C++实现线程池代码

以下是一个简单的C语言实现的线程池代码：

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

#define MAX_THREADS 10
#define MAX_QUEUE_SIZE 100

typedef struct {
  void (*function)(void *);
  void *data;
} 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)) {
    return NULL;
  }

  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;
}

int threadpool_add(threadpool_t *pool, void (*function)(void *), void *data) {
  int next;
  if (pool == NULL || function == NULL) {
    return -1;
  }

  if (pthread_mutex_lock(&(pool->lock)) != 0) {
    return -1;
  }

  next = pool->tail + 1;
  next = (next == pool->queue_size) ? 0 : next;

  if (pool->count == pool->queue_size) {
    pthread_mutex_unlock(&(pool->lock));
    return