| 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 | #ifndef QEMU_CO_SHARED_RESOURCE_H |
| 27 | #define QEMU_CO_SHARED_RESOURCE_H |
| 28 | |
| 29 | /* Accesses to co-shared-resource API are thread-safe */ |
| 30 | typedef struct SharedResource SharedResource; |
| 31 | |
| 32 | /* |
| 33 | * Create SharedResource structure |
| 34 | * |
| 35 | * @total: total amount of some resource to be shared between clients |
| 36 | */ |
| 37 | SharedResource *shres_create(uint64_t total); |
| 38 | |
| 39 | /* |
| 40 | * Release SharedResource structure |
| 41 | * |
| 42 | * This function may only be called once everything allocated by all |
| 43 | * clients has been deallocated. |
| 44 | */ |
| 45 | void shres_destroy(SharedResource *s); |
| 46 | |
| 47 | /* |
| 48 | * Allocate an amount of @n, and, if necessary, yield until |
| 49 | * that becomes possible. |
| 50 | */ |
| 51 | void coroutine_fn co_get_from_shres(SharedResource *s, uint64_t n); |
| 52 | |
| 53 | /* |
| 54 | * Deallocate an amount of @n. The total amount allocated by a caller |
| 55 | * does not need to be deallocated/released with a single call, but may |
| 56 | * be split over several calls. For example, get(4), get(3), and then |
| 57 | * put(5), put(2). |
| 58 | */ |
| 59 | void coroutine_fn co_put_to_shres(SharedResource *s, uint64_t n); |
| 60 | |
| 61 | |
| 62 | #endif /* QEMU_CO_SHARED_RESOURCE_H */ |