lab7.5

/* Code for cond-hellothread.c */

#include <pthread.h>

#include <stdio.h>

/* This is the initial thread routine */

void* compute_thread (void*);

/* This is the lock for thread synchronization */

pthread_mutex_t my_sync;

/* This is the condition variable */

pthread_cond_t rx;



#define TRUE 1

#define FALSE 0

/* this is the Boolean predicate */

int thread_done = FALSE;

main( )

{

/* This is data describing the thread created */

pthread_t tid;

pthread_attr_t attr;

char hello[ ] = {"Hello, "};

char thread[ ] = {"thread"};

/* Initialize the thread attributes */

pthread_attr_init (&attr);

/* Initialize the mutex (default attributes) */

pthread_mutex_init (&my_sync, NULL);

/* Initialize the condition variable (default attr) */

pthread_cond_init (&rx, NULL);

/* Create another thread. ID is returned in &tid */

/* The last parameter is passed to the thread function */

pthread_create(&tid, &attr, compute_thread, hello);

/* wait until the thread does its work */

pthread_mutex_lock(&my_sync);

while (!thread_done)

pthread_cond_wait(&rx, &my_sync);

/* When we get here, the thread has been executed */

printf(thread);

printf("\n");

pthread_mutex_unlock(&my_sync);

exit(0);

}


/* The thread to be run by create_thread */

void* compute_thread(void* dummy)

{

/* Lock the mutex - the cond_wait has unlocked it */

pthread_mutex_lock (&my_sync);

printf(dummy);

/* set the predicate and signal the other thread */

thread_done = TRUE;

pthread_cond_signal (&rx);

pthread_mutex_unlock (&my_sync);

return;

}