sysdeps/pthread/timer_create.c

   1 /* Copyright (C) 2000-2015 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 <http://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 (clock_id, evp, timerid)
  31      clockid_t clock_id;
  32      struct sigevent *evp;
  33      timer_t *timerid;
  34 {
  35   int retval = -1;
  36   struct timer_node *newtimer = NULL;
  37   struct thread_node *thread = NULL;
  38
  39   if (0
  40 #if defined _POSIX_CPUTIME && _POSIX_CPUTIME >= 0
  41       || clock_id == CLOCK_PROCESS_CPUTIME_ID
  42 #endif
  43 #if defined _POSIX_THREAD_CPUTIME && _POSIX_THREAD_CPUTIME >= 0
  44       || clock_id == CLOCK_THREAD_CPUTIME_ID
  45 #endif
  46       )
  47     {
  48       /* We don't allow timers for CPU clocks.  At least not in the
  49          moment.  */
  50       __set_errno (ENOTSUP);
  51       return -1;
  52     }
  53
  54   if (clock_id != CLOCK_REALTIME)
  55     {
  56       __set_errno (EINVAL);
  57       return -1;
  58     }
  59
  60   pthread_once (&__timer_init_once_control, __timer_init_once);
  61
  62   if (__timer_init_failed)
  63     {
  64       __set_errno (ENOMEM);
  65       return -1;
  66     }
  67
  68   pthread_mutex_lock (&__timer_mutex);
  69
  70   newtimer = __timer_alloc ();
  71   if (__glibc_unlikely (newtimer == NULL))
  72     {
  73       __set_errno (EAGAIN);
  74       goto unlock_bail;
  75     }
  76
  77   if (evp != NULL)
  78     newtimer->event = *evp;
  79   else
  80     {
  81       newtimer->event.sigev_notify = SIGEV_SIGNAL;
  82       newtimer->event.sigev_signo = SIGALRM;
  83       newtimer->event.sigev_value.sival_ptr = timer_ptr2id (newtimer);
  84       newtimer->event.sigev_notify_function = 0;
  85     }
  86
  87   newtimer->event.sigev_notify_attributes = &newtimer->attr;
  88   newtimer->creator_pid = getpid ();
  89
  90   switch (__builtin_expect (newtimer->event.sigev_notify, SIGEV_SIGNAL))
  91     {
  92     case SIGEV_NONE:
  93     case SIGEV_SIGNAL:
  94       /* We have a global thread for delivering timed signals.
  95          If it is not running, try to start it up.  */
  96       thread = &__timer_signal_thread_rclk;
  97       if (! thread->exists)
  98         {
  99           if (__builtin_expect (__timer_thread_start (thread),
 100                                 1) < 0)
 101             {
 102               __set_errno (EAGAIN);
 103               goto unlock_bail;
 104             }
 105         }
 106       break;
 107
 108     case SIGEV_THREAD:
 109       /* Copy over thread attributes or set up default ones.  */
 110       if (evp->sigev_notify_attributes)
 111         newtimer->attr = *(pthread_attr_t *) evp->sigev_notify_attributes;
 112       else
 113         pthread_attr_init (&newtimer->attr);
 114
 115       /* Ensure thread attributes call for deatched thread.  */
 116       pthread_attr_setdetachstate (&newtimer->attr, PTHREAD_CREATE_DETACHED);
 117
 118       /* Try to find existing thread having the right attributes.  */
 119       thread = __timer_thread_find_matching (&newtimer->attr, clock_id);
 120
 121       /* If no existing thread has these attributes, try to allocate one.  */
 122       if (thread == NULL)
 123         thread = __timer_thread_alloc (&newtimer->attr, clock_id);
 124
 125       /* Out of luck; no threads are available.  */
 126       if (__glibc_unlikely (thread == NULL))
 127         {
 128           __set_errno (EAGAIN);
 129           goto unlock_bail;
 130         }
 131
 132       /* If the thread is not running already, try to start it.  */
 133       if (! thread->exists
 134           && __builtin_expect (! __timer_thread_start (thread), 0))
 135         {
 136           __set_errno (EAGAIN);
 137           goto unlock_bail;
 138         }
 139       break;
 140
 141     default:
 142       __set_errno (EINVAL);
 143       goto unlock_bail;
 144     }
 145
 146   newtimer->clock = clock_id;
 147   newtimer->abstime = 0;
 148   newtimer->armed = 0;
 149   newtimer->thread = thread;
 150
 151   *timerid = timer_ptr2id (newtimer);
 152   retval = 0;
 153
 154   if (__builtin_expect (retval, 0) == -1)
 155     {
 156     unlock_bail:
 157       if (thread != NULL)
 158         __timer_thread_dealloc (thread);
 159       if (newtimer != NULL)
 160         {
 161           timer_delref (newtimer);
 162           __timer_dealloc (newtimer);
 163         }
 164     }
 165
 166   pthread_mutex_unlock (&__timer_mutex);
 167
 168   return retval;
 169 }