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    • net.snowflake.client.jdbc.SFBaseFileTransferAgent Maven / Gradle / Ivy

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    /*
 * Copyright (c) 2012-2021 Snowflake Computing Inc. All rights reserved.
 */

package net.snowflake.client.jdbc;

import java.io.InputStream;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import net.snowflake.client.core.SFBaseSession;
import net.snowflake.common.util.ClassUtil;

/**
 * Base class for file transfers: given a SnowflakeConnection, files may be uploaded or downloaded
 * from/to an InputStream.
 *
 * 
    Note that while SnowflakeFileTransferAgent is used liberally throughout the codebase for
 * performing uploads, the "alternative" implementations may have quite different ways of uploading
 * to cloud storage, so this is a rather "thin" abstract class that leaves much of the
 * implementation up to the implementing class.
 *
 * 
    It is also expected that a command (GET/PUT) is parsed by the FileTransferAgent before either
 * execute() or downloadStream() is called. This is not enforced by the abstract class's interface,
 * but will be passed to the SFConnectionHandler's getFileTransferAgent().
 *
 * 
    In general, besides the abstract methods execute() and downloadStream(), an implementing class
 * needs to also populate the statusRows List with the file-metadata rows forming the fixed view, as
 * well as set the showEncryptionParameter boolean (usually returned by the session parameter;
 * default is false).
 */
public abstract class SFBaseFileTransferAgent implements SnowflakeFixedView {
  protected boolean compressSourceFromStream;
  protected String destStagePath;
  protected String destFileNameForStreamSource;
  protected InputStream sourceStream;
  protected boolean sourceFromStream;
  protected boolean showEncryptionParameter;
  protected List statusRows = new ArrayList<>();
  protected CommandType commandType = CommandType.UPLOAD;
  private int currentRowIndex;

  /**
   * Gets the total number of rows that this GET/PUT command's output returns in the fixed-view
   * result. The statusRows list must be populated with the FileMetadata.
   *
   * @return The number of rows that this fixed-view represents.
   */
  @Override
  public int getTotalRows() {
    return statusRows.size();
  }

  /**
   * Move on to the next row of file metadata. The statusRows list must be populated with the
   * file-metadata output of the GET/PUT command.
   *
   * @return The row, represented as a list of Object.
   */
  @Override
  public List getNextRow() throws Exception {
    if (currentRowIndex < statusRows.size()) {
      return ClassUtil.getFixedViewObjectAsRow(
          commandType == CommandType.UPLOAD
              ? (showEncryptionParameter
                  ? SnowflakeFileTransferAgent.UploadCommandEncryptionFacade.class
                  : SnowflakeFileTransferAgent.UploadCommandFacade.class)
              : (showEncryptionParameter
                  ? SnowflakeFileTransferAgent.DownloadCommandEncryptionFacade.class
                  : SnowflakeFileTransferAgent.DownloadCommandFacade.class),
          statusRows.get(currentRowIndex++));
    } else {
      return null;
    }
  }

  /**
   * Describe the metadata of a fixed view.
   *
   * @return list of column meta data
   * @throws Exception failed to construct list
   */
  @Override
  public List describeColumns(SFBaseSession session) throws Exception {
    return SnowflakeUtil.describeFixedViewColumns(
        commandType == CommandType.UPLOAD
            ? (showEncryptionParameter
                ? SnowflakeFileTransferAgent.UploadCommandEncryptionFacade.class
                : SnowflakeFileTransferAgent.UploadCommandFacade.class)
            : (showEncryptionParameter
                ? SnowflakeFileTransferAgent.DownloadCommandEncryptionFacade.class
                : SnowflakeFileTransferAgent.DownloadCommandFacade.class),
        session);
  }

  /**
   * Sets the source data stream to be uploaded.
   *
   * @param sourceStream The source data to upload.
   */
  public void setSourceStream(InputStream sourceStream) {
    this.sourceStream = sourceStream;
    this.sourceFromStream = true;
  }

  /**
   * Sets the destination stage path
   *
   * @param destStagePath The target destination stage path.
   */
  public void setDestStagePath(String destStagePath) {
    this.destStagePath = destStagePath;
  }

  /**
   * Sets the target filename for uploading
   *
   * @param destFileNameForStreamSource The target destination filename once the file is uploaded.
   */
  public void setDestFileNameForStreamSource(String destFileNameForStreamSource) {
    this.destFileNameForStreamSource = destFileNameForStreamSource;
  }

  /**
   * Whether to compress the source stream before upload.
   *
   * @param compressSourceFromStream boolean for whether to compress the data stream before upload.
   */
  public void setCompressSourceFromStream(boolean compressSourceFromStream) {
    this.compressSourceFromStream = compressSourceFromStream;
  }

  /**
   * Run the PUT/GET command, if a command has been set.
   *
   * @return Whether the operation was completed successfully, and completely.
   * @throws SQLException for SQL or upload errors
   */
  public abstract boolean execute() throws SQLException;

  /**
   * Download data from a stage.
   *
   * @param fileName A file on a stage to download.
   * @return An InputStream for the requested file.
   * @throws SnowflakeSQLException If the file does not exist, or if an error occurred during
   *     transport.
   */
  public abstract InputStream downloadStream(String fileName) throws SnowflakeSQLException;

  /** The types of file transfer: upload and download. */
  public enum CommandType {
    UPLOAD,
    DOWNLOAD
  }
}
    
    
    
    

    




    
    
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