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 { 31 uint64_t total; 32 uint64_t available; 33 34 CoQueue queue; 35 }; 36 37 SharedResource *shres_create(uint64_t total) 38 { 39 SharedResource *s = g_new0(SharedResource, 1); 40 41 s->total = s->available = total; 42 qemu_co_queue_init(&s->queue); 43 44 return s; 45 } 46 47 void shres_destroy(SharedResource *s) 48 { 49 assert(s->available == s->total); 50 g_free(s); 51 } 52 53 bool co_try_get_from_shres(SharedResource *s, uint64_t n) 54 { 55 if (s->available >= n) { 56 s->available -= n; 57 return true; 58 } 59 60 return false; 61 } 62 63 void coroutine_fn co_get_from_shres(SharedResource *s, uint64_t n) 64 { 65 assert(n <= s->total); 66 while (!co_try_get_from_shres(s, n)) { 67 qemu_co_queue_wait(&s->queue, NULL); 68 } 69 } 70 71 void coroutine_fn co_put_to_shres(SharedResource *s, uint64_t n) 72 { 73 assert(s->total - s->available >= n); 74 s->available += n; 75 qemu_co_queue_restart_all(&s->queue); 76 } 77