循环优先级队列解决客户优先级服务问题

问题：
客服坐席处理客户（手机号码，带有优先级）来电按照5个优先级别（级别为1~5）进行处理，不同优先级别的用户在对应级别的队列中等候，如果前一级别的队列为空，则后继队列中等待的客户优先级自动升高一级，例如级别3的队列为空，则级别4和5的队列中客户的优先级自动升高一级。为了防止优先级低的用户饿死，低优先级的队列需要随着时间提高优先级，请写出程序实现解决该问题。

分析：

首先建立5个节点的循环队列（单向循环队列即可），每个节点指向一个队列的地址，该队列中存储用户信息，每隔10分钟，把循环队列中head位置指向的队列加入到head所指向的下一个位置的队列的前面，然后把循环队列head移向下一个位置，tail指针移到原来的head位置，相当于把原来优先级为1的队列降为5，2、3、4、5队列的优先级升为1、2、3、4，同时把原来队列1中没有处理完毕的用户插入到新的队列1中的前部继续处理。

头文件PRQueue.h：

#include <stdio.h>#include <malloc.h>#include <time.h>#include <string.h>#define MAXMSISDNLENGTH 14 //手机号码长度#define PRIORITIES 5 //循环队列长度#define SUCCESS 0#define ERROR -1#define TIMETOSWITCH 2 //切换优先级的时间间隔（单位:分钟）//用户信息，暂时只有用户号码typedef struct customer{ char MSISDN[MAXMSISDNLENGTH];} LCustomer;//保存用户信息的节点typedef struct CusNode{customer cus;CusNode *next;} LCusNode;//循环队列节点，用来实现按照优先级入用户和取用户typedef struct PRNode{CusNode *value;PRNode *next;} LPRNode;time_t curTime;time_t oldTime;PRNode *PRhead, *PRtail;

 

main文件：

#include "PRQueue.h"//创建循环队列int createPRQueue(){int i;PRNode *p, *q;p = PRhead = (PRNode*)malloc(sizeof(PRNode)); if (NULL == PRhead){printf("malloc memory fail./n");return ERROR;}PRhead->value = (CusNode*)malloc(sizeof(CusNode));if (NULL == PRhead->value) {printf("malloc memory fail./n");return ERROR;}PRhead->value->cus.MSISDN[0] = '/0';PRhead->value->next = NULL;for (i=1; i<PRIORITIES; i++){q = (PRNode*)malloc(sizeof(PRNode)); if (NULL == q) { printf("malloc memory fail./n"); return ERROR; }q->value = (CusNode*)malloc(sizeof(CusNode));if (NULL == q->value) { printf("malloc memory fail./n"); return ERROR; }q->value->cus.MSISDN[0] = '/0';q->value->next = NULL;q->next = NULL;p->next = q;p = p->next;}PRtail = p;PRtail->next = PRhead;//记录时间用于优先级切换，防止饿死oldTime = time(NULL);return SUCCESS;}//每隔10分钟切换优先级int switchPRQueue(){double elapseTime = difftime(curTime, oldTime); if (elapseTime >= TIMETOSWITCH * 10){//队列头CusNode *p = PRhead->value;//队列尾CusNode *q = p;while(NULL != q->next){q = q->next;}//把PRhead指向队列中所有的节点移到PRhead->next指向的队列前面PRNode *PRnext = PRhead->next;q->next = PRnext->value->next;PRnext->value->next = p->next;PRhead->value->next = NULL;//然后把PRhead指向PRhead->nextPRhead = PRhead->next;PRtail = PRtail->next;//记录时间用于优先级切换，防止饿死 oldTime = time(NULL);}return SUCCESS;}//从队尾插入队列int insertNode(CusNode *head, CusNode *cur){CusNode *p = head;while(NULL != p->next){p = p->next;}p->next = cur;cur->next = NULL;return SUCCESS;}//从队头获取节点CusNode *getNode(CusNode *head){CusNode *tmp;tmp = head->next;head->next = tmp->next;return tmp;}//插入用户int insertCus(char *msisdn, int pri){int i=0;PRNode *p = PRhead; CusNode *cusNode = (CusNode*)malloc(sizeof(CusNode));if (NULL == cusNode){printf("malloc memory fail./n");return ERROR;}strcpy(cusNode->cus.MSISDN, msisdn);printf("msisdn = [%s]/n", cusNode->cus.MSISDN);//循环队列的头节点默认优先级为1，依次类推 while (pri != i+1){p = p->next;i++;}insertNode(p->value, cusNode);return SUCCESS;}//获取用户int getCus(char* msisdn){PRNode *tmp = PRhead;while (NULL == tmp->value->next){tmp = tmp->next;}CusNode *p = getNode(tmp->value);strcpy(msisdn, p->cus.MSISDN);return SUCCESS;}int printPRNode(){PRNode *p = PRhead;CusNode *tmp;int i;for (i=0; i<PRIORITIES; i++){printf("queue %d's content is:", i+1); tmp = p->value;while (NULL != tmp){printf(" %s", tmp->cus.MSISDN);tmp = tmp->next;}printf("/n");p = p->next;} return SUCCESS;}int main(){char msisdn[MAXMSISDNLENGTH];char command;int pri;createPRQueue();while(1){//更新当前时间用于优先级切换，防止饿死 curTime = time(NULL); switchPRQueue();printf("please input 'i' to insert a msisdn or 'g' to get a msisdn/n"); scanf("%c", &command);if (command == 'i'){scanf("%s", msisdn);printf("Please input priority between 1and 5./n"); scanf("%d", &pri);if (SUCCESS == insertCus(msisdn, pri)){ printf("insert a msisdn[%s] to queue success/n", msisdn);}else{printf("insert a msisdn[%s] to queue fail/n", msisdn);}}else if (command == 'g'){if(SUCCESS == getCus(msisdn)){ printf("get a msisdn from queue, msisdn=[%s]/n", msisdn);}else{printf("get a msisdn from queue fail, msisdn=[%s]/n", msisdn);}}else if (command == 'q'){break;}printPRNode();}return SUCCESS;}