/* $NetBSD: counter.c,v 1.1.2.2 2024/02/24 13:07:19 martin Exp $ */ /* * Copyright (C) Internet Systems Consortium, Inc. ("ISC") * * SPDX-License-Identifier: MPL-2.0 * * This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this * file, you can obtain one at https://mozilla.org/MPL/2.0/. * * See the COPYRIGHT file distributed with this work for additional * information regarding copyright ownership. */ /*! \file */ #include #include #include #include #include #include #include #include #define COUNTER_MAGIC ISC_MAGIC('C', 'n', 't', 'r') #define VALID_COUNTER(r) ISC_MAGIC_VALID(r, COUNTER_MAGIC) struct isc_counter { unsigned int magic; isc_mem_t *mctx; isc_refcount_t references; atomic_uint_fast32_t limit; atomic_uint_fast32_t used; }; isc_result_t isc_counter_create(isc_mem_t *mctx, int limit, isc_counter_t **counterp) { isc_counter_t *counter; REQUIRE(counterp != NULL && *counterp == NULL); counter = isc_mem_get(mctx, sizeof(*counter)); counter->mctx = NULL; isc_mem_attach(mctx, &counter->mctx); isc_refcount_init(&counter->references, 1); atomic_init(&counter->limit, limit); atomic_init(&counter->used, 0); counter->magic = COUNTER_MAGIC; *counterp = counter; return (ISC_R_SUCCESS); } isc_result_t isc_counter_increment(isc_counter_t *counter) { uint32_t used = atomic_fetch_add_relaxed(&counter->used, 1) + 1; uint32_t limit = atomic_load_acquire(&counter->limit); if (limit != 0 && used >= limit) { return (ISC_R_QUOTA); } return (ISC_R_SUCCESS); } unsigned int isc_counter_used(isc_counter_t *counter) { REQUIRE(VALID_COUNTER(counter)); return (atomic_load_acquire(&counter->used)); } void isc_counter_setlimit(isc_counter_t *counter, int limit) { REQUIRE(VALID_COUNTER(counter)); atomic_store(&counter->limit, limit); } void isc_counter_attach(isc_counter_t *source, isc_counter_t **targetp) { REQUIRE(VALID_COUNTER(source)); REQUIRE(targetp != NULL && *targetp == NULL); isc_refcount_increment(&source->references); *targetp = source; } static void destroy(isc_counter_t *counter) { isc_refcount_destroy(&counter->references); counter->magic = 0; isc_mem_putanddetach(&counter->mctx, counter, sizeof(*counter)); } void isc_counter_detach(isc_counter_t **counterp) { isc_counter_t *counter; REQUIRE(counterp != NULL && *counterp != NULL); counter = *counterp; *counterp = NULL; REQUIRE(VALID_COUNTER(counter)); if (isc_refcount_decrement(&counter->references) == 1) { destroy(counter); } }