我正在研究生产者和消费者问题。生产者正在生成一个随机变量并将其放入缓冲区。完成此操作后，我想打印出缓冲区的内容。我还想在消费者使用缓冲区中的变量后打印缓冲区的内容。所以，举个例子，
生产者线程34567834将43添加到缓冲区，当前缓冲区包含7,29,43
我不确定在一个printf（）语句中打印缓冲区内容的方法。谢谢你的帮助。
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <semaphore.h>
//Submit with screen shot of compiling and running code.
#define SIZE 20
#define NUMB_THREADS 10
#define PRODUCER_LOOPS 10
#define CONSUMER_LOOPS 2
#define TRUE 1
#define FALSE 0
typedef int buffer_t;
buffer_t buffer[SIZE];
int buffer_index;
pthread_mutex_t buffer_mutex;
/* initially buffer will be empty. full_sem
will be initialized to buffer SIZE, which means
SIZE number of producer threads can write to it.
And empty_sem will be initialized to 0, so no
consumer can read from buffer until a producer
thread posts to empty_sem */
sem_t full_sem; /* when 0, buffer is full */
sem_t empty_sem; /* when 0, buffer is empty. Kind of
like an index for the buffer */
/* sem_post algorithm:
mutex_lock sem_t->mutex
sem_t->value++
mutex_unlock sem_t->mutex
sem_wait algorithn:
mutex_lock sem_t->mutex
while (sem_t->value > 0) {
mutex_unlock sem_t->mutex
sleep... wake up
mutex_lock sem_t->mutex
}
sem_t->value--
mutex_unlock sem_t->mutex
*/
void insertbuffer(buffer_t value) {
if (buffer_index < SIZE) {
buffer[buffer_index++] = value;
} else {
printf("Buffer overflow\n");
}
}
buffer_t dequeuebuffer() {
if (buffer_index > 0) {
return buffer[--buffer_index]; // buffer_index-- would be error!
} else {
printf("Buffer underflow\n");
}
return 0;
}
int isempty() {
if (buffer_index == 0)
return TRUE;
return FALSE;
}
int isfull() {
if (buffer_index == SIZE)
return TRUE;
return FALSE;
}
void *producer2(void *thread_n) {
int thread_numb = *(int *)thread_n;
buffer_t value;
int i=0;
while (i++ < PRODUCER_LOOPS) {
sleep(rand() % 10);
value = rand() % 100;
pthread_mutex_lock(&buffer_mutex);
do {
// cond variables do the unlock/wait and wakeup/lock atomically,
// which avoids possible race conditions
pthread_mutex_unlock(&buffer_mutex);
// cannot go to slepp holding lock
sem_wait(&full_sem); // sem=0: wait. sem>0: go and decrement it
// there could still be race condition here. another
// thread could wake up and aqcuire lock and fill up
// buffer. that's why we need to check for spurious wakeups
pthread_mutex_lock(&buffer_mutex);
} while (isfull()); // check for spurios wake-ups
insertbuffer(value);
pthread_mutex_unlock(&buffer_mutex);
sem_post(&empty_sem); // post (increment) emptybuffer semaphore
//printf("Producer Thread %d adds %d added %d to buffer\n", pthread_self(), thread_numb, value);
printf("Producer Thread %d adds %d to the buffer, and the current buffer contains %d \n", pthread_self(), value, *buffer);
}
pthread_exit(0);
}
void *consumer2(void *thread_n) {
int thread_numb = *(int *)thread_n;
buffer_t value;
int i=0;
while (i++ < CONSUMER_LOOPS) {
pthread_mutex_lock(&buffer_mutex);
do {
pthread_mutex_unlock(&buffer_mutex);
sem_wait(&empty_sem);
pthread_mutex_lock(&buffer_mutex);
} while (isempty()); //check for spurios wakeups
value = dequeuebuffer(value);
pthread_mutex_unlock(&buffer_mutex);
sem_post(&full_sem); // post (increment) fullbuffer semaphore
printf("Consumer Thread %d dequeue %d from buffer, and the current buffer contains %d \n", pthread_self(), value, *buffer);
}
pthread_exit(0);
}
int main(int argc, int **argv) {
buffer_index = 0;
pthread_mutex_init(&buffer_mutex, NULL);
sem_init(&full_sem, // sem_t *sem
0, // int pshared. 0 = shared between threads of process, 1 = shared between processes
SIZE); // unsigned int value. Initial value
sem_init(&empty_sem,
0,
0);
/* full_sem is initialized to buffer size because SIZE number of
producers can add one element to buffer each. They will wait
semaphore each time, which will decrement semaphore value.
empty_sem is initialized to 0, because buffer starts empty and
consumer cannot take any element from it. They will have to wait
until producer posts to that semaphore (increments semaphore
value) */
pthread_t thread[NUMB_THREADS];
int thread_numb[NUMB_THREADS];
int i;
for (i = 0; i < NUMB_THREADS; ) {
thread_numb[i] = i;
if(i <= 2)
{
pthread_create(thread + i, // pthread_t *t
NULL, // const pthread_attr_t *attr
producer2, // void *(*start_routine) (void *)
thread_numb + i); // void *arg
}
thread_numb[i] = i;
// playing a bit with thread and thread_numb pointers...
pthread_create(&thread[i], // pthread_t *t
NULL, // const pthread_attr_t *attr
consumer2, // void *(*start_routine) (void *)
&thread_numb[i]); // void *arg
i++;
}
for (i = 0; i < NUMB_THREADS; i++)
pthread_join(thread[i], NULL);
pthread_mutex_destroy(&buffer_mutex);
sem_destroy(&full_sem);
sem_destroy(&empty_sem);
return 0;
}
答案 0 :(得分：0)
您无法在一行中打印未知长度的数组，但您可以修改insertbuffer以在每次插入值时显示详细信息。或者，将打印实现为单独的功能。然后称它为单行，显然。
void insertbuffer(int threadnum, buffer_t value) {
int i;
if (buffer_index < SIZE) {
buffer[buffer_index++] = value;
printf("Producer Thread %d adds %d to the buffer, and the current buffer contains",
threadnum, (int)value);
for(i=0; i<buffer_index; i++) {
if(i)
printf(",");
printf(" %d", (int)buffer[i]);
}
printf("\n");
} else {
printf("Buffer overflow\n");
}
}