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432 lines
15 KiB
432 lines
15 KiB
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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#ifndef STORAGE_LEVELDB_DB_DB_IMPL_H_
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#define STORAGE_LEVELDB_DB_DB_IMPL_H_
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#include <atomic>
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#include <deque>
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#include <set>
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#include <vector>
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#include "db/dbformat.h"
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#include "db/log_file.h"
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#include "db/log_writer.h"
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#include "db/snapshot.h"
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#include "leveldb/db.h"
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#include "leveldb/env.h"
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#include "port/port.h"
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#include "util/stats_logger.h"
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#include "memtablelist.h"
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#include "leveldb/memtablerep.h"
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#ifdef USE_SCRIBE
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#include "scribe/scribe_logger.h"
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#endif
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namespace leveldb {
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class MemTable;
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class TableCache;
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class Version;
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class VersionEdit;
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class VersionSet;
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class DBImpl : public DB {
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public:
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DBImpl(const Options& options, const std::string& dbname);
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virtual ~DBImpl();
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// Implementations of the DB interface
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virtual Status Put(const WriteOptions&, const Slice& key, const Slice& value);
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virtual Status Merge(const WriteOptions&, const Slice& key,
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const Slice& value);
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virtual Status Delete(const WriteOptions&, const Slice& key);
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virtual Status Write(const WriteOptions& options, WriteBatch* updates);
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virtual Status Get(const ReadOptions& options,
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const Slice& key,
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std::string* value);
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virtual std::vector<Status> MultiGet(const ReadOptions& options,
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const std::vector<Slice>& keys,
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std::vector<std::string>* values);
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// Returns false if key doesn't exist in the database and true if it may.
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// If value_found is not passed in as null, then return the value if found in
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// memory. On return, if value was found, then value_found will be set to true
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// , otherwise false.
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virtual bool KeyMayExist(const ReadOptions& options,
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const Slice& key,
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std::string* value,
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bool* value_found = nullptr);
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virtual Iterator* NewIterator(const ReadOptions&);
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virtual const Snapshot* GetSnapshot();
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virtual void ReleaseSnapshot(const Snapshot* snapshot);
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virtual bool GetProperty(const Slice& property, std::string* value);
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virtual void GetApproximateSizes(const Range* range, int n, uint64_t* sizes);
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virtual void CompactRange(const Slice* begin, const Slice* end,
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bool reduce_level = false);
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virtual int NumberLevels();
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virtual int MaxMemCompactionLevel();
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virtual int Level0StopWriteTrigger();
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virtual Status Flush(const FlushOptions& options);
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virtual Status DisableFileDeletions();
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virtual Status EnableFileDeletions();
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virtual Status GetLiveFiles(std::vector<std::string>&,
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uint64_t* manifest_file_size);
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virtual SequenceNumber GetLatestSequenceNumber();
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virtual Status GetUpdatesSince(SequenceNumber seq_number,
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unique_ptr<TransactionLogIterator>* iter);
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// Extra methods (for testing) that are not in the public DB interface
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// Compact any files in the named level that overlap [*begin, *end]
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void TEST_CompactRange(int level, const Slice* begin, const Slice* end);
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// Force current memtable contents to be compacted.
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Status TEST_CompactMemTable();
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// Wait for memtable compaction
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Status TEST_WaitForCompactMemTable();
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// Wait for any compaction
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Status TEST_WaitForCompact();
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// Return an internal iterator over the current state of the database.
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// The keys of this iterator are internal keys (see format.h).
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// The returned iterator should be deleted when no longer needed.
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Iterator* TEST_NewInternalIterator();
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// Return the maximum overlapping data (in bytes) at next level for any
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// file at a level >= 1.
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int64_t TEST_MaxNextLevelOverlappingBytes();
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// Simulate a db crash, no elegant closing of database.
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void TEST_Destroy_DBImpl();
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// Return the current manifest file no.
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uint64_t TEST_Current_Manifest_FileNo();
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// Trigger's a background call for testing.
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void TEST_PurgeObsoleteteWAL();
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protected:
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Env* const env_;
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const std::string dbname_;
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unique_ptr<VersionSet> versions_;
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const InternalKeyComparator internal_comparator_;
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const Options options_; // options_.comparator == &internal_comparator_
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const Comparator* user_comparator() const {
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return internal_comparator_.user_comparator();
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}
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MemTable* GetMemTable() {
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return mem_;
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}
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Iterator* NewInternalIterator(const ReadOptions&,
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SequenceNumber* latest_snapshot);
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private:
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friend class DB;
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struct CompactionState;
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struct Writer;
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struct DeletionState;
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Status NewDB();
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// Recover the descriptor from persistent storage. May do a significant
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// amount of work to recover recently logged updates. Any changes to
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// be made to the descriptor are added to *edit.
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Status Recover(VersionEdit* edit, MemTable* external_table = nullptr,
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bool error_if_log_file_exist = false);
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void MaybeIgnoreError(Status* s) const;
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const Status CreateArchivalDirectory();
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// Delete any unneeded files and stale in-memory entries.
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void DeleteObsoleteFiles();
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// Compact the in-memory write buffer to disk. Switches to a new
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// log-file/memtable and writes a new descriptor iff successful.
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Status CompactMemTable(bool* madeProgress = nullptr);
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Status RecoverLogFile(uint64_t log_number,
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VersionEdit* edit,
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SequenceNumber* max_sequence,
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MemTable* external_table);
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// The following two methods are used to flush a memtable to
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// storage. The first one is used atdatabase RecoveryTime (when the
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// database is opened) and is heavyweight because it holds the mutex
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// for the entire period. The second method WriteLevel0Table supports
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// concurrent flush memtables to storage.
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Status WriteLevel0TableForRecovery(MemTable* mem, VersionEdit* edit);
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Status WriteLevel0Table(std::vector<MemTable*> &mems, VersionEdit* edit,
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uint64_t* filenumber);
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uint64_t SlowdownAmount(int num_level0_files);
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Status MakeRoomForWrite(bool force /* compact even if there is room? */);
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WriteBatch* BuildBatchGroup(Writer** last_writer);
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// Force current memtable contents to be flushed.
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Status FlushMemTable(const FlushOptions& options);
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// Wait for memtable compaction
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Status WaitForCompactMemTable();
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void MaybeScheduleLogDBDeployStats();
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static void BGLogDBDeployStats(void* db);
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void LogDBDeployStats();
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void MaybeScheduleCompaction();
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static void BGWork(void* db);
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void BackgroundCall();
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Status BackgroundCompaction(bool* madeProgress, DeletionState& deletion_state);
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void CleanupCompaction(CompactionState* compact);
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Status DoCompactionWork(CompactionState* compact);
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Status OpenCompactionOutputFile(CompactionState* compact);
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Status FinishCompactionOutputFile(CompactionState* compact, Iterator* input);
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Status InstallCompactionResults(CompactionState* compact);
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void AllocateCompactionOutputFileNumbers(CompactionState* compact);
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void ReleaseCompactionUnusedFileNumbers(CompactionState* compact);
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// Returns the list of live files in 'live' and the list
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// of all files in the filesystem in 'allfiles'.
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void FindObsoleteFiles(DeletionState& deletion_state);
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// Diffs the files listed in filenames and those that do not
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// belong to live files are posibly removed. If the removed file
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// is a sst file, then it returns the file number in files_to_evict.
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void PurgeObsoleteFiles(DeletionState& deletion_state);
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// Removes the file listed in files_to_evict from the table_cache
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void EvictObsoleteFiles(DeletionState& deletion_state);
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void PurgeObsoleteWALFiles();
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Status ListAllWALFiles(const std::string& path,
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std::vector<LogFile>* logFiles,
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WalFileType type);
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// Find's all the log files which contain updates with seq no.
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// Greater Than or Equal to the requested SequenceNumber
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Status FindProbableWALFiles(std::vector<LogFile>* const allLogs,
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std::vector<LogFile>* const result,
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const SequenceNumber target);
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// return true if
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bool CheckFileExistsAndEmpty(const LogFile& file);
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Status ReadFirstRecord(const LogFile& file, WriteBatch* const result);
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Status ReadFirstLine(const std::string& fname, WriteBatch* const batch);
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void PrintStatistics();
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// dump leveldb.stats to LOG
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void MaybeDumpStats();
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// Return the minimum empty level that could hold the total data in the
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// input level. Return the input level, if such level could not be found.
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int FindMinimumEmptyLevelFitting(int level);
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// Move the files in the input level to the minimum level that could hold
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// the data set.
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void ReFitLevel(int level);
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// Constant after construction
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const InternalFilterPolicy internal_filter_policy_;
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bool owns_info_log_;
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// table_cache_ provides its own synchronization
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unique_ptr<TableCache> table_cache_;
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// Lock over the persistent DB state. Non-nullptr iff successfully acquired.
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FileLock* db_lock_;
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// State below is protected by mutex_
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port::Mutex mutex_;
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port::AtomicPointer shutting_down_;
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port::CondVar bg_cv_; // Signalled when background work finishes
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std::shared_ptr<MemTableRepFactory> mem_rep_factory_;
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MemTable* mem_;
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MemTableList imm_; // Memtable that are not changing
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uint64_t logfile_number_;
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unique_ptr<log::Writer> log_;
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std::string host_name_;
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// Queue of writers.
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std::deque<Writer*> writers_;
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WriteBatch tmp_batch_;
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SnapshotList snapshots_;
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// Set of table files to protect from deletion because they are
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// part of ongoing compactions.
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std::set<uint64_t> pending_outputs_;
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// count how many background compaction been scheduled or is running?
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int bg_compaction_scheduled_;
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// Has a background stats log thread scheduled?
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bool bg_logstats_scheduled_;
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// Information for a manual compaction
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struct ManualCompaction {
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int level;
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bool done;
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bool in_progress; // compaction request being processed?
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const InternalKey* begin; // nullptr means beginning of key range
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const InternalKey* end; // nullptr means end of key range
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InternalKey tmp_storage; // Used to keep track of compaction progress
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};
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ManualCompaction* manual_compaction_;
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// Have we encountered a background error in paranoid mode?
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Status bg_error_;
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std::unique_ptr<StatsLogger> logger_;
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int64_t volatile last_log_ts;
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// shall we disable deletion of obsolete files
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bool disable_delete_obsolete_files_;
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// last time when DeleteObsoleteFiles was invoked
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uint64_t delete_obsolete_files_last_run_;
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// last time when PurgeObsoleteWALFiles ran.
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uint64_t purge_wal_files_last_run_;
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// last time stats were dumped to LOG
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std::atomic<uint64_t> last_stats_dump_time_microsec_;
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// These count the number of microseconds for which MakeRoomForWrite stalls.
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uint64_t stall_level0_slowdown_;
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uint64_t stall_memtable_compaction_;
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uint64_t stall_level0_num_files_;
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std::vector<uint64_t> stall_leveln_slowdown_;
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uint64_t stall_level0_slowdown_count_;
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uint64_t stall_memtable_compaction_count_;
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uint64_t stall_level0_num_files_count_;
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std::vector<uint64_t> stall_leveln_slowdown_count_;
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// Time at which this instance was started.
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const uint64_t started_at_;
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bool flush_on_destroy_; // Used when disableWAL is true.
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// Per level compaction stats. stats_[level] stores the stats for
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// compactions that produced data for the specified "level".
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struct CompactionStats {
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uint64_t micros;
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// Bytes read from level N during compaction between levels N and N+1
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int64_t bytes_readn;
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// Bytes read from level N+1 during compaction between levels N and N+1
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int64_t bytes_readnp1;
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// Total bytes written during compaction between levels N and N+1
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int64_t bytes_written;
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// Files read from level N during compaction between levels N and N+1
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int files_in_leveln;
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// Files read from level N+1 during compaction between levels N and N+1
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int files_in_levelnp1;
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// Files written during compaction between levels N and N+1
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int files_out_levelnp1;
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// Number of compactions done
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int count;
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CompactionStats() : micros(0), bytes_readn(0), bytes_readnp1(0),
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bytes_written(0), files_in_leveln(0),
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files_in_levelnp1(0), files_out_levelnp1(0),
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count(0) { }
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void Add(const CompactionStats& c) {
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this->micros += c.micros;
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this->bytes_readn += c.bytes_readn;
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this->bytes_readnp1 += c.bytes_readnp1;
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this->bytes_written += c.bytes_written;
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this->files_in_leveln += c.files_in_leveln;
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this->files_in_levelnp1 += c.files_in_levelnp1;
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this->files_out_levelnp1 += c.files_out_levelnp1;
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this->count += 1;
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}
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};
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std::vector<CompactionStats> stats_;
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// Used to compute per-interval statistics
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struct StatsSnapshot {
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uint64_t bytes_read_;
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uint64_t bytes_written_;
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uint64_t bytes_new_;
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double seconds_up_;
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StatsSnapshot() : bytes_read_(0), bytes_written_(0),
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bytes_new_(0), seconds_up_(0) {}
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};
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StatsSnapshot last_stats_;
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static const int KEEP_LOG_FILE_NUM = 1000;
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std::string db_absolute_path_;
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// count of the number of contiguous delaying writes
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int delayed_writes_;
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// store the last flushed sequence.
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// Used by transaction log iterator.
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SequenceNumber last_flushed_sequence_;
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// The options to access storage files
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const EnvOptions storage_options_;
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// A value of true temporarily disables scheduling of background work
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bool bg_work_gate_closed_;
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// Guard against multiple concurrent refitting
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bool refitting_level_;
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// No copying allowed
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DBImpl(const DBImpl&);
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void operator=(const DBImpl&);
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// dump the delayed_writes_ to the log file and reset counter.
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void DelayLoggingAndReset();
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// Return the earliest snapshot where seqno is visible.
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// Store the snapshot right before that, if any, in prev_snapshot
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inline SequenceNumber findEarliestVisibleSnapshot(
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SequenceNumber in,
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std::vector<SequenceNumber>& snapshots,
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SequenceNumber* prev_snapshot);
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// Function that Get and KeyMayExist call with no_io true or false
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// Note: 'value_found' from KeyMayExist propagates here
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Status GetImpl(const ReadOptions& options,
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const Slice& key,
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std::string* value,
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const bool no_io = false,
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bool* value_found = nullptr);
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};
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// Sanitize db options. The caller should delete result.info_log if
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// it is not equal to src.info_log.
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extern Options SanitizeOptions(const std::string& db,
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const InternalKeyComparator* icmp,
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const InternalFilterPolicy* ipolicy,
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const Options& src);
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} // namespace leveldb
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#endif // STORAGE_LEVELDB_DB_DB_IMPL_H_
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