ex_thread_pool_discard.c

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/*
 * Nilorea Library
 * Copyright (C) 2005-2026 Castagnier Mickael
 *
 * 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
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include "nilorea/n_common.h"
#include "nilorea/n_log.h"
#include "nilorea/n_thread_pool.h"
 
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

static int ran = 0, discarded = 0;
static pthread_mutex_t count_lock = PTHREAD_MUTEX_INITIALIZER;

static void* slow_job(void* p) {
    usleep(300000);
    pthread_mutex_lock(&count_lock);
    ran++;
    pthread_mutex_unlock(&count_lock);
    free(p);
    return NULL;
}

static void discard_job(void* p) {
    pthread_mutex_lock(&count_lock);
    discarded++;
    pthread_mutex_unlock(&count_lock);
    free(p);
}

static int run(unsigned int delay) {
    THREAD_POOL* pool = new_thread_pool(1, 0);
    int i = 0;
 
    if (!pool) return 1;
    set_thread_pool_discard(pool, discard_job);
    ran = discarded = 0;
    for (i = 0; i < 4; i++) {
        int* p = malloc(sizeof(int));
        if (!p) return 1;
        *p = i;
        if (add_threaded_process(pool, slow_job, p, NORMAL_PROC) != TRUE) {
            free(p);
            return 1;
        }
    }
    usleep(20000); /* let the first one start */
    destroy_threaded_pool(&pool, delay);
    return 0;
}
 
int main(void) {
    int failures = 0;
 
    /* The error line destroy logs for the short budget is the expected
       outcome here, so it is not shown. */
    set_log_level(LOG_NULL);
 
    /* 1000 retries of 100 us is 0.1 s, shorter than the running job. */
    if (run(100) != 0) failures++;
    if (ran != 1 || discarded != 3) {
        fprintf(stderr, "short budget: %d ran and %d discarded, wanted 1 and 3\n", ran, discarded);
        failures++;
    }
    /* 1000 retries of 1 ms is a second: the queue drains inside it. */
    if (run(1000) != 0) failures++;
    if (ran != 4 || discarded != 0) {
        fprintf(stderr, "long budget: %d ran and %d discarded, wanted 4 and 0\n", ran, discarded);
        failures++;
    }
    if (failures) {
        fprintf(stderr, "ex_thread_pool_discard: %d failure(s)\n", failures);
        return 1;
    }
    printf("ex_thread_pool_discard: all checks passed\n");
    return 0;
}