content: /*
   * 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.arrow.adapter.orc;
  
  import java.io.IOException;
  
  /** JNI wrapper for Orc reader. */
  class OrcReaderJniWrapper {
  
    private static volatile OrcReaderJniWrapper INSTANCE;
  
    static OrcReaderJniWrapper getInstance() throws IOException, IllegalAccessException {
      if (INSTANCE == null) {
        synchronized (OrcReaderJniWrapper.class) {
          if (INSTANCE == null) {
            OrcJniUtils.loadOrcAdapterLibraryFromJar();
            INSTANCE = new OrcReaderJniWrapper();
          }
        }
      }
  
      return INSTANCE;
    }
  
    /**
     * Construct a orc file reader over the target file.
     *
     * @param fileName absolute file path of target file
     * @return id of the orc reader instance if file opened successfully, otherwise return error code
     *     * -1.
     */
    native long open(String fileName);
  
    /**
     * Release resources associated with designated reader instance.
     *
     * @param readerId id of the reader instance.
     */
    native void close(long readerId);
  
    /**
     * Seek to designated row. Invoke nextStripeReader() after seek will return id of stripe reader
     * starting from designated row.
     *
     * @param readerId id of the reader instance
     * @param rowNumber the rows number to seek
     * @return true if seek operation is succeeded
     */
    native boolean seek(long readerId, int rowNumber);
  
    /**
     * The number of stripes in the file.
     *
     * @param readerId id of the reader instance
     * @return number of stripes
     */
    native int getNumberOfStripes(long readerId);
  
    /**
     * Get a stripe level ArrowReader with specified batchSize in each record batch.
     *
     * @param readerId id of the reader instance
     * @param batchSize the number of rows loaded on each iteration
     * @return id of the stripe reader instance.
     */
    native long nextStripeReader(long readerId, long batchSize);
  }
  