스마트 컨트롤러

20150810

2015 스마트 콘트롤러/업무일지 2015. 8. 10. 23:49

==공유메모리

: shmget() :

: shmat() : attach

: shmdt() : detach

: shmctl() : 관리

-확인

: ipcs -m

<sharedmem.c>

#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <stdio.h>

int main(int argc, char **argv)
{
    key_t keyval = 2345;
    int shmid;
    shmid = shmget(keyval, 1024, IPC_CREAT |0666);
    if(shmid == -1)
    {
        printf("shm Create failure\n");
        return 1;
    }
    printf("shm Create success\n");
    return 0;
}

:권한

소유자 그룹 기타

-666 : rwx rwx rwx

110 110 110

<shm_producer>실행 전/후

<shm_procuder.c>

#include <sys/ipc.h>
#include <sys/shm.h>
#include <string.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>

int main(int argc, char **argv)
{
    int shmid;

    int *cal_num;
    void *shared_memory = NULL;

    shmid = shmget((key_t) 1234, sizeof(int), 0666|IPC_CREAT);
    if(shmid == -1)
    {
        perror("shmget failed : ");
        exit(0);
    }

    shared_memory = shmat(shmid, NULL, 0);
    if(shared_memory == (void *)-1)
    {
        perror("shmat failed : ");
        exit(0);
    }

    cal_num = (int *)shared_memory;
    while(1)
    {
        *cal_num = *cal_num +2;
        sleep(1);
    }
    return 0;
}

<shm_consumer.c>

#include <sys/ipc.h>
#include <sys/shm.h>
#include <string.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>

int main(int argc, char ** argv)
{
    int shmid;

    int *cal_num;
    void *shared_memory = NULL;

    shmid =shmget((key_t)1234, sizeof(int), 0);
    if(shmid == -1)
    {
        perror("shmget failed : ");
        exit(0);
    }

    shared_memory = shmat(shmid, NULL, 0);
    if(shared_memory == (void *)-1)
    {
        perror("shmat failed : ");
        exit(0);
    }

    cal_num = (int *)shared_memory;

    while(1)
    {
        sleep(1);
        printf("Read Data : %d\n", *cal_num);
    }
    return 0;
}

1. 멀티 P : PROCESS 여러개

2. 멀티 T : PROCESS 1개 THREAD 여러개

3. 다중 입출력 : PROCESS 1개

==세마포어(키)

(비행기 좌석 예약 : 같은좌석 중복 예약 안되도록 한사람이 예약 하는 동안 lock) : 동기화

=> 공유메모리 / 파이프 사용 불가 => 세마포어 사용(

<shm_producer_sem.c>

#include <sys/ipc.h>
#include <sys/shm.h>
#include <sys/sem.h>
#include <string.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>

union semun
{
  int val;
};

int main(int argc, char **argv)
{
  int shmid;
  int semid;

  int *cal_num;
  void *shared_memory = NULL;
  union semun sem_union;

  struct sembuf semopen = { 0, -1, SEM_UNDO};
  struct sembuf semclose = { 0, 1, SEM_UNDO};

  shmid = shmget((key_t)1234, sizeof(int), 0666|IPC_CREAT);
  if(shmid == -1)
  {
    return 1;
  }

  semid = semget((key_t)3477, 1, IPC_CREAT|0666);
  if(semid == -1)
  {
    return 1;
  }

  shared_memory = shmat(shmid, NULL, 0);
  if(shared_memory == (void *)-1)
  {
    return 1;
  }

  cal_num = (int *)shared_memory;
  sem_union.val = 1;
  if(-1 == semctl(semid, 0, SETVAL, sem_union))
  {
    return 1;
  }

  while(1)
  {
    int local_var = 0;
    if(semop(semid, &semopen, 1) == -1)
    {
      return 1;
    }
    local_var = *cal_num +1;
    sleep(1);
    *cal_num = local_var;
    printf("%d\n", *cal_num);
    semop(semid, &semclose, 1);
  }
  return 0;
}

<shm_consumer_sem.c>

#include <sys/ipc.h>
#include <sys/shm.h>
#include <sys/sem.h>
#include <string.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>

int main(int argc, char **argv)
{
  int shmid;
  int semid;

  int *cal_num;
  void *shared_memory = NULL;

  struct sembuf semopen = {0, -1, SEM_UNDO};
  struct sembuf semclose = {0, 1, SEM_UNDO};

  shmid = shmget((key_t)1234, sizeof(int), 0666);
  if(shmid ==-1)
  {
    perror("shmget failed : ");
    exit(0);
  }

  semid = semget((key_t) 3477, 0, 0666);
  if(semid == -1)
  {
    perror("semget failed : ");
    return 1;
  }

  shared_memory = shmat(shmid, NULL, 0);
  if(shared_memory == (void *)-1)
  {
    perror("shmat failed : ");
    exit(0);
  }

  cal_num = (int *)shared_memory;

  while(1)
  {
    int local_var = 0;
    // 세마포어 획득 실패시 : IPC_NOWAIT 아니므로 무한대기
    if(semop(semid, &semopen, 1) == -1)
    {
      perror("semop error : ");
    }
    local_var = *cal_num +1;
    sleep(2);
    *cal_num = local_var;
    printf("count %d\n", *cal_num);
    semop(semid, &semclose, 1);
  }
  return 0;
}

=시그널(소프트웨어 인터럽트: ctrl+C)(자바: 이벤트)(윈도우: 메세지)

<sig1.c>

#include <stdio.h>
#include <stdlib.h>
#include <signal.h>

void smart(int iNum)
{
    printf("INTERRUPT : %d\n", iNum);
    //exit(0);
}

int main()
{
    signal(SIGINT, smart);
    while(1)
    {
        sleep(1);
        printf("-----------------------------\n");
    }
    return 0;
}