实验六 线程同步实验
https://www.icourse163.org/learn/UESTC-1003040002?tid=1455108444#/learn/content?type=detail&id=1228729539&cid=1245454470
需求描述
程序流程图
知识点记录：
实验的一种实现方式：
1 #include "stdio.h"
2 #include "stdint.h"
3 #include "stdlib.h"
4 #include "pthread.h"
5 #include "sys/types.h"
6 #include "sys/wait.h"
7 //#include <stdlib.h>
8 #include "unistd.h"
9
10 #define PH_NUM (5u) /* 哲学家数量 */
11 #define THINKING_TIME (2u) /* 思考时间 */
12 #define EATING_TIME (2u) /* 进餐时间 */
13
14 static uint8_t table[PH_NUM] = {0};
15 pthread_mutex_t tableMutex;
16
17 //尝试拿起筷子，1-成功拿起 0-筷子已被其他人拿起
18 static uint8_t takechopstick(int number)
19 {
20 uint8_t ret = 0;
21
22 if(0 == pthread_mutex_trylock(&tableMutex))
23 {
24 if(number >= sizeof(table)) number = 0;
25 if(table[number]) ret = 0;
26 else
27 {
28 table[number] = 1;
29 ret = 1;
30 }
31
32 if(0 == pthread_mutex_unlock(&tableMutex))
33 /*printf("taking %d chopstick is successful\n",number)*/;
34 }else /*printf("taking %d chopstick is failure\n",number)*/;
35
36 return ret;
37 }
38 //放下筷子
39 static void putchopstick(int number)
40 {
41 if(0 == pthread_mutex_lock(&tableMutex))
42 {
43 if(number >= sizeof(table)) number = 0;
44 if(table[number])
45 table[number] = 0;
46
47 if(0 == pthread_mutex_unlock(&tableMutex))
48 /*printf("putting %d chopstick is successful\n",number)*/;
49 }
50 }
51
52 //单哲学家任务
53 void *philosopher(int *Ptr)
54 {
55 int number = *Ptr;
56 while(1)
57 {
58 printf("philosopher %d is thinking\n",number);
59 sleep(THINKING_TIME);
60 if(takechopstick(number))
61 {
62 if(takechopstick((int)((number + 1)%(sizeof table))))
63 {
64 printf("philosopher %d is eating\n",number);
65 sleep(EATING_TIME);
66 putchopstick(number);
67 putchopstick((int)((number + 1)%(sizeof table)));
68 }
69 else
70 {
71 //printf("philosopher %d taking %d chopstick failure\n",(int)((number + 1)%(sizeof table)),(int)((number + 1)%(sizeof table)));
72 putchopstick(number);
73 }
74 }
75 else /*printf("philosopher %d taking %d chopstick failure\n",number,number)*/;
76 }
77 return 0;
78 }
79
80 int main(int argc ,char ** argv)
81 {
82 const int PHList[PH_NUM] = {0,1,2,3,4};
83 pthread_t tid[PH_NUM];
84 printf("create mainThread\n");
85 if(0 == pthread_mutex_init(&tableMutex,NULL))
86 printf("mutex init is successful\n");
87 else
88 printf("mutex init is failure\n");
89 //sprintf(str,"str from parent");
90 for(int i = 0; i < PH_NUM; i++)
91 pthread_create(&(tid[i]),NULL,(void *)philosopher,(void *)&(PHList[i]));
92
93 pthread_join(tid[4],NULL);
94 pthread_mutex_destroy(&tableMutex);
95 printf("mainThread exit \n");
96
97 return 0;
98 }
执行结果：
./test6 create mainThread mutex init is successful philosopher 0 is thinking philosopher 1 is thinking philosopher 2 is thinking philosopher 3 is thinking philosopher 4 is thinking philosopher 1 is eating philosopher 0 is thinking philosopher 3 is eating philosopher 4 is thinking philosopher 2 is thinking philosopher 1 is thinking philosopher 0 is thinking philosopher 3 is thinking philosopher 4 is eating philosopher 2 is eating philosopher 1 is thinking philosopher 0 is thinking philosopher 3 is thinking philosopher 4 is thinking philosopher 2 is thinking philosopher 1 is eating philosopher 0 is thinking philosopher 3 is eating philosopher 4 is thinking philosopher 2 is thinking philosopher 1 is thinking philosopher 0 is eating philosopher 3 is thinking philosopher 4 is thinking philosopher 2 is eating philosopher 1 is thinking philosopher 0 is thinking philosopher 3 is thinking philosopher 4 is eating philosopher 2 is thinking philosopher 1 is eating philosopher 0 is thinking philosopher 4 is thinking philosopher 3 is thinking philosopher 2 is thinking philosopher 1 is thinking philosopher 3 is thinking philosopher 0 is thinking philosopher 4 is eating philosopher 2 is eating philosopher 1 is thinking philosopher 3 is thinking philosopher 2 is thinking philosopher 4 is thinking philosopher 0 is thinking philosopher 1 is eating philosopher 2 is thinking philosopher 3 is eating philosopher 4 is thinking philosopher 0 is thinking philosopher 1 is thinking philosopher 4 is eating philosopher 3 is thinking philosopher 0 is thinking philosopher 2 is thinking philosopher 1 is eating philosopher 0 is thinking philosopher 3 is thinking philosopher 2 is thinking philosopher 4 is thinking philosopher 1 is thinking philosopher 3 is eating philosopher 0 is eating philosopher 2 is thinking philosopher 4 is thinking philosopher 1 is thinking philosopher 3 is thinking philosopher 0 is thinking philosopher 4 is eating philosopher 2 is eating philosopher 3 is thinking philosopher 0 is thinking philosopher 1 is thinking philosopher 2 is thinking philosopher 4 is thinking philosopher 3 is thinking philosopher 2 is eating philosopher 1 is thinking philosopher 0 is eating philosopher 4 is thinking philosopher 3 is thinking philosopher 1 is thinking philosopher 0 is thinking philosopher 4 is eating philosopher 2 is thinking philosopher 1 is thinking philosopher 4 is thinking philosopher 3 is thinking philosopher 2 is eating philosopher 0 is thinking philosopher 4 is thinking philosopher 1 is thinking philosopher 2 is thinking philosopher 0 is eating philosopher 3 is eating philosopher 4 is thinking philosopher 1 is thinking philosopher 3 is thinking philosopher 2 is thinking philosopher 0 is thinking philosopher 4 is eating philosopher 3 is thinking philosopher 2 is thinking philosopher 0 is thinking philosopher 1 is eating philosopher 4 is thinking philosopher 2 is thinking philosopher 0 is thinking philosopher 1 is thinking philosopher 3 is eating philosopher 4 is thinking philosopher 2 is thinking philosopher 3 is thinking philosopher 1 is thinking philosopher 0 is eating philosopher 4 is thinking philosopher 2 is eating philosopher 3 is thinking philosopher 1 is thinking philosopher 0 is thinking