/*

 * Copyright (c) 2020 Red Hat, Inc.

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version 2

 * of the License, or (at your option) any later version.

 * 

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

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

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 * 

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

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

 * 02110-1301, USA. 

 *

 * $Id: //eng/vdo-releases/aluminum/src/c++/vdo/base/compressionState.h#2 $

 */

#ifndef COMPRESSION_STATE_H

#define COMPRESSION_STATE_H

#include "atomic.h"

#include "types.h"

/**

 * Where a DataVIO is on the compression path; advanceStatus() depends on the

 * order of this enum.

 **/

typedef enum {

  /* A VIO which has not yet entered the compression path */

  VIO_PRE_COMPRESSOR = 0,

  /* A VIO which is in the compressor */

  VIO_COMPRESSING,

  /* A VIO which is blocked in the packer */

  VIO_PACKING,

  /* A VIO which is no longer on the compression path (and never will be) */

  VIO_POST_PACKER,

} VIOCompressionStatus;

typedef struct {

  VIOCompressionStatus status;

  bool                 mayNotCompress;

} VIOCompressionState;

/**

 * Get the compression state of a DataVIO.

 *

 * @param dataVIO  The DataVIO

 *

 * @return The compression state

 **/

__attribute__((warn_unused_result))

VIOCompressionState getCompressionState(DataVIO *dataVIO);

/**

 * Check whether a DataVIO may go to the compressor.

 *

 * @param dataVIO  The DataVIO to check

 *

 * @return true if the DataVIO may be compressed at this time

 **/

bool mayCompressDataVIO(DataVIO *dataVIO)

  __attribute__((warn_unused_result));

/**

 * Check whether a DataVIO may go to the packer.

 *

 * @param dataVIO  The DataVIO to check

 *

 * @return true if the DataVIO may be packed at this time

 **/

bool mayPackDataVIO(DataVIO *dataVIO)

  __attribute__((warn_unused_result));

/**

 * Check whether a DataVIO which has gone to the packer may block there. Any

 * cancelation after this point and before the DataVIO is written out requires

 * this DataVIO to be picked up by the canceling DataVIO.

 *

 * @param dataVIO  The DataVIO to check

 *

 * @return true if the DataVIO may block in the packer

 **/

bool mayBlockInPacker(DataVIO *dataVIO)

  __attribute__((warn_unused_result));

/**

 * Check whether the packer may write out a DataVIO as part of a compressed

 * block.

 *

 * @param dataVIO  The DataVIO to check

 *

 * @return true if the DataVIO may be written as part of a

 *         compressed block at this time

 **/

bool mayWriteCompressedDataVIO(DataVIO *dataVIO)

  __attribute__((warn_unused_result));

/**

 * Indicate that this DataVIO is leaving the compression path.

 *

 * @param dataVIO  The DataVIO leaving the compression path

 **/

void setCompressionDone(DataVIO *dataVIO);

/**

 * Prevent this DataVIO from being compressed or packed.

 *

 * @param dataVIO  The DataVIO to cancel

 *

 * @return true if the DataVIO is in the packer and the caller

 *         was the first caller to cancel it

 **/

bool cancelCompression(DataVIO *dataVIO);

#endif /* COMPRESSION_STATE_H */