// Open opens a LevelDB whose files live in the given directory. func Open(dirname string, opts *db.Options) (*DB, error) { d := &DB{ dirname: dirname, opts: opts, icmp: internalKeyComparer{opts.GetComparer()}, pendingOutputs: make(map[uint64]struct{}), } if opts != nil { d.icmpOpts = *opts } d.icmpOpts.Comparer = d.icmp tableCacheSize := opts.GetMaxOpenFiles() - numNonTableCacheFiles if tableCacheSize < minTableCacheSize { tableCacheSize = minTableCacheSize } d.tableCache.init(dirname, opts.GetFileSystem(), &d.icmpOpts, tableCacheSize) d.mem = memdb.New(&d.icmpOpts) d.compactionCond = sync.Cond{L: &d.mu} fs := opts.GetFileSystem() d.mu.Lock() defer d.mu.Unlock() // Lock the database directory. err := fs.MkdirAll(dirname, 0755) if err != nil { return nil, err } fileLock, err := fs.Lock(dbFilename(dirname, fileTypeLock, 0)) if err != nil { return nil, err } defer func() { if fileLock != nil { fileLock.Close() } }() if _, err := fs.Stat(dbFilename(dirname, fileTypeCurrent, 0)); os.IsNotExist(err) { // Create the DB if it did not already exist. if err := createDB(dirname, opts); err != nil { return nil, err } } else if err != nil { return nil, fmt.Errorf("leveldb: database %q: %v", dirname, err) } else if opts.GetErrorIfDBExists() { return nil, fmt.Errorf("leveldb: database %q already exists", dirname) } // Load the version set. err = d.versions.load(dirname, opts) if err != nil { return nil, err } // Replay any newer log files than the ones named in the manifest. var ve versionEdit ls, err := fs.List(dirname) if err != nil { return nil, err } var logFiles fileNumAndNameSlice for _, filename := range ls { ft, fn, ok := parseDBFilename(filename) if ok && ft == fileTypeLog && (fn >= d.versions.logNumber || fn == d.versions.prevLogNumber) { logFiles = append(logFiles, fileNumAndName{fn, filename}) } } sort.Sort(logFiles) for _, lf := range logFiles { maxSeqNum, err := d.replayLogFile(&ve, fs, filepath.Join(dirname, lf.name)) if err != nil { return nil, err } d.versions.markFileNumUsed(lf.num) if d.versions.lastSequence < maxSeqNum { d.versions.lastSequence = maxSeqNum } } // Create an empty .log file. ve.logNumber = d.versions.nextFileNum() d.logNumber = ve.logNumber logFile, err := fs.Create(dbFilename(dirname, fileTypeLog, ve.logNumber)) if err != nil { return nil, err } defer func() { if logFile != nil { logFile.Close() } }() d.log = record.NewWriter(logFile) // Write a new manifest to disk. if err := d.versions.logAndApply(dirname, &ve); err != nil { return nil, err } d.deleteObsoleteFiles() d.maybeScheduleCompaction() d.logFile, logFile = logFile, nil d.fileLock, fileLock = fileLock, nil return d, nil }