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glibc  2.9
Functions
timer_create.c File Reference
#include <errno.h>
#include <signal.h>
#include <pthread.h>
#include <time.h>
#include <unistd.h>
#include "posix-timer.h"

Go to the source code of this file.

Functions

int timer_create (clockid_t clock_id, struct sigevent *evp, timer_t *timerid)

Function Documentation

int timer_create ( clockid_t  clock_id,
struct sigevent *  evp,
timer_t *  timerid 
)

Definition at line 31 of file timer_create.c.

{
  int retval = -1;
  struct timer_node *newtimer = NULL;
  struct thread_node *thread = NULL;

  if (0
#ifdef _POSIX_CPUTIME
      || clock_id == CLOCK_PROCESS_CPUTIME_ID
#endif
#ifdef _POSIX_THREAD_CPUTIME
      || clock_id == CLOCK_THREAD_CPUTIME_ID
#endif
      )
    {
      /* We don't allow timers for CPU clocks.  At least not in the
        moment.  */
      __set_errno (ENOTSUP);
      return -1;
    }

  if (clock_id != CLOCK_REALTIME)
    {
      __set_errno (EINVAL);
      return -1;
    }

  pthread_once (&__timer_init_once_control, __timer_init_once);

  if (__timer_init_failed)
    {
      __set_errno (ENOMEM);
      return -1;
    }

  pthread_mutex_lock (&__timer_mutex);

  newtimer = __timer_alloc ();
  if (__builtin_expect (newtimer == NULL, 0))
    {
      __set_errno (EAGAIN);
      goto unlock_bail;
    }

  if (evp != NULL)
    newtimer->event = *evp;
  else
    {
      newtimer->event.sigev_notify = SIGEV_SIGNAL;
      newtimer->event.sigev_signo = SIGALRM;
      newtimer->event.sigev_value.sival_int = timer_ptr2id (newtimer);
      newtimer->event.sigev_notify_function = 0;
    }

  newtimer->event.sigev_notify_attributes = &newtimer->attr;
  newtimer->creator_pid = getpid ();

  switch (__builtin_expect (newtimer->event.sigev_notify, SIGEV_SIGNAL))
    {
    case SIGEV_NONE:
    case SIGEV_SIGNAL:
      /* We have a global thread for delivering timed signals.
        If it is not running, try to start it up.  */
      thread = &__timer_signal_thread_rclk;
      if (! thread->exists)
       {
         if (__builtin_expect (__timer_thread_start (thread),
                            1) < 0)
           {
             __set_errno (EAGAIN);
             goto unlock_bail;
            }
        }
      break;

    case SIGEV_THREAD:
      /* Copy over thread attributes or set up default ones.  */
      if (evp->sigev_notify_attributes)
       newtimer->attr = *(pthread_attr_t *) evp->sigev_notify_attributes;
      else
       pthread_attr_init (&newtimer->attr);

      /* Ensure thread attributes call for deatched thread.  */
      pthread_attr_setdetachstate (&newtimer->attr, PTHREAD_CREATE_DETACHED);

      /* Try to find existing thread having the right attributes.  */
      thread = __timer_thread_find_matching (&newtimer->attr, clock_id);

      /* If no existing thread has these attributes, try to allocate one.  */
      if (thread == NULL)
       thread = __timer_thread_alloc (&newtimer->attr, clock_id);

      /* Out of luck; no threads are available.  */
      if (__builtin_expect (thread == NULL, 0))
       {
         __set_errno (EAGAIN);
         goto unlock_bail;
       }

      /* If the thread is not running already, try to start it.  */
      if (! thread->exists
         && __builtin_expect (! __timer_thread_start (thread), 0))
       {
         __set_errno (EAGAIN);
         goto unlock_bail;
       }
      break;

    default:
      __set_errno (EINVAL);
      goto unlock_bail;
    }

  newtimer->clock = clock_id;
  newtimer->abstime = 0;
  newtimer->armed = 0;
  newtimer->thread = thread;

  *timerid = timer_ptr2id (newtimer);
  retval = 0;

  if (__builtin_expect (retval, 0) == -1)
    {
    unlock_bail:
      if (thread != NULL)
       __timer_thread_dealloc (thread);
      if (newtimer != NULL)
       {
         timer_delref (newtimer);
         __timer_dealloc (newtimer);
       }
    }

  pthread_mutex_unlock (&__timer_mutex);

  return retval;
}

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