sysdeps/pthread/aio_suspend.c

   1 /* Suspend until termination of a requests.
   2    Copyright (C) 1997,1998,1999,2000,2002,2003 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21
  22 /* We use an UGLY hack to prevent gcc from finding us cheating.  The
  23    implementations of aio_suspend and aio_suspend64 are identical and so
  24    we want to avoid code duplication by using aliases.  But gcc sees
  25    the different parameter lists and prints a warning.  We define here
  26    a function so that aio_suspend64 has no prototype.  */
  27 #define aio_suspend64 XXX
  28 #include <aio.h>
  29 /* And undo the hack.  */
  30 #undef aio_suspend64
  31
  32 #include <assert.h>
  33 #include <errno.h>
  34 #include <stdbool.h>
  35 #include <stdlib.h>
  36 #include <sys/time.h>
  37
  38 #include <bits/libc-lock.h>
  39 #include "aio_misc.h"
  40
  41
  42 struct clparam
  43 {
  44   const struct aiocb *const *list;
  45   struct waitlist *waitlist;
  46   struct requestlist **requestlist;
  47   pthread_cond_t *cond;
  48   int nent;
  49 };
  50
  51
  52 static void
  53 cleanup (void *arg)
  54 {
  55   const struct clparam *param = (const struct clparam *) arg;
  56
  57   /* Now remove the entry in the waiting list for all requests
  58      which didn't terminate.  */
  59   int cnt = param->nent;
  60   while (cnt-- > 0)
  61     if (param->list[cnt] != NULL
  62         && param->list[cnt]->__error_code == EINPROGRESS)
  63       {
  64         struct waitlist **listp;
  65
  66         assert (param->requestlist[cnt] != NULL);
  67
  68         /* There is the chance that we cannot find our entry anymore. This
  69            could happen if the request terminated and restarted again.  */
  70         listp = &param->requestlist[cnt]->waiting;
  71         while (*listp != NULL && *listp != &param->waitlist[cnt])
  72           listp = &(*listp)->next;
  73
  74         if (*listp != NULL)
  75           *listp = (*listp)->next;
  76       }
  77
  78   /* Release the conditional variable.  */
  79   (void) pthread_cond_destroy (param->cond);
  80
  81   /* Release the mutex.  */
  82   pthread_mutex_unlock (&__aio_requests_mutex);
  83 }
  84
  85
  86 int
  87 aio_suspend (list, nent, timeout)
  88      const struct aiocb *const list[];
  89      int nent;
  90      const struct timespec *timeout;
  91 {
  92   struct waitlist waitlist[nent];
  93   struct requestlist *requestlist[nent];
  94   pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
  95   int cnt;
  96   bool any = false;
  97   int result = 0;
  98   int dummy;
  99
 100   /* Request the mutex.  */
 101   pthread_mutex_lock (&__aio_requests_mutex);
 102
 103   /* There is not yet a finished request.  Signal the request that
 104      we are working for it.  */
 105   for (cnt = 0; cnt < nent; ++cnt)
 106     if (list[cnt] != NULL)
 107       {
 108         if (list[cnt]->__error_code == EINPROGRESS)
 109           {
 110             requestlist[cnt] = __aio_find_req ((aiocb_union *) list[cnt]);
 111
 112             if (requestlist[cnt] != NULL)
 113               {
 114                 waitlist[cnt].cond = &cond;
 115                 waitlist[cnt].next = requestlist[cnt]->waiting;
 116                 waitlist[cnt].counterp = &dummy;
 117                 waitlist[cnt].sigevp = NULL;
 118                 waitlist[cnt].caller_pid = 0;   /* Not needed.  */
 119                 requestlist[cnt]->waiting = &waitlist[cnt];
 120                 any = true;
 121               }
 122             else
 123               /* We will never suspend.  */
 124               break;
 125           }
 126         else
 127           /* We will never suspend.  */
 128           break;
 129       }
 130
 131
 132   /* Only if none of the entries is NULL or finished to be wait.  */
 133   if (cnt == nent && any)
 134     {
 135       struct clparam clparam =
 136         {
 137           .list = list,
 138           .waitlist = waitlist,
 139           .requestlist = requestlist,
 140           .cond = &cond,
 141           .nent = nent
 142         };
 143
 144       __libc_cleanup_region_start (1, cleanup, &clparam);
 145
 146       if (timeout == NULL)
 147         result = pthread_cond_wait (&cond, &__aio_requests_mutex);
 148       else
 149         {
 150           /* We have to convert the relative timeout value into an
 151              absolute time value with pthread_cond_timedwait expects.  */
 152           struct timeval now;
 153           struct timespec abstime;
 154
 155           __gettimeofday (&now, NULL);
 156           abstime.tv_nsec = timeout->tv_nsec + now.tv_usec * 1000;
 157           abstime.tv_sec = timeout->tv_sec + now.tv_sec;
 158           if (abstime.tv_nsec >= 1000000000)
 159             {
 160               abstime.tv_nsec -= 1000000000;
 161               abstime.tv_sec += 1;
 162             }
 163
 164           result = pthread_cond_timedwait (&cond, &__aio_requests_mutex,
 165                                            &abstime);
 166         }
 167
 168       __libc_cleanup_region_end (0);
 169     }
 170
 171   /* Now remove the entry in the waiting list for all requests
 172      which didn't terminate.  */
 173   while (cnt-- > 0)
 174     if (list[cnt] != NULL && list[cnt]->__error_code == EINPROGRESS)
 175       {
 176         struct waitlist **listp;
 177
 178         assert (requestlist[cnt] != NULL);
 179
 180         /* There is the chance that we cannot find our entry anymore. This
 181            could happen if the request terminated and restarted again.  */
 182         listp = &requestlist[cnt]->waiting;
 183         while (*listp != NULL && *listp != &waitlist[cnt])
 184           listp = &(*listp)->next;
 185
 186         if (*listp != NULL)
 187           *listp = (*listp)->next;
 188       }
 189
 190   /* Release the conditional variable.  */
 191   if (__builtin_expect (pthread_cond_destroy (&cond) != 0, 0))
 192     /* This must never happen.  */
 193     abort ();
 194
 195   if (result != 0)
 196     {
 197       /* An error occurred.  Possibly it's EINTR.  We have to translate
 198          the timeout error report of `pthread_cond_timedwait' to the
 199          form expected from `aio_suspend'.  */
 200       if (result == ETIMEDOUT)
 201         __set_errno (EAGAIN);
 202       else if (result == EINTR)
 203         __set_errno (EINTR);
 204
 205       result = -1;
 206     }
 207
 208   /* Release the mutex.  */
 209   pthread_mutex_unlock (&__aio_requests_mutex);
 210
 211   return result;
 212 }
 213
 214 weak_alias (aio_suspend, aio_suspend64)