linux下C语言实现读者写者写者优先

可以并发读，读写、写读、写写互斥，写者优先，代码已在Ubuntu11.10下编译运行通过

#include
#include

#define W_NUM 5    //最大写者数
#define R_NUM 10  //最大读者数
#define MAX_NUM 10

	
pthread_mutex_t write_lock;      
pthread_mutex_t read_lock;    
pthread_mutex_t change_writer_num_lock;   
pthread_mutex_t chane_reader_num_lock;   

pthread_t writers[MAX_NUM];
pthread_t readers[MAX_NUM];

int writer_cnt = 0;
int reader_cnt = 0;


void *writer（void *writer_id）{
	int *ptr_idtask_id;
	ptr_id = （int *）writer_id;
	task_id = *ptr_id;

	printf（“	Writer %d send write require\n“task_id）;

	
	pthread_mutex_lock（&change_writer_num_lock）;
	writer_cnt++;
	//printf（“  %d\n“writer_cnt）;
	if（writer_cnt == 1）{
		pthread_mutex_lock（&read_lock）;     //   读者将阻塞在这儿
	}
	pthread_mutex_unlock（&change_writer_num_lock）;

	pthread_mutex_lock（&write_lock）;
	printf（“	Writer %d begin to writing\n“task_id）;
	printf（“	Writer %d is writing.......\n“task_id）;
	sleep（1）;
	printf（“	Writer %d finished writing\n“task_id）;
	//sleep（2）;
	pthread_mutex_unlock（&write_lock）;

	pthread_mutex_lock（&change_writer_num_lock）;
	writer_cnt--;
	//printf（“  %d\n“writer_cnt）;
	if（writer_cnt == 0）{
		pthread_mutex_unlock（&read_lock）;
	}
	pthread_mutex_unlock（&change_writer_num_lock）;
	sleep（3）;  
	
	pthread_exit（NULL）;
}

void *reader（void *reader_id）{
	int *ptr_idtask_id;
	ptr_id = （int *）reader_id;
	task_id = *ptr_id;

	printf（“Reader %d send read require\n“task_id）;
	
	pthread_mutex_lock（&read_lock）;    //readers choked here
	pthread_mutex_lock（&chane_reader_num_lock）;
	reader_cnt++;
	if（reader_cnt == 1）{
		pthread_mutex_lock（&write_lock）;
	}
	pthread_mutex_unlock（&chane_reader_num_lock）;
	pthread_mutex_unlock（&read_lock）;

	printf（“Reader %d begin to reading\n“task_id）;
	printf（“Reader %d is reading.......\n“task_id）;
	sleep（1）;
	printf（“Reader %d finished reading\n“task_id）;
	//sleep（1）;

	pthread_mutex_lock（&chane_reader_num_lock）;
	reader_cnt--;
	if（reader_cnt == 0）{
		pthread_mutex_unlock（&write_lock）;
	}
	pthread_mutex_unlock（&chane_reader_num_lock）;
	sleep（3）;
	
	pthread_exit（NULL）;
}

int main（）{
	
	int writer_id[MAX_NUM];
	int reader_id[MAX_NUM];

	pthread_mutex_init（&write_lockNULL）;
	pthread_mutex_init（&read_lockNULL）;
	pthread_mutex_init（&change_writer_num_lockNULL）;
	pthread_mutex_init（&chane_reader_num_lockNULL）;

	int i_W = 0;
	int i_R = 0;
	
	for（i_W = 0; i_W < W_NUM; i_W++）{
		writer_id[i_W] = i_W;
		pthread_create（&writers[i_W]NULLwriter（void *）&writer_id[i_W]）;
		//sleep（0.5）;
	}
	for（i_R = 0; i_R < R_NUM; i_R++）{
		reader_id[i_R] = i_R;
		pthread_create（&readers[i_R]NULLreader（void *）&reader_id[i_R]）;
		//sleep（0.5）;
	}

    sleep（10）;

    for（i_W = 0; i_W < W_NUM; i_W++）{
    	pthread_join（writers[i_W]NULL）;
    }
    for（i_R = 0; i_R < R_NUM; i_R++）{
    	pthread_join（readers[i_R]NULL）;
    }

	return 0;

}

 属性            大小     日期    时间   名称
----------- ---------  ---------- -----  ----
     目录           0  2014-04-18 10:39  writer_reader\
     文件        2820  2014-04-18 10:37  writer_reader\main.c