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/*
GoToSocial
Copyright (C) 2021-2023 GoToSocial Authors admin@gotosocial.org
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package federatingdb
import (
"context"
"errors"
"net/url"
)
// Lock takes a lock for the object at the specified id. If an error
// is returned, the lock must not have been taken.
//
// The lock must be able to succeed for an id that does not exist in
// the database. This means acquiring the lock does not guarantee the
// entry exists in the database.
//
// Locks are encouraged to be lightweight and in the Go layer, as some
// processes require tight loops acquiring and releasing locks.
//
// Used to ensure race conditions in multiple requests do not occur.
func (f *federatingDB) Lock(c context.Context, id *url.URL) (func(), error) {
if id == nil {
return nil, errors.New("Lock: id was nil")
}
unlock := f.locks.Lock(id.String())
return unlock, nil
}
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