关于线程信号量的一段小代码

最新推荐文章于 2016-04-13 21:05:44 发布

devilrays

最新推荐文章于 2016-04-13 21:05:44 发布

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分类专栏：能力提升

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本文展示了一个使用多线程进行数据读取与处理的C程序实例。程序通过两个线程分别从两个文件中读取数据，并将数据存入共享数组中；另外两个线程则从该数组中取出数据进行加法和乘法运算。使用信号量来同步线程间的操作，确保数据正确处理。

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#include<pthread.h>
#include<string.h>
#include<semaphore.h>
#include<errno.h>
#include<stdio.h>
#include<stdlib.h>

#define MAXSTACK 100
int stack[MAXSTACK][2]; 
int size=0;
sem_t sem;
int m = 0;
int n = 0;

void readdata1(void);
void readdata2(void);
void handledata1(void);
void handledata2(void);

int main()
{
	pthread_t t1, t2, t3, t4;
	sem_init(&sem, 0, 0);
	int i;
	pthread_create(&t1, NULL, (void*)handledata1, NULL);
	pthread_create(&t2, NULL, (void*)handledata2, NULL);
	pthread_create(&t3, NULL, (void*)readdata1, NULL);
	pthread_create(&t4, NULL, (void*)readdata2, NULL);
	printf("-----------------create over-----------------\n");

	pthread_join(t1, NULL);
	pthread_join(t2, NULL);
	pthread_join(t3, NULL);
	pthread_join(t4, NULL);
	printf("-----------------join over-----------------\n");

	sem_destroy(&sem);

	return 0;
}

void readdata1(void)
{
	FILE* fp;

	if((fp = fopen("1.data", "r")) < 0){
		printf("%s fopen failed: %s\n", __FUNCTION__, strerror(errno));
	}

	while(!feof(fp)){
		fscanf(fp, "%d %d", &stack[size][0], &stack[size][1]);
		printf("----%s: stack[%d][0][1]: %d %d \n", __FUNCTION__, size, stack[size][0], stack[size][1]);
		sem_post(&sem);
		size++;
	}
	printf("\n");

	fclose(fp);
	printf("%s exit\n", __FUNCTION__);
	pthread_exit(0);
}

void readdata2(void)
{
	FILE* fp;
	if((fp = fopen("2.data", "r")) < 0){
		printf("%s fopen failed: %s", __FUNCTION__, strerror(errno));
	}
	while(!feof(fp)){
		fscanf(fp, "%d %d", &stack[size][0], &stack[size][1]);
		printf("----%s: stack[%d][0][1]: %d %d \n", __FUNCTION__, size, stack[size][0], stack[size][1]);
		sem_post(&sem);
		size++;
	}
	printf("\n");
	fclose(fp);
	printf("%s exit\n", __FUNCTION__);
	pthread_exit(0);
}


void handledata1(void)
{
	while(1){
		printf("%s blocked %d\n", __FUNCTION__, m);
		sem_wait(&sem);
		printf("%s block released %d\n", __FUNCTION__, m++);
		printf("Plus: stack[%d][0][1] %d + %d = %d\n", size, stack[size][0], stack[size][1], stack[size][0]+stack[size][1]);
		--size;
	}
	printf("%s exit\n", __FUNCTION__);
	pthread_exit(0);
}


void handledata2(void)
{
	while(1){
		printf("%s blocked %d\n", __FUNCTION__, n);
		sem_wait(&sem);
		printf("%s block released %d\n", __FUNCTION__, n++);
		//printf("multiply: %d * %d = %d\n", stack[size][0], stack[size][1], stack[size][0]*stack[size][0]);
		printf("Multiply: stack[%d][0][1] %d * %d = %d\n", size, stack[size][0], stack[size][1], (stack[size][0])*(stack[size][1]));
		--size;
	}
	printf("%s exit\n", __FUNCTION__);
	pthread_exit(0);
}