/*
* 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 <code>true</code> 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 <code>true</code> 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 <code>true</code> 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 <code>true</code> 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 <code>true</code> 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 */