/* System V Semaphores and pthreads. */
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>

#include <pthread.h>
#include <sys/types.h>

#include "array.h"

#define massert( cond, msg )                                                  \
   if( cond ) {                                                               \
      perror( msg );                                                          \
      exit(-1);                                                               \
   }

#define SLEEP 1000000

char buf[] = "abcdefghijklmnopqrstuvwsyz";
pthread_rwlock_t lock;

void *inv( ) {
   int len = strlen(buf);
   while( 1 ) {
      massert(pthread_rwlock_wrlock( &lock ) != 0, "pthread_rwlock_wrlock");
         inverse(buf, len);
      massert(pthread_rwlock_unlock( &lock ) != 0, "pthread_rwlock_unlock");
      usleep( SLEEP );
   }
}
void *rev( ) {
   int len = strlen(buf);
   while( 1 ) {
      massert(pthread_rwlock_wrlock( &lock ) != 0, "pthread_rwlock_wrlock");
         reverse(buf, len);
      massert(pthread_rwlock_unlock( &lock ) != 0, "pthread_rwlock_unlock");
      usleep( SLEEP );
   }
}  

void *cnt( ) {
   int len = strlen(buf), ct;
   while( 1 ) {
      massert(pthread_rwlock_rdlock( &lock ) != 0, "pthread_rwlock_rdlock");
         ct = count( buf, len);
         printf("%d\n", ct);
      massert(pthread_rwlock_unlock( &lock ) != 0, "pthread_rwlock_unlock");
      usleep( SLEEP );
   }
}

int main( int argc, char* argv[] ) {
   
   pthread_t inv_pthread, rev_pthread, cnt_pthread;

   massert(pthread_rwlock_init( &lock, NULL ) != 0, "pthread_rwlock_init");
   massert(pthread_create( &inv_pthread, NULL, inv, NULL ) != 0, "pthread" );
   massert(pthread_create( &rev_pthread, NULL, rev, NULL ) != 0, "pthread" );
   massert(pthread_create( &cnt_pthread, NULL, cnt, NULL ) != 0, "pthread" );
  
   while(1) {
      massert(pthread_rwlock_rdlock( &lock ), "pthread_rwlock_rdlock");
         puts(buf);
      massert(pthread_rwlock_unlock( &lock ), "pthread_rwlock_unlock");
      usleep( SLEEP );
   }
   pthread_exit( NULL );
   return 0;
}