indexreader.java

lucene2.2.0版本

   * @throws StaleReaderException if the index has changed
   * since this reader was opened
   * @throws CorruptIndexException if the index is corrupt
   * @throws LockObtainFailedException if another writer
   *  has this index open (<code>write.lock</code> could not
   *  be obtained)
   * @throws IOException if there is a low-level IO error
   */
  public final synchronized void deleteDocument(int docNum) throws StaleReaderException, CorruptIndexException, LockObtainFailedException, IOException {
    ensureOpen();
    if(directoryOwner)
      acquireWriteLock();
    hasChanges = true;
    doDelete(docNum);
  }


  /** Implements deletion of the document numbered <code>docNum</code>.
   * Applications should call {@link #deleteDocument(int)} or {@link #deleteDocuments(Term)}.
   */
  protected abstract void doDelete(int docNum) throws CorruptIndexException, IOException;


  /** Deletes all documents that have a given <code>term</code> indexed.
   * This is useful if one uses a document field to hold a unique ID string for
   * the document.  Then to delete such a document, one merely constructs a
   * term with the appropriate field and the unique ID string as its text and
   * passes it to this method.
   * See {@link #deleteDocument(int)} for information about when this deletion will 
   * become effective.
   *
   * @return the number of documents deleted
   * @throws StaleReaderException if the index has changed
   *  since this reader was opened
   * @throws CorruptIndexException if the index is corrupt
   * @throws LockObtainFailedException if another writer
   *  has this index open (<code>write.lock</code> could not
   *  be obtained)
   * @throws IOException if there is a low-level IO error
   */
  public final int deleteDocuments(Term term) throws StaleReaderException, CorruptIndexException, LockObtainFailedException, IOException {
    ensureOpen();
    TermDocs docs = termDocs(term);
    if (docs == null) return 0;
    int n = 0;
    try {
      while (docs.next()) {
        deleteDocument(docs.doc());
        n++;
      }
    } finally {
      docs.close();
    }
    return n;
  }

  /** Undeletes all documents currently marked as deleted in this index.
   *
   * @throws StaleReaderException if the index has changed
   *  since this reader was opened
   * @throws LockObtainFailedException if another writer
   *  has this index open (<code>write.lock</code> could not
   *  be obtained)
   * @throws CorruptIndexException if the index is corrupt
   * @throws IOException if there is a low-level IO error
   */
  public final synchronized void undeleteAll() throws StaleReaderException, CorruptIndexException, LockObtainFailedException, IOException {
    ensureOpen();
    if(directoryOwner)
      acquireWriteLock();
    hasChanges = true;
    doUndeleteAll();
  }

  /** Implements actual undeleteAll() in subclass. */
  protected abstract void doUndeleteAll() throws CorruptIndexException, IOException;

  /**
   * Should internally checkpoint state that will change
   * during commit so that we can rollback if necessary.
   */
  void startCommit() {
    if (directoryOwner) {
      rollbackSegmentInfos = (SegmentInfos) segmentInfos.clone();
    }
    rollbackHasChanges = hasChanges;
  }

  /**
   * Rolls back state to just before the commit (this is
   * called by commit() if there is some exception while
   * committing).
   */
  void rollbackCommit() {
    if (directoryOwner) {
      for(int i=0;i<segmentInfos.size();i++) {
        // Rollback each segmentInfo.  Because the
        // SegmentReader holds a reference to the
        // SegmentInfo we can't [easily] just replace
        // segmentInfos, so we reset it in place instead:
        segmentInfos.info(i).reset(rollbackSegmentInfos.info(i));
      }
      rollbackSegmentInfos = null;
    }

    hasChanges = rollbackHasChanges;
  }

  /**
   * Commit changes resulting from delete, undeleteAll, or
   * setNorm operations
   *
   * If an exception is hit, then either no changes or all
   * changes will have been committed to the index
   * (transactional semantics).
   * @throws IOException if there is a low-level IO error
   */
  protected final synchronized void commit() throws IOException {
    if(hasChanges){
      if(directoryOwner){

        // Default deleter (for backwards compatibility) is
        // KeepOnlyLastCommitDeleter:
        IndexFileDeleter deleter =  new IndexFileDeleter(directory,
                                                         deletionPolicy == null ? new KeepOnlyLastCommitDeletionPolicy() : deletionPolicy,
                                                         segmentInfos, null);

        // Checkpoint the state we are about to change, in
        // case we have to roll back:
        startCommit();

        boolean success = false;
        try {
          doCommit();
          segmentInfos.write(directory);
          success = true;
        } finally {

          if (!success) {

            // Rollback changes that were made to
            // SegmentInfos but failed to get [fully]
            // committed.  This way this reader instance
            // remains consistent (matched to what's
            // actually in the index):
            rollbackCommit();

            // Recompute deletable files & remove them (so
            // partially written .del files, etc, are
            // removed):
            deleter.refresh();
          }
        }

        // Have the deleter remove any now unreferenced
        // files due to this commit:
        deleter.checkpoint(segmentInfos, true);

        if (writeLock != null) {
          writeLock.release();  // release write lock
          writeLock = null;
        }
      }
      else
        doCommit();
    }
    hasChanges = false;
  }

  /** Implements commit. */
  protected abstract void doCommit() throws IOException;

  /**
   * Closes files associated with this index.
   * Also saves any new deletions to disk.
   * No other methods should be called after this has been called.
   * @throws IOException if there is a low-level IO error
   */
  public final synchronized void close() throws IOException {
    if (!closed) {
      commit();
      doClose();
      if (directoryOwner)
        closed = true;
      if(closeDirectory)
        directory.close();
    }
  }

  /** Implements close. */
  protected abstract void doClose() throws IOException;

  /** Release the write lock, if needed. */
  protected void finalize() throws Throwable {
    try {
      if (writeLock != null) {
        writeLock.release();                        // release write lock
        writeLock = null;
      }
    } finally {
      super.finalize();
    }
  }


  /**
   * Get a list of unique field names that exist in this index and have the specified
   * field option information.
   * @param fldOption specifies which field option should be available for the returned fields
   * @return Collection of Strings indicating the names of the fields.
   * @see IndexReader.FieldOption
   */
  public abstract Collection getFieldNames(FieldOption fldOption);

  /**
   * Returns <code>true</code> iff the index in the named directory is
   * currently locked.
   * @param directory the directory to check for a lock
   * @throws IOException if there is a low-level IO error
   */
  public static boolean isLocked(Directory directory) throws IOException {
    return
      directory.makeLock(IndexWriter.WRITE_LOCK_NAME).isLocked();
  }

  /**
   * Returns <code>true</code> iff the index in the named directory is
   * currently locked.
   * @param directory the directory to check for a lock
   * @throws IOException if there is a low-level IO error
   */
  public static boolean isLocked(String directory) throws IOException {
    Directory dir = FSDirectory.getDirectory(directory);
    boolean result = isLocked(dir);
    dir.close();
    return result;
  }

  /**
   * Forcibly unlocks the index in the named directory.
   * <P>
   * Caution: this should only be used by failure recovery code,
   * when it is known that no other process nor thread is in fact
   * currently accessing this index.
   */
  public static void unlock(Directory directory) throws IOException {
    directory.makeLock(IndexWriter.WRITE_LOCK_NAME).release();
  }

  /**
   * Prints the filename and size of each file within a given compound file.
   * Add the -extract flag to extract files to the current working directory.
   * In order to make the extracted version of the index work, you have to copy
   * the segments file from the compound index into the directory where the extracted files are stored.
   * @param args Usage: org.apache.lucene.index.IndexReader [-extract] &lt;cfsfile&gt;
   */
  public static void main(String [] args) {
    String filename = null;
    boolean extract = false;

    for (int i = 0; i < args.length; ++i) {
      if (args[i].equals("-extract")) {
        extract = true;
      } else if (filename == null) {
        filename = args[i];
      }
    }

    if (filename == null) {
      System.out.println("Usage: org.apache.lucene.index.IndexReader [-extract] <cfsfile>");
      return;
    }

    Directory dir = null;
    CompoundFileReader cfr = null;

    try {
      File file = new File(filename);
      String dirname = file.getAbsoluteFile().getParent();
      filename = file.getName();
      dir = FSDirectory.getDirectory(dirname);
      cfr = new CompoundFileReader(dir, filename);

      String [] files = cfr.list();
      Arrays.sort(files);   // sort the array of filename so that the output is more readable

      for (int i = 0; i < files.length; ++i) {
        long len = cfr.fileLength(files[i]);

        if (extract) {
          System.out.println("extract " + files[i] + " with " + len + " bytes to local directory...");
          IndexInput ii = cfr.openInput(files[i]);

          FileOutputStream f = new FileOutputStream(files[i]);

          // read and write with a small buffer, which is more effectiv than reading byte by byte
          byte[] buffer = new byte[1024];
          int chunk = buffer.length;
          while(len > 0) {
            final int bufLen = (int) Math.min(chunk, len);
            ii.readBytes(buffer, 0, bufLen);
            f.write(buffer, 0, bufLen);
            len -= bufLen;
          }

          f.close();
          ii.close();
        }
        else
          System.out.println(files[i] + ": " + len + " bytes");
      }
    } catch (IOException ioe) {
      ioe.printStackTrace();
    }
    finally {
      try {
        if (dir != null)
          dir.close();
        if (cfr != null)
          cfr.close();
      }
      catch (IOException ioe) {
        ioe.printStackTrace();
      }
    }
  }
}