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/*
* 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 <stdbool.h>
#include <stddef.h>
#include <isc/atomic.h>
#include <isc/counter.h>
#include <isc/magic.h>
#include <isc/mem.h>
#include <isc/refcount.h>
#include <isc/util.h>
#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);
}
}
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