/*

 * 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;

};

void

isc_counter_create(isc_mem_t *mctx, int limit, isc_counter_t **counterp) {

  REQUIRE(counterp != NULL && *counterp == NULL);

  isc_counter_t *counter = isc_mem_get(mctx, sizeof(*counter));

  *counter = (isc_counter_t){

    .magic = COUNTER_MAGIC,

    .references = 1,

    .limit = limit,

  };

  isc_mem_attach(mctx, &counter->mctx);

  *counterp = counter;

}

isc_result_t

isc_counter_increment(isc_counter_t *counter) {

  uint_fast32_t used = atomic_fetch_add_relaxed(&counter->used, 1) + 1;

  uint_fast32_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_relaxed(&counter->used);

}

void

isc_counter_setlimit(isc_counter_t *counter, int limit) {

  REQUIRE(VALID_COUNTER(counter));

  atomic_store_release(&counter->limit, limit);

}

unsigned int

isc_counter_getlimit(isc_counter_t *counter) {

  REQUIRE(VALID_COUNTER(counter));

  return atomic_load_acquire(&counter->limit);

}

static void

isc__counter_destroy(isc_counter_t *counter) {

  REQUIRE(VALID_COUNTER(counter));

  isc_refcount_destroy(&counter->references);

  counter->magic = 0;

  isc_mem_putanddetach(&counter->mctx, counter, sizeof(*counter));

}

ISC_REFCOUNT_IMPL(isc_counter, isc__counter_destroy);