POSIX生产者 - 消费者

Question

我有一个与生产者和消费者有关的问题。我有1个生产者和3个消费者。制作人出示我放在队列中的信件，消费者拿着这封信。据认为，当两个消费者接受信件时，信件已经从队列中移除，但是有一个选项，消费者A和消费者C不能接受同一封信（可能A会先写信，那么con。B将首先采用第二或con。B，然后con C（或A）秒，但当A和C在一起时不可能）。

我写了一个解决这个问题的代码，但是现在我不能从函数中打印任何东西。

#include <stdio.h> 
#include <stdlib.h> 
#include <pthread.h> 
#include <semaphore.h> 
#include <unistd.h> 
#include "FIFO.h" 

#define semaphore sem_t 
#define MAX_SIZE _SIZE 
#define SLEEP 1 
#define true 1 

FIFO buff; 
semaphore full, empty, a_read, b_read, c_read, mutex; 

void randSleep(int max) { 
    double x = rand()/(double)RAND_MAX; 
    usleep((int)floor(x*max)); 
} 


void* producer_func() 
{ 
    char c='A'; 
    while(GetAmount(&buff)<MAX_SIZE) 
    { 
     sem_wait(&empty); 
     sem_wait(&mutex); 

     Push(&buff, c); 

     sem_post(&mutex); 
     sem_post(&full); 

     randSleep(SLEEP); 
    } 
    pthread_exit(NULL); 
} 

void* consumer_a_func() 
{ 
    char c; 
    long int first_met; 

    while(true) 
    { 
     sem_wait(&a_read); 
     sem_wait(&full); 

     if (sem_getvalue(&b_read,&first_met)) printf("Error with returning b_read value"); 
     sem_wait(&mutex); 

     if (first_met) 
     { 
      c = First(&buff); 
      sem_post(&mutex); 
     } 
     else 
     { 
      c = Pop(&buff); 
      sem_post(&mutex); 
      sem_post(&a_read); 
      sem_post(&b_read); 
      sem_post(&empty); 
     } 
     //printf("c value %s\n", c); 
     randSleep(SLEEP); 
    } 

    pthread_exit(NULL); 
} 

void* consumer_b_func() 
{ 
    char c; 
    long int first_met_a, first_met_c ; 

    while(true) 
    { 
     sem_wait(&b_read); 
     sem_wait(&full); 

     if (sem_getvalue(&a_read,&first_met_a)) printf("Error with returning a_read value"); 
     if (sem_getvalue(&c_read,&first_met_c)) printf("Error with returning c_read value"); 

     sem_wait(&mutex); 
     if (first_met_a && first_met_c) 
     { 
      c = First(&buff); 
      sem_post(&mutex); 
     } 
     else 
     { 
      c = Pop(&buff); 
      sem_post(&mutex); 
      sem_post(&b_read); 
      if (first_met_a) 
       sem_post(&c_read); 
      else 
       sem_post(&a_read); 
      sem_post(&empty); 
     } 
     //printf("c value %s\n", c); 
     randSleep(SLEEP); 
    } 

    pthread_exit(NULL); 
} 

void* consumer_c_func() 
{ 
    char c; 
    long int first_met; 

    while(true) 
    { 

     sem_wait(&c_read); 
     sem_wait(&full); 

     if (sem_getvalue(&b_read,&first_met)) printf("Error with returning b_read value"); 

     sem_wait(&mutex); 

     if (first_met) 
     { 
      c = First(&buff); 
      sem_post(&mutex); 
     } 
     else 
     { 
      c = Pop(&buff); 
      sem_post(&mutex); 
      sem_post(&c_read); 
      sem_post(&b_read); 
      sem_post(&empty); 
     } 
     printf("c value %s\n", c); 
     randSleep(SLEEP); 
    } 

    pthread_exit(NULL); 
} 

int main() 
{ 
    Init(&buff); 
    sem_init(&empty, 0, MAX_SIZE); 
    sem_init(&full, 0, 0); 
    sem_init(&a_read, 0, 1); 
    sem_init(&b_read, 0, 1); 
    sem_init(&c_read, 0, 1); 
    sem_init(&mutex, 0, 1); 

    pthread_t producer, consumer_a, consumer_b, consumer_c; 

    pthread_create(&producer, NULL, producer_func, NULL); 
    printf("All right\n"); 
    pthread_create(&consumer_a, NULL, consumer_a_func, NULL); 
    printf("All right\n"); 
    pthread_create(&consumer_b, NULL, consumer_b_func, NULL); 
    printf("All right\n"); 
    pthread_create(&consumer_c, NULL, consumer_c_func, NULL); 
    printf("All right\n"); 

    pthread_join(&producer, (void**)NULL); 
    pthread_join(&consumer_a, (void**)NULL); 
    pthread_join(&consumer_b, (void**)NULL); 
    pthread_join(&consumer_c, (void**)NULL); 

} 

文件FIFO.h，FIFO.c

误差看起来像

在_IO_vfprintf_internal（S = 0x7ffff78ac620 < _IO_2_1_stdout_>，格式=，AP = AP @条目= 0x7ffff6acfe58）在vfprintf.c： 1632（）

或分段错误（核心转储）

但有时这种代码运行正常，但没有任何的printf的我在生产者 - 消费者功能写道

Answer 1

//printf("c value %s\n", c); 

c是一个字符，打印它，你应该使用

printf("c value %c\n", c); 

你可以试试使用-Wformat进行编译，所以如果在printf调用中对变量使用无效格式，则会发生警告。