Vladimir Sementsov-Ogievskiy | f16ba00 | 2019-10-22 14:18:03 +0300 | [diff] [blame] | 1 | /* |
| 2 | * Helper functionality for distributing a fixed total amount of |
| 3 | * an abstract resource among multiple coroutines. |
| 4 | * |
| 5 | * Copyright (c) 2019 Virtuozzo International GmbH |
| 6 | * |
| 7 | * Permission is hereby granted, free of charge, to any person obtaining a copy |
| 8 | * of this software and associated documentation files (the "Software"), to deal |
| 9 | * in the Software without restriction, including without limitation the rights |
| 10 | * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
| 11 | * copies of the Software, and to permit persons to whom the Software is |
| 12 | * furnished to do so, subject to the following conditions: |
| 13 | * |
| 14 | * The above copyright notice and this permission notice shall be included in |
| 15 | * all copies or substantial portions of the Software. |
| 16 | * |
| 17 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| 18 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| 19 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
| 20 | * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| 21 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
| 22 | * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN |
| 23 | * THE SOFTWARE. |
| 24 | */ |
| 25 | |
| 26 | #include "qemu/osdep.h" |
| 27 | #include "qemu/coroutine.h" |
| 28 | #include "qemu/co-shared-resource.h" |
| 29 | |
| 30 | struct SharedResource { |
Emanuele Giuseppe Esposito | 55fa54a | 2021-06-14 10:11:30 +0200 | [diff] [blame] | 31 | uint64_t total; /* Set in shres_create() and not changed anymore */ |
Vladimir Sementsov-Ogievskiy | f16ba00 | 2019-10-22 14:18:03 +0300 | [diff] [blame] | 32 | |
Emanuele Giuseppe Esposito | 55fa54a | 2021-06-14 10:11:30 +0200 | [diff] [blame] | 33 | /* State fields protected by lock */ |
| 34 | uint64_t available; |
Vladimir Sementsov-Ogievskiy | f16ba00 | 2019-10-22 14:18:03 +0300 | [diff] [blame] | 35 | CoQueue queue; |
Emanuele Giuseppe Esposito | 55fa54a | 2021-06-14 10:11:30 +0200 | [diff] [blame] | 36 | |
| 37 | QemuMutex lock; |
Vladimir Sementsov-Ogievskiy | f16ba00 | 2019-10-22 14:18:03 +0300 | [diff] [blame] | 38 | }; |
| 39 | |
| 40 | SharedResource *shres_create(uint64_t total) |
| 41 | { |
| 42 | SharedResource *s = g_new0(SharedResource, 1); |
| 43 | |
| 44 | s->total = s->available = total; |
| 45 | qemu_co_queue_init(&s->queue); |
Emanuele Giuseppe Esposito | 55fa54a | 2021-06-14 10:11:30 +0200 | [diff] [blame] | 46 | qemu_mutex_init(&s->lock); |
Vladimir Sementsov-Ogievskiy | f16ba00 | 2019-10-22 14:18:03 +0300 | [diff] [blame] | 47 | |
| 48 | return s; |
| 49 | } |
| 50 | |
| 51 | void shres_destroy(SharedResource *s) |
| 52 | { |
| 53 | assert(s->available == s->total); |
Emanuele Giuseppe Esposito | 55fa54a | 2021-06-14 10:11:30 +0200 | [diff] [blame] | 54 | qemu_mutex_destroy(&s->lock); |
Vladimir Sementsov-Ogievskiy | f16ba00 | 2019-10-22 14:18:03 +0300 | [diff] [blame] | 55 | g_free(s); |
| 56 | } |
| 57 | |
Emanuele Giuseppe Esposito | 55fa54a | 2021-06-14 10:11:30 +0200 | [diff] [blame] | 58 | /* Called with lock held. */ |
| 59 | static bool co_try_get_from_shres_locked(SharedResource *s, uint64_t n) |
Vladimir Sementsov-Ogievskiy | f16ba00 | 2019-10-22 14:18:03 +0300 | [diff] [blame] | 60 | { |
| 61 | if (s->available >= n) { |
| 62 | s->available -= n; |
| 63 | return true; |
| 64 | } |
| 65 | |
| 66 | return false; |
| 67 | } |
| 68 | |
Emanuele Giuseppe Esposito | 55fa54a | 2021-06-14 10:11:30 +0200 | [diff] [blame] | 69 | bool co_try_get_from_shres(SharedResource *s, uint64_t n) |
| 70 | { |
| 71 | QEMU_LOCK_GUARD(&s->lock); |
| 72 | return co_try_get_from_shres_locked(s, n); |
| 73 | } |
| 74 | |
Vladimir Sementsov-Ogievskiy | f16ba00 | 2019-10-22 14:18:03 +0300 | [diff] [blame] | 75 | void coroutine_fn co_get_from_shres(SharedResource *s, uint64_t n) |
| 76 | { |
| 77 | assert(n <= s->total); |
Emanuele Giuseppe Esposito | 55fa54a | 2021-06-14 10:11:30 +0200 | [diff] [blame] | 78 | QEMU_LOCK_GUARD(&s->lock); |
| 79 | while (!co_try_get_from_shres_locked(s, n)) { |
| 80 | qemu_co_queue_wait(&s->queue, &s->lock); |
Vladimir Sementsov-Ogievskiy | f16ba00 | 2019-10-22 14:18:03 +0300 | [diff] [blame] | 81 | } |
| 82 | } |
| 83 | |
| 84 | void coroutine_fn co_put_to_shres(SharedResource *s, uint64_t n) |
| 85 | { |
Emanuele Giuseppe Esposito | 55fa54a | 2021-06-14 10:11:30 +0200 | [diff] [blame] | 86 | QEMU_LOCK_GUARD(&s->lock); |
Vladimir Sementsov-Ogievskiy | f16ba00 | 2019-10-22 14:18:03 +0300 | [diff] [blame] | 87 | assert(s->total - s->available >= n); |
| 88 | s->available += n; |
| 89 | qemu_co_queue_restart_all(&s->queue); |
| 90 | } |