libev/ev_select.c

/*
 * libev select fd activity backend
 *
 * Copyright (c) 2007 Marc Alexander Lehmann <libev@schmorp.de>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *
 *     * Redistributions in binary form must reproduce the above
 *       copyright notice, this list of conditions and the following
 *       disclaimer in the documentation and/or other materials provided
 *       with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/* for broken bsd's */
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>

/* for unix systems */
#include <sys/select.h>

#include <string.h>
#include <inttypes.h>

static unsigned char *vec_ri, *vec_ro, *vec_wi, *vec_wo;
static int vec_max;

static void
select_modify (int fd, int oev, int nev)
{
  int offs = fd >> 3;
  int mask = 1 << (fd & 7);

  if (vec_max < (fd >> 5) + 1)
    {
      int new_max = (fd >> 5) + 1;

      vec_ri = (unsigned char *)realloc (vec_ri, new_max * 4);
      vec_ro = (unsigned char *)realloc (vec_ro, new_max * 4); /* could free/malloc */
      vec_wi = (unsigned char *)realloc (vec_wi, new_max * 4);
      vec_wo = (unsigned char *)realloc (vec_wo, new_max * 4); /* could free/malloc */

      for (; vec_max < new_max; ++vec_max)
        ((uint32_t *)vec_ri)[vec_max] =
        ((uint32_t *)vec_wi)[vec_max] = 0;
    }

  vec_ri [offs] |= mask;
  if (!(nev & EV_READ))
    vec_ri [offs] &= ~mask;

  vec_wi [offs] |= mask;
  if (!(nev & EV_WRITE))
    vec_wi [offs] &= ~mask;
}

static void
select_poll (ev_tstamp timeout)
{
  struct timeval tv;
  int res;

  memcpy (vec_ro, vec_ri, vec_max * 4);
  memcpy (vec_wo, vec_wi, vec_max * 4);

  tv.tv_sec  = (long)timeout;
  tv.tv_usec = (long)((timeout - (ev_tstamp)tv.tv_sec) * 1e6);

  res = select (vec_max * 32, (fd_set *)vec_ro, (fd_set *)vec_wo, 0, &tv);

  if (res > 0)
    {
      int word, offs;

      for (word = vec_max; word--; )
        {
          if (((uint32_t *)vec_ro) [word] | ((uint32_t *)vec_wo) [word])
            for (offs = 4; offs--; )
              {
                int idx = word * 4 + offs;
                unsigned char byte_r = vec_ro [idx];
                unsigned char byte_w = vec_wo [idx];
                int bit;

                if (byte_r | byte_w)
                  for (bit = 8; bit--; )
                    {
                      int events = 0;
                      events |= byte_r & (1 << bit) ? EV_READ  : 0;
                      events |= byte_w & (1 << bit) ? EV_WRITE : 0;

                      if (events)
                        fd_event (idx * 8 + bit, events);
                    }
              }
        }
    }
  else if (res < 0)
    {
      if (errno == EBADF)
        fd_ebadf ();
      else if (errno == ENOMEM)
        fd_enomem ();
    }
}

static void
select_init (int flags)
{
  ev_method     = EVMETHOD_SELECT;
  method_fudge  = 1e-2; /* needed to compensate for select returning early, very conservative */
  method_modify = select_modify;
  method_poll   = select_poll;
}

Revision:	1.8
Committed:	Fri Nov 2 16:54:35 2007 UTC (18 years, 6 months ago) by root
Content type:	text/plain
Branch:	MAIN
Changes since 1.7:	+3 -1 lines
Log Message:	implement poll method, handle enomem by closing a 'random' fd
#	User	Rev	Content
1	root	1.4	/*
2	root	1.7	* libev select fd activity backend
3			*
4	root	1.4	* Copyright (c) 2007 Marc Alexander Lehmann <libev@schmorp.de>
5			* All rights reserved.
6			*
7			* Redistribution and use in source and binary forms, with or without
8			* modification, are permitted provided that the following conditions are
9			* met:
10			*
11			* * Redistributions of source code must retain the above copyright
12			* notice, this list of conditions and the following disclaimer.
13			*
14			* * Redistributions in binary form must reproduce the above
15			* copyright notice, this list of conditions and the following
16			* disclaimer in the documentation and/or other materials provided
17			* with the distribution.
18			*
19			* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
20			* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
21			* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
22			* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
23			* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
24			* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
25			* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26			* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27			* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28			* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
29			* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30			*/
31
32	root	1.2	/* for broken bsd's */
33			#include <sys/time.h>
34			#include <sys/types.h>
35			#include <unistd.h>
36
37			/* for unix systems */
38			#include <sys/select.h>
39
40			#include <string.h>
41			#include <inttypes.h>
42
43			static unsigned char vec_ri, vec_ro, vec_wi, vec_wo;
44			static int vec_max;
45
46			static void
47			select_modify (int fd, int oev, int nev)
48			{
49			int offs = fd >> 3;
50			int mask = 1 << (fd & 7);
51
52			if (vec_max < (fd >> 5) + 1)
53			{
54	root	1.5	int new_max = (fd >> 5) + 1;
55	root	1.2
56	root	1.5	vec_ri = (unsigned char )realloc (vec_ri, new_max 4);
57			vec_ro = (unsigned char )realloc (vec_ro, new_max 4); /* could free/malloc */
58			vec_wi = (unsigned char )realloc (vec_wi, new_max 4);
59			vec_wo = (unsigned char )realloc (vec_wo, new_max 4); /* could free/malloc */
60
61			for (; vec_max < new_max; ++vec_max)
62			((uint32_t *)vec_ri)[vec_max] =
63			((uint32_t *)vec_wi)[vec_max] = 0;
64	root	1.2	}
65
66			vec_ri [offs] \|= mask;
67			if (!(nev & EV_READ))
68			vec_ri [offs] &= ~mask;
69
70			vec_wi [offs] \|= mask;
71			if (!(nev & EV_WRITE))
72			vec_wi [offs] &= ~mask;
73			}
74
75	root	1.6	static void
76			select_poll (ev_tstamp timeout)
77	root	1.2	{
78			struct timeval tv;
79			int res;
80
81			memcpy (vec_ro, vec_ri, vec_max * 4);
82			memcpy (vec_wo, vec_wi, vec_max * 4);
83
84			tv.tv_sec = (long)timeout;
85			tv.tv_usec = (long)((timeout - (ev_tstamp)tv.tv_sec) * 1e6);
86
87			res = select (vec_max * 32, (fd_set )vec_ro, (fd_set )vec_wo, 0, &tv);
88
89			if (res > 0)
90			{
91			int word, offs;
92
93			for (word = vec_max; word--; )
94			{
95			if (((uint32_t )vec_ro) [word] \| ((uint32_t )vec_wo) [word])
96			for (offs = 4; offs--; )
97			{
98			int idx = word * 4 + offs;
99			unsigned char byte_r = vec_ro [idx];
100			unsigned char byte_w = vec_wo [idx];
101			int bit;
102
103			if (byte_r \| byte_w)
104			for (bit = 8; bit--; )
105			{
106			int events = 0;
107			events \|= byte_r & (1 << bit) ? EV_READ : 0;
108			events \|= byte_w & (1 << bit) ? EV_WRITE : 0;
109
110			if (events)
111			fd_event (idx * 8 + bit, events);
112			}
113			}
114			}
115			}
116	root	1.5	else if (res < 0)
117			{
118			if (errno == EBADF)
119	root	1.8	fd_ebadf ();
120			else if (errno == ENOMEM)
121			fd_enomem ();
122	root	1.5	}
123	root	1.2	}
124
125	root	1.6	static void
126			select_init (int flags)
127	root	1.2	{
128	root	1.3	ev_method = EVMETHOD_SELECT;
129	root	1.2	method_fudge = 1e-2; /* needed to compensate for select returning early, very conservative */
130			method_modify = select_modify;
131			method_poll = select_poll;
132			}
133