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package packed
import (
"errors"
"os"
"sync"
"lindenii.org/go/furgit/internal/cache/clock"
"lindenii.org/go/furgit/internal/mru"
"lindenii.org/go/furgit/object/id"
"lindenii.org/go/furgit/object/store"
)
// ErrMalformedPackedStore reports that
// a pack or pack index in the store is
// truncated, inconsistent, or otherwise corrupt.
var ErrMalformedPackedStore = errors.New("object/store/packed: malformed packed store")
// Packed reads Git objects from pack/index files
// under an objects/pack root.
//
// Packs appearing after construction are only visible
// after an explicit [Packed.Refresh].
//
// Labels: Close-Caller.
type Packed struct {
// root is the objects/pack directory
// used for all pack and index file access.
root *os.Root
// objectFormat is the expected object format for lookups.
objectFormat id.ObjectFormat
// order contains the packs to probe, MRU-first.
order *mru.Order[*pack]
// baseCache caches delta bases consumed during resolution.
baseCache *clock.Clock[baseKey, cachedBase]
// refreshMu serializes Refresh.
// Readers uses none of these.
refreshMu sync.Mutex
// byName supports reusing surviving packs across Refresh,
// and retired holds dropped packs until Close,
// since concurrent readers may still use them.
byName map[string]*pack
retired []*pack
}
var _ store.ObjectReader = (*Packed)(nil)
// New creates a packed-object store rooted at an objects/pack directory,
// performing an initial Refresh.
//
// Labels: Deps-Borrowed, Life-Parent.
func New(root *os.Root, objectFormat id.ObjectFormat) (*Packed, error) {
if objectFormat.Size() == 0 {
return nil, id.ErrInvalidObjectFormat
}
packed := &Packed{
root: root,
objectFormat: objectFormat,
order: mru.New[*pack](mru.Options{Interval: 48}),
baseCache: newBaseCache(),
refreshMu: sync.Mutex{},
byName: nil,
retired: nil,
}
err := packed.Refresh()
if err != nil {
return nil, err
}
return packed, nil
}
// Close releases mapped pack/index resources associated with the store.
//
// Labels: MT-Unsafe.
func (packed *Packed) Close() error {
errs := make([]error, 0, len(packed.byName)+len(packed.retired))
for _, p := range packed.byName {
errs = append(errs, p.close())
}
for _, p := range packed.retired {
errs = append(errs, p.close())
}
packed.byName = nil
packed.retired = nil
packed.baseCache.Clear()
return errors.Join(errs...)
}
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