C++实现线程池代码

以下是一份简单的C语言实现的线程池代码：

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>

#define MAX_THREADS 10
#define MAX_QUEUE_SIZE 100

typedef struct {
    void *(*function)(void *);
    void *arg;
} threadpool_task_t;

typedef struct {
    pthread_mutex_t lock;
    pthread_cond_t notify;
    pthread_t *threads;
    threadpool_task_t *queue;
    int thread_count;
    int queue_size;
    int head;
    int tail;
    int count;
    int shutdown;
    int started;
} threadpool_t;

threadpool_t *threadpool_create(int thread_count, int queue_size, int flags)
{
    threadpool_t *pool;
    int i;

    if (thread_count <= 0 || thread_count > MAX_THREADS || queue_size <= 0 || queue_size > MAX_QUEUE_SIZE) {
        return NULL;
    }

    if ((pool = (threadpool_t *)malloc(sizeof(threadpool_t))) == NULL) {
        return NULL;
    }

    pool->thread_count = 0;
    pool->queue_size = queue_size;
    pool->head = pool->tail = pool->count = 0;
    pool->shutdown = pool->started = 0;

    pool->threads = (pthread_t *)malloc(sizeof(pthread_t) * thread_count);
    pool->queue = (threadpool_task_t *)malloc(sizeof(threadpool_task_t) * queue_size);

    if ((pthread_mutex_init(&(pool->lock), NULL) != 0) ||
        (pthread_cond_init(&(pool->notify), NULL) != 0) ||
        (pool->threads == NULL) ||
        (pool->queue == NULL)) {
        goto error;
    }

    for (i = 0; i < thread_count; i++) {
        if (pthread_create(&(pool->threads[i]), NULL, threadpool_thread, (void*)pool) != 0) {
            threadpool_destroy(pool, 0);
            return NULL;
        }
        pool->thread_count++;
        pool->started++;
    }

    return pool;

error:
    if (pool) {
        threadpool_free(pool);
    }
    return NULL;
}

int threadpool_add(threadpool_t *pool, void *(*function)(void *), void *argument, int flags)
{
    int err = 0;
    int next;

    if (pool == NULL || function == NULL) {
        return threadpool_invalid;
    }

    if (pthread_mutex_lock(&(pool->lock)) != 0) {
        return threadpool_lock_failure;
    }

    next = (pool->tail + 1) %