Adding upstream version 14.2.21.upstream/14.2.21upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1756 insertions, 0 deletions

diff --git a/src/rocksdb/db/db_impl.h b/src/rocksdb/db/db_impl.h
new file mode 100644
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--- /dev/null
+++ b/src/rocksdb/db/db_impl.h
@@ -0,0 +1,1756 @@
+//  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 <atomic>
+#include <deque>
+#include <functional>
+#include <limits>
+#include <list>
+#include <map>
+#include <set>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include "db/column_family.h"
+#include "db/compaction_job.h"
+#include "db/dbformat.h"
+#include "db/error_handler.h"
+#include "db/event_helpers.h"
+#include "db/external_sst_file_ingestion_job.h"
+#include "db/flush_job.h"
+#include "db/flush_scheduler.h"
+#include "db/internal_stats.h"
+#include "db/log_writer.h"
+#include "db/logs_with_prep_tracker.h"
+#include "db/pre_release_callback.h"
+#include "db/range_del_aggregator.h"
+#include "db/read_callback.h"
+#include "db/snapshot_checker.h"
+#include "db/snapshot_impl.h"
+#include "db/version_edit.h"
+#include "db/wal_manager.h"
+#include "db/write_controller.h"
+#include "db/write_thread.h"
+#include "memtable_list.h"
+#include "monitoring/instrumented_mutex.h"
+#include "options/db_options.h"
+#include "port/port.h"
+#include "rocksdb/db.h"
+#include "rocksdb/env.h"
+#include "rocksdb/memtablerep.h"
+#include "rocksdb/status.h"
+#include "rocksdb/trace_reader_writer.h"
+#include "rocksdb/transaction_log.h"
+#include "rocksdb/write_buffer_manager.h"
+#include "table/scoped_arena_iterator.h"
+#include "util/autovector.h"
+#include "util/event_logger.h"
+#include "util/hash.h"
+#include "util/repeatable_thread.h"
+#include "util/stop_watch.h"
+#include "util/thread_local.h"
+#include "util/trace_replay.h"
+
+namespace rocksdb {
+
+class Arena;
+class ArenaWrappedDBIter;
+class InMemoryStatsHistoryIterator;
+class MemTable;
+class TableCache;
+class TaskLimiterToken;
+class Version;
+class VersionEdit;
+class VersionSet;
+class WriteCallback;
+struct JobContext;
+struct ExternalSstFileInfo;
+struct MemTableInfo;
+
+class DBImpl : public DB {
+ public:
+  DBImpl(const DBOptions& options, const std::string& dbname,
+         const bool seq_per_batch = false, const bool batch_per_txn = true);
+  virtual ~DBImpl();
+
+  using DB::Resume;
+  virtual Status Resume() override;
+
+  // Implementations of the DB interface
+  using DB::Put;
+  virtual Status Put(const WriteOptions& options,
+                     ColumnFamilyHandle* column_family, const Slice& key,
+                     const Slice& value) override;
+  using DB::Merge;
+  virtual Status Merge(const WriteOptions& options,
+                       ColumnFamilyHandle* column_family, const Slice& key,
+                       const Slice& value) override;
+  using DB::Delete;
+  virtual Status Delete(const WriteOptions& options,
+                        ColumnFamilyHandle* column_family,
+                        const Slice& key) override;
+  using DB::SingleDelete;
+  virtual Status SingleDelete(const WriteOptions& options,
+                              ColumnFamilyHandle* column_family,
+                              const Slice& key) override;
+  using DB::Write;
+  virtual Status Write(const WriteOptions& options,
+                       WriteBatch* updates) override;
+
+  using DB::Get;
+  virtual Status Get(const ReadOptions& options,
+                     ColumnFamilyHandle* column_family, const Slice& key,
+                     PinnableSlice* value) override;
+
+  // Function that Get and KeyMayExist call with no_io true or false
+  // Note: 'value_found' from KeyMayExist propagates here
+  Status GetImpl(const ReadOptions& options, ColumnFamilyHandle* column_family,
+                 const Slice& key, PinnableSlice* value,
+                 bool* value_found = nullptr, ReadCallback* callback = nullptr,
+                 bool* is_blob_index = nullptr);
+
+  using DB::MultiGet;
+  virtual std::vector<Status> MultiGet(
+      const ReadOptions& options,
+      const std::vector<ColumnFamilyHandle*>& column_family,
+      const std::vector<Slice>& keys,
+      std::vector<std::string>* values) override;
+
+  virtual Status CreateColumnFamily(const ColumnFamilyOptions& cf_options,
+                                    const std::string& column_family,
+                                    ColumnFamilyHandle** handle) override;
+  virtual Status CreateColumnFamilies(
+      const ColumnFamilyOptions& cf_options,
+      const std::vector<std::string>& column_family_names,
+      std::vector<ColumnFamilyHandle*>* handles) override;
+  virtual Status CreateColumnFamilies(
+      const std::vector<ColumnFamilyDescriptor>& column_families,
+      std::vector<ColumnFamilyHandle*>* handles) override;
+  virtual Status DropColumnFamily(ColumnFamilyHandle* column_family) override;
+  virtual Status DropColumnFamilies(
+      const std::vector<ColumnFamilyHandle*>& column_families) override;
+
+  // Returns false if key doesn't exist in the database and true if it may.
+  // If value_found is not passed in as null, then return the value if found in
+  // memory. On return, if value was found, then value_found will be set to true
+  // , otherwise false.
+  using DB::KeyMayExist;
+  virtual bool KeyMayExist(const ReadOptions& options,
+                           ColumnFamilyHandle* column_family, const Slice& key,
+                           std::string* value,
+                           bool* value_found = nullptr) override;
+
+  using DB::NewIterator;
+  virtual Iterator* NewIterator(const ReadOptions& options,
+                                ColumnFamilyHandle* column_family) override;
+  virtual Status NewIterators(
+      const ReadOptions& options,
+      const std::vector<ColumnFamilyHandle*>& column_families,
+      std::vector<Iterator*>* iterators) override;
+  ArenaWrappedDBIter* NewIteratorImpl(const ReadOptions& options,
+                                      ColumnFamilyData* cfd,
+                                      SequenceNumber snapshot,
+                                      ReadCallback* read_callback,
+                                      bool allow_blob = false,
+                                      bool allow_refresh = true);
+
+  virtual const Snapshot* GetSnapshot() override;
+  virtual void ReleaseSnapshot(const Snapshot* snapshot) override;
+  using DB::GetProperty;
+  virtual bool GetProperty(ColumnFamilyHandle* column_family,
+                           const Slice& property, std::string* value) override;
+  using DB::GetMapProperty;
+  virtual bool GetMapProperty(
+      ColumnFamilyHandle* column_family, const Slice& property,
+      std::map<std::string, std::string>* value) override;
+  using DB::GetIntProperty;
+  virtual bool GetIntProperty(ColumnFamilyHandle* column_family,
+                              const Slice& property, uint64_t* value) override;
+  using DB::GetAggregatedIntProperty;
+  virtual bool GetAggregatedIntProperty(const Slice& property,
+                                        uint64_t* aggregated_value) override;
+  using DB::GetApproximateSizes;
+  virtual void GetApproximateSizes(
+      ColumnFamilyHandle* column_family, const Range* range, int n,
+      uint64_t* sizes, uint8_t include_flags = INCLUDE_FILES) override;
+  using DB::GetApproximateMemTableStats;
+  virtual void GetApproximateMemTableStats(ColumnFamilyHandle* column_family,
+                                           const Range& range,
+                                           uint64_t* const count,
+                                           uint64_t* const size) override;
+  using DB::CompactRange;
+  virtual Status CompactRange(const CompactRangeOptions& options,
+                              ColumnFamilyHandle* column_family,
+                              const Slice* begin, const Slice* end) override;
+
+  using DB::CompactFiles;
+  virtual Status CompactFiles(
+      const CompactionOptions& compact_options,
+      ColumnFamilyHandle* column_family,
+      const std::vector<std::string>& input_file_names, const int output_level,
+      const int output_path_id = -1,
+      std::vector<std::string>* const output_file_names = nullptr,
+      CompactionJobInfo* compaction_job_info = nullptr) override;
+
+  virtual Status PauseBackgroundWork() override;
+  virtual Status ContinueBackgroundWork() override;
+
+  virtual Status EnableAutoCompaction(
+      const std::vector<ColumnFamilyHandle*>& column_family_handles) override;
+
+  using DB::SetOptions;
+  Status SetOptions(
+      ColumnFamilyHandle* column_family,
+      const std::unordered_map<std::string, std::string>& options_map) override;
+
+  virtual Status SetDBOptions(
+      const std::unordered_map<std::string, std::string>& options_map) override;
+
+  using DB::NumberLevels;
+  virtual int NumberLevels(ColumnFamilyHandle* column_family) override;
+  using DB::MaxMemCompactionLevel;
+  virtual int MaxMemCompactionLevel(ColumnFamilyHandle* column_family) override;
+  using DB::Level0StopWriteTrigger;
+  virtual int Level0StopWriteTrigger(
+      ColumnFamilyHandle* column_family) override;
+  virtual const std::string& GetName() const override;
+  virtual Env* GetEnv() const override;
+  using DB::GetOptions;
+  virtual Options GetOptions(ColumnFamilyHandle* column_family) const override;
+  using DB::GetDBOptions;
+  virtual DBOptions GetDBOptions() const override;
+  using DB::Flush;
+  virtual Status Flush(const FlushOptions& options,
+                       ColumnFamilyHandle* column_family) override;
+  virtual Status Flush(
+      const FlushOptions& options,
+      const std::vector<ColumnFamilyHandle*>& column_families) override;
+  virtual Status FlushWAL(bool sync) override;
+  bool TEST_WALBufferIsEmpty(bool lock = true);
+  virtual Status SyncWAL() override;
+  virtual Status LockWAL() override;
+  virtual Status UnlockWAL() override;
+
+  virtual SequenceNumber GetLatestSequenceNumber() const override;
+  virtual SequenceNumber GetLastPublishedSequence() const {
+    if (last_seq_same_as_publish_seq_) {
+      return versions_->LastSequence();
+    } else {
+      return versions_->LastPublishedSequence();
+    }
+  }
+  // REQUIRES: joined the main write queue if two_write_queues is disabled, and
+  // the second write queue otherwise.
+  virtual void SetLastPublishedSequence(SequenceNumber seq);
+  // Returns LastSequence in last_seq_same_as_publish_seq_
+  // mode and LastAllocatedSequence otherwise. This is useful when visiblility
+  // depends also on data written to the WAL but not to the memtable.
+  SequenceNumber TEST_GetLastVisibleSequence() const;
+
+  virtual bool SetPreserveDeletesSequenceNumber(SequenceNumber seqnum) override;
+
+#ifndef ROCKSDB_LITE
+  using DB::ResetStats;
+  virtual Status ResetStats() override;
+  virtual Status DisableFileDeletions() override;
+  virtual Status EnableFileDeletions(bool force) override;
+  virtual int IsFileDeletionsEnabled() const;
+  // All the returned filenames start with "/"
+  virtual Status GetLiveFiles(std::vector<std::string>&,
+                              uint64_t* manifest_file_size,
+                              bool flush_memtable = true) override;
+  virtual Status GetSortedWalFiles(VectorLogPtr& files) override;
+
+  virtual Status GetUpdatesSince(
+      SequenceNumber seq_number, std::unique_ptr<TransactionLogIterator>* iter,
+      const TransactionLogIterator::ReadOptions& read_options =
+          TransactionLogIterator::ReadOptions()) override;
+  virtual Status DeleteFile(std::string name) override;
+  Status DeleteFilesInRanges(ColumnFamilyHandle* column_family,
+                             const RangePtr* ranges, size_t n,
+                             bool include_end = true);
+
+  virtual void GetLiveFilesMetaData(
+      std::vector<LiveFileMetaData>* metadata) override;
+
+  // Obtains the meta data of the specified column family of the DB.
+  // Status::NotFound() will be returned if the current DB does not have
+  // any column family match the specified name.
+  // TODO(yhchiang): output parameter is placed in the end in this codebase.
+  virtual void GetColumnFamilyMetaData(ColumnFamilyHandle* column_family,
+                                       ColumnFamilyMetaData* metadata) override;
+
+  Status SuggestCompactRange(ColumnFamilyHandle* column_family,
+                             const Slice* begin, const Slice* end) override;
+
+  Status PromoteL0(ColumnFamilyHandle* column_family,
+                   int target_level) override;
+
+  // Similar to Write() but will call the callback once on the single write
+  // thread to determine whether it is safe to perform the write.
+  virtual Status WriteWithCallback(const WriteOptions& write_options,
+                                   WriteBatch* my_batch,
+                                   WriteCallback* callback);
+
+  // Returns the sequence number that is guaranteed to be smaller than or equal
+  // to the sequence number of any key that could be inserted into the current
+  // memtables. It can then be assumed that any write with a larger(or equal)
+  // sequence number will be present in this memtable or a later memtable.
+  //
+  // If the earliest sequence number could not be determined,
+  // kMaxSequenceNumber will be returned.
+  //
+  // If include_history=true, will also search Memtables in MemTableList
+  // History.
+  SequenceNumber GetEarliestMemTableSequenceNumber(SuperVersion* sv,
+                                                   bool include_history);
+
+  // For a given key, check to see if there are any records for this key
+  // in the memtables, including memtable history.  If cache_only is false,
+  // SST files will also be checked.
+  //
+  // If a key is found, *found_record_for_key will be set to true and
+  // *seq will be set to the stored sequence number for the latest
+  // operation on this key or kMaxSequenceNumber if unknown.
+  // If no key is found, *found_record_for_key will be set to false.
+  //
+  // Note: If cache_only=false, it is possible for *seq to be set to 0 if
+  // the sequence number has been cleared from the record.  If the caller is
+  // holding an active db snapshot, we know the missing sequence must be less
+  // than the snapshot's sequence number (sequence numbers are only cleared
+  // when there are no earlier active snapshots).
+  //
+  // If NotFound is returned and found_record_for_key is set to false, then no
+  // record for this key was found.  If the caller is holding an active db
+  // snapshot, we know that no key could have existing after this snapshot
+  // (since we do not compact keys that have an earlier snapshot).
+  //
+  // Returns OK or NotFound on success,
+  // other status on unexpected error.
+  // TODO(andrewkr): this API need to be aware of range deletion operations
+  Status GetLatestSequenceForKey(SuperVersion* sv, const Slice& key,
+                                 bool cache_only, SequenceNumber* seq,
+                                 bool* found_record_for_key,
+                                 bool* is_blob_index = nullptr);
+
+  using DB::IngestExternalFile;
+  virtual Status IngestExternalFile(
+      ColumnFamilyHandle* column_family,
+      const std::vector<std::string>& external_files,
+      const IngestExternalFileOptions& ingestion_options) override;
+
+  using DB::IngestExternalFiles;
+  virtual Status IngestExternalFiles(
+      const std::vector<IngestExternalFileArg>& args) override;
+
+  virtual Status VerifyChecksum() override;
+
+  using DB::StartTrace;
+  virtual Status StartTrace(
+      const TraceOptions& options,
+      std::unique_ptr<TraceWriter>&& trace_writer) override;
+
+  using DB::EndTrace;
+  virtual Status EndTrace() override;
+  Status TraceIteratorSeek(const uint32_t& cf_id, const Slice& key);
+  Status TraceIteratorSeekForPrev(const uint32_t& cf_id, const Slice& key);
+#endif  // ROCKSDB_LITE
+
+  // Similar to GetSnapshot(), but also lets the db know that this snapshot
+  // will be used for transaction write-conflict checking.  The DB can then
+  // make sure not to compact any keys that would prevent a write-conflict from
+  // being detected.
+  const Snapshot* GetSnapshotForWriteConflictBoundary();
+
+  // checks if all live files exist on file system and that their file sizes
+  // match to our in-memory records
+  virtual Status CheckConsistency();
+
+  virtual Status GetDbIdentity(std::string& identity) const override;
+
+  Status RunManualCompaction(ColumnFamilyData* cfd, int input_level,
+                             int output_level, uint32_t output_path_id,
+                             uint32_t max_subcompactions, const Slice* begin,
+                             const Slice* end, bool exclusive,
+                             bool disallow_trivial_move = false);
+
+  // Return an internal iterator over the current state of the database.
+  // The keys of this iterator are internal keys (see format.h).
+  // The returned iterator should be deleted when no longer needed.
+  InternalIterator* NewInternalIterator(
+      Arena* arena, RangeDelAggregator* range_del_agg, SequenceNumber sequence,
+      ColumnFamilyHandle* column_family = nullptr);
+
+  LogsWithPrepTracker* logs_with_prep_tracker() {
+    return &logs_with_prep_tracker_;
+  }
+
+#ifndef NDEBUG
+  // Extra methods (for testing) that are not in the public DB interface
+  // Implemented in db_impl_debug.cc
+
+  // Compact any files in the named level that overlap [*begin, *end]
+  Status TEST_CompactRange(int level, const Slice* begin, const Slice* end,
+                           ColumnFamilyHandle* column_family = nullptr,
+                           bool disallow_trivial_move = false);
+
+  void TEST_SwitchWAL();
+
+  bool TEST_UnableToReleaseOldestLog() { return unable_to_release_oldest_log_; }
+
+  bool TEST_IsLogGettingFlushed() {
+    return alive_log_files_.begin()->getting_flushed;
+  }
+
+  Status TEST_SwitchMemtable(ColumnFamilyData* cfd = nullptr);
+
+  // Force current memtable contents to be flushed.
+  Status TEST_FlushMemTable(bool wait = true, bool allow_write_stall = false,
+                            ColumnFamilyHandle* cfh = nullptr);
+
+  // Wait for memtable compaction
+  Status TEST_WaitForFlushMemTable(ColumnFamilyHandle* column_family = nullptr);
+
+  // Wait for any compaction
+  // We add a bool parameter to wait for unscheduledCompactions_ == 0, but this
+  // is only for the special test of CancelledCompactions
+  Status TEST_WaitForCompact(bool waitUnscheduled = false);
+
+  // Return the maximum overlapping data (in bytes) at next level for any
+  // file at a level >= 1.
+  int64_t TEST_MaxNextLevelOverlappingBytes(
+      ColumnFamilyHandle* column_family = nullptr);
+
+  // Return the current manifest file no.
+  uint64_t TEST_Current_Manifest_FileNo();
+
+  // Returns the number that'll be assigned to the next file that's created.
+  uint64_t TEST_Current_Next_FileNo();
+
+  // get total level0 file size. Only for testing.
+  uint64_t TEST_GetLevel0TotalSize();
+
+  void TEST_GetFilesMetaData(ColumnFamilyHandle* column_family,
+                             std::vector<std::vector<FileMetaData>>* metadata);
+
+  void TEST_LockMutex();
+
+  void TEST_UnlockMutex();
+
+  // REQUIRES: mutex locked
+  void* TEST_BeginWrite();
+
+  // REQUIRES: mutex locked
+  // pass the pointer that you got from TEST_BeginWrite()
+  void TEST_EndWrite(void* w);
+
+  uint64_t TEST_MaxTotalInMemoryState() const {
+    return max_total_in_memory_state_;
+  }
+
+  size_t TEST_LogsToFreeSize();
+
+  uint64_t TEST_LogfileNumber();
+
+  uint64_t TEST_total_log_size() const { return total_log_size_; }
+
+  // Returns column family name to ImmutableCFOptions map.
+  Status TEST_GetAllImmutableCFOptions(
+      std::unordered_map<std::string, const ImmutableCFOptions*>* iopts_map);
+
+  // Return the lastest MutableCFOptions of a column family
+  Status TEST_GetLatestMutableCFOptions(ColumnFamilyHandle* column_family,
+                                        MutableCFOptions* mutable_cf_options);
+
+  Cache* TEST_table_cache() { return table_cache_.get(); }
+
+  WriteController& TEST_write_controler() { return write_controller_; }
+
+  uint64_t TEST_FindMinLogContainingOutstandingPrep();
+  uint64_t TEST_FindMinPrepLogReferencedByMemTable();
+  size_t TEST_PreparedSectionCompletedSize();
+  size_t TEST_LogsWithPrepSize();
+
+  int TEST_BGCompactionsAllowed() const;
+  int TEST_BGFlushesAllowed() const;
+  size_t TEST_GetWalPreallocateBlockSize(uint64_t write_buffer_size) const;
+  void TEST_WaitForDumpStatsRun(std::function<void()> callback) const;
+  void TEST_WaitForPersistStatsRun(std::function<void()> callback) const;
+  bool TEST_IsPersistentStatsEnabled() const;
+  size_t TEST_EstiamteStatsHistorySize() const;
+
+#endif  // NDEBUG
+
+  struct BGJobLimits {
+    int max_flushes;
+    int max_compactions;
+  };
+  // Returns maximum background flushes and compactions allowed to be scheduled
+  BGJobLimits GetBGJobLimits() const;
+  // Need a static version that can be called during SanitizeOptions().
+  static BGJobLimits GetBGJobLimits(int max_background_flushes,
+                                    int max_background_compactions,
+                                    int max_background_jobs,
+                                    bool parallelize_compactions);
+
+  // move logs pending closing from job_context to the DB queue and
+  // schedule a purge
+  void ScheduleBgLogWriterClose(JobContext* job_context);
+
+  uint64_t MinLogNumberToKeep();
+
+  // Returns the lower bound file number for SSTs that won't be deleted, even if
+  // they're obsolete. This lower bound is used internally to prevent newly
+  // created flush/compaction output files from being deleted before they're
+  // installed. This technique avoids the need for tracking the exact numbers of
+  // files pending creation, although it prevents more files than necessary from
+  // being deleted.
+  uint64_t MinObsoleteSstNumberToKeep();
+
+  // Returns the list of live files in 'live' and the list
+  // of all files in the filesystem in 'candidate_files'.
+  // If force == false and the last call was less than
+  // db_options_.delete_obsolete_files_period_micros microseconds ago,
+  // it will not fill up the job_context
+  void FindObsoleteFiles(JobContext* job_context, bool force,
+                         bool no_full_scan = false);
+
+  // Diffs the files listed in filenames and those that do not
+  // belong to live files are possibly removed. Also, removes all the
+  // files in sst_delete_files and log_delete_files.
+  // It is not necessary to hold the mutex when invoking this method.
+  // If FindObsoleteFiles() was run, we need to also run
+  // PurgeObsoleteFiles(), even if disable_delete_obsolete_files_ is true
+  void PurgeObsoleteFiles(JobContext& background_contet,
+                          bool schedule_only = false);
+
+  void SchedulePurge();
+
+  ColumnFamilyHandle* DefaultColumnFamily() const override;
+
+  const SnapshotList& snapshots() const { return snapshots_; }
+
+  const ImmutableDBOptions& immutable_db_options() const {
+    return immutable_db_options_;
+  }
+
+  void CancelAllBackgroundWork(bool wait);
+
+  // Find Super version and reference it. Based on options, it might return
+  // the thread local cached one.
+  // Call ReturnAndCleanupSuperVersion() when it is no longer needed.
+  SuperVersion* GetAndRefSuperVersion(ColumnFamilyData* cfd);
+
+  // Similar to the previous function but looks up based on a column family id.
+  // nullptr will be returned if this column family no longer exists.
+  // REQUIRED: this function should only be called on the write thread or if the
+  // mutex is held.
+  SuperVersion* GetAndRefSuperVersion(uint32_t column_family_id);
+
+  // Un-reference the super version and clean it up if it is the last reference.
+  void CleanupSuperVersion(SuperVersion* sv);
+
+  // Un-reference the super version and return it to thread local cache if
+  // needed. If it is the last reference of the super version. Clean it up
+  // after un-referencing it.
+  void ReturnAndCleanupSuperVersion(ColumnFamilyData* cfd, SuperVersion* sv);
+
+  // Similar to the previous function but looks up based on a column family id.
+  // nullptr will be returned if this column family no longer exists.
+  // REQUIRED: this function should only be called on the write thread.
+  void ReturnAndCleanupSuperVersion(uint32_t colun_family_id, SuperVersion* sv);
+
+  // REQUIRED: this function should only be called on the write thread or if the
+  // mutex is held.  Return value only valid until next call to this function or
+  // mutex is released.
+  ColumnFamilyHandle* GetColumnFamilyHandle(uint32_t column_family_id);
+
+  // Same as above, should called without mutex held and not on write thread.
+  std::unique_ptr<ColumnFamilyHandle> GetColumnFamilyHandleUnlocked(
+      uint32_t column_family_id);
+
+  // Returns the number of currently running flushes.
+  // REQUIREMENT: mutex_ must be held when calling this function.
+  int num_running_flushes() {
+    mutex_.AssertHeld();
+    return num_running_flushes_;
+  }
+
+  // Returns the number of currently running compactions.
+  // REQUIREMENT: mutex_ must be held when calling this function.
+  int num_running_compactions() {
+    mutex_.AssertHeld();
+    return num_running_compactions_;
+  }
+
+  const WriteController& write_controller() { return write_controller_; }
+
+  InternalIterator* NewInternalIterator(
+      const ReadOptions&, ColumnFamilyData* cfd, SuperVersion* super_version,
+      Arena* arena, RangeDelAggregator* range_del_agg, SequenceNumber sequence);
+
+  // hollow transactions shell used for recovery.
+  // these will then be passed to TransactionDB so that
+  // locks can be reacquired before writing can resume.
+  struct RecoveredTransaction {
+    std::string name_;
+    bool unprepared_;
+
+    struct BatchInfo {
+      uint64_t log_number_;
+      // TODO(lth): For unprepared, the memory usage here can be big for
+      // unprepared transactions. This is only useful for rollbacks, and we
+      // can in theory just keep keyset for that.
+      WriteBatch* batch_;
+      // Number of sub-batches. A new sub-batch is created if txn attempts to
+      // insert a duplicate key,seq to memtable. This is currently used in
+      // WritePreparedTxn/WriteUnpreparedTxn.
+      size_t batch_cnt_;
+    };
+
+    // This maps the seq of the first key in the batch to BatchInfo, which
+    // contains WriteBatch and other information relevant to the batch.
+    //
+    // For WriteUnprepared, batches_ can have size greater than 1, but for
+    // other write policies, it must be of size 1.
+    std::map<SequenceNumber, BatchInfo> batches_;
+
+    explicit RecoveredTransaction(const uint64_t log, const std::string& name,
+                                  WriteBatch* batch, SequenceNumber seq,
+                                  size_t batch_cnt, bool unprepared)
+        : name_(name), unprepared_(unprepared) {
+      batches_[seq] = {log, batch, batch_cnt};
+    }
+
+    ~RecoveredTransaction() {
+      for (auto& it : batches_) {
+        delete it.second.batch_;
+      }
+    }
+
+    void AddBatch(SequenceNumber seq, uint64_t log_number, WriteBatch* batch,
+                  size_t batch_cnt, bool unprepared) {
+      assert(batches_.count(seq) == 0);
+      batches_[seq] = {log_number, batch, batch_cnt};
+      // Prior state must be unprepared, since the prepare batch must be the
+      // last batch.
+      assert(unprepared_);
+      unprepared_ = unprepared;
+    }
+  };
+
+  bool allow_2pc() const { return immutable_db_options_.allow_2pc; }
+
+  std::unordered_map<std::string, RecoveredTransaction*>
+  recovered_transactions() {
+    return recovered_transactions_;
+  }
+
+  RecoveredTransaction* GetRecoveredTransaction(const std::string& name) {
+    auto it = recovered_transactions_.find(name);
+    if (it == recovered_transactions_.end()) {
+      return nullptr;
+    } else {
+      return it->second;
+    }
+  }
+
+  void InsertRecoveredTransaction(const uint64_t log, const std::string& name,
+                                  WriteBatch* batch, SequenceNumber seq,
+                                  size_t batch_cnt, bool unprepared_batch) {
+    // For WriteUnpreparedTxn, InsertRecoveredTransaction is called multiple
+    // times for every unprepared batch encountered during recovery.
+    //
+    // If the transaction is prepared, then the last call to
+    // InsertRecoveredTransaction will have unprepared_batch = false.
+    auto rtxn = recovered_transactions_.find(name);
+    if (rtxn == recovered_transactions_.end()) {
+      recovered_transactions_[name] = new RecoveredTransaction(
+          log, name, batch, seq, batch_cnt, unprepared_batch);
+    } else {
+      rtxn->second->AddBatch(seq, log, batch, batch_cnt, unprepared_batch);
+    }
+    logs_with_prep_tracker_.MarkLogAsContainingPrepSection(log);
+  }
+
+  void DeleteRecoveredTransaction(const std::string& name) {
+    auto it = recovered_transactions_.find(name);
+    assert(it != recovered_transactions_.end());
+    auto* trx = it->second;
+    recovered_transactions_.erase(it);
+    for (const auto& info : trx->batches_) {
+      logs_with_prep_tracker_.MarkLogAsHavingPrepSectionFlushed(
+          info.second.log_number_);
+    }
+    delete trx;
+  }
+
+  void DeleteAllRecoveredTransactions() {
+    for (auto it = recovered_transactions_.begin();
+         it != recovered_transactions_.end(); it++) {
+      delete it->second;
+    }
+    recovered_transactions_.clear();
+  }
+
+  void AddToLogsToFreeQueue(log::Writer* log_writer) {
+    logs_to_free_queue_.push_back(log_writer);
+  }
+
+  void SetSnapshotChecker(SnapshotChecker* snapshot_checker);
+
+  // Fill JobContext with snapshot information needed by flush and compaction.
+  void GetSnapshotContext(JobContext* job_context,
+                          std::vector<SequenceNumber>* snapshot_seqs,
+                          SequenceNumber* earliest_write_conflict_snapshot,
+                          SnapshotChecker** snapshot_checker);
+
+  // Not thread-safe.
+  void SetRecoverableStatePreReleaseCallback(PreReleaseCallback* callback);
+
+  InstrumentedMutex* mutex() { return &mutex_; }
+
+  Status NewDB();
+
+  // This is to be used only by internal rocksdb classes.
+  static Status Open(const DBOptions& db_options, const std::string& name,
+                     const std::vector<ColumnFamilyDescriptor>& column_families,
+                     std::vector<ColumnFamilyHandle*>* handles, DB** dbptr,
+                     const bool seq_per_batch, const bool batch_per_txn);
+
+  virtual Status Close() override;
+
+  static Status CreateAndNewDirectory(Env* env, const std::string& dirname,
+                                      std::unique_ptr<Directory>* directory);
+
+  // Given a time window, return an iterator for accessing stats history
+  Status GetStatsHistory(
+      uint64_t start_time, uint64_t end_time,
+      std::unique_ptr<StatsHistoryIterator>* stats_iterator) override;
+
+  // find stats map from stats_history_ with smallest timestamp in
+  // the range of [start_time, end_time)
+  bool FindStatsByTime(uint64_t start_time, uint64_t end_time,
+                       uint64_t* new_time,
+                       std::map<std::string, uint64_t>* stats_map);
+
+ protected:
+  Env* const env_;
+  const std::string dbname_;
+  std::unique_ptr<VersionSet> versions_;
+  // Flag to check whether we allocated and own the info log file
+  bool own_info_log_;
+  const DBOptions initial_db_options_;
+  const ImmutableDBOptions immutable_db_options_;
+  MutableDBOptions mutable_db_options_;
+  Statistics* stats_;
+  std::unordered_map<std::string, RecoveredTransaction*>
+      recovered_transactions_;
+  std::unique_ptr<Tracer> tracer_;
+  InstrumentedMutex trace_mutex_;
+
+  // State below is protected by mutex_
+  // With two_write_queues enabled, some of the variables that accessed during
+  // WriteToWAL need different synchronization: log_empty_, alive_log_files_,
+  // logs_, logfile_number_. Refer to the definition of each variable below for
+  // more description.
+  mutable InstrumentedMutex mutex_;
+
+  ColumnFamilyHandleImpl* default_cf_handle_;
+  InternalStats* default_cf_internal_stats_;
+
+  // only used for dynamically adjusting max_total_wal_size. it is a sum of
+  // [write_buffer_size * max_write_buffer_number] over all column families
+  uint64_t max_total_in_memory_state_;
+  // If true, we have only one (default) column family. We use this to optimize
+  // some code-paths
+  bool single_column_family_mode_;
+
+  // The options to access storage files
+  const EnvOptions env_options_;
+
+  // Additonal options for compaction and flush
+  EnvOptions env_options_for_compaction_;
+
+  // Except in DB::Open(), WriteOptionsFile can only be called when:
+  // Persist options to options file.
+  // If need_mutex_lock = false, the method will lock DB mutex.
+  // If need_enter_write_thread = false, the method will enter write thread.
+  Status WriteOptionsFile(bool need_mutex_lock, bool need_enter_write_thread);
+
+  // The following two functions can only be called when:
+  // 1. WriteThread::Writer::EnterUnbatched() is used.
+  // 2. db_mutex is NOT held
+  Status RenameTempFileToOptionsFile(const std::string& file_name);
+  Status DeleteObsoleteOptionsFiles();
+
+  void NotifyOnFlushBegin(ColumnFamilyData* cfd, FileMetaData* file_meta,
+                          const MutableCFOptions& mutable_cf_options,
+                          int job_id, TableProperties prop);
+
+  void NotifyOnFlushCompleted(ColumnFamilyData* cfd, FileMetaData* file_meta,
+                              const MutableCFOptions& mutable_cf_options,
+                              int job_id, TableProperties prop);
+
+  void NotifyOnCompactionBegin(ColumnFamilyData* cfd, Compaction* c,
+                               const Status& st,
+                               const CompactionJobStats& job_stats, int job_id);
+
+  void NotifyOnCompactionCompleted(ColumnFamilyData* cfd, Compaction* c,
+                                   const Status& st,
+                                   const CompactionJobStats& job_stats,
+                                   int job_id);
+  void NotifyOnMemTableSealed(ColumnFamilyData* cfd,
+                              const MemTableInfo& mem_table_info);
+
+#ifndef ROCKSDB_LITE
+  void NotifyOnExternalFileIngested(
+      ColumnFamilyData* cfd, const ExternalSstFileIngestionJob& ingestion_job);
+#endif  // !ROCKSDB_LITE
+
+  void NewThreadStatusCfInfo(ColumnFamilyData* cfd) const;
+
+  void EraseThreadStatusCfInfo(ColumnFamilyData* cfd) const;
+
+  void EraseThreadStatusDbInfo() const;
+
+  // If disable_memtable is set the application logic must guarantee that the
+  // batch will still be skipped from memtable during the recovery. An excption
+  // to this is seq_per_batch_ mode, in which since each batch already takes one
+  // seq, it is ok for the batch to write to memtable during recovery as long as
+  // it only takes one sequence number: i.e., no duplicate keys.
+  // In WriteCommitted it is guarnateed since disable_memtable is used for
+  // prepare batch which will be written to memtable later during the commit,
+  // and in WritePrepared it is guaranteed since it will be used only for WAL
+  // markers which will never be written to memtable. If the commit marker is
+  // accompanied with CommitTimeWriteBatch that is not written to memtable as
+  // long as it has no duplicate keys, it does not violate the one-seq-per-batch
+  // policy.
+  // batch_cnt is expected to be non-zero in seq_per_batch mode and
+  // indicates the number of sub-patches. A sub-patch is a subset of the write
+  // batch that does not have duplicate keys.
+  Status WriteImpl(const WriteOptions& options, WriteBatch* updates,
+                   WriteCallback* callback = nullptr,
+                   uint64_t* log_used = nullptr, uint64_t log_ref = 0,
+                   bool disable_memtable = false, uint64_t* seq_used = nullptr,
+                   size_t batch_cnt = 0,
+                   PreReleaseCallback* pre_release_callback = nullptr);
+
+  Status PipelinedWriteImpl(const WriteOptions& options, WriteBatch* updates,
+                            WriteCallback* callback = nullptr,
+                            uint64_t* log_used = nullptr, uint64_t log_ref = 0,
+                            bool disable_memtable = false,
+                            uint64_t* seq_used = nullptr);
+
+  // batch_cnt is expected to be non-zero in seq_per_batch mode and indicates
+  // the number of sub-patches. A sub-patch is a subset of the write batch that
+  // does not have duplicate keys.
+  Status WriteImplWALOnly(const WriteOptions& options, WriteBatch* updates,
+                          WriteCallback* callback = nullptr,
+                          uint64_t* log_used = nullptr, uint64_t log_ref = 0,
+                          uint64_t* seq_used = nullptr, size_t batch_cnt = 0,
+                          PreReleaseCallback* pre_release_callback = nullptr);
+
+  // write cached_recoverable_state_ to memtable if it is not empty
+  // The writer must be the leader in write_thread_ and holding mutex_
+  Status WriteRecoverableState();
+
+  // Actual implementation of Close()
+  Status CloseImpl();
+
+  // Recover the descriptor from persistent storage.  May do a significant
+  // amount of work to recover recently logged updates.  Any changes to
+  // be made to the descriptor are added to *edit.
+  virtual Status Recover(
+      const std::vector<ColumnFamilyDescriptor>& column_families,
+      bool read_only = false, bool error_if_log_file_exist = false,
+      bool error_if_data_exists_in_logs = false);
+
+ private:
+  friend class DB;
+  friend class ErrorHandler;
+  friend class InternalStats;
+  friend class PessimisticTransaction;
+  friend class TransactionBaseImpl;
+  friend class WriteCommittedTxn;
+  friend class WritePreparedTxn;
+  friend class WritePreparedTxnDB;
+  friend class WriteBatchWithIndex;
+  friend class WriteUnpreparedTxnDB;
+  friend class WriteUnpreparedTxn;
+
+#ifndef ROCKSDB_LITE
+  friend class ForwardIterator;
+#endif
+  friend struct SuperVersion;
+  friend class CompactedDBImpl;
+  friend class DBTest_ConcurrentFlushWAL_Test;
+  friend class DBTest_MixedSlowdownOptionsStop_Test;
+  friend class DBCompactionTest_CompactBottomLevelFilesWithDeletions_Test;
+#ifndef NDEBUG
+  friend class DBTest2_ReadCallbackTest_Test;
+  friend class WriteCallbackTest_WriteWithCallbackTest_Test;
+  friend class XFTransactionWriteHandler;
+  friend class DBBlobIndexTest;
+  friend class WriteUnpreparedTransactionTest_RecoveryTest_Test;
+#endif
+  struct CompactionState;
+
+  struct WriteContext {
+    SuperVersionContext superversion_context;
+    autovector<MemTable*> memtables_to_free_;
+
+    explicit WriteContext(bool create_superversion = false)
+        : superversion_context(create_superversion) {}
+
+    ~WriteContext() {
+      superversion_context.Clean();
+      for (auto& m : memtables_to_free_) {
+        delete m;
+      }
+    }
+  };
+
+  struct PrepickedCompaction;
+  struct PurgeFileInfo;
+
+  Status ResumeImpl();
+
+  void MaybeIgnoreError(Status* s) const;
+
+  const Status CreateArchivalDirectory();
+
+  Status CreateColumnFamilyImpl(const ColumnFamilyOptions& cf_options,
+                                const std::string& cf_name,
+                                ColumnFamilyHandle** handle);
+
+  Status DropColumnFamilyImpl(ColumnFamilyHandle* column_family);
+
+  // Delete any unneeded files and stale in-memory entries.
+  void DeleteObsoleteFiles();
+  // Delete obsolete files and log status and information of file deletion
+  void DeleteObsoleteFileImpl(int job_id, const std::string& fname,
+                              const std::string& path_to_sync, FileType type,
+                              uint64_t number);
+
+  // Background process needs to call
+  //     auto x = CaptureCurrentFileNumberInPendingOutputs()
+  //     auto file_num = versions_->NewFileNumber();
+  //     <do something>
+  //     ReleaseFileNumberFromPendingOutputs(x)
+  // This will protect any file with number `file_num` or greater from being
+  // deleted while <do something> is running.
+  // -----------
+  // This function will capture current file number and append it to
+  // pending_outputs_. This will prevent any background process to delete any
+  // file created after this point.
+  std::list<uint64_t>::iterator CaptureCurrentFileNumberInPendingOutputs();
+  // This function should be called with the result of
+  // CaptureCurrentFileNumberInPendingOutputs(). It then marks that any file
+  // created between the calls CaptureCurrentFileNumberInPendingOutputs() and
+  // ReleaseFileNumberFromPendingOutputs() can now be deleted (if it's not live
+  // and blocked by any other pending_outputs_ calls)
+  void ReleaseFileNumberFromPendingOutputs(std::list<uint64_t>::iterator v);
+
+  Status SyncClosedLogs(JobContext* job_context);
+
+  // Flush the in-memory write buffer to storage.  Switches to a new
+  // log-file/memtable and writes a new descriptor iff successful. Then
+  // installs a new super version for the column family.
+  Status FlushMemTableToOutputFile(
+      ColumnFamilyData* cfd, const MutableCFOptions& mutable_cf_options,
+      bool* madeProgress, JobContext* job_context,
+      SuperVersionContext* superversion_context,
+      std::vector<SequenceNumber>& snapshot_seqs,
+      SequenceNumber earliest_write_conflict_snapshot,
+      SnapshotChecker* snapshot_checker, LogBuffer* log_buffer,
+      Env::Priority thread_pri);
+
+  // Argument required by background flush thread.
+  struct BGFlushArg {
+    BGFlushArg()
+        : cfd_(nullptr), max_memtable_id_(0), superversion_context_(nullptr) {}
+    BGFlushArg(ColumnFamilyData* cfd, uint64_t max_memtable_id,
+               SuperVersionContext* superversion_context)
+        : cfd_(cfd),
+          max_memtable_id_(max_memtable_id),
+          superversion_context_(superversion_context) {}
+
+    // Column family to flush.
+    ColumnFamilyData* cfd_;
+    // Maximum ID of memtable to flush. In this column family, memtables with
+    // IDs smaller than this value must be flushed before this flush completes.
+    uint64_t max_memtable_id_;
+    // Pointer to a SuperVersionContext object. After flush completes, RocksDB
+    // installs a new superversion for the column family. This operation
+    // requires a SuperVersionContext object (currently embedded in JobContext).
+    SuperVersionContext* superversion_context_;
+  };
+
+  // Argument passed to flush thread.
+  struct FlushThreadArg {
+    DBImpl* db_;
+
+    Env::Priority thread_pri_;
+  };
+
+  // Flush the memtables of (multiple) column families to multiple files on
+  // persistent storage.
+  Status FlushMemTablesToOutputFiles(
+      const autovector<BGFlushArg>& bg_flush_args, bool* made_progress,
+      JobContext* job_context, LogBuffer* log_buffer, Env::Priority thread_pri);
+
+  Status AtomicFlushMemTablesToOutputFiles(
+      const autovector<BGFlushArg>& bg_flush_args, bool* made_progress,
+      JobContext* job_context, LogBuffer* log_buffer, Env::Priority thread_pri);
+
+  // REQUIRES: log_numbers are sorted in ascending order
+  Status RecoverLogFiles(const std::vector<uint64_t>& log_numbers,
+                         SequenceNumber* next_sequence, bool read_only);
+
+  // The following two methods are used to flush a memtable to
+  // storage. The first one is used at database RecoveryTime (when the
+  // database is opened) and is heavyweight because it holds the mutex
+  // for the entire period. The second method WriteLevel0Table supports
+  // concurrent flush memtables to storage.
+  Status WriteLevel0TableForRecovery(int job_id, ColumnFamilyData* cfd,
+                                     MemTable* mem, VersionEdit* edit);
+
+  // Restore alive_log_files_ and total_log_size_ after recovery.
+  // It needs to run only when there's no flush during recovery
+  // (e.g. avoid_flush_during_recovery=true). May also trigger flush
+  // in case total_log_size > max_total_wal_size.
+  Status RestoreAliveLogFiles(const std::vector<uint64_t>& log_numbers);
+
+  // num_bytes: for slowdown case, delay time is calculated based on
+  //            `num_bytes` going through.
+  Status DelayWrite(uint64_t num_bytes, const WriteOptions& write_options);
+
+  Status ThrottleLowPriWritesIfNeeded(const WriteOptions& write_options,
+                                      WriteBatch* my_batch);
+
+  Status ScheduleFlushes(WriteContext* context);
+
+  Status SwitchMemtable(ColumnFamilyData* cfd, WriteContext* context);
+
+  void SelectColumnFamiliesForAtomicFlush(autovector<ColumnFamilyData*>* cfds);
+
+  // Force current memtable contents to be flushed.
+  Status FlushMemTable(ColumnFamilyData* cfd, const FlushOptions& options,
+                       FlushReason flush_reason, bool writes_stopped = false);
+
+  Status AtomicFlushMemTables(
+      const autovector<ColumnFamilyData*>& column_family_datas,
+      const FlushOptions& options, FlushReason flush_reason,
+      bool writes_stopped = false);
+
+  // Wait until flushing this column family won't stall writes
+  Status WaitUntilFlushWouldNotStallWrites(ColumnFamilyData* cfd,
+                                           bool* flush_needed);
+
+  // Wait for memtable flushed.
+  // If flush_memtable_id is non-null, wait until the memtable with the ID
+  // gets flush. Otherwise, wait until the column family don't have any
+  // memtable pending flush.
+  // resuming_from_bg_err indicates whether the caller is attempting to resume
+  // from background error.
+  Status WaitForFlushMemTable(ColumnFamilyData* cfd,
+                              const uint64_t* flush_memtable_id = nullptr,
+                              bool resuming_from_bg_err = false) {
+    return WaitForFlushMemTables({cfd}, {flush_memtable_id},
+                                 resuming_from_bg_err);
+  }
+  // Wait for memtables to be flushed for multiple column families.
+  Status WaitForFlushMemTables(
+      const autovector<ColumnFamilyData*>& cfds,
+      const autovector<const uint64_t*>& flush_memtable_ids,
+      bool resuming_from_bg_err);
+
+  // REQUIRES: mutex locked and in write thread.
+  void AssignAtomicFlushSeq(const autovector<ColumnFamilyData*>& cfds);
+
+  // REQUIRES: mutex locked
+  Status SwitchWAL(WriteContext* write_context);
+
+  // REQUIRES: mutex locked
+  Status HandleWriteBufferFull(WriteContext* write_context);
+
+  // REQUIRES: mutex locked
+  Status PreprocessWrite(const WriteOptions& write_options, bool* need_log_sync,
+                         WriteContext* write_context);
+
+  WriteBatch* MergeBatch(const WriteThread::WriteGroup& write_group,
+                         WriteBatch* tmp_batch, size_t* write_with_wal,
+                         WriteBatch** to_be_cached_state);
+
+  Status WriteToWAL(const WriteBatch& merged_batch, log::Writer* log_writer,
+                    uint64_t* log_used, uint64_t* log_size);
+
+  Status WriteToWAL(const WriteThread::WriteGroup& write_group,
+                    log::Writer* log_writer, uint64_t* log_used,
+                    bool need_log_sync, bool need_log_dir_sync,
+                    SequenceNumber sequence);
+
+  Status ConcurrentWriteToWAL(const WriteThread::WriteGroup& write_group,
+                              uint64_t* log_used, SequenceNumber* last_sequence,
+                              size_t seq_inc);
+
+  // Used by WriteImpl to update bg_error_ if paranoid check is enabled.
+  void WriteStatusCheck(const Status& status);
+
+  // Used by WriteImpl to update bg_error_ in case of memtable insert error.
+  void MemTableInsertStatusCheck(const Status& memtable_insert_status);
+
+#ifndef ROCKSDB_LITE
+
+  Status CompactFilesImpl(const CompactionOptions& compact_options,
+                          ColumnFamilyData* cfd, Version* version,
+                          const std::vector<std::string>& input_file_names,
+                          std::vector<std::string>* const output_file_names,
+                          const int output_level, int output_path_id,
+                          JobContext* job_context, LogBuffer* log_buffer,
+                          CompactionJobInfo* compaction_job_info);
+
+  // Wait for current IngestExternalFile() calls to finish.
+  // REQUIRES: mutex_ held
+  void WaitForIngestFile();
+
+#else
+  // IngestExternalFile is not supported in ROCKSDB_LITE so this function
+  // will be no-op
+  void WaitForIngestFile() {}
+#endif  // ROCKSDB_LITE
+
+  ColumnFamilyData* GetColumnFamilyDataByName(const std::string& cf_name);
+
+  void MaybeScheduleFlushOrCompaction();
+
+  // A flush request specifies the column families to flush as well as the
+  // largest memtable id to persist for each column family. Once all the
+  // memtables whose IDs are smaller than or equal to this per-column-family
+  // specified value, this flush request is considered to have completed its
+  // work of flushing this column family. After completing the work for all
+  // column families in this request, this flush is considered complete.
+  typedef std::vector<std::pair<ColumnFamilyData*, uint64_t>> FlushRequest;
+
+  void GenerateFlushRequest(const autovector<ColumnFamilyData*>& cfds,
+                            FlushRequest* req);
+
+  void SchedulePendingFlush(const FlushRequest& req, FlushReason flush_reason);
+
+  void SchedulePendingCompaction(ColumnFamilyData* cfd);
+  void SchedulePendingPurge(std::string fname, std::string dir_to_sync,
+                            FileType type, uint64_t number, int job_id);
+  static void BGWorkCompaction(void* arg);
+  // Runs a pre-chosen universal compaction involving bottom level in a
+  // separate, bottom-pri thread pool.
+  static void BGWorkBottomCompaction(void* arg);
+  static void BGWorkFlush(void* arg);
+  static void BGWorkPurge(void* arg);
+  static void UnscheduleCompactionCallback(void* arg);
+  static void UnscheduleFlushCallback(void* arg);
+  void BackgroundCallCompaction(PrepickedCompaction* prepicked_compaction,
+                                Env::Priority thread_pri);
+  void BackgroundCallFlush(Env::Priority thread_pri);
+  void BackgroundCallPurge();
+  Status BackgroundCompaction(bool* madeProgress, JobContext* job_context,
+                              LogBuffer* log_buffer,
+                              PrepickedCompaction* prepicked_compaction,
+                              Env::Priority thread_pri);
+  Status BackgroundFlush(bool* madeProgress, JobContext* job_context,
+                         LogBuffer* log_buffer, FlushReason* reason,
+                         Env::Priority thread_pri);
+
+  bool EnoughRoomForCompaction(ColumnFamilyData* cfd,
+                               const std::vector<CompactionInputFiles>& inputs,
+                               bool* sfm_bookkeeping, LogBuffer* log_buffer);
+
+  // Request compaction tasks token from compaction thread limiter.
+  // It always succeeds if force = true or limiter is disable.
+  bool RequestCompactionToken(ColumnFamilyData* cfd, bool force,
+                              std::unique_ptr<TaskLimiterToken>* token,
+                              LogBuffer* log_buffer);
+
+  // Schedule background tasks
+  void StartTimedTasks();
+
+  void PrintStatistics();
+
+  size_t EstiamteStatsHistorySize() const;
+
+  // persist stats to column family "_persistent_stats"
+  void PersistStats();
+
+  // dump rocksdb.stats to LOG
+  void DumpStats();
+
+  // Return the minimum empty level that could hold the total data in the
+  // input level. Return the input level, if such level could not be found.
+  int FindMinimumEmptyLevelFitting(ColumnFamilyData* cfd,
+                                   const MutableCFOptions& mutable_cf_options,
+                                   int level);
+
+  // Move the files in the input level to the target level.
+  // If target_level < 0, automatically calculate the minimum level that could
+  // hold the data set.
+  Status ReFitLevel(ColumnFamilyData* cfd, int level, int target_level = -1);
+
+  // helper functions for adding and removing from flush & compaction queues
+  void AddToCompactionQueue(ColumnFamilyData* cfd);
+  ColumnFamilyData* PopFirstFromCompactionQueue();
+  FlushRequest PopFirstFromFlushQueue();
+
+  // Pick the first unthrottled compaction with task token from queue.
+  ColumnFamilyData* PickCompactionFromQueue(
+      std::unique_ptr<TaskLimiterToken>* token, LogBuffer* log_buffer);
+
+  // helper function to call after some of the logs_ were synced
+  void MarkLogsSynced(uint64_t up_to, bool synced_dir, const Status& status);
+
+  SnapshotImpl* GetSnapshotImpl(bool is_write_conflict_boundary,
+                                bool lock = true);
+
+  uint64_t GetMaxTotalWalSize() const;
+
+  Directory* GetDataDir(ColumnFamilyData* cfd, size_t path_id) const;
+
+  Status CloseHelper();
+
+  void WaitForBackgroundWork();
+
+  // table_cache_ provides its own synchronization
+  std::shared_ptr<Cache> table_cache_;
+
+  // Lock over the persistent DB state.  Non-nullptr iff successfully acquired.
+  FileLock* db_lock_;
+
+  // In addition to mutex_, log_write_mutex_ protected writes to stats_history_
+  InstrumentedMutex stats_history_mutex_;
+  // In addition to mutex_, log_write_mutex_ protected writes to logs_ and
+  // logfile_number_. With two_write_queues it also protects alive_log_files_,
+  // and log_empty_. Refer to the definition of each variable below for more
+  // details.
+  InstrumentedMutex log_write_mutex_;
+
+  std::atomic<bool> shutting_down_;
+  // This condition variable is signaled on these conditions:
+  // * whenever bg_compaction_scheduled_ goes down to 0
+  // * if AnyManualCompaction, whenever a compaction finishes, even if it hasn't
+  // made any progress
+  // * whenever a compaction made any progress
+  // * whenever bg_flush_scheduled_ or bg_purge_scheduled_ value decreases
+  // (i.e. whenever a flush is done, even if it didn't make any progress)
+  // * whenever there is an error in background purge, flush or compaction
+  // * whenever num_running_ingest_file_ goes to 0.
+  // * whenever pending_purge_obsolete_files_ goes to 0.
+  // * whenever disable_delete_obsolete_files_ goes to 0.
+  // * whenever SetOptions successfully updates options.
+  // * whenever a column family is dropped.
+  InstrumentedCondVar bg_cv_;
+  // Writes are protected by locking both mutex_ and log_write_mutex_, and reads
+  // must be under either mutex_ or log_write_mutex_. Since after ::Open,
+  // logfile_number_ is currently updated only in write_thread_, it can be read
+  // from the same write_thread_ without any locks.
+  uint64_t logfile_number_;
+  std::deque<uint64_t>
+      log_recycle_files_;  // a list of log files that we can recycle
+  bool log_dir_synced_;
+  // Without two_write_queues, read and writes to log_empty_ are protected by
+  // mutex_. Since it is currently updated/read only in write_thread_, it can be
+  // accessed from the same write_thread_ without any locks. With
+  // two_write_queues writes, where it can be updated in different threads,
+  // read and writes are protected by log_write_mutex_ instead. This is to avoid
+  // expesnive mutex_ lock during WAL write, which update log_empty_.
+  bool log_empty_;
+
+  std::unique_ptr<ColumnFamilyMemTablesImpl> column_family_memtables_;
+  struct LogFileNumberSize {
+    explicit LogFileNumberSize(uint64_t _number) : number(_number) {}
+    void AddSize(uint64_t new_size) { size += new_size; }
+    uint64_t number;
+    uint64_t size = 0;
+    bool getting_flushed = false;
+  };
+  struct LogWriterNumber {
+    // pass ownership of _writer
+    LogWriterNumber(uint64_t _number, log::Writer* _writer)
+        : number(_number), writer(_writer) {}
+
+    log::Writer* ReleaseWriter() {
+      auto* w = writer;
+      writer = nullptr;
+      return w;
+    }
+    Status ClearWriter() {
+      Status s = writer->WriteBuffer();
+      delete writer;
+      writer = nullptr;
+      return s;
+    }
+
+    uint64_t number;
+    // Visual Studio doesn't support deque's member to be noncopyable because
+    // of a std::unique_ptr as a member.
+    log::Writer* writer;  // own
+    // true for some prefix of logs_
+    bool getting_synced = false;
+  };
+  // Without two_write_queues, read and writes to alive_log_files_ are
+  // protected by mutex_. However since back() is never popped, and push_back()
+  // is done only from write_thread_, the same thread can access the item
+  // reffered by back() without mutex_. With two_write_queues_, writes
+  // are protected by locking both mutex_ and log_write_mutex_, and reads must
+  // be under either mutex_ or log_write_mutex_.
+  std::deque<LogFileNumberSize> alive_log_files_;
+  // Log files that aren't fully synced, and the current log file.
+  // Synchronization:
+  //  - push_back() is done from write_thread_ with locked mutex_ and
+  //  log_write_mutex_
+  //  - pop_front() is done from any thread with locked mutex_ and
+  //  log_write_mutex_
+  //  - reads are done with either locked mutex_ or log_write_mutex_
+  //  - back() and items with getting_synced=true are not popped,
+  //  - The same thread that sets getting_synced=true will reset it.
+  //  - it follows that the object referred by back() can be safely read from
+  //  the write_thread_ without using mutex
+  //  - it follows that the items with getting_synced=true can be safely read
+  //  from the same thread that has set getting_synced=true
+  std::deque<LogWriterNumber> logs_;
+  // Signaled when getting_synced becomes false for some of the logs_.
+  InstrumentedCondVar log_sync_cv_;
+  // This is the app-level state that is written to the WAL but will be used
+  // only during recovery. Using this feature enables not writing the state to
+  // memtable on normal writes and hence improving the throughput. Each new
+  // write of the state will replace the previous state entirely even if the
+  // keys in the two consecuitive states do not overlap.
+  // It is protected by log_write_mutex_ when two_write_queues_ is enabled.
+  // Otherwise only the heaad of write_thread_ can access it.
+  WriteBatch cached_recoverable_state_;
+  std::atomic<bool> cached_recoverable_state_empty_ = {true};
+  std::atomic<uint64_t> total_log_size_;
+
+  // If this is non-empty, we need to delete these log files in background
+  // threads. Protected by db mutex.
+  autovector<log::Writer*> logs_to_free_;
+
+  bool is_snapshot_supported_;
+
+  std::map<uint64_t, std::map<std::string, uint64_t>> stats_history_;
+
+  std::map<std::string, uint64_t> stats_slice_;
+
+  bool stats_slice_initialized_ = false;
+
+  // Class to maintain directories for all database paths other than main one.
+  class Directories {
+   public:
+    Status SetDirectories(Env* env, const std::string& dbname,
+                          const std::string& wal_dir,
+                          const std::vector<DbPath>& data_paths);
+
+    Directory* GetDataDir(size_t path_id) const;
+
+    Directory* GetWalDir() {
+      if (wal_dir_) {
+        return wal_dir_.get();
+      }
+      return db_dir_.get();
+    }
+
+    Directory* GetDbDir() { return db_dir_.get(); }
+
+   private:
+    std::unique_ptr<Directory> db_dir_;
+    std::vector<std::unique_ptr<Directory>> data_dirs_;
+    std::unique_ptr<Directory> wal_dir_;
+  };
+
+  Directories directories_;
+
+  WriteBufferManager* write_buffer_manager_;
+
+  WriteThread write_thread_;
+  WriteBatch tmp_batch_;
+  // The write thread when the writers have no memtable write. This will be used
+  // in 2PC to batch the prepares separately from the serial commit.
+  WriteThread nonmem_write_thread_;
+
+  WriteController write_controller_;
+
+  std::unique_ptr<RateLimiter> low_pri_write_rate_limiter_;
+
+  // Size of the last batch group. In slowdown mode, next write needs to
+  // sleep if it uses up the quota.
+  // Note: This is to protect memtable and compaction. If the batch only writes
+  // to the WAL its size need not to be included in this.
+  uint64_t last_batch_group_size_;
+
+  FlushScheduler flush_scheduler_;
+
+  SnapshotList snapshots_;
+
+  // For each background job, pending_outputs_ keeps the current file number at
+  // the time that background job started.
+  // FindObsoleteFiles()/PurgeObsoleteFiles() never deletes any file that has
+  // number bigger than any of the file number in pending_outputs_. Since file
+  // numbers grow monotonically, this also means that pending_outputs_ is always
+  // sorted. After a background job is done executing, its file number is
+  // deleted from pending_outputs_, which allows PurgeObsoleteFiles() to clean
+  // it up.
+  // State is protected with db mutex.
+  std::list<uint64_t> pending_outputs_;
+
+  // PurgeFileInfo is a structure to hold information of files to be deleted in
+  // purge_queue_
+  struct PurgeFileInfo {
+    std::string fname;
+    std::string dir_to_sync;
+    FileType type;
+    uint64_t number;
+    int job_id;
+    PurgeFileInfo(std::string fn, std::string d, FileType t, uint64_t num,
+                  int jid)
+        : fname(fn), dir_to_sync(d), type(t), number(num), job_id(jid) {}
+  };
+
+  // flush_queue_ and compaction_queue_ hold column families that we need to
+  // flush and compact, respectively.
+  // A column family is inserted into flush_queue_ when it satisfies condition
+  // cfd->imm()->IsFlushPending()
+  // A column family is inserted into compaction_queue_ when it satisfied
+  // condition cfd->NeedsCompaction()
+  // Column families in this list are all Ref()-erenced
+  // TODO(icanadi) Provide some kind of ReferencedColumnFamily class that will
+  // do RAII on ColumnFamilyData
+  // Column families are in this queue when they need to be flushed or
+  // compacted. Consumers of these queues are flush and compaction threads. When
+  // column family is put on this queue, we increase unscheduled_flushes_ and
+  // unscheduled_compactions_. When these variables are bigger than zero, that
+  // means we need to schedule background threads for flush and compaction.
+  // Once the background threads are scheduled, we decrease unscheduled_flushes_
+  // and unscheduled_compactions_. That way we keep track of number of
+  // compaction and flush threads we need to schedule. This scheduling is done
+  // in MaybeScheduleFlushOrCompaction()
+  // invariant(column family present in flush_queue_ <==>
+  // ColumnFamilyData::pending_flush_ == true)
+  std::deque<FlushRequest> flush_queue_;
+  // invariant(column family present in compaction_queue_ <==>
+  // ColumnFamilyData::pending_compaction_ == true)
+  std::deque<ColumnFamilyData*> compaction_queue_;
+
+  // A queue to store filenames of the files to be purged
+  std::deque<PurgeFileInfo> purge_queue_;
+
+  // A vector to store the file numbers that have been assigned to certain
+  // JobContext. Current implementation tracks ssts only.
+  std::vector<uint64_t> files_grabbed_for_purge_;
+
+  // A queue to store log writers to close
+  std::deque<log::Writer*> logs_to_free_queue_;
+  int unscheduled_flushes_;
+  int unscheduled_compactions_;
+
+  // count how many background compactions are running or have been scheduled in
+  // the BOTTOM pool
+  int bg_bottom_compaction_scheduled_;
+
+  // count how many background compactions are running or have been scheduled
+  int bg_compaction_scheduled_;
+
+  // stores the number of compactions are currently running
+  int num_running_compactions_;
+
+  // number of background memtable flush jobs, submitted to the HIGH pool
+  int bg_flush_scheduled_;
+
+  // stores the number of flushes are currently running
+  int num_running_flushes_;
+
+  // number of background obsolete file purge jobs, submitted to the HIGH pool
+  int bg_purge_scheduled_;
+
+  // Information for a manual compaction
+  struct ManualCompactionState {
+    ColumnFamilyData* cfd;
+    int input_level;
+    int output_level;
+    uint32_t output_path_id;
+    Status status;
+    bool done;
+    bool in_progress;            // compaction request being processed?
+    bool incomplete;             // only part of requested range compacted
+    bool exclusive;              // current behavior of only one manual
+    bool disallow_trivial_move;  // Force actual compaction to run
+    const InternalKey* begin;    // nullptr means beginning of key range
+    const InternalKey* end;      // nullptr means end of key range
+    InternalKey* manual_end;     // how far we are compacting
+    InternalKey tmp_storage;     // Used to keep track of compaction progress
+    InternalKey tmp_storage1;    // Used to keep track of compaction progress
+  };
+  struct PrepickedCompaction {
+    // background compaction takes ownership of `compaction`.
+    Compaction* compaction;
+    // caller retains ownership of `manual_compaction_state` as it is reused
+    // across background compactions.
+    ManualCompactionState* manual_compaction_state;  // nullptr if non-manual
+    // task limiter token is requested during compaction picking.
+    std::unique_ptr<TaskLimiterToken> task_token;
+  };
+  std::deque<ManualCompactionState*> manual_compaction_dequeue_;
+
+  struct CompactionArg {
+    // caller retains ownership of `db`.
+    DBImpl* db;
+    // background compaction takes ownership of `prepicked_compaction`.
+    PrepickedCompaction* prepicked_compaction;
+  };
+
+  // shall we disable deletion of obsolete files
+  // if 0 the deletion is enabled.
+  // if non-zero, files will not be getting deleted
+  // This enables two different threads to call
+  // EnableFileDeletions() and DisableFileDeletions()
+  // without any synchronization
+  int disable_delete_obsolete_files_;
+
+  // Number of times FindObsoleteFiles has found deletable files and the
+  // corresponding call to PurgeObsoleteFiles has not yet finished.
+  int pending_purge_obsolete_files_;
+
+  // last time when DeleteObsoleteFiles with full scan was executed. Originaly
+  // initialized with startup time.
+  uint64_t delete_obsolete_files_last_run_;
+
+  // last time stats were dumped to LOG
+  std::atomic<uint64_t> last_stats_dump_time_microsec_;
+
+  // Each flush or compaction gets its own job id. this counter makes sure
+  // they're unique
+  std::atomic<int> next_job_id_;
+
+  // A flag indicating whether the current rocksdb database has any
+  // data that is not yet persisted into either WAL or SST file.
+  // Used when disableWAL is true.
+  std::atomic<bool> has_unpersisted_data_;
+
+  // if an attempt was made to flush all column families that
+  // the oldest log depends on but uncommitted data in the oldest
+  // log prevents the log from being released.
+  // We must attempt to free the dependent memtables again
+  // at a later time after the transaction in the oldest
+  // log is fully commited.
+  bool unable_to_release_oldest_log_;
+
+  static const int KEEP_LOG_FILE_NUM = 1000;
+  // MSVC version 1800 still does not have constexpr for ::max()
+  static const uint64_t kNoTimeOut = port::kMaxUint64;
+
+  std::string db_absolute_path_;
+
+  // Number of running IngestExternalFile() calls.
+  // REQUIRES: mutex held
+  int num_running_ingest_file_;
+
+#ifndef ROCKSDB_LITE
+  WalManager wal_manager_;
+#endif  // ROCKSDB_LITE
+
+  // Unified interface for logging events
+  EventLogger event_logger_;
+
+  // A value of > 0 temporarily disables scheduling of background work
+  int bg_work_paused_;
+
+  // A value of > 0 temporarily disables scheduling of background compaction
+  int bg_compaction_paused_;
+
+  // Guard against multiple concurrent refitting
+  bool refitting_level_;
+
+  // Indicate DB was opened successfully
+  bool opened_successfully_;
+
+  // The min threshold to triggere bottommost compaction for removing
+  // garbages, among all column families.
+  SequenceNumber bottommost_files_mark_threshold_ = kMaxSequenceNumber;
+
+  LogsWithPrepTracker logs_with_prep_tracker_;
+
+  // Callback for compaction to check if a key is visible to a snapshot.
+  // REQUIRES: mutex held
+  std::unique_ptr<SnapshotChecker> snapshot_checker_;
+
+  // Callback for when the cached_recoverable_state_ is written to memtable
+  // Only to be set during initialization
+  std::unique_ptr<PreReleaseCallback> recoverable_state_pre_release_callback_;
+
+  // handle for scheduling stats dumping at fixed intervals
+  // REQUIRES: mutex locked
+  std::unique_ptr<rocksdb::RepeatableThread> thread_dump_stats_;
+
+  // handle for scheduling stats snapshoting at fixed intervals
+  // REQUIRES: mutex locked
+  std::unique_ptr<rocksdb::RepeatableThread> thread_persist_stats_;
+
+  // No copying allowed
+  DBImpl(const DBImpl&);
+  void operator=(const DBImpl&);
+
+  // Background threads call this function, which is just a wrapper around
+  // the InstallSuperVersion() function. Background threads carry
+  // sv_context which can have new_superversion already
+  // allocated.
+  // All ColumnFamily state changes go through this function. Here we analyze
+  // the new state and we schedule background work if we detect that the new
+  // state needs flush or compaction.
+  void InstallSuperVersionAndScheduleWork(
+      ColumnFamilyData* cfd, SuperVersionContext* sv_context,
+      const MutableCFOptions& mutable_cf_options);
+
+#ifndef ROCKSDB_LITE
+  using DB::GetPropertiesOfAllTables;
+  virtual Status GetPropertiesOfAllTables(
+      ColumnFamilyHandle* column_family,
+      TablePropertiesCollection* props) override;
+  virtual Status GetPropertiesOfTablesInRange(
+      ColumnFamilyHandle* column_family, const Range* range, std::size_t n,
+      TablePropertiesCollection* props) override;
+
+#endif  // ROCKSDB_LITE
+
+  bool GetIntPropertyInternal(ColumnFamilyData* cfd,
+                              const DBPropertyInfo& property_info,
+                              bool is_locked, uint64_t* value);
+  bool GetPropertyHandleOptionsStatistics(std::string* value);
+
+  bool HasPendingManualCompaction();
+  bool HasExclusiveManualCompaction();
+  void AddManualCompaction(ManualCompactionState* m);
+  void RemoveManualCompaction(ManualCompactionState* m);
+  bool ShouldntRunManualCompaction(ManualCompactionState* m);
+  bool HaveManualCompaction(ColumnFamilyData* cfd);
+  bool MCOverlap(ManualCompactionState* m, ManualCompactionState* m1);
+#ifndef ROCKSDB_LITE
+  void BuildCompactionJobInfo(const ColumnFamilyData* cfd, Compaction* c,
+                              const Status& st,
+                              const CompactionJobStats& compaction_job_stats,
+                              const int job_id, const Version* current,
+                              CompactionJobInfo* compaction_job_info) const;
+  // Reserve the next 'num' file numbers for to-be-ingested external SST files,
+  // and return the current file_number in 'next_file_number'.
+  // Write a version edit to the MANIFEST.
+  Status ReserveFileNumbersBeforeIngestion(
+      ColumnFamilyData* cfd, uint64_t num,
+      std::list<uint64_t>::iterator* pending_output_elem,
+      uint64_t* next_file_number);
+#endif  //! ROCKSDB_LITE
+
+  bool ShouldPurge(uint64_t file_number) const;
+  void MarkAsGrabbedForPurge(uint64_t file_number);
+
+  size_t GetWalPreallocateBlockSize(uint64_t write_buffer_size) const;
+  Env::WriteLifeTimeHint CalculateWALWriteHint() { return Env::WLTH_SHORT; }
+
+  // When set, we use a separate queue for writes that dont write to memtable.
+  // In 2PC these are the writes at Prepare phase.
+  const bool two_write_queues_;
+  const bool manual_wal_flush_;
+  // Increase the sequence number after writing each batch, whether memtable is
+  // disabled for that or not. Otherwise the sequence number is increased after
+  // writing each key into memtable. This implies that when disable_memtable is
+  // set, the seq is not increased at all.
+  //
+  // Default: false
+  const bool seq_per_batch_;
+  // This determines during recovery whether we expect one writebatch per
+  // recovered transaction, or potentially multiple writebatches per
+  // transaction. For WriteUnprepared, this is set to false, since multiple
+  // batches can exist per transaction.
+  //
+  // Default: true
+  const bool batch_per_txn_;
+  // LastSequence also indicates last published sequence visibile to the
+  // readers. Otherwise LastPublishedSequence should be used.
+  const bool last_seq_same_as_publish_seq_;
+  // It indicates that a customized gc algorithm must be used for
+  // flush/compaction and if it is not provided vis SnapshotChecker, we should
+  // disable gc to be safe.
+  const bool use_custom_gc_;
+  // Flag to indicate that the DB instance shutdown has been initiated. This
+  // different from shutting_down_ atomic in that it is set at the beginning
+  // of shutdown sequence, specifically in order to prevent any background
+  // error recovery from going on in parallel. The latter, shutting_down_,
+  // is set a little later during the shutdown after scheduling memtable
+  // flushes
+  std::atomic<bool> shutdown_initiated_;
+  // Flag to indicate whether sst_file_manager object was allocated in
+  // DB::Open() or passed to us
+  bool own_sfm_;
+
+  // Clients must periodically call SetPreserveDeletesSequenceNumber()
+  // to advance this seqnum. Default value is 0 which means ALL deletes are
+  // preserved. Note that this has no effect if DBOptions.preserve_deletes
+  // is set to false.
+  std::atomic<SequenceNumber> preserve_deletes_seqnum_;
+  const bool preserve_deletes_;
+
+  // Flag to check whether Close() has been called on this DB
+  bool closed_;
+
+  ErrorHandler error_handler_;
+
+  // Conditional variable to coordinate installation of atomic flush results.
+  // With atomic flush, each bg thread installs the result of flushing multiple
+  // column families, and different threads can flush different column
+  // families. It's difficult to rely on one thread to perform batch
+  // installation for all threads. This is different from the non-atomic flush
+  // case.
+  // atomic_flush_install_cv_ makes sure that threads install atomic flush
+  // results sequentially. Flush results of memtables with lower IDs get
+  // installed to MANIFEST first.
+  InstrumentedCondVar atomic_flush_install_cv_;
+};
+
+extern Options SanitizeOptions(const std::string& db, const Options& src);
+
+extern DBOptions SanitizeOptions(const std::string& db, const DBOptions& src);
+
+extern CompressionType GetCompressionFlush(
+    const ImmutableCFOptions& ioptions,
+    const MutableCFOptions& mutable_cf_options);
+
+// Return the earliest log file to keep after the memtable flush is
+// finalized.
+// `cfd_to_flush` is the column family whose memtable (specified in
+// `memtables_to_flush`) will be flushed and thus will not depend on any WAL
+// file.
+// The function is only applicable to 2pc mode.
+extern uint64_t PrecomputeMinLogNumberToKeep(
+    VersionSet* vset, const ColumnFamilyData& cfd_to_flush,
+    autovector<VersionEdit*> edit_list,
+    const autovector<MemTable*>& memtables_to_flush,
+    LogsWithPrepTracker* prep_tracker);
+
+// `cfd_to_flush` is the column family whose memtable will be flushed and thus
+// will not depend on any WAL file. nullptr means no memtable is being flushed.
+// The function is only applicable to 2pc mode.
+extern uint64_t FindMinPrepLogReferencedByMemTable(
+    VersionSet* vset, const ColumnFamilyData* cfd_to_flush,
+    const autovector<MemTable*>& memtables_to_flush);
+
+// Fix user-supplied options to be reasonable
+template <class T, class V>
+static void ClipToRange(T* ptr, V minvalue, V maxvalue) {
+  if (static_cast<V>(*ptr) > maxvalue) *ptr = maxvalue;
+  if (static_cast<V>(*ptr) < minvalue) *ptr = minvalue;
+}
+
+}  // namespace rocksdb