esp-idf/examples/system/eventfd/main/eventfd_example.c

/* eventfd example

   This example code is in the Public Domain (or CC0 licensed, at your option.)

   Unless required by applicable law or agreed to in writing, this
   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
   CONDITIONS OF ANY KIND, either express or implied.
*/

#include <stdio.h>
#include <sys/select.h>

#include "driver/timer.h"
#include "esp_err.h"
#include "esp_log.h"
#include "esp_vfs.h"
#include "esp_vfs_dev.h"
#include "esp_vfs_eventfd.h"
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "hal/timer_types.h"

#define TIMER_DIVIDER         16
#define TIMER_SCALE           (TIMER_BASE_CLK / TIMER_DIVIDER)
#define MS_PER_S              1000
#define TIMER_INTERVAL_SEC    2.5
#define TEST_WITHOUT_RELOAD   0
#define PROGRESS_INTERVAL_MS  3500
#define TIMER_SIGNAL          1
#define PROGRESS_SIGNAL       2

static const char *TAG = "eventfd_example";

int s_timer_fd;
int s_progress_fd;

static bool eventfd_timer_isr_callback(void *arg)
{
    int timer_idx = (int) arg;

    uint32_t timer_intr = timer_group_get_intr_status_in_isr(TIMER_GROUP_0);
    uint64_t timer_counter_value = timer_group_get_counter_value_in_isr(TIMER_GROUP_0, timer_idx);

    if (timer_intr & TIMER_INTR_T0) {
        timer_group_clr_intr_status_in_isr(TIMER_GROUP_0, TIMER_0);
        timer_counter_value += (uint64_t) (TIMER_INTERVAL_SEC * TIMER_SCALE);
        timer_group_set_alarm_value_in_isr(TIMER_GROUP_0, timer_idx, timer_counter_value);
    }

    timer_group_enable_alarm_in_isr(TIMER_GROUP_0, timer_idx);

    uint64_t signal = TIMER_SIGNAL;
    ssize_t val = write(s_timer_fd, &signal, sizeof(signal));
    assert(val == sizeof(signal));

    return true;
}

static void eventfd_timer_init(int timer_idx, double timer_interval_sec)
{
    timer_config_t config = {
        .divider = TIMER_DIVIDER,
        .counter_dir = TIMER_COUNT_UP,
        .counter_en = TIMER_PAUSE,
        .alarm_en = TIMER_ALARM_EN,
        .auto_reload = true,
    };
    ESP_ERROR_CHECK(timer_init(TIMER_GROUP_0, timer_idx, &config));

    ESP_ERROR_CHECK(timer_set_counter_value(TIMER_GROUP_0, timer_idx, 0x00000000ULL));

    ESP_ERROR_CHECK(timer_set_alarm_value(TIMER_GROUP_0, timer_idx, timer_interval_sec * TIMER_SCALE));
    ESP_ERROR_CHECK(timer_enable_intr(TIMER_GROUP_0, timer_idx));
    ESP_ERROR_CHECK(timer_isr_callback_add(TIMER_GROUP_0, timer_idx, &eventfd_timer_isr_callback, (void*) timer_idx, 0));

    ESP_ERROR_CHECK(timer_start(TIMER_GROUP_0, timer_idx));
}

static void worker_task(void *arg)
{
    while (true) {
        vTaskDelay(pdMS_TO_TICKS(PROGRESS_INTERVAL_MS));
        uint64_t signal = PROGRESS_SIGNAL;
        ssize_t val = write(s_progress_fd, &signal, sizeof(signal));
        assert(val == sizeof(signal));
    }
    vTaskDelete(NULL);
}

static void collector_task(void *arg)
{
    esp_vfs_eventfd_config_t config = ESP_VFS_EVENTD_CONFIG_DEFAULT();
    ESP_ERROR_CHECK(esp_vfs_eventfd_register(&config));

    s_timer_fd = eventfd(0, EFD_SUPPORT_ISR);
    s_progress_fd = eventfd(0, 0);
    assert(s_timer_fd > 0);
    assert(s_progress_fd > 0);

    int maxFd = s_progress_fd > s_timer_fd ? s_progress_fd : s_timer_fd;
    int select_timeout_count = 0;
    int timer_trigger_count = 0;
    int progress_trigger_count = 0;

    for (size_t i = 0; ; i++) {
        struct timeval timeout;
        uint64_t signal;

        timeout.tv_sec = 2;
        timeout.tv_usec = 0;

        fd_set readfds;
        FD_ZERO(&readfds);
        FD_SET(s_timer_fd, &readfds);
        FD_SET(s_progress_fd, &readfds);

        int num_triggered = select(maxFd + 1, &readfds, NULL, NULL, &timeout);
        assert(num_triggered >= 0);

        uint64_t task_counter_value;
        timer_get_counter_value(TIMER_GROUP_0, TIMER_0, &task_counter_value);
        ESP_LOGI(TAG, "Time: %.2fs", (double)task_counter_value / TIMER_SCALE);

        if (FD_ISSET(s_progress_fd, &readfds)) {
            ssize_t ret = read(s_progress_fd, &signal, sizeof(signal));
            assert(ret == sizeof(signal));
            assert(signal == PROGRESS_SIGNAL);
            progress_trigger_count++;
            ESP_LOGI(TAG, "Progress fd event triggered");
        }
        if (FD_ISSET(s_timer_fd, &readfds)) {
            ssize_t ret = read(s_timer_fd, &signal, sizeof(signal));
            assert(ret == sizeof(signal));
            assert(signal == TIMER_SIGNAL);
            timer_trigger_count++;
            ESP_LOGI(TAG, "TimerEvent fd event triggered");
        }
        if (num_triggered == 0) {
            select_timeout_count++;
            ESP_LOGI(TAG, "Select timeout");
        }

        if (i % 10 == 0) {
            ESP_LOGI(TAG, "=================================");
            ESP_LOGI(TAG, "Select timeouted for %d times", select_timeout_count);
            ESP_LOGI(TAG, "Timer triggerred for %d times", timer_trigger_count);
            ESP_LOGI(TAG, "Progress triggerred for %d times", progress_trigger_count);
            ESP_LOGI(TAG, "=================================");

        }
    }

    timer_deinit(TIMER_GROUP_0, TIMER_0);
    close(s_timer_fd);
    close(s_progress_fd);
    esp_vfs_eventfd_unregister();
    vTaskDelete(NULL);
}

void app_main(void)
{
    eventfd_timer_init(TIMER_0, TIMER_INTERVAL_SEC);
    xTaskCreate(worker_task, "worker_task", 4 * 1024, NULL, 5, NULL);
    xTaskCreate(collector_task, "collector_task", 4 * 1024, NULL, 5, NULL);
}