Add missing fs/space.go

fs/space.go

+package fs
+
+import (
+	"golang.org/x/xerrors"
+	"io/ioutil"
+	"path/filepath"
+	"syscall"
+)
+
+// reserve reserves storage for the sector. `path` is the path of the directory containing sectors
+func (f *FS) reserve(typ DataType, path StoragePath, size uint64) error {
+	f.lk.Lock()
+	defer f.lk.Unlock()
+
+	avail, fsavail, err := f.availableBytes(path)
+	if err != nil {
+		return err
+	}
+
+	if int64(size) > avail {
+		return xerrors.Errorf("not enough space in '%s', need %dB, available %dB (fs: %dB, reserved: %dB)",
+			f.paths,
+			size,
+			avail,
+			fsavail,
+			f.reservedBytes(path))
+	}
+
+	if _, ok := f.reserved[path]; !ok {
+		f.reserved[path] = map[DataType]uint64{}
+	}
+	f.reserved[path][typ] += size
+
+	return nil
+}
+
+func (f *FS) Release(path SectorPath, sectorSize uint64) {
+	f.lk.Lock()
+	defer f.lk.Unlock()
+
+	f.reserved[path.storage()][path.typ()] -= overheadMul[path.typ()] * sectorSize
+}
+
+func (f *FS) List(path StoragePath, typ DataType) ([]SectorPath, error) {
+	tp := filepath.Join(string(path), string(typ))
+
+	ents, err := ioutil.ReadDir(tp)
+	if err != nil {
+		return nil, err
+	}
+
+	out := make([]SectorPath, len(ents))
+	for i, ent := range ents {
+		out[i] = SectorPath(filepath.Join(tp, ent.Name()))
+	}
+
+	return out, nil
+}
+
+func (f *FS) reservedBytes(path StoragePath) int64 {
+	var out int64
+	rsvs, ok := f.reserved[path]
+	if !ok {
+		return 0
+	}
+	for _, r := range rsvs {
+		out += int64(r)
+	}
+	return out
+}
+
+func (f *FS) availableBytes(path StoragePath) (int64, int64, error) {
+	var fsstat syscall.Statfs_t
+
+	if err := syscall.Statfs(string(path), &fsstat); err != nil {
+		return 0, 0, err
+	}
+
+	fsavail := int64(fsstat.Bavail) * int64(fsstat.Bsize)
+
+	avail := fsavail - f.reservedBytes(path)
+
+	return avail, fsavail, nil
+}