maddy

 1/*
 2Maddy Mail Server - Composable all-in-one email server.
 3Copyright © 2019-2020 Max Mazurov <fox.cpp@disroot.org>, Maddy Mail Server contributors
 4
 5This program is free software: you can redistribute it and/or modify
 6it under the terms of the GNU General Public License as published by
 7the Free Software Foundation, either version 3 of the License, or
 8(at your option) any later version.
 9
10This program is distributed in the hope that it will be useful,
11but WITHOUT ANY WARRANTY; without even the implied warranty of
12MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13GNU General Public License for more details.
14
15You should have received a copy of the GNU General Public License
16along with this program.  If not, see <https://www.gnu.org/licenses/>.
17*/
18
19package limiters
20
21import "context"
22
23// MultiLimit wraps multiple L implementations into a single one, locking them
24// in the specified order.
25//
26// It does not implement any deadlock detection or avoidance algorithms.
27type MultiLimit struct {
28	Wrapped []L
29}
30
31func (ml *MultiLimit) Take() bool {
32	for i := 0; i < len(ml.Wrapped); i++ {
33		if !ml.Wrapped[i].Take() {
34			// Acquire failed, undo acquire for all other resources we already
35			// got.
36			for _, l := range ml.Wrapped[:i] {
37				l.Release()
38			}
39			return false
40		}
41	}
42	return true
43}
44
45func (ml *MultiLimit) TakeContext(ctx context.Context) error {
46	for i := 0; i < len(ml.Wrapped); i++ {
47		if err := ml.Wrapped[i].TakeContext(ctx); err != nil {
48			// Acquire failed, undo acquire for all other resources we already
49			// got.
50			for _, l := range ml.Wrapped[:i] {
51				l.Release()
52			}
53			return err
54		}
55	}
56	return nil
57}
58
59func (ml *MultiLimit) Release() {
60	for _, l := range ml.Wrapped {
61		l.Release()
62	}
63}
64
65func (ml *MultiLimit) Close() {
66	for _, l := range ml.Wrapped {
67		l.Close()
68	}
69}