about summary refs log tree commit diff
path: root/sysdeps/pthread/aio_suspend.c
blob: 1a3ec7cc04fd7e9f539fa0ee4e366342a99d0500 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
/* Suspend until termination of a requests.
   Copyright (C) 1997,1998,1999,2000,2002,2003 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */


/* We use an UGLY hack to prevent gcc from finding us cheating.  The
   implementations of aio_suspend and aio_suspend64 are identical and so
   we want to avoid code duplication by using aliases.  But gcc sees
   the different parameter lists and prints a warning.  We define here
   a function so that aio_suspend64 has no prototype.  */
#define aio_suspend64 XXX
#include <aio.h>
/* And undo the hack.  */
#undef aio_suspend64

#include <assert.h>
#include <errno.h>
#include <stdlib.h>
#include <sys/time.h>

#include "aio_misc.h"


int
aio_suspend (list, nent, timeout)
     const struct aiocb *const list[];
     int nent;
     const struct timespec *timeout;
{
  struct waitlist waitlist[nent];
  struct requestlist *requestlist[nent];
  pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
  int cnt;
  int result = 0;
  int dummy;

  /* Request the mutex.  */
  pthread_mutex_lock (&__aio_requests_mutex);

  /* There is not yet a finished request.  Signal the request that
     we are working for it.  */
  for (cnt = 0; cnt < nent; ++cnt)
    if (list[cnt] != NULL)
      {
	if (list[cnt]->__error_code == EINPROGRESS)
	  {
	    requestlist[cnt] = __aio_find_req ((aiocb_union *) list[cnt]);

	    if (requestlist[cnt] != NULL)
	      {
		waitlist[cnt].cond = &cond;
		waitlist[cnt].next = requestlist[cnt]->waiting;
		waitlist[cnt].counterp = &dummy;
		waitlist[cnt].sigevp = NULL;
		waitlist[cnt].caller_pid = 0;	/* Not needed.  */
		requestlist[cnt]->waiting = &waitlist[cnt];
	      }
	    else
	      /* We will never suspend.  */
	      break;
	  }
	else
	  /* We will never suspend.  */
	  break;
      }


  /* Only if none of the entries is NULL or finished to be wait.  */
  if (cnt == nent)
    {
      int oldstate;

      /* Since `pthread_cond_wait'/`pthread_cond_timedwait' are cancelation
	 points we must be careful.  We added entries to the waiting lists
	 which we must remove.  So defer cancelation for now.  */
      pthread_setcancelstate (PTHREAD_CANCEL_DISABLE, &oldstate);

      if (timeout == NULL)
	result = pthread_cond_wait (&cond, &__aio_requests_mutex);
      else
	{
	  /* We have to convert the relative timeout value into an
	     absolute time value with pthread_cond_timedwait expects.  */
	  struct timeval now;
	  struct timespec abstime;

	  __gettimeofday (&now, NULL);
	  abstime.tv_nsec = timeout->tv_nsec + now.tv_usec * 1000;
	  abstime.tv_sec = timeout->tv_sec + now.tv_sec;
	  if (abstime.tv_nsec >= 1000000000)
	    {
	      abstime.tv_nsec -= 1000000000;
	      abstime.tv_sec += 1;
	    }

	  result = pthread_cond_timedwait (&cond, &__aio_requests_mutex,
					   &abstime);
	}

      /* Now it's time to restore the cancellation state.  */
      pthread_setcancelstate (oldstate, NULL);
    }

  /* Now remove the entry in the waiting list for all requests
     which didn't terminate.  */
  while (cnt-- > 0)
    if (list[cnt] != NULL && list[cnt]->__error_code == EINPROGRESS)
      {
	struct waitlist **listp;

	assert (requestlist[cnt] != NULL);

	/* There is the chance that we cannot find our entry anymore. This
	   could happen if the request terminated and restarted again.  */
	listp = &requestlist[cnt]->waiting;
	while (*listp != NULL && *listp != &waitlist[cnt])
	  listp = &(*listp)->next;

	if (*listp != NULL)
	  *listp = (*listp)->next;
      }

  /* Release the conditional variable.  */
  if (__builtin_expect (pthread_cond_destroy (&cond) != 0, 0))
    /* This must never happen.  */
    abort ();

  if (result != 0)
    {
      /* An error occurred.  Possibly it's EINTR.  We have to translate
	 the timeout error report of `pthread_cond_timedwait' to the
	 form expected from `aio_suspend'.  */
      if (result == ETIMEDOUT)
	__set_errno (EAGAIN);

      result = -1;
    }

  /* Release the mutex.  */
  pthread_mutex_unlock (&__aio_requests_mutex);

  return result;
}

weak_alias (aio_suspend, aio_suspend64)