#include <pthread.h>

#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#define NUM_THREADS 3

#define TCOUNT 10

#define COUNT_LIMIT 12

int count = 0;

pthread_mutex_t count_mutex;

pthread_cond_t count_threshold_cv;

void *inc_count(void *t)

{

int i;

long my_id = (long)t;

for (i = 0; i < TCOUNT; i++)

{

pthread_mutex_lock(&count_mutex);

count++;

if (count == COUNT_LIMIT)

{

printf("inc_count(): thread %ld, count = %d -- threshold reached.",

my_id, count);

pthread_cond_signal(&count_threshold_cv);

printf("Just sent signal.\n");

}

printf("inc_count(): thread %ld, count = %d -- unlocking mutex\n",

my_id, count);

pthread_mutex_unlock(&count_mutex);

sleep(1);

}

pthread_exit(NULL);

}

void *watch_count(void *t)

{

long my_id = (long)t;

printf("Starting watch_count(): thread %ld\n", my_id);

pthread_mutex_lock(&count_mutex);

while (count < COUNT_LIMIT)

{

printf("watch_count(): thread %ld Count= %d. Going into wait...\n", my_id, count);

pthread_cond_wait(&count_threshold_cv, &count_mutex);

printf("watch_count(): thread %ld Condition signal received. Count= %d\n", my_id, count);

}

printf("watch_count(): thread %ld Updating the value of count...\n", my_id);

count += 125;

printf("watch_count(): thread %ld count now = %d.\n", my_id, count);

printf("watch_count(): thread %ld Unlocking mutex.\n", my_id);

pthread_mutex_unlock(&count_mutex);

pthread_exit(NULL);

}

int main(int argc, char *argv[])

{

int i, rc;

long t1 = 1,

t2 = 2,

t3 = 3;

pthread_t threads[3];

pthread_attr_t attr;

pthread_mutex_init(&count_mutex, NULL);

pthread_cond_init(&count_threshold_cv, NULL);

pthread_attr_init(&attr);

pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);

pthread_create(&threads[0], &attr, watch_count, (void *)t1);

pthread_create(&threads[1], &attr, inc_count, (void *)t2);

pthread_create(&threads[2], &attr, inc_count, (void *)t3);

for (i = 0; i < NUM_THREADS; i++)

{

pthread_join(threads[i], NULL);

}

printf("Main(): Waited and joined with %d threads. Final value of count = %d. Done.\n",

NUM_THREADS, count);

pthread_attr_destroy(&attr);

pthread_mutex_destroy(&count_mutex);

pthread_cond_destroy(&count_threshold_cv);

pthread_exit(NULL);

}