1 files changed, 130 insertions, 0 deletions
diff --git a/internal/store/compat.go b/internal/store/compat.go
new file mode 100644
index 00000000..c0ef6dd7
--- /dev/null
+++ b/internal/store/compat.go
@@ -0,0 +1,130 @@
+package store
+
+import (
+	"strconv"
+
+	"hakurei.app/container/check"
+	"hakurei.app/hst"
+	"hakurei.app/message"
+)
+
+/* this provides an implementation of Store on top of the improved state tracking to ease in the changes */
+
+type Store interface {
+	// Do calls f exactly once and ensures store exclusivity until f returns.
+	// Returns whether f is called and any errors during the locking process.
+	// Cursor provided to f becomes invalid as soon as f returns.
+	Do(identity int, f func(c Cursor)) (ok bool, err error)
+
+	// List queries the store and returns a list of identities known to the store.
+	// Note that some or all returned identities might not have any active apps.
+	List() (identities []int, err error)
+}
+
+func (s *stateStore) Do(identity int, f func(c Cursor)) (bool, error) {
+	if h, err := s.identityHandle(identity); err != nil {
+		return false, err
+	} else {
+		return h.do(f)
+	}
+}
+
+// storeAdapter satisfies [Store] via stateStore.
+type storeAdapter struct {
+	msg message.Msg
+	*stateStore
+}
+
+func (s storeAdapter) List() ([]int, error) {
+	segments, n, err := s.segments()
+	if err != nil {
+		return nil, err
+	}
+
+	identities := make([]int, 0, n)
+	for si := range segments {
+		if si.err != nil {
+			if m, ok := message.GetMessage(err); ok {
+				s.msg.Verbose(m)
+			} else {
+				// unreachable
+				return nil, err
+			}
+			continue
+		}
+		identities = append(identities, si.identity)
+	}
+	return identities, nil
+}
+
+// NewMulti returns an instance of the multi-file store.
+func NewMulti(msg message.Msg, prefix *check.Absolute) Store {
+	return storeAdapter{msg, newStore(prefix.Append("state"))}
+}
+
+// Cursor provides access to the store of an identity.
+type Cursor interface {
+	Save(state *hst.State) error
+	Destroy(id hst.ID) error
+	Load() (map[hst.ID]*hst.State, error)
+	Len() (int, error)
+}
+
+// do implements stateStore.Do on storeHandle.
+func (h *storeHandle) do(f func(c Cursor)) (bool, error) {
+	if unlock, err := h.fileMu.Lock(); err != nil {
+		return false, &hst.AppError{Step: "acquire lock on store segment " + strconv.Itoa(h.identity), Err: err}
+	} else {
+		defer unlock()
+	}
+
+	f(h)
+	return true, nil
+}
+
+/* these compatibility methods must only be called while fileMu is held */
+
+func (h *storeHandle) Save(state *hst.State) error {
+	return (&stateEntryHandle{nil, h.path.Append(state.ID.String()), state.ID}).save(state)
+}
+
+func (h *storeHandle) Destroy(id hst.ID) error {
+	return (&stateEntryHandle{nil, h.path.Append(id.String()), id}).destroy()
+}
+
+func (h *storeHandle) Load() (map[hst.ID]*hst.State, error) {
+	entries, n, err := h.entries()
+	if err != nil {
+		return nil, err
+	}
+
+	r := make(map[hst.ID]*hst.State, n)
+	for eh := range entries {
+		if eh.decodeErr != nil {
+			err = eh.decodeErr
+			break
+		}
+		var s hst.State
+		if _, err = eh.load(&s); err != nil {
+			break
+		}
+		r[eh.ID] = &s
+	}
+	return r, err
+}
+
+func (h *storeHandle) Len() (int, error) {
+	entries, _, err := h.entries()
+	if err != nil {
+		return -1, err
+	}
+
+	var n int
+	for eh := range entries {
+		if eh.decodeErr != nil {
+			err = eh.decodeErr
+		}
+		n++
+	}
+	return n, err
+}