/*

 * 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/slabSummaryInternals.h#7 $

 */

#ifndef SLAB_SUMMARY_INTERNALS_H

#define SLAB_SUMMARY_INTERNALS_H

#include "slabSummary.h"

#include "adminState.h"

#include "atomic.h"

typedef struct slabSummaryEntry {

  /** Bits 7..0: The offset of the tail block within the slab journal */

  TailBlockOffset tailBlockOffset;

#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__

  /** Bits 13..8: A hint about the fullness of the slab */

  unsigned int    fullnessHint  : 6;

  /** Bit 14: Whether the refCounts must be loaded from the layer */

  unsigned int    loadRefCounts : 1;

  /** Bit 15: The believed cleanliness of this slab */

  unsigned int    isDirty       : 1;

#else

  /** Bit 15: The believed cleanliness of this slab */

  unsigned int    isDirty       : 1;

  /** Bit 14: Whether the refCounts must be loaded from the layer */

  unsigned int    loadRefCounts : 1;

  /** Bits 13..8: A hint about the fullness of the slab */

  unsigned int    fullnessHint  : 6;

#endif

}  __attribute__((packed)) SlabSummaryEntry;

typedef struct slabSummaryBlock {

  /** The zone to which this block belongs */

  SlabSummaryZone  *zone;

  /** The index of this block in its zone's summary */

  BlockCount        index;

  /** Whether this block has a write outstanding */

  bool              writing;

  /** Ring of updates waiting on the outstanding write */

  WaitQueue         currentUpdateWaiters;

  /** Ring of updates waiting on the next write */

  WaitQueue         nextUpdateWaiters;

  /** The active SlabSummaryEntry array for this block */

  SlabSummaryEntry *entries;

  /** The VIO used to write this block */

  VIO              *vio;

  /** The packed entries, one block long, backing the VIO */

  char             *outgoingEntries;

} SlabSummaryBlock;

/**

 * The statistics for all the slab summary zones owned by this slab summary.

 * These fields are all mutated only by their physical zone threads, but are

 * read by other threads when gathering statistics for the entire depot.

 **/

typedef struct atomicSlabSummaryStatistics {

  /** Number of blocks written */

  Atomic64 blocksWritten;

} AtomicSlabSummaryStatistics;

struct slabSummaryZone {

  /** The summary of which this is a zone */

  SlabSummary      *summary;

  /** The number of this zone */

  ZoneCount         zoneNumber;

  /** Count of the number of blocks currently out for writing */

  BlockCount        writeCount;

  /** The state of this zone */

  AdminState        state;

  /** The array (owned by the blocks) of all entries */

  SlabSummaryEntry *entries;

  /** The array of SlabSummaryEntryBlocks */

  SlabSummaryBlock  summaryBlocks[];

};

struct slabSummary {

  /** The context for entering read-only mode */

  ReadOnlyNotifier            *readOnlyNotifier;

  /** The statistics for this slab summary */

  AtomicSlabSummaryStatistics  statistics;

  /** The start of the slab summary partition relative to the layer */

  PhysicalBlockNumber          origin;

  /** The number of bits to shift to get a 7-bit fullness hint */

  unsigned int                 hintShift;

  /** The number of blocks (calculated based on MAX_SLABS) */

  BlockCount                   blocksPerZone;

  /** The number of slabs per block (calculated from block size) */

  SlabCount                    entriesPerBlock;

  /** The entries for all of the zones the partition can hold */

  SlabSummaryEntry            *entries;

  /** The number of zones which were active at the time of the last update */

  ZoneCount                    zonesToCombine;

  /** The current number of active zones */

  ZoneCount                    zoneCount;

  /** The currently active zones */

  SlabSummaryZone             *zones[];

};

/**

 * Treating the current entries buffer as the on-disk value of all zones,

 * update every zone to the correct values for every slab.

 *

 * @param summary       The summary whose entries should be combined

 **/

void combineZones(SlabSummary *summary);

#endif // SLAB_SUMMARY_INTERNALS_H