/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
/* dbus-socket-set-poll.c - a socket set implemented via _dbus_poll
*
* Copyright © 2011 Nokia Corporation
*
* Licensed under the Academic Free License version 2.1
*
* This program 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 this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301 USA
*
*/
#include <config.h>
#include "dbus-socket-set.h"
#include <dbus/dbus-internals.h>
#include <dbus/dbus-list.h>
#include <dbus/dbus-sysdeps.h>
#include <dbus/dbus-watch.h>
#ifndef DOXYGEN_SHOULD_SKIP_THIS
typedef struct {
DBusSocketSet parent;
DBusPollFD *fds;
int n_fds;
int n_reserved;
int n_allocated;
} DBusSocketSetPoll;
#define REALLOC_INCREMENT 8
#define MINIMUM_SIZE 8
/* If we're in the regression tests, force reallocation to happen sooner */
#ifdef DBUS_BUILD_TESTS
#define DEFAULT_SIZE_HINT 1
#else
#define DEFAULT_SIZE_HINT MINIMUM_SIZE
#endif
static inline DBusSocketSetPoll *
socket_set_poll_cast (DBusSocketSet *set)
{
_dbus_assert (set->cls == &_dbus_socket_set_poll_class);
return (DBusSocketSetPoll *) set;
}
/* this is safe to call on a partially-allocated socket set */
static void
socket_set_poll_free (DBusSocketSet *set)
{
DBusSocketSetPoll *self = socket_set_poll_cast (set);
dbus_free (self->fds);
dbus_free (self);
_dbus_verbose ("freed socket set %p\n", self);
}
DBusSocketSet *
_dbus_socket_set_poll_new (int size_hint)
{
DBusSocketSetPoll *ret;
if (size_hint <= 0)
size_hint = DEFAULT_SIZE_HINT;
ret = dbus_new0 (DBusSocketSetPoll, 1);
if (ret == NULL)
return NULL;
ret->parent.cls = &_dbus_socket_set_poll_class;
ret->n_fds = 0;
ret->n_allocated = size_hint;
ret->fds = dbus_new0 (DBusPollFD, size_hint);
if (ret->fds == NULL)
{
/* socket_set_poll_free specifically supports half-constructed
* socket sets */
socket_set_poll_free ((DBusSocketSet *) ret);
return NULL;
}
_dbus_verbose ("new socket set at %p\n", ret);
return (DBusSocketSet *) ret;
}
static short
watch_flags_to_poll_events (unsigned int flags)
{
short events = 0;
if (flags & DBUS_WATCH_READABLE)
events |= _DBUS_POLLIN;
if (flags & DBUS_WATCH_WRITABLE)
events |= _DBUS_POLLOUT;
return events;
}
static dbus_bool_t
socket_set_poll_add (DBusSocketSet *set,
int fd,
unsigned int flags,
dbus_bool_t enabled)
{
DBusSocketSetPoll *self = socket_set_poll_cast (set);
#ifndef DBUS_DISABLE_ASSERT
int i;
for (i = 0; i < self->n_fds; i++)
_dbus_assert (self->fds[i].fd != fd);
#endif
if (self->n_reserved >= self->n_allocated)
{
DBusPollFD *new_fds = dbus_realloc (self->fds,
sizeof (DBusPollFD) * (self->n_allocated + REALLOC_INCREMENT));
_dbus_verbose ("inflating set %p from %d en/%d res/%d alloc to %d\n",
self, self->n_fds, self->n_reserved, self->n_allocated,
self->n_allocated + REALLOC_INCREMENT);
if (new_fds == NULL)
return FALSE;
self->fds = new_fds;
self->n_allocated += REALLOC_INCREMENT;
}
_dbus_verbose ("before adding fd %d to %p, %d en/%d res/%d alloc\n",
fd, self, self->n_fds, self->n_reserved, self->n_allocated);
_dbus_assert (self->n_reserved >= self->n_fds);
_dbus_assert (self->n_allocated > self->n_reserved);
self->n_reserved++;
if (enabled)
{
self->fds[self->n_fds].fd = fd;
self->fds[self->n_fds].events = watch_flags_to_poll_events (flags);
self->n_fds++;
}
return TRUE;
}
static void
socket_set_poll_enable (DBusSocketSet *set,
int fd,
unsigned int flags)
{
DBusSocketSetPoll *self = socket_set_poll_cast (set);
int i;
for (i = 0; i < self->n_fds; i++)
{
if (self->fds[i].fd == fd)
{
self->fds[i].events = watch_flags_to_poll_events (flags);
return;
}
}
/* we allocated space when the socket was added */
_dbus_assert (self->n_fds < self->n_reserved);
_dbus_assert (self->n_reserved <= self->n_allocated);
self->fds[self->n_fds].fd = fd;
self->fds[self->n_fds].events = watch_flags_to_poll_events (flags);
self->n_fds++;
}
static void
socket_set_poll_disable (DBusSocketSet *set,
int fd)
{
DBusSocketSetPoll *self = socket_set_poll_cast (set);
int i;
for (i = 0; i < self->n_fds; i++)
{
if (self->fds[i].fd == fd)
{
if (i != self->n_fds - 1)
{
self->fds[i].fd = self->fds[self->n_fds - 1].fd;
self->fds[i].events = self->fds[self->n_fds - 1].events;
}
self->n_fds--;
return;
}
}
}
static void
socket_set_poll_remove (DBusSocketSet *set,
int fd)
{
DBusSocketSetPoll *self = socket_set_poll_cast (set);
socket_set_poll_disable (set, fd);
self->n_reserved--;
_dbus_verbose ("after removing fd %d from %p, %d en/%d res/%d alloc\n",
fd, self, self->n_fds, self->n_reserved, self->n_allocated);
_dbus_assert (self->n_fds <= self->n_reserved);
_dbus_assert (self->n_reserved <= self->n_allocated);
if (self->n_reserved + MINIMUM_SIZE < self->n_allocated / 2)
{
/* Our array is twice as big as it needs to be - deflate it until it's
* only slightly larger than the number reserved. */
DBusPollFD *new_fds = dbus_realloc (self->fds,
sizeof (DBusPollFD) * (self->n_reserved + MINIMUM_SIZE));
_dbus_verbose ("before deflating %p, %d en/%d res/%d alloc\n",
self, self->n_fds, self->n_reserved, self->n_allocated);
if (_DBUS_UNLIKELY (new_fds == NULL))
{
/* Weird. Oh well, never mind, the too-big array is untouched */
return;
}
self->fds = new_fds;
self->n_allocated = self->n_reserved;
}
}
static unsigned int
watch_flags_from_poll_revents (short revents)
{
unsigned int condition = 0;
if (revents & _DBUS_POLLIN)
condition |= DBUS_WATCH_READABLE;
if (revents & _DBUS_POLLOUT)
condition |= DBUS_WATCH_WRITABLE;
if (revents & _DBUS_POLLHUP)
condition |= DBUS_WATCH_HANGUP;
if (revents & _DBUS_POLLERR)
condition |= DBUS_WATCH_ERROR;
if (_DBUS_UNLIKELY (revents & _DBUS_POLLNVAL))
condition |= _DBUS_WATCH_NVAL;
return condition;
}
/** This is basically Linux's epoll_wait(2) implemented in terms of poll(2);
* it returns results into a caller-supplied buffer so we can be reentrant. */
static int
socket_set_poll_poll (DBusSocketSet *set,
DBusSocketEvent *revents,
int max_events,
int timeout_ms)
{
DBusSocketSetPoll *self = socket_set_poll_cast (set);
int i;
int n_events;
int n_ready;
_dbus_assert (max_events > 0);
for (i = 0; i < self->n_fds; i++)
self->fds[i].revents = 0;
n_ready = _dbus_poll (self->fds, self->n_fds, timeout_ms);
if (n_ready <= 0)
return n_ready;
n_events = 0;
for (i = 0; i < self->n_fds; i++)
{
if (self->fds[i].revents != 0)
{
revents[n_events].fd = self->fds[i].fd;
revents[n_events].flags = watch_flags_from_poll_revents (self->fds[i].revents);
n_events += 1;
/* We ignore events beyond max_events because we have nowhere to
* put them. _dbus_poll is level-triggered, so we'll just be told
* about them next time round the main loop anyway. */
if (n_events == max_events)
return n_events;
}
}
return n_events;
}
DBusSocketSetClass _dbus_socket_set_poll_class = {
socket_set_poll_free,
socket_set_poll_add,
socket_set_poll_remove,
socket_set_poll_enable,
socket_set_poll_disable,
socket_set_poll_poll
};
#endif /* !DOXYGEN_SHOULD_SKIP_THIS */