/*
* Helper functionality for distributing a fixed total amount of
* an abstract resource among multiple coroutines.
*
* Copyright (c) 2019 Virtuozzo International GmbH
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#ifndef QEMU_CO_SHARED_RESOURCE_H
#define QEMU_CO_SHARED_RESOURCE_H
/* Accesses to co-shared-resource API are thread-safe */
typedef struct SharedResource SharedResource;
/*
* Create SharedResource structure
*
* @total: total amount of some resource to be shared between clients
*/
SharedResource *shres_create(uint64_t total);
/*
* Release SharedResource structure
*
* This function may only be called once everything allocated by all
* clients has been deallocated.
*/
void shres_destroy(SharedResource *s);
/*
* Try to allocate an amount of @n. Return true on success, and false
* if there is too little left of the collective resource to fulfill
* the request.
*/
bool co_try_get_from_shres(SharedResource *s, uint64_t n);
/*
* Allocate an amount of @n, and, if necessary, yield until
* that becomes possible.
*/
void coroutine_fn co_get_from_shres(SharedResource *s, uint64_t n);
/*
* Deallocate an amount of @n. The total amount allocated by a caller
* does not need to be deallocated/released with a single call, but may
* be split over several calls. For example, get(4), get(3), and then
* put(5), put(2).
*/
void coroutine_fn co_put_to_shres(SharedResource *s, uint64_t n);
#endif /* QEMU_CO_SHARED_RESOURCE_H */
