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|
package store
import (
"errors"
"maps"
"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 Compat 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 *Store) Do(identity int, f func(c Cursor)) (bool, error) {
if h, err := s.Handle(identity); err != nil {
return false, err
} else {
return h.do(f)
}
}
// storeAdapter satisfies [Compat] via [Store].
type storeAdapter struct {
msg message.Msg
*Store
}
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) Compat {
return storeAdapter{msg, New(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 [Compat.Do] on [Handle].
func (h *Handle) do(f func(c Cursor)) (bool, error) {
if unlock, err := h.Lock(); err != nil {
return false, err
} else {
defer unlock()
}
f(h)
return true, nil
}
/* these compatibility methods must only be called while fileMu is held */
func (h *Handle) Save(state *hst.State) error {
return (&EntryHandle{nil, h.Path.Append(state.ID.String()), state.ID}).Save(state)
}
func (h *Handle) Destroy(id hst.ID) error {
return (&EntryHandle{nil, h.Path.Append(id.String()), id}).Destroy()
}
func (h *Handle) 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 *Handle) 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
}
var (
ErrDuplicate = errors.New("store contains duplicates")
)
// Joiner is the interface that wraps the Join method.
//
// The Join function uses Joiner if available.
type Joiner interface {
Join() (map[hst.ID]*hst.State, error)
}
// Join returns joined state entries of all active identities.
func Join(s Compat) (map[hst.ID]*hst.State, error) {
if j, ok := s.(Joiner); ok {
return j.Join()
}
var (
aids []int
entries = make(map[hst.ID]*hst.State)
el int
res map[hst.ID]*hst.State
loadErr error
)
if ln, err := s.List(); err != nil {
return nil, err
} else {
aids = ln
}
for _, aid := range aids {
if _, err := s.Do(aid, func(c Cursor) {
res, loadErr = c.Load()
}); err != nil {
return nil, err
}
if loadErr != nil {
return nil, loadErr
}
// save expected length
el = len(entries) + len(res)
maps.Copy(entries, res)
if len(entries) != el {
return nil, ErrDuplicate
}
}
return entries, nil
}
|
