text: /*
   *   BSD LICENSE
   *   Copyright (c) 2021 Samsung Electronics Corporation
   *   All rights reserved.
   *
   *   Redistribution and use in source and binary forms, with or without
   *   modification, are permitted provided that the following conditions
   *   are met:
   *
   *     * Redistributions of source code must retain the above copyright
   *       notice, this list of conditions and the following disclaimer.
   *     * Redistributions in binary form must reproduce the above copyright
   *       notice, this list of conditions and the following disclaimer in
   *       the documentation and/or other materials provided with the
   *       distribution.
   *     * Neither the name of Samsung Electronics Corporation nor the names of
   *       its contributors may be used to endorse or promote products derived
   *       from this software without specific prior written permission.
   *
   *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
   *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  #pragma once
  
  #include <map>
  #include <string>
  #include <tuple>
  #include <vector>
  
  #include "src/mapper/i_stripemap.h"
  #include "src/mapper/vsamap/vsamap_manager.h"
  #include "src/meta_file_intf/async_context.h"
  
  namespace pos
  {
  const uint32_t REVMAP_MAGIC = 0xCAFEBABE;
  
  const int TIME_AS_TEXT_LEN = 32;
  const int REVMAP_ENTRY_SIZE = 12;
  const int VOLUME_ID_BIT = 10;
  const int DEFAULT_REVMAP_PAGE_SIZE = 4032;
  
  const int REVMAP_SECTOR_SIZE = DEFAULT_REVMAP_PAGE_SIZE / 16; // 252
  const int NUM_SECTOR_ENTRIES = DEFAULT_REVMAP_PAGE_SIZE /
      REVMAP_SECTOR_SIZE;                                         // 16
  const int NUM_ENTRIES = REVMAP_SECTOR_SIZE / REVMAP_ENTRY_SIZE; // 21
  
  class MetaFileIntf;
  class Stripe;
  class IVolumeManager;
  
  // The first page can have 21 * (16 - 1) == 315 entries
  // since the second page, it has 21 * 16 = 336 entries
  
  constexpr int
  ReservedBit(int usedBit)
  {
      return REVMAP_ENTRY_SIZE * 8 - usedBit;
  }
  
  enum class ACTION
  {
      OPEN,
      CLOSE,
  };
  
  enum IoDirection
  {
      IO_FLUSH = 1,
      IO_LOAD,
  };
  
  struct RevMapEntry
  {
      union
      {
          uint8_t byte[REVMAP_ENTRY_SIZE];
  
          struct __attribute__((packed))
          {
              BlkAddr rba;                                                         // 8 B
              uint32_t volumeId : VOLUME_ID_BIT;                                   // 10 b
              uint32_t reserved : ReservedBit(BLOCK_ADDR_BIT_LEN + VOLUME_ID_BIT); // 22 b
          } entry;
      } u;
  };
  
  struct RevMapSector
  {
      union
      {
          uint8_t byte[REVMAP_SECTOR_SIZE];
  
          struct __attribute__((packed))
          {
              uint32_t magic;    // 4
              StripeId vsid;     // 4
              uint32_t volumeId; // 4
              StripeId wbLsid;   // 4
  
              uint32_t openSec;                // 4
              uint32_t openNsec;               // 4
              char openTime[TIME_AS_TEXT_LEN]; // 32
  
              uint32_t closeSec;                // 4
              uint32_t closeNsec;               // 4
              char closeTime[TIME_AS_TEXT_LEN]; // 32
          } header;
  
          struct __attribute__((packed))
          {
              RevMapEntry entry[NUM_ENTRIES];
          } body;
      } u;
  };
  
  struct RevMap
  {
      RevMapSector sector[NUM_SECTOR_ENTRIES];
  };
  
  class RevMapPageAsyncIoCtx : public AsyncMetaFileIoCtx
  {
  public:
      int mpageNum;
      Stripe* stripeToFlush = nullptr;
  };
  
  class ReverseMapPack
  {
      friend class ReverseMapTest;
  
  public:
      ReverseMapPack(void);
      virtual ~ReverseMapPack(void);
  
      virtual void Init(MetaFileIntf* file, StripeId wbLsid_, StripeId vsid_, uint32_t mpageSize_, uint32_t numMpagesPerStripe_);
      virtual void Assign(StripeId vsid);
  
      virtual int Load(uint64_t fileOffset, EventSmartPtr cb, uint32_t vsid);
      virtual int Flush(Stripe* stripe, uint64_t fileOffset, EventSmartPtr cb, uint32_t vsid);
  
      virtual int SetReverseMapEntry(uint64_t offset, BlkAddr rba, uint32_t volumeId);
      virtual std::tuple<BlkAddr, uint32_t> GetReverseMapEntry(uint64_t offset);
      virtual char* GetRevMapPtrForWBT(void) { return reinterpret_cast<char*>(&revMaps[0]->sector[0]); }
  
  private:
      void _SetHeader(StripeId wblsid, StripeId vsid);
      std::tuple<uint32_t, uint32_t, uint32_t> _ReverseMapGeometry(uint64_t offset);
      void _RevMapPageIoDone(AsyncMetaFileIoCtx* ctx);
  
      StripeId wbLsid;
      StripeId vsid;   // SSD LSID
      std::vector<RevMap*> revMaps;
  
      MetaFileIntf* revMapfile; // MFS file
      uint32_t mpageSize;
      std::atomic<uint32_t> mfsAsyncIoDonePages;
      uint64_t numMpagesPerStripe; // It depends on block count per a stripe
      int ioError; // indicates if there is an Async-IO error among mpages
      int ioDirection;
      EventSmartPtr callback;
  };
  
  } // namespace pos
  