diff options
-rw-r--r-- | include/qemu/co-shared-resource.h | 71 | ||||
-rw-r--r-- | util/Makefile.objs | 1 | ||||
-rw-r--r-- | util/qemu-co-shared-resource.c | 76 |
3 files changed, 148 insertions, 0 deletions
diff --git a/include/qemu/co-shared-resource.h b/include/qemu/co-shared-resource.h new file mode 100644 index 0000000..4e45030 --- /dev/null +++ b/include/qemu/co-shared-resource.h @@ -0,0 +1,71 @@ +/* + * 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 + + +typedef struct SharedResource SharedResource; + +/* + * Create SharedResource structure + * + * @total: total amount of some resource to be shared between clients + * + * Note: this API is not thread-safe. + */ +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 */ diff --git a/util/Makefile.objs b/util/Makefile.objs index 41bf59d..df124af 100644 --- a/util/Makefile.objs +++ b/util/Makefile.objs @@ -37,6 +37,7 @@ util-obj-y += rcu.o util-obj-$(CONFIG_MEMBARRIER) += sys_membarrier.o util-obj-y += qemu-coroutine.o qemu-coroutine-lock.o qemu-coroutine-io.o util-obj-y += qemu-coroutine-sleep.o +util-obj-y += qemu-co-shared-resource.o util-obj-y += coroutine-$(CONFIG_COROUTINE_BACKEND).o util-obj-y += buffer.o util-obj-y += timed-average.o diff --git a/util/qemu-co-shared-resource.c b/util/qemu-co-shared-resource.c new file mode 100644 index 0000000..1c83cd9 --- /dev/null +++ b/util/qemu-co-shared-resource.c @@ -0,0 +1,76 @@ +/* + * 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. + */ + +#include "qemu/osdep.h" +#include "qemu/coroutine.h" +#include "qemu/co-shared-resource.h" + +struct SharedResource { + uint64_t total; + uint64_t available; + + CoQueue queue; +}; + +SharedResource *shres_create(uint64_t total) +{ + SharedResource *s = g_new0(SharedResource, 1); + + s->total = s->available = total; + qemu_co_queue_init(&s->queue); + + return s; +} + +void shres_destroy(SharedResource *s) +{ + assert(s->available == s->total); + g_free(s); +} + +bool co_try_get_from_shres(SharedResource *s, uint64_t n) +{ + if (s->available >= n) { + s->available -= n; + return true; + } + + return false; +} + +void coroutine_fn co_get_from_shres(SharedResource *s, uint64_t n) +{ + assert(n <= s->total); + while (!co_try_get_from_shres(s, n)) { + qemu_co_queue_wait(&s->queue, NULL); + } +} + +void coroutine_fn co_put_to_shres(SharedResource *s, uint64_t n) +{ + assert(s->total - s->available >= n); + s->available += n; + qemu_co_queue_restart_all(&s->queue); +} |