分别写客户端和服务端的函数,在主任务中创建两个client和一个server,考虑到实际情况,应该server的优先级高并且先用taskSpawn函数创建server任务。然后等待客户端获得服务端的应答,则删除队列,程序结束。为了演示client请求,server应答的过程,本次实验采取client发送时发送一个value,在创建任务时给定,每次请求时value加一,服务端获得value之后将该值加一,并根据客户端的id,返回给相应的响应队列。Client函数中首先根据请求队列的大小发送数据,然后开始等待接收响应队列的返回结果。Server函数中等待请求队列不为空,获得请求并返回给对应的响应队列。
main.h#ifndef MAIN_H_INCLUDED#define MAIN_H_INCLUDED#include "vxWorks.h"#include "semLib.h"#include "taskLib.h"#include "msgQLib.h"#include "sysLib.h"#include "stdio.h"#define CLIENT_TASK_PRI 99#define SERVER_TASK_PRI 98#define TASK_STACK_SIZE 5000struct msg{ int id; int value;};LOCAL MSG_Q_ID requestQId;LOCAL MSG_Q_ID response1QId;LOCAL MSG_Q_ID response2QId;LOCAL BOOL notDone;LOCAL int numMsg = 3;LOCAL STATUS clientTask (int cid, int value);LOCAL STATUS serverTask(void);#endif // MAIN_H_INCLUDED
#include "main.h"STATUS clientTask(int cid, int value){ int i, j, k; struct msg request_msg, response_msg; printf ("clientTask started: cid = %d\n", cid); for(i=0; i<numMsg; i++) { request_msg.id = cid; request_msg.value = value+i; /* semTake(request_semMutex, WAIT_FOREVER);*/ if (( msgQSend (requestQId, (char *) &request_msg, sizeof (request_msg), WAIT_FOREVER, MSG_PRI_NORMAL)) == ERROR) { perror ("Error in sending the message to request queue\n"); return (ERROR); } else { printf ("clientTask: cid = %d, value = %d \n", cid, value+i); } /*semGive(request_semMutex);*/ }/*接收数据从responseQ*/ if(1 == cid) { for(j=0; j<numMsg; j++) { /* semTake(response1_semMutex, WAIT_FOREVER);*/ if (( msgQReceive (response1QId, (char *) &response_msg, sizeof (response_msg), WAIT_FOREVER)) == ERROR) { perror ("Error in receiving the response1 message\n"); return (ERROR); } else { printf ("clientTask: get msg of value %d from cid = %d\n", response_msg.value, response_msg.id); } /* semGive(response1_semMutex);*/ } } else if(2 == cid) { for(k=0; k<numMsg; k++) { /* semTake(response2_semMutex, WAIT_FOREVER);*/ if (( msgQReceive (response2QId, (char *) &response_msg, sizeof (response_msg), WAIT_FOREVER)) == ERROR) { perror ("Error in receiving the response2 message\n"); return (ERROR); } else { printf ("clientTask: get msg of value %d from cid = %d\n", response_msg.value, response_msg.id); } /* semGive(response2_semMutex);*/ } } else { printf("clientTask: cid error!\n"); } notDone = FALSE; return (OK);}STATUS serverTask(void){ int i; struct msg response_msg ; printf ("\nserverTask Started \n"); for(i=0; i<numMsg*2; i++) { /* semTake(request_semMutex, WAIT_FOREVER);*/ if (( msgQReceive (requestQId, (char *) &response_msg, sizeof (response_msg), WAIT_FOREVER)) == ERROR) { perror ("Error in receiving the message\n"); return (ERROR); } else { printf ("serverTask: get msg of value %d from cid = %d\n", response_msg.value, response_msg.id); } /*semGive(request_semMutex);*/ /*将获得的value加一后,根据cid发给相应的应答序列*/ response_msg.value += 1; if(response_msg.id==1) { /*semTake(response1_semMutex, WAIT_FOREVER);*/ if (( msgQSend (response1QId, (char *) &response_msg, sizeof (response_msg), WAIT_FOREVER, MSG_PRI_NORMAL)) == ERROR) { perror ("Error in sending the message to response1 queue\n"); return (ERROR); } else { printf ("serverTask sending to response Q1: value = %d \n", response_msg.value); } /*semGive(response1_semMutex);*/ } else if(response_msg.id==2) { /*semTake(response2_semMutex, WAIT_FOREVER);*/ if (( msgQSend (response2QId, (char *) &response_msg, sizeof (response_msg), WAIT_FOREVER, MSG_PRI_NORMAL)) == ERROR) { perror ("Error in sending the message to response2 queue\n"); return (ERROR); } else { printf ("serverTask sending to response Q2: value = %d \n", response_msg.value); } /*semGive(response2_semMutex);*/ } else { printf("error in response_msg, the id = %d\n", response_msg.id); } } return (OK);}STATUS main(){ notDone = TRUE; /* request_semMutex = semBCreate(SEM_Q_FIFO, SEM_FULL); response1_semMutex = semBCreate(SEM_Q_FIFO, SEM_FULL); response2_semMutex = semBCreate(SEM_Q_FIFO, SEM_FULL);*/ if ((requestQId = msgQCreate(numMsg*2, sizeof (struct msg), MSG_Q_FIFO)) == NULL) { perror ("Error in creating requestQ"); return (ERROR); } if ((response1QId = msgQCreate(numMsg, sizeof (struct msg), MSG_Q_FIFO)) == NULL) { perror ("Error in creating response1Q"); return (ERROR); } if ((response2QId = msgQCreate(numMsg, sizeof (struct msg), MSG_Q_FIFO)) == NULL) { perror ("Error in creating response2Q"); return (ERROR); } if (taskSpawn (" tserverTask ", SERVER_TASK_PRI, 0, TASK_STACK_SIZE, (FUNCPTR) serverTask, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) == ERROR) { perror ("serverTask: Error in spawning serverTask"); return (ERROR); } if (taskSpawn (" tclientTask ", CLIENT_TASK_PRI, 0, TASK_STACK_SIZE, (FUNCPTR) clientTask, 1, 10, 0, 0, 0, 0, 0, 0, 0, 0) == ERROR) { perror ("clientTask: Error in spawning clientTask1"); return (ERROR); } if (taskSpawn (" tclientTask ", CLIENT_TASK_PRI, 0, TASK_STACK_SIZE, (FUNCPTR) clientTask, 2, 10, 0, 0, 0, 0, 0, 0, 0, 0) == ERROR) { perror ("clientTask: Error in spawning clientTask2"); return (ERROR); } while (notDone) { taskDelay (sysClkRateGet ()); } if (msgQDelete(requestQId) == ERROR || msgQDelete(response1QId) == ERROR || msgQDelete(response2QId) == ERROR) { perror ("Error in deleting msgQs"); return (ERROR); } return (OK);}
可以看出,首先进入了server任务,然后进入client任务,client发送给请求队列消息后,服务端立刻获得value值,因为server优先级高,所以打印发送信息也是在server阻塞后打印的,并且能够看出serverl立刻向相应的响应队列发送了消息,此时value的值比client发过来的值多一,符合程序的设计,后来也是如此。直到client1的请求都被响应了,client1从自己的响应队列中得到加一后的值,之后client2也同理。
下面是windview演示结果:
第一幅能看出t1即主任务创建了三个任务,然后切换到Server,但是server被阻塞,因为请求队列为空,又切换到client1,当client1有请求之后再切换到server给予响应,依次进行,client2也是如此。下图是过了一段时间的截图,因为主程序一直在等待客户端接收到响应队列的消息,结束之后能从下图看出删除了请求队列和响应队列1,响应队列2,程序结束。
1、 C语言的单行注释“//”不能使用,编译不能通过。
2、 刚开始使用二进制信号量控制队列只能有一个任务在发送或接受,造成死锁。发送之前将请求队列take,然后发送,由于server优先级高,此时还没有来得及释放信号量就切换到server任务,server接收请求队列获取不到信号量,造成一直等待的死锁局面。
3、 刚开始没有考虑实际情况,先创建了client1,client2,并且优先级设定为一致,而事实上应该先启动服务器在允许客户端请求,故更改顺序,先创建server任务。
4、用windview观察的时候要选择task state transition,刚开始使用默认的context switch观察不到想要的结果。之后观察成功,鼠标悬停就能看到相关的信息,非常方便。
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