C语言实现基于流的加权公平队列

以下是一个基于C语言的简单实现：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

// 定义流结构体
typedef struct flow {
    int id;              // 流ID
    int weight;          // 流权重
    int length;          // 流数据包数量
    int *packet_length;  // 每个数据包的长度
    int *packet_time;    // 每个数据包的到达时间
} flow_t;

// 定义数据包结构体
typedef struct packet {
    int flow_id;         // 数据包所属流ID
    int packet_length;   // 数据包的长度
    int arrival_time;    // 数据包的到达时间
} packet_t;

// 定义队列结构体
typedef struct queue {
    int length;          // 队列数据包数量
    int max_length;      // 队列最大长度
    packet_t *packets;   // 数据包数组
} queue_t;

// 定义比较函数
int compare(const void *p1, const void *p2) {
    packet_t *packet1 = (packet_t *)p1;
    packet_t *packet2 = (packet_t *)p2;
    return packet1->arrival_time - packet2->arrival_time;
}

// 计算流传输速率上限
int calculate_rate(int weight, int max_weight, int max_rate) {
    return weight * max_rate / max_weight;
}

// 初始化流
void init_flow(flow_t *flow, int id, int weight, int length, int max_packet_length, int max_rate) {
    flow->id = id;
    flow->weight = weight;
    flow->length = length;
    flow->packet_length = (int *)malloc(length * sizeof(int));
    flow->packet_time = (int *)malloc(length * sizeof(int));
    int i;
    for (i = 0; i < length; i++) {
        flow->packet_length[i] = rand() % max_packet_length + 1;
        if (i == 0) {
            flow->packet_time[i] = 0;
        } else {
            flow->packet_time[i] = flow->packet_time[i-1] + rand() % max_rate + 1;
        }
    }
}

// 初始化队列
void init_queue(queue_t *queue, int max_length) {
    queue->length = 0;
    queue->max_length = max_length;
    queue->packets = (packet_t *)malloc(max_length * sizeof(packet_t));
}

// 添加数据包到队列
void add_packet_to_queue(queue_t *queue, packet_t *packet) {
    if (queue->length < queue->max_length) {
        queue->packets[queue->length] = *packet;
        queue->length++;
    }
}

// 从队列中取出数据包
void get_packet_from_queue(queue_t *queue, int index, packet_t *packet) {
    *packet = queue->packets[index];
    int i;
    for (i = index; i < queue->length - 1; i++) {
        queue->packets[i] = queue->packets[i+1];
    }
    queue->length--;
}

// WFQ算法
void wfq(flow_t *flows, int num_flows, int max_weight, int max_rate, int max_packet_length, int max_queue_length) {
    // 初始化队列
    queue_t *queues = (queue_t *)malloc(num_flows * sizeof(queue_t));
    int i;
    for (i = 0; i < num_flows; i++) {
        init_queue(&queues[i], max_queue_length);
    }

    // 初始化数据包
    packet_t *packets = (packet_t *)malloc(num_flows * max_queue_length * sizeof(packet_t));
    int num_packets = 0;
    for (i = 0; i < num_flows; i++) {
        int j;
        for (j = 0; j < flows[i].length; j++) {
            packet_t packet;
            packet.flow_id = i;
            packet.packet_length = flows[i].packet_length[j];
            packet.arrival_time = flows[i].packet_time[j];
            packets[num_packets] = packet;
            num_packets++;
        }
    }

    // 按到达时间排序
    qsort(packets, num_packets, sizeof(packet_t), compare);

    // WFQ算法主循环
    int current_time = 0;
    while (num_packets > 0) {
        // 计算每个流的传输速率上限
        int max_rate_per_flow[num_flows];
        int sum_weight = 0;
        for (i = 0; i < num_flows; i++) {
            sum_weight += flows[i].weight;
        }
        for (i = 0; i < num_flows; i++) {
            max_rate_per_flow[i] = calculate_rate(flows[i].weight, sum_weight, max_rate);
        }

        // 计算每个流的虚拟时刻
        int virtual_time[num_flows];
        for (i = 0; i < num_flows; i++) {
            virtual_time[i] = current_time - flows[i].packet_time[0];
            if (virtual_time[i] < 0) {
                virtual_time[i] = 0;
            }
            virtual_time[i] = virtual_time[i] * max_rate_per_flow[i] / max_rate;
        }

        // 选择队列并公平分配数据包
        for (i = 0; i < num_flows; i++) {
            if (queues[i].length > 0) {
                int j;
                for (j = 0; j < queues[i].length; j++) {
                    virtual_time[i] += queues[i].packets[j].packet_length * max_rate_per_flow[i] / max_rate;
                }
            }
        }
        int min_virtual_time = virtual_time[0];
        int min_flow_id = 0;
        for (i = 1; i < num_flows; i++) {
            if (virtual_time[i] < min_virtual_time) {
                min_virtual_time = virtual_time[i];
                min_flow_id = i;
            }
        }
        packet_t packet;
        get_packet_from_queue(&queues[min_flow_id], 0, &packet);
        printf("Transmit packet from Flow %d, Packet Length %d, Arrival Time %d, Transmit Time %d\n", packet.flow_id, packet.packet_length, packet.arrival_time, current_time);
        flows[packet.flow_id].packet_length[0] -= packet.packet_length;
        if (flows[packet.flow_id].packet_length[0] == 0) {
            flows[packet.flow_id].length--;
            if (flows[packet.flow_id].length > 0) {
                flows[packet.flow_id].packet_length++;
                flows[packet.flow_id].packet_time++;
            }
        }

        // 将新到达的数据包加入队列
        int j = 0;
        while (j < num_packets && packets[j].arrival_time <= current_time) {
            add_packet_to_queue(&queues[packets[j].flow_id], &packets[j]);
            j++;
        }
        for (i = j; i < num_packets; i++) {
            packets[i-j] = packets[i];
        }
        num_packets -= j;

        // 更新时间
        current_time++;
    }

    // 释放内存
    for (i = 0; i < num_flows; i++) {
        free(queues[i].packets);
    }
    free(queues);
    free(packets);
}

int main() {
    srand(time(NULL));
    int num_flows = 5;
    flow_t flows[num_flows];
    init_flow(&flows[0], 0, 1, 10, 1000, 10000);
    init_flow(&flows[1], 1, 2, 5, 2000, 10000);
    init_flow(&flows[2], 2, 3, 8, 1500, 10000);
    init_flow(&flows[3], 3, 4, 6, 2500, 10000);
    init_flow(&flows[4], 4, 5, 7, 1800, 10000);
    wfq(flows, num_flows, 15, 10000, 3000, 100);
    return 0;
}

以上是一个简单的实现，实际应用中还需要考虑更多的情况和细节，比如数据包丢失、优化算法效率等问题。