZoieReaderAccessor:
        // when doing UID->docid mapping, the freshest index needs to be first

        if (memIndexB != null) // load memory index B
        {
          synchronized (memIndexB) {
            reader = memIndexB.openIndexReader();
            if (reader != null) {
              reader = reader.copy();
              readers.add(reader);
            }
          }
          _memBVersion = memIndexB.getVersion();
        }

        if (memIndexA != null) // load memory index A
        {
          synchronized (memIndexA) {
            reader = memIndexA.openIndexReader();
            if (reader != null) {
              reader = reader.copy();
              readers.add(reader);
            }
          }
          _memAVersion = memIndexA.getVersion();
        }

        // load disk index
        {
          reader = mem.get_diskIndexReader();
          if (reader != null) {
            reader = reader.copy();
            readers.add(reader);
          }
          _diskVersion = getCurrentDiskVersion();
        }
      }
    }
    return readers;
  }

  @Override
  public String getCurrentReaderVersion() {
    String version = _memAVersion;
    if (_versionComparator.compare(version, _memBVersion) < 0) {
      version = _memBVersion;
    }
    if (_versionComparator.compare(version, _diskVersion) < 0) {
      version = _diskVersion;
    }
    return version;

  }

  public Comparator<String> getVersionComparator() {
    return _versionComparator;
  }

  @Override
  public void returnIndexReaders(List<ZoieMultiReader<R>> readers) {
    for (ZoieMultiReader<R> r : readers) {
      r.decZoieRef();
    }
  }

  public synchronized void setDiskIndexerStatus(Status status) {
    if (_diskIndexerStatus == status) {
      return;
    }
    // going from sleep to wake, disk index starts to index
    // which according to the spec, index B is created and it starts to collect data
    // IMPORTANT: do nothing if the status is not being changed.
    log.info("updating batch indexer status from " + _diskIndexerStatus + " to " + status);

    if (status == Status.Working) { // sleeping to working
      String version = _diskIndex.getVersion();
      Mem<R> oldMem = _mem;

      RAMSearchIndex<R> memIndexA = oldMem.get_memIndexA();
      if (memIndexA != null) {
        memIndexA.closeIndexWriter();
      }

      RAMSearchIndex<R> memIndexB = _ramIndexFactory.newInstance(version, _indexReaderDecorator,
        this);

      Mem<R> mem = new Mem<R>(memIndexA, memIndexB, memIndexB, memIndexA,
          oldMem.get_diskIndexReader());
      synchronized (_memLock) {
        _mem = mem;
      }
      log.info("Current writable index is B, new B created");
    } else {
      // from working to sleep
      ZoieMultiReader<R> diskIndexReader = null;

      synchronized (_diskIndex) {
        // a new reader is already loaded in loadFromIndex
        diskIndexReader = _diskIndex.openIndexReader();
        if (diskIndexReader != null) {
          diskIndexReader.incZoieRef();
        }
      }

      Mem<R> oldMem = _mem;
      Mem<R> mem = new Mem<R>(oldMem.get_memIndexB(), null, oldMem.get_memIndexB(), null,
          diskIndexReader);
      if (oldMem.get_memIndexA() != null) {
        oldMem.get_memIndexA().close();
      }
      lockAndSwapMem(diskIndexReader, oldMem.get_diskIndexReader(), mem);
      log.info("Current writable index is A, B is flushed");
      if (diskIndexReader != null) {
        diskIndexReader.decZoieRef();
      }
    }
    _diskIndexerStatus = status;
  }

  public DiskSearchIndex<R> getDiskIndex() {
    return _diskIndex;
  }

  public RAMSearchIndex<R> getCurrentWritableMemoryIndex() {
    return _mem.get_currentWritable();
  }

  public RAMSearchIndex<R> getCurrentReadOnlyMemoryIndex() {
    return _mem.get_currentReadOnly();
  }

  /**
   * Clean up
   * @throws IOException
   */
  public void close() {
    Mem<R> mem = _mem;
    if (mem.get_memIndexA() != null) {
      mem.get_memIndexA().close();
    }
    if (mem.get_memIndexB() != null) {
      mem.get_memIndexB().close();
    }
    if (mem.get_diskIndexReader() != null) {
      mem.get_diskIndexReader().decZoieRef();
      _diskIndex.close();
    }
  }

  public String getCurrentDiskVersion() throws IOException {
    return _diskIndex.getVersion();
  }

  public int getDiskIndexSize() {
    return _diskIndex.getNumdocs();
  }

  public int getRamAIndexSize() {
    RAMSearchIndex<R> memIndexA = _mem.get_memIndexA();
    return (memIndexA == null) ? 0 : memIndexA.getNumdocs();
  }

  public String getRamAVersion() {
    RAMSearchIndex<R> memIndexA = _mem.get_memIndexA();
    return (memIndexA == null) ? null : memIndexA.getVersion();
  }

  public int getRamBIndexSize() {
    RAMSearchIndex<R> memIndexB = _mem.get_memIndexB();
    return (memIndexB == null) ? 0 : memIndexB.getNumdocs();
  }

  public String getRamBVersion() {
    RAMSearchIndex<R> memIndexB = _mem.get_memIndexB();
    return (memIndexB == null) ? null : memIndexB.getVersion();
  }

  /**
   * utility method to delete a directory
   * @param dir
   * @throws IOException
   */
  private static void deleteDir(File dir) throws IOException {
    if (dir == null) return;

    if (dir.isDirectory()) {
      File[] files = dir.listFiles();
      for (File file : files) {
        deleteDir(file);
      }
      if (!dir.delete()) {
        throw new IOException("cannot remove directory: " + dir.getAbsolutePath());
      }
    } else {
      if (!dir.delete()) {
        throw new IOException("cannot delete file: " + dir.getAbsolutePath());
      }
    }
  }

  /**
   * Purges an index
   */
  public void purgeIndex() {
    log.info("purging index ...");
    _diskIndex.clearDeletes();
    _diskIndex.refresh();
    _diskIndex.closeIndexWriter();
    _dirMgr.purge();
    _diskIndex.refresh();
    if (_mem.get_memIndexA() != null) {
      _mem.get_memIndexA().close();
    }
    if (_mem.get_memIndexB() != null) {
      _mem.get_memIndexB().close();
    }
    RAMSearchIndex<R> memIndexA = _ramIndexFactory.newInstance(_diskIndex.getVersion(),
      _indexReaderDecorator, this);
    Mem<R> mem = new Mem<R>(memIndexA, null, memIndexA, null, null);
    synchronized (_memLock) {
      _mem = mem;
    }
    log.info("index purged");
  }

  public void refreshDiskReader() throws IOException {
    log.info("refreshing disk reader ...");
    ZoieMultiReader<R> diskIndexReader = null;
    try {
      // load a new reader, not in the lock because this should be done in the background
      // and should not contend with the readers
      diskIndexReader = _diskIndex.getNewReader();
    } catch (IOException e) {
      ZoieHealth.setFatal();
      log.error(e.getMessage(), e);
      throw e;
    }

    synchronized (_memLock) {
      Mem<R> oldMem = _mem;
      ZoieMultiReader<R> oldDiskIndexReader = oldMem.get_diskIndexReader();
      if (diskIndexReader != oldDiskIndexReader) {
        Mem<R> mem = new Mem<R>(oldMem.get_memIndexA(), oldMem.get_memIndexB(),
            oldMem.get_currentWritable(), oldMem.get_currentReadOnly(), diskIndexReader);
        if (oldDiskIndexReader != null) {
          oldDiskIndexReader.decZoieRef();
        }
        diskIndexReader.incZoieRef();
        _mem = mem;
      }
    }
    log.info("disk reader refreshed");
  }

  /**
   * swap the disk IndexReader cached in mem. In order to count the reference properly,
   * we need to lock the access to _mem so that it is safe to compare whether the old
   * and new disk IndexReader are different. decZoieRef the old IndexReader only when they
   * differ.
   * @param diskIndexReader the new disk IndexReader
   * @param oldDiskReader the old disk IndexReader from old mem
   * @param mem the new mem
   */
  private void lockAndSwapMem(ZoieMultiReader<R> diskIndexReader, ZoieMultiReader<R> oldDiskReader,
      Mem<R> mem) {
    synchronized (_memLock) {
      if (oldDiskReader != diskIndexReader) {
        if (oldDiskReader != null) {
          oldDiskReader.decZoieRef();
        }
        diskIndexReader.incZoieRef();
      }
      _mem = mem;
    }
  }

  private final static class Mem<R extends IndexReader> {
    private final RAMSearchIndex<R> _memIndexA;
    private final RAMSearchIndex<R> _memIndexB;
    private final RAMSearchIndex<R> _currentWritable;
    private final RAMSearchIndex<R> _currentReadOnly;
    private final ZoieMultiReader<R> _diskIndexReader;

    Mem(RAMSearchIndex<R> a, RAMSearchIndex<R> b, RAMSearchIndex<R> w, RAMSearchIndex<R> r,
        ZoieMultiReader<R> d) {
      _memIndexA = a;
      _memIndexB = b;
      _currentWritable = w;
      _currentReadOnly = r;
      _diskIndexReader = d;
    }

    protected RAMSearchIndex<R> get_memIndexA() {
      return _memIndexA;
    }

    protected RAMSearchIndex<R> get_memIndexB() {
      return _memIndexB;
    }

    protected RAMSearchIndex<R> get_currentWritable() {
      return _currentWritable;
    }

    protected RAMSearchIndex<R> get_currentReadOnly() {
      return _currentReadOnly;
    }

    protected ZoieMultiReader<R> get_diskIndexReader() {
      return _diskIndexReader;
    }
  }

  @Override
  public Analyzer getAnalyzer() {
    throw new UnsupportedOperationException();
  }
}