// SliceAt implements the fs.SlicerAt interface
func (s *Store) SliceAt(sz, off int64) (p []byte, err error) {
fn := func(i, start, end int64) (stop bool, err error) {
s.segmx.RLock()
if i >= int64(len(s.segs)) {
s.segmx.RUnlock()
return false, io.EOF
}
s.segmx.RUnlock()
seg := s.segs[i]
p = seg.Data[start:end]
// mark that the mmap may have changed (sliced data can be changed)
// TODO We're setting this as changed but the change is going to
// happen later (if it happens at all). Try to fix this problem.
atomic.StoreUint32(&seg.dirty, 1)
return true, nil
}
if err := segments.Bounds(s.size, off, off+sz, fn); err != nil {
return nil, err
}
return p, nil
}
// WriteAt implements the io.WriterAt interface
func (s *Store) WriteAt(p []byte, off int64) (n int, err error) {
sz := int64(len(p))
towrite := p[:]
var toalloc int64
fn := func(i, start, end int64) (stop bool, err error) {
if err := s.ensure(i); err != nil {
return false, err
}
seg := s.segs[i]
c := copy(seg.Data[start:end], towrite)
// mark the segment as changed
atomic.StoreUint32(&seg.dirty, 1)
n += c
towrite = towrite[c:]
toalloc = i + 1
return false, nil
}
if err := segments.Bounds(s.size, off, off+sz, fn); err != nil {
return n, err
}
return n, nil
}
// ReadAt implements the io.ReaderAt interface
func (s *Store) ReadAt(p []byte, off int64) (n int, err error) {
sz := int64(len(p))
toread := p[:]
fn := func(i, start, end int64) (stop bool, err error) {
s.segmx.RLock()
if i >= int64(len(s.segs)) {
s.segmx.RUnlock()
return false, io.EOF
}
s.segmx.RUnlock()
var done int64
req := end - start
seg := s.segs[i]
for done < req {
c, err := seg.ReadAt(toread[:req-done], start+done)
if err != nil {
return false, err
}
n += c
done += int64(c)
toread = toread[c:]
}
return false, nil
}
err = segments.Bounds(s.size, off, off+sz, fn)
return n, err
}
// ReadAt implements the io.ReaderAt interface
func (s *Store) ReadAt(p []byte, off int64) (n int, err error) {
sz := int64(len(p))
toread := p[:]
fn := func(i, start, end int64) (stop bool, err error) {
s.segmx.RLock()
if i >= int64(len(s.segs)) {
s.segmx.RUnlock()
return false, io.EOF
}
s.segmx.RUnlock()
seg := s.segs[i]
c := copy(toread, seg.Data[start:end])
n += c
toread = toread[c:]
return false, nil
}
err = segments.Bounds(s.size, off, off+sz, fn)
return n, err
}
// WriteAt implements the io.WriterAt interface
func (s *Store) WriteAt(p []byte, off int64) (n int, err error) {
sz := int64(len(p))
towrite := p[:]
fn := func(i, start, end int64) (stop bool, err error) {
if err := s.ensure(i); err != nil {
return false, err
}
var done int64
req := end - start
seg := s.segs[i]
for done < req {
c, err := seg.WriteAt(towrite[:req-done], start+done)
if err != nil {
return false, err
}
n += c
done += int64(c)
towrite = towrite[c:]
}
// mark the segment as changed
atomic.StoreUint32(&seg.dirty, 1)
return false, nil
}
if err := segments.Bounds(s.size, off, off+sz, fn); err != nil {
return n, err
}
return n, nil
}