1 /**

     2  * Relational pipes (library)

     3  * Copyright © 2022 František Kučera (Frantovo.cz, GlobalCode.info)

     4  *

     5  * This program is free software: you can redistribute it and/or modify

     6  * it under the terms of the:

     7  *  - GNU Lesser General Public License as published by the Free Software Foundation;

     8  *    version 3 of the License or (at your option)

     9  *  - GNU General Public License as published by the Free Software Foundation;

    10  *    version 2 of the License.

    11  *

    12  * This program is distributed in the hope that it will be useful,

    13  * but WITHOUT ANY WARRANTY; without even the implied warranty of

    14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

    15  * GNU General Public License for more details.

    16  *

    17  * You should have received a copy of the GNU General Public License

    18  * along with this program. If not, see <http://www.gnu.org/licenses/>.

    19  */

    20 #pragma once

    21 

    22 namespace relpipe {

    23 namespace writer {

    24 

    25 /**

    26  * Relational output might be – and usually is – buffered

    27  * i.e. relational data are written to a buffer and flushed later and sent to the actual output stream.

    28  * 

    29  * Through these modes we can control when the flush is done.

    30  * 

    31  * Recommendation:

    32  *  - batch processing: AUTO

    33  *  - interactive processing: RECORD

    34  *  - tools should not set the mode explicitly unless asked by the user or unles specific mode is obvious for given task;

    35  *    then ENVIRONMENT mode is the initial one and it defaults to AUTO when user has not set the environmental variable

    36  */

    37 enum class BufferingMode {

    38 	/**

    39 	 * Output buffer is not explicitly flushed, it is written when full.

    40 	 */

    41 	AUTO,

    42 	/**

    43 	 * Mode is determined by the environmental variable RELPIPE_WRITER_BUFFERING_MODE.

    44 	 * If value is missing or has invalid value, AUTO is used as default.

    45 	 */

    46 	ENVIRONMENT,

    47 	/**

    48 	 * Output buffer is flushed at least at the end of each relation.

    49 	 */

    50 	RELATION,

    51 	/**

    52 	 * Output buffer is flushed at least at the end of each record.

    53 	 */

    54 	RECORD,

    55 	/**

    56 	 * Output buffer is flushed at least at the end of each attribute.

    57 	 */

    58 	ATTRIBUTE

    59 };

    60 

    61 }

    62 }