func()

in file.go [439:476]

• 31 lines of code
• 7 McCabe index (conditional complexity)

func (f *File) mmap() reason {
	const op = "txfile/mmap"

	// update real file size
	fileSize, fileErr := f.file.Size()
	if fileErr != nil {
		const msg = "unable to determine file size for mmap region"
		return f.errWrap(op, fileErr).report(msg)
	}
	if fileSize < 0 {
		msg := fmt.Sprintf("file size %v < 0", fileSize)
		return f.err(op).of(InvalidFileSize).report(msg)
	}
	f.size = fileSize
	f.sizeEstimate = fileSize // reset estimate

	maxSize := f.allocator.maxSize
	if em := uint(f.allocator.meta.endMarker); maxSize > 0 && em > f.allocator.maxPages {
		maxSize = em * f.allocator.pageSize
	}
	pageSize := f.allocator.pageSize
	sz, err := computePlatformMmapSize(uint(fileSize), maxSize, uint(pageSize))
	if err != nil {
		return err
	}

	// map file
	buf, fileErr := f.file.MMap(int(sz))
	if err != nil {
		return f.errWrap(op, err).report("can not mmap file")
	}

	f.mapped = buf
	f.meta[0] = castMetaPage(buf[0:])
	f.meta[1] = castMetaPage(buf[pageSize:])

	return nil
}