nptl/sysdeps/pthread/timer_create.c

   1 /* Copyright (C) 2000, 2003, 2004 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 not,
  17    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18    Boston, MA 02111-1307, USA.  */
  19
  20 #include <errno.h>
  21 #include <signal.h>
  22 #include <pthread.h>
  23 #include <time.h>
  24 #include <unistd.h>
  25
  26 #include "posix-timer.h"
  27
  28
  29 /* Create new per-process timer using CLOCK.  */
  30 int
  31 timer_create (clock_id, evp, timerid)
  32      clockid_t clock_id;
  33      struct sigevent *evp;
  34      timer_t *timerid;
  35 {
  36   int retval = -1;
  37   struct timer_node *newtimer = NULL;
  38   struct thread_node *thread = NULL;
  39
  40   if (0
  41 #if defined _POSIX_CPUTIME && _POSIX_CPUTIME >= 0
  42       || clock_id == CLOCK_PROCESS_CPUTIME_ID
  43 #endif
  44 #if defined _POSIX_THREAD_CPUTIME && _POSIX_THREAD_CPUTIME >= 0
  45       || clock_id == CLOCK_THREAD_CPUTIME_ID
  46 #endif
  47       )
  48     {
  49       /* We don't allow timers for CPU clocks.  At least not in the
  50          moment.  */
  51       __set_errno (ENOTSUP);
  52       return -1;
  53     }
  54
  55   if (clock_id != CLOCK_REALTIME)
  56     {
  57       __set_errno (EINVAL);
  58       return -1;
  59     }
  60
  61   pthread_once (&__timer_init_once_control, __timer_init_once);
  62
  63   if (__timer_init_failed)
  64     {
  65       __set_errno (ENOMEM);
  66       return -1;
  67     }
  68
  69   pthread_mutex_lock (&__timer_mutex);
  70
  71   newtimer = __timer_alloc ();
  72   if (__builtin_expect (newtimer == NULL, 0))
  73     {
  74       __set_errno (EAGAIN);
  75       goto unlock_bail;
  76     }
  77
  78   if (evp != NULL)
  79     newtimer->event = *evp;
  80   else
  81     {
  82       newtimer->event.sigev_notify = SIGEV_SIGNAL;
  83       newtimer->event.sigev_signo = SIGALRM;
  84       newtimer->event.sigev_value.sival_ptr = timer_ptr2id (newtimer);
  85       newtimer->event.sigev_notify_function = 0;
  86     }
  87
  88   newtimer->event.sigev_notify_attributes = &newtimer->attr;
  89   newtimer->creator_pid = getpid ();
  90
  91   switch (__builtin_expect (newtimer->event.sigev_notify, SIGEV_SIGNAL))
  92     {
  93     case SIGEV_NONE:
  94     case SIGEV_SIGNAL:
  95       /* We have a global thread for delivering timed signals.
  96          If it is not running, try to start it up.  */
  97       thread = &__timer_signal_thread_rclk;
  98       if (! thread->exists)
  99         {
 100           if (__builtin_expect (__timer_thread_start (thread),
 101                                 1) < 0)
 102             {
 103               __set_errno (EAGAIN);
 104               goto unlock_bail;
 105             }
 106         }
 107       break;
 108
 109     case SIGEV_THREAD:
 110       /* Copy over thread attributes or set up default ones.  */
 111       if (evp->sigev_notify_attributes)
 112         newtimer->attr = *(pthread_attr_t *) evp->sigev_notify_attributes;
 113       else
 114         pthread_attr_init (&newtimer->attr);
 115
 116       /* Ensure thread attributes call for deatched thread.  */
 117       pthread_attr_setdetachstate (&newtimer->attr, PTHREAD_CREATE_DETACHED);
 118
 119       /* Try to find existing thread having the right attributes.  */
 120       thread = __timer_thread_find_matching (&newtimer->attr, clock_id);
 121
 122       /* If no existing thread has these attributes, try to allocate one.  */
 123       if (thread == NULL)
 124         thread = __timer_thread_alloc (&newtimer->attr, clock_id);
 125
 126       /* Out of luck; no threads are available.  */
 127       if (__builtin_expect (thread == NULL, 0))
 128         {
 129           __set_errno (EAGAIN);
 130           goto unlock_bail;
 131         }
 132
 133       /* If the thread is not running already, try to start it.  */
 134       if (! thread->exists
 135           && __builtin_expect (! __timer_thread_start (thread), 0))
 136         {
 137           __set_errno (EAGAIN);
 138           goto unlock_bail;
 139         }
 140       break;
 141
 142     default:
 143       __set_errno (EINVAL);
 144       goto unlock_bail;
 145     }
 146
 147   newtimer->clock = clock_id;
 148   newtimer->abstime = 0;
 149   newtimer->armed = 0;
 150   newtimer->thread = thread;
 151
 152   *timerid = timer_ptr2id (newtimer);
 153   retval = 0;
 154
 155   if (__builtin_expect (retval, 0) == -1)
 156     {
 157     unlock_bail:
 158       if (thread != NULL)
 159         __timer_thread_dealloc (thread);
 160       if (newtimer != NULL)
 161         {
 162           timer_delref (newtimer);
 163           __timer_dealloc (newtimer);
 164         }
 165     }
 166
 167   pthread_mutex_unlock (&__timer_mutex);
 168
 169   return retval;
 170 }