gotosocial/vendor/git.iim.gay/grufwub/go-errors/once.go
kim (grufwub) e43a46e982 add git.iim.gay/grufwub/go-store for storage backend, replacing blob.Storage
Signed-off-by: kim (grufwub) <grufwub@gmail.com>
2021-09-11 20:12:47 +01:00

46 lines
747 B
Go

package errors
import (
"sync/atomic"
"unsafe"
)
// OnceError is an error structure that supports safe multi-threaded
// usage and setting only once (until reset)
type OnceError struct {
err unsafe.Pointer
}
// NewOnce returns a new OnceError instance
func NewOnce() OnceError {
return OnceError{
err: nil,
}
}
func (e *OnceError) Store(err error) {
// Nothing to do
if err == nil {
return
}
// Only set if not already
atomic.CompareAndSwapPointer(
&e.err,
nil,
unsafe.Pointer(&err),
)
}
func (e *OnceError) Load() error {
return *(*error)(atomic.LoadPointer(&e.err))
}
func (e *OnceError) IsSet() bool {
return (atomic.LoadPointer(&e.err) != nil)
}
func (e *OnceError) Reset() {
atomic.StorePointer(&e.err, nil)
}