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Producer-Consumer problem in C using semaphores
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#include <stdio.h> | |
#include <stdlib.h> | |
#include <time.h> | |
#include <string.h> | |
#include <unistd.h> | |
#include <pthread.h> | |
#include <semaphore.h> | |
/* | |
use the pthread flag with gcc to compile this code | |
~$ gcc -pthread producer_consumer.c -o producer_consumer | |
*/ | |
pthread_t *producers; | |
pthread_t *consumers; | |
sem_t buf_mutex,empty_count,fill_count; | |
int *buf,buf_pos=-1,prod_count,con_count,buf_len; | |
int produce(pthread_t self){ | |
int i = 0; | |
int p = 1 + rand()%40; | |
while(!pthread_equal(*(producers+i),self) && i < prod_count){ | |
i++; | |
} | |
printf("Producer %d produced %d \n",i+1,p); | |
return p; | |
} | |
void consume(int p,pthread_t self){ | |
int i = 0; | |
while(!pthread_equal(*(consumers+i),self) && i < con_count){ | |
i++; | |
} | |
printf("Buffer:"); | |
for(i=0;i<=buf_pos;++i) | |
printf("%d ",*(buf+i)); | |
printf("\nConsumer %d consumed %d \nCurrent buffer len: %d\n",i+1,p,buf_pos); | |
} | |
void* producer(void *args){ | |
while(1){ | |
int p = produce(pthread_self()); | |
sem_wait(&empty_count); | |
sem_wait(&buf_mutex); | |
++buf_pos; // critical section | |
*(buf + buf_pos) = p; | |
sem_post(&buf_mutex); | |
sem_post(&fill_count); | |
sleep(1 + rand()%3); | |
} | |
return NULL; | |
} | |
void* consumer(void *args){ | |
int c; | |
while(1){ | |
sem_wait(&fill_count); | |
sem_wait(&buf_mutex); | |
c = *(buf+buf_pos); | |
consume(c,pthread_self()); | |
--buf_pos; | |
sem_post(&buf_mutex); | |
sem_post(&empty_count); | |
sleep(1+rand()%5); | |
} | |
return NULL; | |
} | |
int main(void){ | |
int i,err; | |
srand(time(NULL)); | |
sem_init(&buf_mutex,0,1); | |
sem_init(&fill_count,0,0); | |
printf("Enter the number of Producers:"); | |
scanf("%d",&prod_count); | |
producers = (pthread_t*) malloc(prod_count*sizeof(pthread_t)); | |
printf("Enter the number of Consumers:"); | |
scanf("%d",&con_count); | |
consumers = (pthread_t*) malloc(con_count*sizeof(pthread_t)); | |
printf("Enter buffer capacity:"); | |
scanf("%d",&buf_len); | |
buf = (int*) malloc(buf_len*sizeof(int)); | |
sem_init(&empty_count,0,buf_len); | |
for(i=0;i<prod_count;i++){ | |
err = pthread_create(producers+i,NULL,&producer,NULL); | |
if(err != 0){ | |
printf("Error creating producer %d: %s\n",i+1,strerror(err)); | |
}else{ | |
printf("Successfully created producer %d\n",i+1); | |
} | |
} | |
for(i=0;i<con_count;i++){ | |
err = pthread_create(consumers+i,NULL,&consumer,NULL); | |
if(err != 0){ | |
printf("Error creating consumer %d: %s\n",i+1,strerror(err)); | |
}else{ | |
printf("Successfully created consumer %d\n",i+1); | |
} | |
} | |
for(i=0;i<prod_count;i++){ | |
pthread_join(*(producers+i),NULL); | |
} | |
for(i=0;i<con_count;i++){ | |
pthread_join(*(consumers+i),NULL); | |
} | |
return 0; | |
} | |
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