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/*
* Author: Evgeny Khramtsov <ekhramtsov@process-one.net>
* Created : 26 Apr 2017 by Evgeny Khramtsov <ekhramtsov@process-one.net>
*
*
* Copyright (C) 2002-2021 ProcessOne, SARL. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
#include <erl_nif.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#define MAX_UINT64 ((ErlNifUInt64) -1)
typedef struct State {
unsigned int max_counters;
unsigned int counters_num;
ErlNifUInt64 *counters;
ErlNifMutex *counters_lock;
} State;
static int load(ErlNifEnv* env, void** priv, ERL_NIF_TERM max)
{
size_t size;
unsigned int max_counters;
State *state;
if (!(state = enif_alloc(sizeof(*state)))) {
return ENOMEM;
}
if (enif_get_uint(env, max, &max_counters)) {
size = sizeof(ErlNifUInt64) * max_counters;
if ((state->counters = enif_alloc(size))) {
memset(state->counters, -1, size);
state->counters_num = 0;
state->counters_lock = enif_mutex_create("counters_lock");
*priv = state;
return 0;
} else {
enif_free(state);
}
}
return ENOMEM;
}
static void unload(ErlNifEnv* env, void* priv)
{
if (!priv)
return;
State *state = (State*)priv;
if (state->counters_lock) enif_mutex_destroy(state->counters_lock);
if (state->counters) enif_free(state->counters);
enif_free(state);
}
static int upgrade(ErlNifEnv* caller_env, void** priv_data, void** old_priv_data, ERL_NIF_TERM load_info) {
if (!*old_priv_data) {
return 1;
}
*priv_data = *old_priv_data;
*old_priv_data = NULL;
return 0;
}
static ERL_NIF_TERM new_counter(ErlNifEnv* env, int argc,
const ERL_NIF_TERM argv[])
{
unsigned int counter;
State *state = (State*)enif_priv_data(env);
enif_mutex_lock(state->counters_lock);
if (state->counters_num < state->max_counters) {
counter = state->counters_num++;
state->counters[counter] = 0;
enif_mutex_unlock(state->counters_lock);
return enif_make_tuple2(env, enif_make_atom(env, "ok"),
enif_make_ulong(env, counter));
} else {
for (counter = 0; counter < state->max_counters; counter++) {
if (state->counters[counter] == MAX_UINT64) {
state->counters[counter] = 0;
enif_mutex_unlock(state->counters_lock);
return enif_make_tuple2(env, enif_make_atom(env, "ok"),
enif_make_ulong(env, counter));
}
}
enif_mutex_unlock(state->counters_lock);
return enif_make_tuple2(env, enif_make_atom(env, "error"),
enif_make_tuple2(env, enif_make_atom(env, "system_limit"),
enif_make_uint(env, state->max_counters)));
}
}
static ERL_NIF_TERM delete_counter(ErlNifEnv* env, int argc,
const ERL_NIF_TERM argv[])
{
unsigned int counter;
State *state = (State*)enif_priv_data(env);
if (enif_get_uint(env, argv[0], &counter))
if (counter < state->max_counters) {
state->counters[counter] = MAX_UINT64;
return enif_make_atom(env, "ok");
}
return enif_make_badarg(env);
}
static ERL_NIF_TERM incr_counter(ErlNifEnv* env, int argc,
const ERL_NIF_TERM argv[])
{
unsigned int counter;
State *state = (State*)enif_priv_data(env);
if (enif_get_uint(env, argv[0], &counter))
if (counter < state->max_counters) {
if (state->counters[counter] != MAX_UINT64)
return enif_make_uint64(env, __atomic_add_fetch(state->counters + counter, 1, __ATOMIC_SEQ_CST));
}
return enif_make_badarg(env);
}
static ERL_NIF_TERM get_counter(ErlNifEnv* env, int argc,
const ERL_NIF_TERM argv[])
{
unsigned int counter;
ErlNifUInt64 val;
State *state = (State*)enif_priv_data(env);
if (enif_get_uint(env, argv[0], &counter))
if (counter < state->max_counters) {
val = state->counters[counter];
if (val != MAX_UINT64)
return enif_make_uint64(env, val);
}
return enif_make_badarg(env);
}
static ErlNifFunc nif_funcs[] =
{
{"new_counter_nif", 0, new_counter},
{"delete_counter_nif", 1, delete_counter},
{"incr_counter_nif", 1, incr_counter},
{"get_counter_nif", 1, get_counter}
};
ERL_NIF_INIT(ets_cache, nif_funcs, load, NULL, upgrade, unload)
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