//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.

//  This source code is licensed under both the GPLv2 (found in the

//  COPYING file in the root directory) and Apache 2.0 License

//  (found in the LICENSE.Apache file in the root directory).

//

// Copyright (c) 2011 The LevelDB Authors. All rights reserved.

// Use of this source code is governed by a BSD-style license that can be

// found in the LICENSE file. See the AUTHORS file for names of contributors.

//

#pragma once

#include <map>

#include <memory>

#include <string>

#include <vector>

#include "cache/cache_entry_roles.h"

#include "db/version_set.h"

#include "rocksdb/system_clock.h"

#include "util/hash_containers.h"

namespace ROCKSDB_NAMESPACE {

template <class Stats>

class CacheEntryStatsCollector;

class DBImpl;

class MemTableList;

// Config for retrieving a property's value.

struct DBPropertyInfo {

  bool need_out_of_mutex;

  // gcc had an internal error for initializing union of pointer-to-member-

  // functions. Workaround is to populate exactly one of the following function

  // pointers with a non-nullptr value.

  // @param value Value-result argument for storing the property's string value

  // @param suffix Argument portion of the property. For example, suffix would

  //      be "5" for the property "rocksdb.num-files-at-level5". So far, only

  //      certain string properties take an argument.

  bool (InternalStats::*handle_string)(std::string* value, Slice suffix);

  // @param value Value-result argument for storing the property's uint64 value

  // @param db Many of the int properties rely on DBImpl methods.

  // @param version Version is needed in case the property is retrieved without

  //      holding db mutex, which is only supported for int properties.

  bool (InternalStats::*handle_int)(uint64_t* value, DBImpl* db,

                                    Version* version);

  // @param props Map of general properties to populate

  // @param suffix Argument portion of the property. (see handle_string)

  bool (InternalStats::*handle_map)(std::map<std::string, std::string>* props,

                                    Slice suffix);

  // handle the string type properties rely on DBImpl methods

  // @param value Value-result argument for storing the property's string value

  bool (DBImpl::*handle_string_dbimpl)(std::string* value);

};

const DBPropertyInfo* GetPropertyInfo(const Slice& property);

#undef SCORE

enum class LevelStatType {

  INVALID = 0,

  NUM_FILES,

  COMPACTED_FILES,

  SIZE_BYTES,

  SCORE,

  READ_GB,

  RN_GB,

  RNP1_GB,

  WRITE_GB,

  W_NEW_GB,

  MOVED_GB,

  WRITE_AMP,

  READ_MBPS,

  WRITE_MBPS,

  COMP_SEC,

  COMP_CPU_SEC,

  COMP_COUNT,

  AVG_SEC,

  KEY_IN,

  KEY_DROP,

  R_BLOB_GB,

  W_BLOB_GB,

  TOTAL  // total number of types

};

struct LevelStat {

  // This what will be L?.property_name in the flat map returned to the user

  std::string property_name;

  // This will be what we will print in the header in the cli

  std::string header_name;

};

struct DBStatInfo {

  // This what will be property_name in the flat map returned to the user

  std::string property_name;

};

class InternalStats {

 public:

  static const std::map<LevelStatType, LevelStat> compaction_level_stats;

  enum InternalCFStatsType {

    MEMTABLE_LIMIT_DELAYS,

    MEMTABLE_LIMIT_STOPS,

    L0_FILE_COUNT_LIMIT_DELAYS,

    L0_FILE_COUNT_LIMIT_STOPS,

    PENDING_COMPACTION_BYTES_LIMIT_DELAYS,

    PENDING_COMPACTION_BYTES_LIMIT_STOPS,

    // Write slowdown caused by l0 file count limit while there is ongoing L0

    // compaction

    L0_FILE_COUNT_LIMIT_DELAYS_WITH_ONGOING_COMPACTION,

    // Write stop caused by l0 file count limit while there is ongoing L0

    // compaction

    L0_FILE_COUNT_LIMIT_STOPS_WITH_ONGOING_COMPACTION,

    WRITE_STALLS_ENUM_MAX,

    // End of all write stall stats

    BYTES_FLUSHED,

    BYTES_INGESTED_ADD_FILE,

    INGESTED_NUM_FILES_TOTAL,

    INGESTED_LEVEL0_NUM_FILES_TOTAL,

    INGESTED_NUM_KEYS_TOTAL,

    INTERNAL_CF_STATS_ENUM_MAX,

  };

  enum InternalDBStatsType {

    kIntStatsWalFileBytes,

    kIntStatsWalFileSynced,

    kIntStatsBytesWritten,

    kIntStatsNumKeysWritten,

    kIntStatsWriteDoneByOther,

    kIntStatsWriteDoneBySelf,

    kIntStatsWriteWithWal,

    // TODO(hx235): Currently `kIntStatsWriteStallMicros` only measures

    // "delayed" time of CF-scope write stalls, not including the "stopped" time

    // nor any DB-scope write stalls (e.g, ones triggered by

    // `WriteBufferManager`).

    //

    // However, the word "write stall" includes both "delayed" and "stopped"

    // (see `WriteStallCondition`) and DB-scope writes stalls (see

    // `WriteStallCause`).

    //

    // So we should improve, rename or clarify it

    kIntStatsWriteStallMicros,

    kIntStatsWriteBufferManagerLimitStopsCounts,

    kIntStatsNumMax,

  };

  static const std::map<InternalDBStatsType, DBStatInfo> db_stats_type_to_info;

  InternalStats(int num_levels, SystemClock* clock, ColumnFamilyData* cfd);

  // Per level compaction stats

  struct CompactionOutputsStats {

    uint64_t num_output_records = 0;

    uint64_t bytes_written = 0;

    uint64_t bytes_written_blob = 0;

    uint64_t num_output_files = 0;

    uint64_t num_output_files_blob = 0;

    void Add(const CompactionOutputsStats& stats) {

      this->num_output_records += stats.num_output_records;

      this->bytes_written += stats.bytes_written;

      this->bytes_written_blob += stats.bytes_written_blob;

      this->num_output_files += stats.num_output_files;

      this->num_output_files_blob += stats.num_output_files_blob;

    }

  };

  // Per level compaction stats.  comp_stats_[level] stores the stats for

  // compactions that produced data for the specified "level".

  struct CompactionStats {

    uint64_t micros;

    uint64_t cpu_micros;

    // The number of bytes read from all non-output levels (table files)

    uint64_t bytes_read_non_output_levels;

    // The number of bytes read from the compaction output level (table files)

    uint64_t bytes_read_output_level;

    // The number of bytes read from blob files

    uint64_t bytes_read_blob;

    // Total number of bytes written to table files during compaction

    uint64_t bytes_written;

    // Total number of bytes written to blob files during compaction

    uint64_t bytes_written_blob;

    // Total number of bytes moved to the output level (table files)

    uint64_t bytes_moved;

    // The number of compaction input files in all non-output levels (table

    // files)

    int num_input_files_in_non_output_levels;

    // The number of compaction input files in the output level (table files)

    int num_input_files_in_output_level;

    // The number of compaction output files (table files)

    int num_output_files;

    // The number of compaction output files (blob files)

    int num_output_files_blob;

    // Total incoming entries during compaction between levels N and N+1

    uint64_t num_input_records;

    // Accumulated diff number of entries

    // (num input entries - num output entries) for compaction levels N and N+1

    uint64_t num_dropped_records;

    // Total output entries from compaction

    uint64_t num_output_records;

    // Number of compactions done

    int count;

    // Number of compactions done per CompactionReason

    int counts[static_cast<int>(CompactionReason::kNumOfReasons)]{};

    explicit CompactionStats()

        : micros(0),

          cpu_micros(0),

          bytes_read_non_output_levels(0),

          bytes_read_output_level(0),

          bytes_read_blob(0),

          bytes_written(0),

          bytes_written_blob(0),

          bytes_moved(0),

          num_input_files_in_non_output_levels(0),

          num_input_files_in_output_level(0),

          num_output_files(0),

          num_output_files_blob(0),

          num_input_records(0),

          num_dropped_records(0),

          num_output_records(0),

          count(0) {

      int num_of_reasons = static_cast<int>(CompactionReason::kNumOfReasons);

      for (int i = 0; i < num_of_reasons; i++) {

        counts[i] = 0;

      }

    }

    explicit CompactionStats(CompactionReason reason, int c)

        : micros(0),

          cpu_micros(0),

          bytes_read_non_output_levels(0),

          bytes_read_output_level(0),

          bytes_read_blob(0),

          bytes_written(0),

          bytes_written_blob(0),

          bytes_moved(0),

          num_input_files_in_non_output_levels(0),

          num_input_files_in_output_level(0),

          num_output_files(0),

          num_output_files_blob(0),

          num_input_records(0),

          num_dropped_records(0),

          num_output_records(0),

          count(c) {

      int num_of_reasons = static_cast<int>(CompactionReason::kNumOfReasons);

      for (int i = 0; i < num_of_reasons; i++) {

        counts[i] = 0;

      }

      int r = static_cast<int>(reason);

      if (r >= 0 && r < num_of_reasons) {

        counts[r] = c;

      } else {

        count = 0;

      }

    }

    CompactionStats(const CompactionStats& c)

        : micros(c.micros),

          cpu_micros(c.cpu_micros),

          bytes_read_non_output_levels(c.bytes_read_non_output_levels),

          bytes_read_output_level(c.bytes_read_output_level),

          bytes_read_blob(c.bytes_read_blob),

          bytes_written(c.bytes_written),

          bytes_written_blob(c.bytes_written_blob),

          bytes_moved(c.bytes_moved),

          num_input_files_in_non_output_levels(

              c.num_input_files_in_non_output_levels),

          num_input_files_in_output_level(c.num_input_files_in_output_level),

          num_output_files(c.num_output_files),

          num_output_files_blob(c.num_output_files_blob),

          num_input_records(c.num_input_records),

          num_dropped_records(c.num_dropped_records),

          num_output_records(c.num_output_records),

          count(c.count) {

      int num_of_reasons = static_cast<int>(CompactionReason::kNumOfReasons);

      for (int i = 0; i < num_of_reasons; i++) {

        counts[i] = c.counts[i];

      }

    }

    CompactionStats& operator=(const CompactionStats& c) {

      micros = c.micros;

      cpu_micros = c.cpu_micros;

      bytes_read_non_output_levels = c.bytes_read_non_output_levels;

      bytes_read_output_level = c.bytes_read_output_level;

      bytes_read_blob = c.bytes_read_blob;

      bytes_written = c.bytes_written;

      bytes_written_blob = c.bytes_written_blob;

      bytes_moved = c.bytes_moved;

      num_input_files_in_non_output_levels =

          c.num_input_files_in_non_output_levels;

      num_input_files_in_output_level = c.num_input_files_in_output_level;

      num_output_files = c.num_output_files;

      num_output_files_blob = c.num_output_files_blob;

      num_input_records = c.num_input_records;

      num_dropped_records = c.num_dropped_records;

      num_output_records = c.num_output_records;

      count = c.count;

      int num_of_reasons = static_cast<int>(CompactionReason::kNumOfReasons);

      for (int i = 0; i < num_of_reasons; i++) {

        counts[i] = c.counts[i];

      }

      return *this;

    }

    void Clear() {

      this->micros = 0;

      this->cpu_micros = 0;

      this->bytes_read_non_output_levels = 0;

      this->bytes_read_output_level = 0;

      this->bytes_read_blob = 0;

      this->bytes_written = 0;

      this->bytes_written_blob = 0;

      this->bytes_moved = 0;

      this->num_input_files_in_non_output_levels = 0;

      this->num_input_files_in_output_level = 0;

      this->num_output_files = 0;

      this->num_output_files_blob = 0;

      this->num_input_records = 0;

      this->num_dropped_records = 0;

      this->num_output_records = 0;

      this->count = 0;

      int num_of_reasons = static_cast<int>(CompactionReason::kNumOfReasons);

      for (int i = 0; i < num_of_reasons; i++) {

        counts[i] = 0;

      }

    }

    void Add(const CompactionStats& c) {

      this->micros += c.micros;

      this->cpu_micros += c.cpu_micros;

      this->bytes_read_non_output_levels += c.bytes_read_non_output_levels;

      this->bytes_read_output_level += c.bytes_read_output_level;

      this->bytes_read_blob += c.bytes_read_blob;

      this->bytes_written += c.bytes_written;

      this->bytes_written_blob += c.bytes_written_blob;

      this->bytes_moved += c.bytes_moved;

      this->num_input_files_in_non_output_levels +=

          c.num_input_files_in_non_output_levels;

      this->num_input_files_in_output_level +=

          c.num_input_files_in_output_level;

      this->num_output_files += c.num_output_files;

      this->num_output_files_blob += c.num_output_files_blob;

      this->num_input_records += c.num_input_records;

      this->num_dropped_records += c.num_dropped_records;

      this->num_output_records += c.num_output_records;

      this->count += c.count;

      int num_of_reasons = static_cast<int>(CompactionReason::kNumOfReasons);

      for (int i = 0; i < num_of_reasons; i++) {

        counts[i] += c.counts[i];

      }

    }

    void Add(const CompactionOutputsStats& stats) {

      this->num_output_files += static_cast<int>(stats.num_output_files);

      this->num_output_records += stats.num_output_records;

      this->bytes_written += stats.bytes_written;

      this->bytes_written_blob += stats.bytes_written_blob;

      this->num_output_files_blob +=

          static_cast<int>(stats.num_output_files_blob);

    }

    void Subtract(const CompactionStats& c) {

      this->micros -= c.micros;

      this->cpu_micros -= c.cpu_micros;

      this->bytes_read_non_output_levels -= c.bytes_read_non_output_levels;

      this->bytes_read_output_level -= c.bytes_read_output_level;

      this->bytes_read_blob -= c.bytes_read_blob;

      this->bytes_written -= c.bytes_written;

      this->bytes_written_blob -= c.bytes_written_blob;

      this->bytes_moved -= c.bytes_moved;

      this->num_input_files_in_non_output_levels -=

          c.num_input_files_in_non_output_levels;

      this->num_input_files_in_output_level -=

          c.num_input_files_in_output_level;

      this->num_output_files -= c.num_output_files;

      this->num_output_files_blob -= c.num_output_files_blob;

      this->num_input_records -= c.num_input_records;

      this->num_dropped_records -= c.num_dropped_records;

      this->num_output_records -= c.num_output_records;

      this->count -= c.count;

      int num_of_reasons = static_cast<int>(CompactionReason::kNumOfReasons);

      for (int i = 0; i < num_of_reasons; i++) {

        counts[i] -= c.counts[i];

      }

    }

    void ResetCompactionReason(CompactionReason reason) {

      int num_of_reasons = static_cast<int>(CompactionReason::kNumOfReasons);

      assert(count == 1);  // only support update one compaction reason

      for (int i = 0; i < num_of_reasons; i++) {

        counts[i] = 0;

      }

      int r = static_cast<int>(reason);

      assert(r >= 0 && r < num_of_reasons);

      counts[r] = 1;

    }

  };

  // Compaction stats, for per_key_placement compaction, it includes 2 levels

  // stats: the last level and the penultimate level.

  struct CompactionStatsFull {

    // the stats for the target primary output level

    CompactionStats stats;

    // stats for penultimate level output if exist

    bool has_penultimate_level_output = false;

    CompactionStats penultimate_level_stats;

    explicit CompactionStatsFull() : stats(), penultimate_level_stats() {}

    explicit CompactionStatsFull(CompactionReason reason, int c)

        : stats(reason, c), penultimate_level_stats(reason, c) {}

    uint64_t TotalBytesWritten() const {

      uint64_t bytes_written = stats.bytes_written + stats.bytes_written_blob;

      if (has_penultimate_level_output) {

        bytes_written += penultimate_level_stats.bytes_written +

                         penultimate_level_stats.bytes_written_blob;

      }

      return bytes_written;

    }

    uint64_t DroppedRecords() {

      uint64_t output_records = stats.num_output_records;

      if (has_penultimate_level_output) {

        output_records += penultimate_level_stats.num_output_records;

      }

      if (stats.num_input_records > output_records) {

        return stats.num_input_records - output_records;

      }

      return 0;

    }

    void SetMicros(uint64_t val) {

      stats.micros = val;

      penultimate_level_stats.micros = val;

    }

    void AddCpuMicros(uint64_t val) {

      stats.cpu_micros += val;

      penultimate_level_stats.cpu_micros += val;

    }

  };

  // For use with CacheEntryStatsCollector

  struct CacheEntryRoleStats {

    uint64_t cache_capacity = 0;

    uint64_t cache_usage = 0;

    size_t table_size = 0;

    size_t occupancy = 0;

    std::string cache_id;

    std::array<uint64_t, kNumCacheEntryRoles> total_charges;

    std::array<size_t, kNumCacheEntryRoles> entry_counts;

    uint32_t collection_count = 0;

    uint32_t copies_of_last_collection = 0;

    uint64_t last_start_time_micros_ = 0;

    uint64_t last_end_time_micros_ = 0;

    uint32_t hash_seed = 0;

    void Clear() {

      // Wipe everything except collection_count

      uint32_t saved_collection_count = collection_count;

      *this = CacheEntryRoleStats();

      collection_count = saved_collection_count;

    }

    void BeginCollection(Cache*, SystemClock*, uint64_t start_time_micros);

    std::function<void(const Slice& key, Cache::ObjectPtr value, size_t charge,

                       const Cache::CacheItemHelper* helper)>

    GetEntryCallback();

    void EndCollection(Cache*, SystemClock*, uint64_t end_time_micros);

    void SkippedCollection();

    std::string ToString(SystemClock* clock) const;

    void ToMap(std::map<std::string, std::string>* values,

               SystemClock* clock) const;

   private:

    uint64_t GetLastDurationMicros() const;

  };

  void Clear() {

    for (int i = 0; i < kIntStatsNumMax; i++) {

      db_stats_[i].store(0);

    }

    for (int i = 0; i < INTERNAL_CF_STATS_ENUM_MAX; i++) {

      cf_stats_count_[i] = 0;

      cf_stats_value_[i] = 0;

    }

    for (auto& comp_stat : comp_stats_) {

      comp_stat.Clear();

    }

    per_key_placement_comp_stats_.Clear();

    for (auto& h : file_read_latency_) {

      h.Clear();

    }

    blob_file_read_latency_.Clear();

    cf_stats_snapshot_.Clear();

    db_stats_snapshot_.Clear();

    bg_error_count_ = 0;

    started_at_ = clock_->NowMicros();

    has_cf_change_since_dump_ = true;

  }

  void AddCompactionStats(int level, Env::Priority thread_pri,

                          const CompactionStats& stats) {

    comp_stats_[level].Add(stats);

    comp_stats_by_pri_[thread_pri].Add(stats);

  }

  void AddCompactionStats(int level, Env::Priority thread_pri,

                          const CompactionStatsFull& comp_stats_full) {

    AddCompactionStats(level, thread_pri, comp_stats_full.stats);

    if (comp_stats_full.has_penultimate_level_output) {

      per_key_placement_comp_stats_.Add(

          comp_stats_full.penultimate_level_stats);

    }

  }

  void IncBytesMoved(int level, uint64_t amount) {

    comp_stats_[level].bytes_moved += amount;

  }

  void AddCFStats(InternalCFStatsType type, uint64_t value) {

    has_cf_change_since_dump_ = true;

    cf_stats_value_[type] += value;

    ++cf_stats_count_[type];

  }

  void AddDBStats(InternalDBStatsType type, uint64_t value,

                  bool concurrent = false) {

    auto& v = db_stats_[type];

    if (concurrent) {

      v.fetch_add(value, std::memory_order_relaxed);

    } else {

      v.store(v.load(std::memory_order_relaxed) + value,

              std::memory_order_relaxed);

    }

  }

  uint64_t GetDBStats(InternalDBStatsType type) {

    return db_stats_[type].load(std::memory_order_relaxed);

  }

  HistogramImpl* GetFileReadHist(int level) {

    return &file_read_latency_[level];

  }

  HistogramImpl* GetBlobFileReadHist() { return &blob_file_read_latency_; }

  uint64_t GetBackgroundErrorCount() const { return bg_error_count_; }

  uint64_t BumpAndGetBackgroundErrorCount() { return ++bg_error_count_; }

  bool GetStringProperty(const DBPropertyInfo& property_info,

                         const Slice& property, std::string* value);

  bool GetMapProperty(const DBPropertyInfo& property_info,

                      const Slice& property,

                      std::map<std::string, std::string>* value);

  bool GetIntProperty(const DBPropertyInfo& property_info, uint64_t* value,

                      DBImpl* db);

  bool GetIntPropertyOutOfMutex(const DBPropertyInfo& property_info,

                                Version* version, uint64_t* value);

  // Unless there is a recent enough collection of the stats, collect and

  // saved new cache entry stats. If `foreground`, require data to be more

  // recent to skip re-collection.

  //

  // This should only be called while NOT holding the DB mutex.

  void CollectCacheEntryStats(bool foreground);

  const uint64_t* TEST_GetCFStatsValue() const { return cf_stats_value_; }

  const std::vector<CompactionStats>& TEST_GetCompactionStats() const {

    return comp_stats_;

  }

  const CompactionStats& TEST_GetPerKeyPlacementCompactionStats() const {

    return per_key_placement_comp_stats_;

  }

  void TEST_GetCacheEntryRoleStats(CacheEntryRoleStats* stats, bool foreground);

  // Store a mapping from the user-facing DB::Properties string to our

  // DBPropertyInfo struct used internally for retrieving properties.

  static const UnorderedMap<std::string, DBPropertyInfo> ppt_name_to_info;

  static const std::string kPeriodicCFStats;

 private:

  void DumpDBMapStats(std::map<std::string, std::string>* db_stats);

  void DumpDBStats(std::string* value);

  void DumpDBMapStatsWriteStall(std::map<std::string, std::string>* value);

  void DumpDBStatsWriteStall(std::string* value);

  void DumpCFMapStats(std::map<std::string, std::string>* cf_stats);

  void DumpCFMapStats(

      const VersionStorageInfo* vstorage,

      std::map<int, std::map<LevelStatType, double>>* level_stats,

      CompactionStats* compaction_stats_sum);

  void DumpCFMapStatsByPriority(

      std::map<int, std::map<LevelStatType, double>>* priorities_stats);

  void DumpCFStats(std::string* value);

  // if is_periodic = true, it is an internal call by RocksDB periodically to

  // dump the status.

  void DumpCFStatsNoFileHistogram(bool is_periodic, std::string* value);

  // if is_periodic = true, it is an internal call by RocksDB periodically to

  // dump the status.

  void DumpCFFileHistogram(std::string* value);

  void DumpCFMapStatsWriteStall(std::map<std::string, std::string>* value);

  void DumpCFStatsWriteStall(std::string* value,

                             uint64_t* total_stall_count = nullptr);

  Cache* GetBlockCacheForStats();

  Cache* GetBlobCacheForStats();

  // Per-DB stats

  std::atomic<uint64_t> db_stats_[kIntStatsNumMax];

  // Per-ColumnFamily stats

  uint64_t cf_stats_value_[INTERNAL_CF_STATS_ENUM_MAX];

  uint64_t cf_stats_count_[INTERNAL_CF_STATS_ENUM_MAX];

  // Initialize/reference the collector in constructor so that we don't need

  // additional synchronization in InternalStats, relying on synchronization

  // in CacheEntryStatsCollector::GetStats. This collector is pinned in cache

  // (through a shared_ptr) so that it does not get immediately ejected from

  // a full cache, which would force a re-scan on the next GetStats.

  std::shared_ptr<CacheEntryStatsCollector<CacheEntryRoleStats>>

      cache_entry_stats_collector_;

  // Per-ColumnFamily/level compaction stats

  std::vector<CompactionStats> comp_stats_;

  std::vector<CompactionStats> comp_stats_by_pri_;

  CompactionStats per_key_placement_comp_stats_;

  std::vector<HistogramImpl> file_read_latency_;

  HistogramImpl blob_file_read_latency_;

  bool has_cf_change_since_dump_;

  // How many periods of no change since the last time stats are dumped for

  // a periodic dump.

  int no_cf_change_period_since_dump_ = 0;

  uint64_t last_histogram_num = std::numeric_limits<uint64_t>::max();

  static const int kMaxNoChangePeriodSinceDump;

  // Used to compute per-interval statistics

  struct CFStatsSnapshot {

    // ColumnFamily-level stats

    CompactionStats comp_stats;

    uint64_t ingest_bytes_flush;  // Bytes written to L0 (Flush)

    uint64_t stall_count;         // Total counts of CF-scope write stalls

    // Stats from compaction jobs - bytes written, bytes read, duration.

    uint64_t compact_bytes_write;

    uint64_t compact_bytes_read;

    uint64_t compact_micros;

    double seconds_up;

    // AddFile specific stats

    uint64_t ingest_bytes_addfile;     // Total Bytes ingested

    uint64_t ingest_files_addfile;     // Total number of files ingested

    uint64_t ingest_l0_files_addfile;  // Total number of files ingested to L0

    uint64_t ingest_keys_addfile;      // Total number of keys ingested

    CFStatsSnapshot()

        : ingest_bytes_flush(0),

          stall_count(0),

          compact_bytes_write(0),

          compact_bytes_read(0),

          compact_micros(0),

          seconds_up(0),

          ingest_bytes_addfile(0),

          ingest_files_addfile(0),

          ingest_l0_files_addfile(0),

          ingest_keys_addfile(0) {}

    void Clear() {

      comp_stats.Clear();

      ingest_bytes_flush = 0;

      stall_count = 0;

      compact_bytes_write = 0;

      compact_bytes_read = 0;

      compact_micros = 0;

      seconds_up = 0;

      ingest_bytes_addfile = 0;

      ingest_files_addfile = 0;

      ingest_l0_files_addfile = 0;

      ingest_keys_addfile = 0;

    }

  } cf_stats_snapshot_;

  struct DBStatsSnapshot {

    // DB-level stats

    uint64_t ingest_bytes;    // Bytes written by user

    uint64_t wal_bytes;       // Bytes written to WAL

    uint64_t wal_synced;      // Number of times WAL is synced

    uint64_t write_with_wal;  // Number of writes that request WAL

    // These count the number of writes processed by the calling thread or

    // another thread.

    uint64_t write_other;

    uint64_t write_self;

    // Total number of keys written. write_self and write_other measure number

    // of write requests written, Each of the write request can contain updates

    // to multiple keys. num_keys_written is total number of keys updated by all

    // those writes.

    uint64_t num_keys_written;

    // Total time writes delayed by stalls.

    uint64_t write_stall_micros;

    double seconds_up;

    DBStatsSnapshot()

        : ingest_bytes(0),

          wal_bytes(0),

          wal_synced(0),

          write_with_wal(0),

          write_other(0),

          write_self(0),

          num_keys_written(0),

          write_stall_micros(0),

          seconds_up(0) {}

    void Clear() {

      ingest_bytes = 0;

      wal_bytes = 0;

      wal_synced = 0;

      write_with_wal = 0;

      write_other = 0;

      write_self = 0;

      num_keys_written = 0;

      write_stall_micros = 0;

      seconds_up = 0;

    }

  } db_stats_snapshot_;

  // Handler functions for getting property values. They use "value" as a value-

  // result argument, and return true upon successfully setting "value".

  bool HandleNumFilesAtLevel(std::string* value, Slice suffix);

  bool HandleCompressionRatioAtLevelPrefix(std::string* value, Slice suffix);

  bool HandleLevelStats(std::string* value, Slice suffix);

  bool HandleStats(std::string* value, Slice suffix);

  bool HandleCFMapStats(std::map<std::string, std::string>* compaction_stats,

                        Slice suffix);

  bool HandleCFStats(std::string* value, Slice suffix);

  bool HandleCFStatsNoFileHistogram(std::string* value, Slice suffix);

  bool HandleCFFileHistogram(std::string* value, Slice suffix);

  bool HandleCFStatsPeriodic(std::string* value, Slice suffix);

  bool HandleCFWriteStallStats(std::string* value, Slice suffix);

  bool HandleCFWriteStallStatsMap(std::map<std::string, std::string>* values,

                                  Slice suffix);

  bool HandleDBMapStats(std::map<std::string, std::string>* compaction_stats,

                        Slice suffix);

  bool HandleDBStats(std::string* value, Slice suffix);

  bool HandleDBWriteStallStats(std::string* value, Slice suffix);

  bool HandleDBWriteStallStatsMap(std::map<std::string, std::string>* values,

                                  Slice suffix);

  bool HandleSsTables(std::string* value, Slice suffix);

  bool HandleAggregatedTableProperties(std::string* value, Slice suffix);

  bool HandleAggregatedTablePropertiesAtLevel(std::string* value, Slice suffix);

  bool HandleAggregatedTablePropertiesMap(

      std::map<std::string, std::string>* values, Slice suffix);

  bool HandleAggregatedTablePropertiesAtLevelMap(

      std::map<std::string, std::string>* values, Slice suffix);

  bool HandleNumImmutableMemTable(uint64_t* value, DBImpl* db,

                                  Version* version);

  bool HandleNumImmutableMemTableFlushed(uint64_t* value, DBImpl* db,

                                         Version* version);

  bool HandleMemTableFlushPending(uint64_t* value, DBImpl* db,

                                  Version* version);

  bool HandleNumRunningFlushes(uint64_t* value, DBImpl* db, Version* version);

  bool HandleCompactionPending(uint64_t* value, DBImpl* db, Version* version);

  bool HandleNumRunningCompactions(uint64_t* value, DBImpl* db,

                                   Version* version);

  bool HandleBackgroundErrors(uint64_t* value, DBImpl* db, Version* version);

  bool HandleCurSizeActiveMemTable(uint64_t* value, DBImpl* db,

                                   Version* version);

  bool HandleCurSizeAllMemTables(uint64_t* value, DBImpl* db, Version* version);

  bool HandleSizeAllMemTables(uint64_t* value, DBImpl* db, Version* version);

  bool HandleNumEntriesActiveMemTable(uint64_t* value, DBImpl* db,

                                      Version* version);

  bool HandleNumEntriesImmMemTables(uint64_t* value, DBImpl* db,

                                    Version* version);

  bool HandleNumDeletesActiveMemTable(uint64_t* value, DBImpl* db,

                                      Version* version);

  bool HandleNumDeletesImmMemTables(uint64_t* value, DBImpl* db,

                                    Version* version);

  bool HandleEstimateNumKeys(uint64_t* value, DBImpl* db, Version* version);

  bool HandleNumSnapshots(uint64_t* value, DBImpl* db, Version* version);

  bool HandleOldestSnapshotTime(uint64_t* value, DBImpl* db, Version* version);

  bool HandleOldestSnapshotSequence(uint64_t* value, DBImpl* db,

                                    Version* version);

  bool HandleNumLiveVersions(uint64_t* value, DBImpl* db, Version* version);

  bool HandleCurrentSuperVersionNumber(uint64_t* value, DBImpl* db,

                                       Version* version);

  bool HandleIsFileDeletionsEnabled(uint64_t* value, DBImpl* db,

                                    Version* version);

  bool HandleBaseLevel(uint64_t* value, DBImpl* db, Version* version);

  bool HandleTotalSstFilesSize(uint64_t* value, DBImpl* db, Version* version);

  bool HandleLiveSstFilesSize(uint64_t* value, DBImpl* db, Version* version);

  bool HandleObsoleteSstFilesSize(uint64_t* value, DBImpl* db,

                                  Version* version);

  bool HandleEstimatePendingCompactionBytes(uint64_t* value, DBImpl* db,

                                            Version* version);

  bool HandleEstimateTableReadersMem(uint64_t* value, DBImpl* db,

                                     Version* version);

  bool HandleEstimateLiveDataSize(uint64_t* value, DBImpl* db,

                                  Version* version);

  bool HandleMinLogNumberToKeep(uint64_t* value, DBImpl* db, Version* version);

  bool HandleMinObsoleteSstNumberToKeep(uint64_t* value, DBImpl* db,

                                        Version* version);

  bool HandleActualDelayedWriteRate(uint64_t* value, DBImpl* db,

                                    Version* version);

  bool HandleIsWriteStopped(uint64_t* value, DBImpl* db, Version* version);

  bool HandleEstimateOldestKeyTime(uint64_t* value, DBImpl* db,

                                   Version* version);

  bool HandleBlockCacheCapacity(uint64_t* value, DBImpl* db, Version* version);

  bool HandleBlockCacheUsage(uint64_t* value, DBImpl* db, Version* version);

  bool HandleBlockCachePinnedUsage(uint64_t* value, DBImpl* db,

                                   Version* version);

  bool HandleBlockCacheEntryStatsInternal(std::string* value, bool fast);

  bool HandleBlockCacheEntryStatsMapInternal(

      std::map<std::string, std::string>* values, bool fast);

  bool HandleBlockCacheEntryStats(std::string* value, Slice suffix);

  bool HandleBlockCacheEntryStatsMap(std::map<std::string, std::string>* values,

                                     Slice suffix);

  bool HandleFastBlockCacheEntryStats(std::string* value, Slice suffix);

  bool HandleFastBlockCacheEntryStatsMap(

      std::map<std::string, std::string>* values, Slice suffix);

  bool HandleLiveSstFilesSizeAtTemperature(std::string* value, Slice suffix);

  bool HandleNumBlobFiles(uint64_t* value, DBImpl* db, Version* version);

  bool HandleBlobStats(std::string* value, Slice suffix);

  bool HandleTotalBlobFileSize(uint64_t* value, DBImpl* db, Version* version);

  bool HandleLiveBlobFileSize(uint64_t* value, DBImpl* db, Version* version);

  bool HandleLiveBlobFileGarbageSize(uint64_t* value, DBImpl* db,

                                     Version* version);

  bool HandleBlobCacheCapacity(uint64_t* value, DBImpl* db, Version* version);

  bool HandleBlobCacheUsage(uint64_t* value, DBImpl* db, Version* version);

  bool HandleBlobCachePinnedUsage(uint64_t* value, DBImpl* db,

                                  Version* version);

  // Total number of background errors encountered. Every time a flush task

  // or compaction task fails, this counter is incremented. The failure can

  // be caused by any possible reason, including file system errors, out of

  // resources, or input file corruption. Failing when retrying the same flush

  // or compaction will cause the counter to increase too.

  uint64_t bg_error_count_;

  const int number_levels_;

  SystemClock* clock_;

  ColumnFamilyData* cfd_;

  uint64_t started_at_;

};

// IntPropertyAggregator aggregates an integer property across all column

// families.

class IntPropertyAggregator {

 public:

  IntPropertyAggregator() {}

  virtual ~IntPropertyAggregator() {}

  IntPropertyAggregator(const IntPropertyAggregator&) = delete;

  void operator=(const IntPropertyAggregator&) = delete;

  // Add a column family's property value to the aggregator.

  virtual void Add(ColumnFamilyData* cfd, uint64_t value) = 0;

  // Get the aggregated value.

  virtual uint64_t Aggregate() const = 0;

};

std::unique_ptr<IntPropertyAggregator> CreateIntPropertyAggregator(

    const Slice& property);

}  // namespace ROCKSDB_NAMESPACE