gvpe/src/iom.C

/*
    iom.C -- generic I/O multiplexer
    Copyright (C) 2003, 2004 Marc Lehmann <gvpe@schmorp.de>
 
    This file is part of GVPE.

    GVPE is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.
 
    This program 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 General Public License for more details.
 
    You should have received a copy of the GNU General Public License
    along with gvpe; if not, write to the Free Software
    Foundation, Inc. 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

#include "iom.h"

#include <cstdio>
#include <cstdlib>
#include <cerrno>

#include <sys/time.h>

#include <assert.h>

#if 1 // older unices need these includes for select (2)
# include <unistd.h>
# include <sys/types.h>
# include <time.h>
#endif

// for IOM_SIG
#if IOM_SIG
# include <csignal>
# include <fcntl.h>
#endif

// if the BSDs would at least be marginally POSIX-compatible.. *sigh*
// until that happens, sys/select.h must come last
#include <sys/select.h>

// TSTAMP_MAX must still fit into a positive struct timeval
#define TSTAMP_MAX (double)(1UL<<31)

#define TIMEVAL timeval
#define TV_FRAC tv_usec
#define TV_MULT 1000000L

#if IOM_IO
static io_manager_vec<io_watcher>    iow;
#endif
#if IOM_CHECK
static io_manager_vec<check_watcher> cw;
#endif
#if IOM_TIME
static io_manager_vec<time_watcher>  tw;
#endif
#if IOM_IDLE
static io_manager_vec<idle_watcher>  iw;
#endif
#if IOM_SIG
static int sigpipe[2]; // signal signalling pipe
static sigset_t sigs;
struct sig_vec : io_manager_vec<sig_watcher> {
  int pending;
  sig_vec ()
    : pending (false)
    { }
};
static vector<sig_vec *> sw;
#endif

// this is a dummy time watcher to ensure that the first
// time watcher is _always_ valid, this gets rid of a lot
// of null-pointer-checks
// (must come _before_ iom is being defined)
static struct tw0 : time_watcher
  {
    void cb (time_watcher &w)
    {
      // should never get called
      // reached end-of-time, or tstamp has a bogus definition,
      // or compiler initialisation order broken, or something else :)
      abort ();
    }

    tw0 ()
      : time_watcher (this, &tw0::cb)
      { }
  } tw0;

tstamp NOW;

#if IOM_TIME
tstamp io_manager::now ()
{
  struct timeval tv;

  gettimeofday (&tv, 0);
  return (tstamp)tv.tv_sec + (tstamp)tv.tv_usec / 1000000.;
}

void io_manager::set_now ()
{
  NOW = now ();
}
#endif

static bool iom_valid;

// used for initialisation only
static struct init {
  init ()
  {
#if IOM_SIG
    sigemptyset (&sigs);

    if (pipe (sigpipe))
      {
        perror ("io_manager: unable to create signal pipe, aborting.");
        abort ();
      }

    fcntl (sigpipe[0], F_SETFL, O_NONBLOCK); fcntl (sigpipe[0], F_SETFD, FD_CLOEXEC);
    fcntl (sigpipe[1], F_SETFL, O_NONBLOCK); fcntl (sigpipe[1], F_SETFD, FD_CLOEXEC);
#endif

    iom_valid = true;

#if IOM_TIME
    io_manager::set_now ();

    tw0.start (TSTAMP_MAX);
#endif
  }

  static void required ();
} init;

void
init::required ()
{
  if (!iom_valid)
    {
      write (2, "io_manager: early registration attempt, aborting.\n",
                sizeof ("io_manager: early registration attempt, aborting.\n") - 1);
      abort ();
    }
}

template<class watcher>
void io_manager::reg (watcher &w, io_manager_vec<watcher> &queue)
{
  init::required ();

  if (!w.active)
    {
      queue.push_back (&w);
      w.active = queue.size ();
    }
}

template<class watcher>
void io_manager::unreg (watcher &w, io_manager_vec<watcher> &queue)
{
  if (!iom_valid)
    return;

  if (w.active)
    {
      queue [w.active - 1] = 0;
      w.active = 0;
    }
}

#if IOM_TIME
void time_watcher::trigger ()
{
  call (*this);
  io_manager::reg (*this);
}

void io_manager::reg   (time_watcher &w)  { io_manager::reg   (w, tw); }
void io_manager::unreg (time_watcher &w)  { io_manager::unreg (w, tw); }
#endif

#if IOM_IO
void io_manager::reg   (io_watcher &w)    { io_manager::reg   (w, iow); }
void io_manager::unreg (io_watcher &w)    { io_manager::unreg (w, iow); }
#endif

#if IOM_CHECK
void io_manager::reg   (check_watcher &w) { io_manager::reg   (w, cw); }
void io_manager::unreg (check_watcher &w) { io_manager::unreg (w, cw); }
#endif

#if IOM_IDLE
void io_manager::reg   (idle_watcher &w)  { io_manager::reg   (w, iw); }
void io_manager::unreg (idle_watcher &w)  { io_manager::unreg (w, iw); }
#endif

#if IOM_SIG
static void
sighandler (int signum)
{
  sw [signum - 1]->pending = true;

  // we use a pipe for signal notifications, as most current
  // OSes (Linux...) do not implement pselect correctly. ugh.
  char ch = signum; // actual content not used
  write (sigpipe[1], &ch, 1);
}

void io_manager::reg (sig_watcher &w)
{
  assert (0 < w.signum);

  sw.reserve (w.signum);

  while (sw.size () < w.signum) // pathetic
    sw.push_back (0);

  sig_vec *&sv = sw[w.signum - 1];

  if (!sv)
    {
      sv = new sig_vec;

      sigaddset (&sigs, w.signum);
      sigprocmask (SIG_BLOCK, &sigs, NULL);

      struct sigaction sa;
      sa.sa_handler = sighandler;
      sigfillset (&sa.sa_mask);
      sa.sa_flags = SA_RESTART;

      if (sigaction (w.signum, &sa, 0))
        {
          perror ("io_manager: error while installing signal handler, ignoring.");
          abort ();
        }

    }

  io_manager::reg (w, *sv);
}

void io_manager::unreg (sig_watcher &w)
{
  if (!w.active)
    return;

  assert (0 < w.signum && w.signum <= sw.size ());
  
  io_manager::unreg (w, *sw[w.signum - 1]);
}

void sig_watcher::start (int signum)
{
  stop ();
  this->signum = signum;
  io_manager::reg (*this);
}
#endif

void io_manager::loop ()
{
  init::required ();

#if IOM_TIME
  set_now ();
#endif

  for (;;)
    {

#if IOM_TIME
      // call pending time watchers
      {
        bool activity;

        do
          {
            activity = false;

            for (int i = tw.size (); i--; )
              if (!tw[i])
                tw.erase_unordered (i);
              else if (tw[i]->at <= NOW)
                {
                  time_watcher &w = *tw[i];
                  
                  unreg (w);
                  w.call (w);

                  activity = true;
                }
          }
        while (activity);
      }
#endif

#if IOM_CHECK
      // call all check watchers
      for (int i = cw.size (); i--; )
        if (!cw[i])
          cw.erase_unordered (i);
        else
          cw[i]->call (*cw[i]);
#endif

      struct TIMEVAL *to = 0;
      struct TIMEVAL tval;

#if IOM_IDLE
      if (iw.size ())
        {
          tval.tv_sec  = 0;
          tval.TV_FRAC = 0;
          to = &tval;
        }
      else
#endif
        {
#if IOM_TIME
          // find earliest active watcher
          time_watcher *next = tw[0]; // the first time-watcher must exist at ALL times

          for (io_manager_vec<time_watcher>::const_iterator i = tw.end (); i-- > tw.begin (); )
            if (*i && (*i)->at < next->at)
              next = *i;

          if (next->at > NOW && next != tw[0])
            {
              double diff = next->at - NOW;
              tval.tv_sec  = (int)diff;
              tval.TV_FRAC = (int) ((diff - tval.tv_sec) * TV_MULT);
              to = &tval;
            }
        }
#endif

#if IOM_IO || IOM_SIG
      fd_set rfd, wfd;

      FD_ZERO (&rfd);
      FD_ZERO (&wfd);

      int fds = 0;

# if IOM_IO
      for (io_manager_vec<io_watcher>::const_iterator i = iow.end (); i-- > iow.begin (); )
        if (*i)
          {
            if ((*i)->events & EVENT_READ ) FD_SET ((*i)->fd, &rfd);
            if ((*i)->events & EVENT_WRITE) FD_SET ((*i)->fd, &wfd);

            if ((*i)->fd >= fds) fds = (*i)->fd + 1;
          }
# endif

      if (!to && !fds) //TODO: also check idle_watchers and check_watchers?
        break; // no events

# if IOM_SIG
      FD_SET (sigpipe[0], &rfd);
      if (sigpipe[0] >= fds) fds = sigpipe[0] + 1;
# endif

# if IOM_SIG
      // there is no race, as we use a pipe for signals, so select
      // will return if a signal is caught.
      sigprocmask (SIG_UNBLOCK, &sigs, NULL);
# endif
      fds = select (fds, &rfd, &wfd, NULL, to);
# if IOM_SIG
      sigprocmask (SIG_BLOCK, &sigs, NULL);
# endif

# if IOM_TIME
      {
        // update time, try to compensate for gross non-monotonic time changes
        tstamp diff = NOW;
        set_now ();
        diff = NOW - diff;

        if (diff < 0)
          for (io_manager_vec<time_watcher>::const_iterator i = tw.end (); i-- > tw.begin (); )
            if (*i)
              (*i)->at += diff;
      }
# endif

      if (fds > 0)
        {
# if IOM_SIG
          if (FD_ISSET (sigpipe[0], &rfd))
            {
              char ch;

              while (read (sigpipe[0], &ch, 1) > 0)
                ;

              for (vector<sig_vec *>::iterator svp = sw.end (); svp-- > sw.begin (); )
                if (*svp && (*svp)->pending)
                  {
                    sig_vec &sv = **svp;
                    for (int i = sv.size (); i--; )
                      if (!sv[i])
                        sv.erase_unordered (i);
                      else
                        sv[i]->call (*sv[i]);

                    sv.pending = false;
                  }
            }
# endif

# if IOM_IO
          for (int i = iow.size (); i--; )
            if (!iow[i])
              iow.erase_unordered (i);
            else
              {
                io_watcher &w = *iow[i];
                short revents = w.events;

                if (!FD_ISSET (w.fd, &rfd)) revents &= ~EVENT_READ;
                if (!FD_ISSET (w.fd, &wfd)) revents &= ~EVENT_WRITE;

                if (revents)
                  w.call (w, revents);
              }
#endif
        }
      else if (fds < 0 && errno != EINTR)
        {
          perror ("io_manager: fatal error while waiting for I/O or time event, aborting.");
          abort ();
        }
#if IOM_IDLE
      else
        for (int i = iw.size (); i--; )
          if (!iw[i])
            iw.erase_unordered (i);
          else
            iw[i]->call (*iw[i]);
#endif

#elif IOM_TIME
      if (!to)
        break;

      select (0, 0, 0, 0, &to);
      set_now ();
#else
      break;
#endif
    }
}

Revision:	1.30
Committed:	Thu Mar 3 16:54:34 2005 UTC (19 years, 2 months ago) by pcg
Content type:	text/plain
Branch:	MAIN
Changes since 1.29:	+5 -3 lines
Log Message:	* empty log message *
#	Content
1	/*
2	iom.C -- generic I/O multiplexer
3	Copyright (C) 2003, 2004 Marc Lehmann <gvpe@schmorp.de>
4
5	This file is part of GVPE.
6
7	GVPE is free software; you can redistribute it and/or modify
8	it under the terms of the GNU General Public License as published by
9	the Free Software Foundation; either version 2 of the License, or
10	(at your option) any later version.
11
12	This program is distributed in the hope that it will be useful,
13	but WITHOUT ANY WARRANTY; without even the implied warranty of
14	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15	GNU General Public License for more details.
16
17	You should have received a copy of the GNU General Public License
18	along with gvpe; if not, write to the Free Software
19	Foundation, Inc. 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20	*/
21
22	#include "iom.h"
23
24	#include <cstdio>
25	#include <cstdlib>
26	#include <cerrno>
27
28	#include <sys/time.h>
29
30	#include <assert.h>
31
32	#if 1 // older unices need these includes for select (2)
33	# include <unistd.h>
34	# include <sys/types.h>
35	# include <time.h>
36	#endif
37
38	// for IOM_SIG
39	#if IOM_SIG
40	# include <csignal>
41	# include <fcntl.h>
42	#endif
43
44	// if the BSDs would at least be marginally POSIX-compatible.. sigh
45	// until that happens, sys/select.h must come last
46	#include <sys/select.h>
47
48	// TSTAMP_MAX must still fit into a positive struct timeval
49	#define TSTAMP_MAX (double)(1UL<<31)
50
51	#define TIMEVAL timeval
52	#define TV_FRAC tv_usec
53	#define TV_MULT 1000000L
54
55	#if IOM_IO
56	static io_manager_vec<io_watcher> iow;
57	#endif
58	#if IOM_CHECK
59	static io_manager_vec<check_watcher> cw;
60	#endif
61	#if IOM_TIME
62	static io_manager_vec<time_watcher> tw;
63	#endif
64	#if IOM_IDLE
65	static io_manager_vec<idle_watcher> iw;
66	#endif
67	#if IOM_SIG
68	static int sigpipe[2]; // signal signalling pipe
69	static sigset_t sigs;
70	struct sig_vec : io_manager_vec<sig_watcher> {
71	int pending;
72	sig_vec ()
73	: pending (false)
74	{ }
75	};
76	static vector<sig_vec *> sw;
77	#endif
78
79	// this is a dummy time watcher to ensure that the first
80	// time watcher is _always_ valid, this gets rid of a lot
81	// of null-pointer-checks
82	// (must come _before_ iom is being defined)
83	static struct tw0 : time_watcher
84	{
85	void cb (time_watcher &w)
86	{
87	// should never get called
88	// reached end-of-time, or tstamp has a bogus definition,
89	// or compiler initialisation order broken, or something else :)
90	abort ();
91	}
92
93	tw0 ()
94	: time_watcher (this, &tw0::cb)
95	{ }
96	} tw0;
97
98	tstamp NOW;
99
100	#if IOM_TIME
101	tstamp io_manager::now ()
102	{
103	struct timeval tv;
104
105	gettimeofday (&tv, 0);
106	return (tstamp)tv.tv_sec + (tstamp)tv.tv_usec / 1000000.;
107	}
108
109	void io_manager::set_now ()
110	{
111	NOW = now ();
112	}
113	#endif
114
115	static bool iom_valid;
116
117	// used for initialisation only
118	static struct init {
119	init ()
120	{
121	#if IOM_SIG
122	sigemptyset (&sigs);
123
124	if (pipe (sigpipe))
125	{
126	perror ("io_manager: unable to create signal pipe, aborting.");
127	abort ();
128	}
129
130	fcntl (sigpipe[0], F_SETFL, O_NONBLOCK); fcntl (sigpipe[0], F_SETFD, FD_CLOEXEC);
131	fcntl (sigpipe[1], F_SETFL, O_NONBLOCK); fcntl (sigpipe[1], F_SETFD, FD_CLOEXEC);
132	#endif
133
134	iom_valid = true;
135
136	#if IOM_TIME
137	io_manager::set_now ();
138
139	tw0.start (TSTAMP_MAX);
140	#endif
141	}
142
143	static void required ();
144	} init;
145
146	void
147	init::required ()
148	{
149	if (!iom_valid)
150	{
151	write (2, "io_manager: early registration attempt, aborting.\n",
152	sizeof ("io_manager: early registration attempt, aborting.\n") - 1);
153	abort ();
154	}
155	}
156
157	template<class watcher>
158	void io_manager::reg (watcher &w, io_manager_vec<watcher> &queue)
159	{
160	init::required ();
161
162	if (!w.active)
163	{
164	queue.push_back (&w);
165	w.active = queue.size ();
166	}
167	}
168
169	template<class watcher>
170	void io_manager::unreg (watcher &w, io_manager_vec<watcher> &queue)
171	{
172	if (!iom_valid)
173	return;
174
175	if (w.active)
176	{
177	queue [w.active - 1] = 0;
178	w.active = 0;
179	}
180	}
181
182	#if IOM_TIME
183	void time_watcher::trigger ()
184	{
185	call (*this);
186	io_manager::reg (*this);
187	}
188
189	void io_manager::reg (time_watcher &w) { io_manager::reg (w, tw); }
190	void io_manager::unreg (time_watcher &w) { io_manager::unreg (w, tw); }
191	#endif
192
193	#if IOM_IO
194	void io_manager::reg (io_watcher &w) { io_manager::reg (w, iow); }
195	void io_manager::unreg (io_watcher &w) { io_manager::unreg (w, iow); }
196	#endif
197
198	#if IOM_CHECK
199	void io_manager::reg (check_watcher &w) { io_manager::reg (w, cw); }
200	void io_manager::unreg (check_watcher &w) { io_manager::unreg (w, cw); }
201	#endif
202
203	#if IOM_IDLE
204	void io_manager::reg (idle_watcher &w) { io_manager::reg (w, iw); }
205	void io_manager::unreg (idle_watcher &w) { io_manager::unreg (w, iw); }
206	#endif
207
208	#if IOM_SIG
209	static void
210	sighandler (int signum)
211	{
212	sw [signum - 1]->pending = true;
213
214	// we use a pipe for signal notifications, as most current
215	// OSes (Linux...) do not implement pselect correctly. ugh.
216	char ch = signum; // actual content not used
217	write (sigpipe[1], &ch, 1);
218	}
219
220	void io_manager::reg (sig_watcher &w)
221	{
222	assert (0 < w.signum);
223
224	sw.reserve (w.signum);
225
226	while (sw.size () < w.signum) // pathetic
227	sw.push_back (0);
228
229	sig_vec *&sv = sw[w.signum - 1];
230
231	if (!sv)
232	{
233	sv = new sig_vec;
234
235	sigaddset (&sigs, w.signum);
236	sigprocmask (SIG_BLOCK, &sigs, NULL);
237
238	struct sigaction sa;
239	sa.sa_handler = sighandler;
240	sigfillset (&sa.sa_mask);
241	sa.sa_flags = SA_RESTART;
242
243	if (sigaction (w.signum, &sa, 0))
244	{
245	perror ("io_manager: error while installing signal handler, ignoring.");
246	abort ();
247	}
248
249	}
250
251	io_manager::reg (w, *sv);
252	}
253
254	void io_manager::unreg (sig_watcher &w)
255	{
256	if (!w.active)
257	return;
258
259	assert (0 < w.signum && w.signum <= sw.size ());
260
261	io_manager::unreg (w, *sw[w.signum - 1]);
262	}
263
264	void sig_watcher::start (int signum)
265	{
266	stop ();
267	this->signum = signum;
268	io_manager::reg (*this);
269	}
270	#endif
271
272	void io_manager::loop ()
273	{
274	init::required ();
275
276	#if IOM_TIME
277	set_now ();
278	#endif
279
280	for (;;)
281	{
282
283	#if IOM_TIME
284	// call pending time watchers
285	{
286	bool activity;
287
288	do
289	{
290	activity = false;
291
292	for (int i = tw.size (); i--; )
293	if (!tw[i])
294	tw.erase_unordered (i);
295	else if (tw[i]->at <= NOW)
296	{
297	time_watcher &w = *tw[i];
298
299	unreg (w);
300	w.call (w);
301
302	activity = true;
303	}
304	}
305	while (activity);
306	}
307	#endif
308
309	#if IOM_CHECK
310	// call all check watchers
311	for (int i = cw.size (); i--; )
312	if (!cw[i])
313	cw.erase_unordered (i);
314	else
315	cw[i]->call (*cw[i]);
316	#endif
317
318	struct TIMEVAL *to = 0;
319	struct TIMEVAL tval;
320
321	#if IOM_IDLE
322	if (iw.size ())
323	{
324	tval.tv_sec = 0;
325	tval.TV_FRAC = 0;
326	to = &tval;
327	}
328	else
329	#endif
330	{
331	#if IOM_TIME
332	// find earliest active watcher
333	time_watcher *next = tw[0]; // the first time-watcher must exist at ALL times
334
335	for (io_manager_vec<time_watcher>::const_iterator i = tw.end (); i-- > tw.begin (); )
336	if (i && (i)->at < next->at)
337	next = *i;
338
339	if (next->at > NOW && next != tw[0])
340	{
341	double diff = next->at - NOW;
342	tval.tv_sec = (int)diff;
343	tval.TV_FRAC = (int) ((diff - tval.tv_sec) * TV_MULT);
344	to = &tval;
345	}
346	}
347	#endif
348
349	#if IOM_IO \|\| IOM_SIG
350	fd_set rfd, wfd;
351
352	FD_ZERO (&rfd);
353	FD_ZERO (&wfd);
354
355	int fds = 0;
356
357	# if IOM_IO
358	for (io_manager_vec<io_watcher>::const_iterator i = iow.end (); i-- > iow.begin (); )
359	if (*i)
360	{
361	if ((i)->events & EVENT_READ ) FD_SET ((i)->fd, &rfd);
362	if ((i)->events & EVENT_WRITE) FD_SET ((i)->fd, &wfd);
363
364	if ((i)->fd >= fds) fds = (i)->fd + 1;
365	}
366	# endif
367
368	if (!to && !fds) //TODO: also check idle_watchers and check_watchers?
369	break; // no events
370
371	# if IOM_SIG
372	FD_SET (sigpipe[0], &rfd);
373	if (sigpipe[0] >= fds) fds = sigpipe[0] + 1;
374	# endif
375
376	# if IOM_SIG
377	// there is no race, as we use a pipe for signals, so select
378	// will return if a signal is caught.
379	sigprocmask (SIG_UNBLOCK, &sigs, NULL);
380	# endif
381	fds = select (fds, &rfd, &wfd, NULL, to);
382	# if IOM_SIG
383	sigprocmask (SIG_BLOCK, &sigs, NULL);
384	# endif
385
386	# if IOM_TIME
387	{
388	// update time, try to compensate for gross non-monotonic time changes
389	tstamp diff = NOW;
390	set_now ();
391	diff = NOW - diff;
392
393	if (diff < 0)
394	for (io_manager_vec<time_watcher>::const_iterator i = tw.end (); i-- > tw.begin (); )
395	if (*i)
396	(*i)->at += diff;
397	}
398	# endif
399
400	if (fds > 0)
401	{
402	# if IOM_SIG
403	if (FD_ISSET (sigpipe[0], &rfd))
404	{
405	char ch;
406
407	while (read (sigpipe[0], &ch, 1) > 0)
408	;
409
410	for (vector<sig_vec *>::iterator svp = sw.end (); svp-- > sw.begin (); )
411	if (svp && (svp)->pending)
412	{
413	sig_vec &sv = **svp;
414	for (int i = sv.size (); i--; )
415	if (!sv[i])
416	sv.erase_unordered (i);
417	else
418	sv[i]->call (*sv[i]);
419
420	sv.pending = false;
421	}
422	}
423	# endif
424
425	# if IOM_IO
426	for (int i = iow.size (); i--; )
427	if (!iow[i])
428	iow.erase_unordered (i);
429	else
430	{
431	io_watcher &w = *iow[i];
432	short revents = w.events;
433
434	if (!FD_ISSET (w.fd, &rfd)) revents &= ~EVENT_READ;
435	if (!FD_ISSET (w.fd, &wfd)) revents &= ~EVENT_WRITE;
436
437	if (revents)
438	w.call (w, revents);
439	}
440	#endif
441	}
442	else if (fds < 0 && errno != EINTR)
443	{
444	perror ("io_manager: fatal error while waiting for I/O or time event, aborting.");
445	abort ();
446	}
447	#if IOM_IDLE
448	else
449	for (int i = iw.size (); i--; )
450	if (!iw[i])
451	iw.erase_unordered (i);
452	else
453	iw[i]->call (*iw[i]);
454	#endif
455
456	#elif IOM_TIME
457	if (!to)
458	break;
459
460	select (0, 0, 0, 0, &to);
461	set_now ();
462	#else
463	break;
464	#endif
465	}
466	}
467