Producer Consumer problem using mutex


 
#include<stdio.h>
#include<pthread.h>
#include<stdlib.h>
 
// Max buffer size user for producing
#define buff_sz 10
 
// buffer index would be the current index
volatile int buff_idx = -1;
// buffer used to produce item
volatile char *buff = NULL;;
 
// Initialization and declaration of muetxt and condition variables
pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t buff_not_full = PTHREAD_COND_INITIALIZER;
pthread_cond_t buff_not_empty = PTHREAD_COND_INITIALIZER;
 
// Consumer thread
void *Consumer()
{
        while(1)
        {
                // Taking lock to avoid race condition
                pthread_mutex_lock(&mutex);
 
                // time to sleep if nothing to consume
                while (buff_idx == -1)
                {
                        // sleeping on condition variable
                        pthread_cond_wait(&buff_not_empty, &mutex);
                }
                // Hey.. we have free index available to produce. Man, it time to produce
                printf("Consumed item from:%d\t", buff_idx--);
 
                // unlock mutex
                pthread_mutex_unlock(&mutex);
 
                // weak up any waiting producer thread as we have just consumed item. So new item can be produced
                pthread_cond_signal(&buff_not_full);
        }
}
 
// Producer
void *Producer()
{
        while(1)
        {
                // Taking lock to avoid race condition
                pthread_mutex_lock(&mutex);
 
                // time to sleep/wait if buffer is full
                while (buff_idx == buff_sz - 1)
                {
                        // sleeping on condition variable
                        pthread_cond_wait(&buff_not_full, &mutex);
                }
 
                // We have empty buffer cell. Put an item into buffer
                buff[++buff_idx] = 'I';
                printf("Produced item at:%d\t", buff_idx);
                // unlock mutex
                pthread_mutex_unlock(&mutex);
 
                // weak up any waiting consumer thread to consume as we have just produced an item
                pthread_cond_signal(&buff_not_empty);
        }
}
 
int main()
{
        pthread_t producer_thread_id, consumer_thread_id;
 
        buff = (char *) malloc(sizeof(char) * buff_sz);
        pthread_create(&producer_thread_id, NULL, Producer, NULL);
        pthread_create(&consumer_thread_id, NULL, Consumer, NULL);
        pthread_join(producer_thread_id, NULL);
        pthread_join(consumer_thread_id, NULL);
 
        return 0;
}



                                                                                                                                                 -> Sachin Birhade

Comments

Post a Comment

Popular posts from this blog

STL Questions

1. Sorting a vector of custom objects     a)Using operator()         struct MyStruct {             int key;             std::string str;             MyStruct(int k, int s) : key(k), str(s) {}         };         struct less_than{             inline bool operator()(const MyStruct &s1, const MyStruct &b)             {                 return s1.key<s2.key;             }         };         std::vector<MyStruct> vec;         vec.push_back(MyStruct(4, "a")); ...
Read more

Interview questions

C++ 1. How to implement vector Answer: http://codefreakr.com/how-is-c-stl-implemented-internally/ 2. how to implement string class Answer: http://www.ccs.neu.edu/home/sbratus/com1101/mystring.txt 3. How to implement list in STL  Answer: http://codefreakr.com/how-is-c-stl-list-implemented-internally/ 4. how many casting are there in c++ & their corresponding use. Answer: http://studymustgoon.blogspot.in/2017/05/casting-in-c.html 5. what is copy constructor, write the syntex. Why we pass reference in copy constructor. 6. Is it possible virtual constructor and virtual copy constructor. 7. why virtual destructor. 8. In copy constructor can we pass pointer as an argument? Linux 1. Difference between mutex & semaphore 2. write a code for producer consumer problem. 3. in which scenario we use semaphore. C 1. how realloc is implemented.  Answer: this concept is just like malloc implementation.
Read more