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#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include "my_global.h"
static void spawn_stern_thread(pthread_t *t);
static int act_goofy(void);
static void *be_stern(void *);
static struct {
pthread_mutex_t lock;
pthread_cond_t cond;
int msg;
} comm = { PTHREAD_MUTEX_INITIALIZER, PTHREAD_COND_INITIALIZER, 0 };
int
main(void)
{
pthread_t t;
spawn_stern_thread(&t);
while (act_goofy() != 0)
/* do nothing */;
pthread_exit(NULL);
/* notreached */
return EXIT_SUCCESS;
}
static void spawn_stern_thread(pthread_t *t)
{
pthread_attr_t attr;
pthread_attr_init(&attr);
pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
if (pthread_create(t, &attr, be_stern, NULL) != 0)
exit(EXIT_FAILURE);
pthread_attr_destroy(&attr);
}
static int act_goofy(void)
{
int ret;
char buf[30];
fputs("Are you ready to act goofy (Y/n)? ", stdout); fflush(stdout);
fgets(buf, sizeof(buf), stdin);
pthread_mutex_lock(&comm.lock);
if (buf[0] == 'y' || buf[0] == '\n') {
fputs("** Waawlwalkwwwaa!!\n", stdout); fflush(stdout);
++comm.msg;
ret = 1;
}
else {
fputs("OK, I hate you. Let me go.\n", stdout); fflush(stdout);
comm.msg = -1;
ret = 0;
}
pthread_mutex_unlock(&comm.lock);
pthread_cond_signal(&comm.cond);
return ret;
}
static void *be_stern(void *v __attribute__((unused)))
{
int msg;
for (;;) {
pthread_mutex_lock(&comm.lock);
while (comm.msg == 0)
pthread_cond_wait(&comm.cond, &comm.lock);
msg = comm.msg;
comm.msg = 0;
pthread_mutex_unlock(&comm.lock);
if (msg < 0)
break; /* the goofy one learned a lesson! */
fputs("I HAVE TO BE STERN WITH YOU!\n", stderr);
fprintf(stderr, "I should give you %d lashes.\n", msg);
sleep(msg);
}
fputs("You are NOTHING!\n", stderr);
return NULL;
}
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