Function newMMapStoreReader

kv/table/reader.go:75–119

newMMapStoreReader creates mmap store file reader.

(path, fileName string)

// newMMapStoreReader creates mmap store file reader.
func newMMapStoreReader(path, fileName string) (r Reader, err error) {
	f, err := openFileFn(path)
	if err != nil {
		return nil, err
	}
	data, err := mapFunc(f)
	defer func() {
		if err != nil && len(data) > 0 {
			defer func() {
				_ = f.Close()
			}()
			// if init err and map data exist, need unmap it
			if e := unmapFunc(f, data); e != nil {
				metrics.TableReadStatistics.UnMMapFailures.Incr()
				tableLogger.Warn("unmap error when new store reader fail",
					logger.String("path", path), logger.Error(err))
			} else {
				metrics.TableReadStatistics.UnMMaps.Incr()
			}
		}
	}()
	if err != nil {
		metrics.TableReadStatistics.MMapFailures.Incr()
		return nil, err
	}
	metrics.TableReadStatistics.MMaps.Incr()

	if len(data) < sstFileFooterSize {
		err = fmt.Errorf("length of sstfile:%s length is too short", path)
		return nil, err
	}
	reader := &storeMMapReader{
		path:      path,
		fileName:  fileName,
		f:         f,
		fullBlock: data,
		keys:      roaring.New(),
	}

	if err := reader.initialize(); err != nil {
		return nil, err
	}

	return reader, nil
}

// initialize store reader, reads index block(keys,offset etc.), then caches it.
func (r *storeMMapReader) initialize() error {