通过sokect来接收外部的数据包，设计缓存类来管理这部分数据包的C++代码

非常感谢您的提问！以下是一个简单的示例代码，用于通过socket接收外部数据包，并使用缓存类来管理这些数据包：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#define MAX_BUFFER_SIZE 1024

// 缓存类
typedef struct {
    char* buffer;
    int size;
    int capacity;
} Cache;

// 初始化缓存类
void init_cache(Cache* cache) {
    cache->buffer = (char*)malloc(MAX_BUFFER_SIZE);
    cache->size = 0;
    cache->capacity = MAX_BUFFER_SIZE;
}

// 释放缓存类
void free_cache(Cache* cache) {
    free(cache->buffer);
    cache->buffer = NULL;
    cache->size = 0;
    cache->capacity = 0;
}

// 扩展缓存类
void expand_cache(Cache* cache, int size) {
    if (cache->size + size > cache->capacity) {
        int new_capacity = cache->capacity * 2;
        while (new_capacity < cache->size + size) {
            new_capacity *= 2;
        }
        char* new_buffer = (char*)malloc(new_capacity);
        memcpy(new_buffer, cache->buffer, cache->size);
        free(cache->buffer);
        cache->buffer = new_buffer;
        cache->capacity = new_capacity;
    }
}

// 接收数据包
int receive_packet(int sockfd, Cache* cache) {
    char buffer[MAX_BUFFER_SIZE];
    int n = recv(sockfd, buffer, MAX_BUFFER_SIZE, 0);
    if (n <= 0) {
        return n;
    }
    expand_cache(cache, n);
    memcpy(cache->buffer + cache->size, buffer, n);
    cache->size += n;
    return n;
}

int main(int argc, char* argv[]) {
    if (argc != 2) {
        printf("Usage: %s <port>\n", argv[0]);
        return 1;
    }

    int port = atoi(argv[1]);

    // 创建socket
    int sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd < 0) {
        perror("socket");
        return 1;
    }

    // 绑定端口
    struct sockaddr_in addr;
    memset(&addr, 0, sizeof(addr));
    addr.sin_family = AF_INET;
    addr.sin_addr.s_addr = htonl(INADDR_ANY);
    addr.sin_port = htons(port);
    if (bind(sockfd, (struct sockaddr*)&addr, sizeof(addr)) < 0) {
        perror("bind");
        return 1;
    }

    // 监听端口
    if (listen(sockfd, 5) < 0) {
        perror("listen");
        return 1;
    }

    printf("Listening on port %d...\n", port);

    // 初始化缓存类
    Cache cache;
    init_cache(&cache);

    while (1) {
        // 接受连接
        struct sockaddr_in client_addr;
        socklen_t client_addrlen = sizeof(client_addr);
        int client_sockfd = accept(sockfd, (struct sockaddr*)&client_addr, &client_addrlen);
        if (client_sockfd < 0) {
            perror("accept");
            continue;
        }

        printf("Accepted connection from %s:%d\n", inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port));

        // 接收数据包
        while (1) {
            int n = receive_packet(client_sockfd, &cache);
            if (n <= 0) {
                if (n < 0) {
                    perror("recv");
                }
                break;
            }
        }

        // 关闭连接
        close(client_sockfd);
        printf("Closed connection from %s:%d\n", inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port));

        // 清空缓存
        free_cache(&cache);
        init_cache(&cache);
    }

    // 关闭socket
    close(sockfd);

    return 0;
}

希望这个示例代码能够帮助您解决问题！如果您还有其它问题，请随时提出，我会尽力回答。