kubo/repo/onlyone.go
Marcin Rataj 6a008fc74c
refactor: apply go fix modernizers from Go 1.26 (#11190)
* chore: apply go fix modernizers from Go 1.26

automated refactoring: interface{} to any, slices.Contains,
and other idiomatic updates.

* feat(ci): add `go fix` check to Go analysis workflow

ensures Go 1.26 modernizers are applied, fails CI if `go fix ./...`
produces any changes (similar to existing `go fmt` enforcement)
2026-02-11 01:01:32 +01:00

73 lines
1.3 KiB
Go

package repo
import (
"sync"
)
// OnlyOne tracks open Repos by arbitrary key and returns the already
// open one.
type OnlyOne struct {
mu sync.Mutex
active map[any]*ref
}
// Open a Repo identified by key. If Repo is not already open, the
// open function is called, and the result is remembered for further
// use.
//
// Key must be comparable, or Open will panic. Make sure to pick keys
// that are unique across different concrete Repo implementations,
// e.g. by creating a local type:
//
// type repoKey string
// r, err := o.Open(repoKey(path), open)
//
// Call Repo.Close when done.
func (o *OnlyOne) Open(key any, open func() (Repo, error)) (Repo, error) {
o.mu.Lock()
defer o.mu.Unlock()
if o.active == nil {
o.active = make(map[any]*ref)
}
item, found := o.active[key]
if !found {
repo, err := open()
if err != nil {
return nil, err
}
item = &ref{
parent: o,
key: key,
Repo: repo,
}
o.active[key] = item
}
item.refs++
return item, nil
}
type ref struct {
parent *OnlyOne
key any
refs uint32
Repo
}
var _ Repo = (*ref)(nil)
func (r *ref) Close() error {
r.parent.mu.Lock()
defer r.parent.mu.Unlock()
r.refs--
if r.refs > 0 {
// others are holding it open
return nil
}
// last one
delete(r.parent.active, r.key)
return r.Repo.Close()
}