lock.go (1560B)
1 // GoToSocial 2 // Copyright (C) GoToSocial Authors admin@gotosocial.org 3 // SPDX-License-Identifier: AGPL-3.0-or-later 4 // 5 // This program is free software: you can redistribute it and/or modify 6 // it under the terms of the GNU Affero General Public License as published by 7 // the Free Software Foundation, either version 3 of the License, or 8 // (at your option) any later version. 9 // 10 // This program is distributed in the hope that it will be useful, 11 // but WITHOUT ANY WARRANTY; without even the implied warranty of 12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 // GNU Affero General Public License for more details. 14 // 15 // You should have received a copy of the GNU Affero General Public License 16 // along with this program. If not, see <http://www.gnu.org/licenses/>. 17 18 package federatingdb 19 20 import ( 21 "context" 22 "errors" 23 "net/url" 24 ) 25 26 // Lock takes a lock for the object at the specified id. If an error 27 // is returned, the lock must not have been taken. 28 // 29 // The lock must be able to succeed for an id that does not exist in 30 // the database. This means acquiring the lock does not guarantee the 31 // entry exists in the database. 32 // 33 // Locks are encouraged to be lightweight and in the Go layer, as some 34 // processes require tight loops acquiring and releasing locks. 35 // 36 // Used to ensure race conditions in multiple requests do not occur. 37 func (f *federatingDB) Lock(c context.Context, id *url.URL) (func(), error) { 38 if id == nil { 39 return nil, errors.New("Lock: id was nil") 40 } 41 unlock := f.locks.Lock(id.String()) 42 return unlock, nil 43 }