28 lines
458 B
Go
28 lines
458 B
Go
|
package locker
|
||
|
|
|
||
|
|
import "context"
|
||
|
|
|
||
|
|
type Locked[T any] struct {
|
||
|
|
state chan *T
|
||
|
|
}
|
||
|
|
|
||
|
|
func New[T any](initial *T) *Locked[T] {
|
||
|
|
s := &Locked[T]{}
|
||
|
|
s.state = make(chan *T, 1)
|
||
|
|
s.state <- initial
|
||
|
|
return s
|
||
|
|
}
|
||
|
|
|
||
|
|
func (s *Locked[T]) Modify(ctx context.Context, fn func(*T) error) error {
|
||
|
|
if ctx.Err() != nil {
|
||
|
|
return ctx.Err()
|
||
|
|
}
|
||
|
|
|
||
|
|
select {
|
||
|
|
case state := <-s.state:
|
||
|
|
defer func() { s.state <- state }()
|
||
|
|
return fn(state)
|
||
|
|
case <-ctx.Done():
|
||
|
|
return ctx.Err()
|
||
|
|
}
|
||
|
|
}
|