sysdeps/pthread/timer_create.c

   1 /* Copyright (C) 2000-2019 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Kaz Kylheku <kaz@ashi.footprints.net>.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public License as
   7    published by the Free Software Foundation; either version 2.1 of the
   8    License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If
  17    not, see <https://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <signal.h>
  21 #include <pthread.h>
  22 #include <time.h>
  23 #include <unistd.h>
  24
  25 #include "posix-timer.h"
  26
  27
  28 /* Create new per-process timer using CLOCK.  */
  29 int
  30 timer_create (clockid_t clock_id, struct sigevent *evp, timer_t *timerid)
  31 {
  32   int retval = -1;
  33   struct timer_node *newtimer = NULL;
  34   struct thread_node *thread = NULL;
  35
  36   if (0
  37 #if defined _POSIX_CPUTIME && _POSIX_CPUTIME >= 0
  38       || clock_id == CLOCK_PROCESS_CPUTIME_ID
  39 #endif
  40 #if defined _POSIX_THREAD_CPUTIME && _POSIX_THREAD_CPUTIME >= 0
  41       || clock_id == CLOCK_THREAD_CPUTIME_ID
  42 #endif
  43       )
  44     {
  45       /* We don't allow timers for CPU clocks.  At least not in the
  46          moment.  */
  47       __set_errno (ENOTSUP);
  48       return -1;
  49     }
  50
  51   if (clock_id != CLOCK_REALTIME)
  52     {
  53       __set_errno (EINVAL);
  54       return -1;
  55     }
  56
  57   pthread_once (&__timer_init_once_control, __timer_init_once);
  58
  59   if (__timer_init_failed)
  60     {
  61       __set_errno (ENOMEM);
  62       return -1;
  63     }
  64
  65   pthread_mutex_lock (&__timer_mutex);
  66
  67   newtimer = __timer_alloc ();
  68   if (__glibc_unlikely (newtimer == NULL))
  69     {
  70       __set_errno (EAGAIN);
  71       goto unlock_bail;
  72     }
  73
  74   if (evp != NULL)
  75     newtimer->event = *evp;
  76   else
  77     {
  78       newtimer->event.sigev_notify = SIGEV_SIGNAL;
  79       newtimer->event.sigev_signo = SIGALRM;
  80       newtimer->event.sigev_value.sival_ptr = newtimer;
  81       newtimer->event.sigev_notify_function = 0;
  82     }
  83
  84   newtimer->event.sigev_notify_attributes = &newtimer->attr;
  85   newtimer->creator_pid = getpid ();
  86
  87   switch (__builtin_expect (newtimer->event.sigev_notify, SIGEV_SIGNAL))
  88     {
  89     case SIGEV_NONE:
  90     case SIGEV_SIGNAL:
  91       /* We have a global thread for delivering timed signals.
  92          If it is not running, try to start it up.  */
  93       thread = &__timer_signal_thread_rclk;
  94       if (! thread->exists)
  95         {
  96           if (__builtin_expect (__timer_thread_start (thread),
  97                                 1) < 0)
  98             {
  99               __set_errno (EAGAIN);
 100               goto unlock_bail;
 101             }
 102         }
 103       break;
 104
 105     case SIGEV_THREAD:
 106       /* Copy over thread attributes or set up default ones.  */
 107       if (evp->sigev_notify_attributes)
 108         newtimer->attr = *(pthread_attr_t *) evp->sigev_notify_attributes;
 109       else
 110         pthread_attr_init (&newtimer->attr);
 111
 112       /* Ensure thread attributes call for deatched thread.  */
 113       pthread_attr_setdetachstate (&newtimer->attr, PTHREAD_CREATE_DETACHED);
 114
 115       /* Try to find existing thread having the right attributes.  */
 116       thread = __timer_thread_find_matching (&newtimer->attr, clock_id);
 117
 118       /* If no existing thread has these attributes, try to allocate one.  */
 119       if (thread == NULL)
 120         thread = __timer_thread_alloc (&newtimer->attr, clock_id);
 121
 122       /* Out of luck; no threads are available.  */
 123       if (__glibc_unlikely (thread == NULL))
 124         {
 125           __set_errno (EAGAIN);
 126           goto unlock_bail;
 127         }
 128
 129       /* If the thread is not running already, try to start it.  */
 130       if (! thread->exists
 131           && __builtin_expect (! __timer_thread_start (thread), 0))
 132         {
 133           __set_errno (EAGAIN);
 134           goto unlock_bail;
 135         }
 136       break;
 137
 138     default:
 139       __set_errno (EINVAL);
 140       goto unlock_bail;
 141     }
 142
 143   newtimer->clock = clock_id;
 144   newtimer->abstime = 0;
 145   newtimer->armed = 0;
 146   newtimer->thread = thread;
 147
 148   *timerid = timer_ptr2id (newtimer);
 149   retval = 0;
 150
 151   if (__builtin_expect (retval, 0) == -1)
 152     {
 153     unlock_bail:
 154       if (thread != NULL)
 155         __timer_thread_dealloc (thread);
 156       if (newtimer != NULL)
 157         {
 158           timer_delref (newtimer);
 159           __timer_dealloc (newtimer);
 160         }
 161     }
 162
 163   pthread_mutex_unlock (&__timer_mutex);
 164
 165   return retval;
 166 }