/**************************************************************************
**
**
**course: Cop4610, Operating Systems
**
**Instructor: Xiuwen LIU
**
**File Name: ~liux/public_html/courses/cop4610/examples/consumer.c
**
**
**Description: This program implements a consumer process using 
**             the bounded-buffer aglorithm.
     Consumer process
	    repeat
	       wait(full)
	       wait(mutex);
	       remove an item from buffer to nextc
	       signal(mutex);
	       signal(empty);
	       consume the item in nextc
	    until false;
**
***************************************************************************/
#include <stdio.h>
#include <signal.h>
#include <stdlib.h>
#include <time.h>

#include "bounded-buffer.h"
int Delay;       /* Delay before exiting */
int Pid;               /* Process ID */
int ExitFlag = 0;
void catch_sig(int sig);

int main(int argc, char *argv[])
{
  void prc_args(), catch_alarm();
  int ii;
  long now;
  key_t key, key_1;
  struct admin *shmaddr;
  struct buffer_record *buffer;
  int semid;
  int shmid, shmid_1;
  struct buffer_record abuf;
  struct sembuf  sops;
  int buf_loc;
  
  Delay = rand()%5+1;
  Pid = getpid();
  key = getppid();
  key_1 = key+1;
  shmid = shmget(key, sizeof(struct admin), 00600);
  if (shmid < 0) {
    fprintf(stderr,"Error: cannot get adminstrative shared memory segment.\n");
    exit(-1);
  }
  signal (SIGINT, catch_sig);
  signal (SIGTERM, catch_sig);
  shmaddr = (struct admin *)shmat(shmid, (void *)0,0);
  shmid_1 = shmget(key_1, sizeof(struct buffer_record) * shmaddr->size,
		   00600);
  if (shmid_1  < 0) {
    fprintf(stderr,"Error: cannot get shared circular buffer.\n");
    exit(-1);
  }
  buffer = (struct  buffer_record *)shmat(shmid_1,  (void *)0,0);
  semid = semget(key, 3, 00600);
  if (semid < 0) {
    fprintf(stderr,"Error: cannot get semphamores with %d\n", semid);
    exit(-1);
  }
  signal(SIGKILL, catch_sig);
   
  while(ExitFlag==0) {
    /* FULL */
    sops.sem_num = FULL_SEM;
    sops.sem_op = -1;
    semop(semid, &sops, 1);
    /* Mutex */
    sops.sem_num = MUTEX_SEM;
    sops.sem_op = -1;
    semop(semid, &sops, 1);
    abuf = buffer[shmaddr->nextc];
    buf_loc = shmaddr->nextc;
    shmaddr->nextc +=1;
    shmaddr->nextc %= shmaddr->size;
    /* Mutex */
    sops.sem_num = MUTEX_SEM;
    sops.sem_op = 1;
    semop(semid, &sops, 1);
    /* EMPTY */
    sops.sem_num = EMPTY_SEM;
    sops.sem_op = 1;
    semop(semid, &sops, 1);
    printf("C(%d) consumed from [%d]: ", 
	   Pid, buf_loc);
    printf("pid = %d seqnu = %d time = %s",
	   abuf.pid, abuf.seqnu,&(ctime(&(abuf.tstamp))[4]));
    if (Delay >0)
      sleep(Delay);
  }
  shmdt((char *)shmaddr);
  shmdt((char *)buffer);
  return 0;
}

void catch_sig(int sig) 
{
  ExitFlag = 1;
}