/*      $NetBSD: evport.c,v 1.1.1.2 2017/01/31 21:14:53 christos Exp $  */
/*
* Submitted by David Pacheco ([email protected])
*
* Copyright 2006-2007 Niels Provos
* Copyright 2007-2012 Niels Provos and Nick Mathewson
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. 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.
* 3. The name of the author may not be used to endorse or promote products
*    derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY SUN MICROSYSTEMS, INC. ``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 SUN MICROSYSTEMS, INC. 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.
*/

/*
* Copyright (c) 2007 Sun Microsystems. All rights reserved.
* Use is subject to license terms.
*/

/*
* evport.c: event backend using Solaris 10 event ports. See port_create(3C).
* This implementation is loosely modeled after the one used for select(2) (in
* select.c).
*
* The outstanding events are tracked in a data structure called evport_data.
* Each entry in the ed_fds array corresponds to a file descriptor, and contains
* pointers to the read and write events that correspond to that fd. (That is,
* when the file is readable, the "read" event should handle it, etc.)
*
* evport_add and evport_del update this data structure. evport_dispatch uses it
* to determine where to callback when an event occurs (which it gets from
* port_getn).
*
* Helper functions are used: grow() grows the file descriptor array as
* necessary when large fd's come in. reassociate() takes care of maintaining
* the proper file-descriptor/event-port associations.
*
* As in the select(2) implementation, signals are handled by evsignal.
*/

#include "event2/event-config.h"
#include <sys/cdefs.h>
__RCSID("$NetBSD: evport.c,v 1.1.1.2 2017/01/31 21:14:53 christos Exp $");
#include "evconfig-private.h"

#ifdef EVENT__HAVE_EVENT_PORTS

#include <sys/time.h>
#include <sys/queue.h>
#include <errno.h>
#include <poll.h>
#include <port.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>

#include "event2/thread.h"

#include "evthread-internal.h"
#include "event-internal.h"
#include "log-internal.h"
#include "evsignal-internal.h"
#include "evmap-internal.h"

#define INITIAL_EVENTS_PER_GETN 8
#define MAX_EVENTS_PER_GETN 4096

/*
* Per-file-descriptor information about what events we're subscribed to. These
* fields are NULL if no event is subscribed to either of them.
*/

struct fd_info {
       /* combinations of EV_READ and EV_WRITE */
       short fdi_what;
       /* Index of this fd within ed_pending, plus 1.  Zero if this fd is
        * not in ed_pending.  (The +1 is a hack so that memset(0) will set
        * it to a nil index. */
       int pending_idx_plus_1;
};

#define FDI_HAS_READ(fdi)  ((fdi)->fdi_what & EV_READ)
#define FDI_HAS_WRITE(fdi) ((fdi)->fdi_what & EV_WRITE)
#define FDI_HAS_EVENTS(fdi) (FDI_HAS_READ(fdi) || FDI_HAS_WRITE(fdi))
#define FDI_TO_SYSEVENTS(fdi) (FDI_HAS_READ(fdi) ? POLLIN : 0) | \
   (FDI_HAS_WRITE(fdi) ? POLLOUT : 0)

struct evport_data {
       int             ed_port;        /* event port for system events  */
       /* How many elements of ed_pending should we look at? */
       int ed_npending;
       /* How many elements are allocated in ed_pending and pevtlist? */
       int ed_maxevents;
       /* fdi's that we need to reassoc */
       int *ed_pending;
       /* storage space for incoming events. */
       port_event_t *ed_pevtlist;

};

static void*    evport_init(struct event_base *);
static int evport_add(struct event_base *, int fd, short old, short events, void *);
static int evport_del(struct event_base *, int fd, short old, short events, void *);
static int      evport_dispatch(struct event_base *, struct timeval *);
static void     evport_dealloc(struct event_base *);
static int      grow(struct evport_data *, int min_events);

const struct eventop evportops = {
       "evport",
       evport_init,
       evport_add,
       evport_del,
       evport_dispatch,
       evport_dealloc,
       1, /* need reinit */
       0, /* features */
       sizeof(struct fd_info), /* fdinfo length */
};

/*
* Initialize the event port implementation.
*/

static void*
evport_init(struct event_base *base)
{
       struct evport_data *evpd;

       if (!(evpd = mm_calloc(1, sizeof(struct evport_data))))
               return (NULL);

       if ((evpd->ed_port = port_create()) == -1) {
               mm_free(evpd);
               return (NULL);
       }

       if (grow(evpd, INITIAL_EVENTS_PER_GETN) < 0) {
               close(evpd->ed_port);
               mm_free(evpd);
               return NULL;
       }

       evpd->ed_npending = 0;

       evsig_init_(base);

       return (evpd);
}

static int
grow(struct evport_data *data, int min_events)
{
       int newsize;
       int *new_pending;
       port_event_t *new_pevtlist;
       if (data->ed_maxevents) {
               newsize = data->ed_maxevents;
               do {
                       newsize *= 2;
               } while (newsize < min_events);
       } else {
               newsize = min_events;
       }

       new_pending = mm_realloc(data->ed_pending, sizeof(int)*newsize);
       if (new_pending == NULL)
               return -1;
       data->ed_pending = new_pending;
       new_pevtlist = mm_realloc(data->ed_pevtlist, sizeof(port_event_t)*newsize);
       if (new_pevtlist == NULL)
               return -1;
       data->ed_pevtlist = new_pevtlist;

       data->ed_maxevents = newsize;
       return 0;
}

#ifdef CHECK_INVARIANTS
/*
* Checks some basic properties about the evport_data structure. Because it
* checks all file descriptors, this function can be expensive when the maximum
* file descriptor ever used is rather large.
*/

static void
check_evportop(struct evport_data *evpd)
{
       EVUTIL_ASSERT(evpd);
       EVUTIL_ASSERT(evpd->ed_port > 0);
}

/*
* Verifies very basic integrity of a given port_event.
*/
static void
check_event(port_event_t* pevt)
{
       /*
        * We've only registered for PORT_SOURCE_FD events. The only
        * other thing we can legitimately receive is PORT_SOURCE_ALERT,
        * but since we're not using port_alert either, we can assume
        * PORT_SOURCE_FD.
        */
       EVUTIL_ASSERT(pevt->portev_source == PORT_SOURCE_FD);
}

#else
#define check_evportop(epop)
#define check_event(pevt)
#endif /* CHECK_INVARIANTS */

/*
* (Re)associates the given file descriptor with the event port. The OS events
* are specified (implicitly) from the fd_info struct.
*/
static int
reassociate(struct evport_data *epdp, struct fd_info *fdip, int fd)
{
       int sysevents = FDI_TO_SYSEVENTS(fdip);

       if (sysevents != 0) {
               if (port_associate(epdp->ed_port, PORT_SOURCE_FD,
                                  fd, sysevents, fdip) == -1) {
                       event_warn("port_associate");
                       return (-1);
               }
       }

       check_evportop(epdp);

       return (0);
}

/*
* Main event loop - polls port_getn for some number of events, and processes
* them.
*/

static int
evport_dispatch(struct event_base *base, struct timeval *tv)
{
       int i, res;
       struct evport_data *epdp = base->evbase;
       port_event_t *pevtlist = epdp->ed_pevtlist;

       /*
        * port_getn will block until it has at least nevents events. It will
        * also return how many it's given us (which may be more than we asked
        * for, as long as it's less than our maximum (ed_maxevents)) in
        * nevents.
        */
       int nevents = 1;

       /*
        * We have to convert a struct timeval to a struct timespec
        * (only difference is nanoseconds vs. microseconds). If no time-based
        * events are active, we should wait for I/O (and tv == NULL).
        */
       struct timespec ts;
       struct timespec *ts_p = NULL;
       if (tv != NULL) {
               ts.tv_sec = tv->tv_sec;
               ts.tv_nsec = tv->tv_usec * 1000;
               ts_p = &ts;
       }

       /*
        * Before doing anything else, we need to reassociate the events we hit
        * last time which need reassociation. See comment at the end of the
        * loop below.
        */
       for (i = 0; i < epdp->ed_npending; ++i) {
               struct fd_info *fdi = NULL;
               const int fd = epdp->ed_pending[i];
               if (fd != -1) {
                       /* We might have cleared out this event; we need
                        * to be sure that it's still set. */
                       fdi = evmap_io_get_fdinfo_(&base->io, fd);
               }

               if (fdi != NULL && FDI_HAS_EVENTS(fdi)) {
                       reassociate(epdp, fdi, fd);
                       /* epdp->ed_pending[i] = -1; */
                       fdi->pending_idx_plus_1 = 0;
               }
       }

       EVBASE_RELEASE_LOCK(base, th_base_lock);

       res = port_getn(epdp->ed_port, pevtlist, epdp->ed_maxevents,
           (unsigned int *) &nevents, ts_p);

       EVBASE_ACQUIRE_LOCK(base, th_base_lock);

       if (res == -1) {
               if (errno == EINTR || errno == EAGAIN) {
                       return (0);
               } else if (errno == ETIME) {
                       if (nevents == 0)
                               return (0);
               } else {
                       event_warn("port_getn");
                       return (-1);
               }
       }

       event_debug(("%s: port_getn reports %d events", __func__, nevents));

       for (i = 0; i < nevents; ++i) {
               port_event_t *pevt = &pevtlist[i];
               int fd = (int) pevt->portev_object;
               struct fd_info *fdi = pevt->portev_user;
               /*EVUTIL_ASSERT(evmap_io_get_fdinfo_(&base->io, fd) == fdi);*/

               check_evportop(epdp);
               check_event(pevt);
               epdp->ed_pending[i] = fd;
               fdi->pending_idx_plus_1 = i + 1;

               /*
                * Figure out what kind of event it was
                * (because we have to pass this to the callback)
                */
               res = 0;
               if (pevt->portev_events & (POLLERR|POLLHUP)) {
                       res = EV_READ | EV_WRITE;
               } else {
                       if (pevt->portev_events & POLLIN)
                               res |= EV_READ;
                       if (pevt->portev_events & POLLOUT)
                               res |= EV_WRITE;
               }

               /*
                * Check for the error situations or a hangup situation
                */
               if (pevt->portev_events & (POLLERR|POLLHUP|POLLNVAL))
                       res |= EV_READ|EV_WRITE;

               evmap_io_active_(base, fd, res);
       } /* end of all events gotten */
       epdp->ed_npending = nevents;

       if (nevents == epdp->ed_maxevents &&
           epdp->ed_maxevents < MAX_EVENTS_PER_GETN) {
               /* we used all the space this time.  We should be ready
                * for more events next time around. */
               grow(epdp, epdp->ed_maxevents * 2);
       }

       check_evportop(epdp);

       return (0);
}


/*
* Adds the given event (so that you will be notified when it happens via
* the callback function).
*/

static int
evport_add(struct event_base *base, int fd, short old, short events, void *p)
{
       struct evport_data *evpd = base->evbase;
       struct fd_info *fdi = p;

       check_evportop(evpd);

       fdi->fdi_what |= events;

       return reassociate(evpd, fdi, fd);
}

/*
* Removes the given event from the list of events to wait for.
*/

static int
evport_del(struct event_base *base, int fd, short old, short events, void *p)
{
       struct evport_data *evpd = base->evbase;
       struct fd_info *fdi = p;
       int associated = ! fdi->pending_idx_plus_1;

       check_evportop(evpd);

       fdi->fdi_what &= ~(events &(EV_READ|EV_WRITE));

       if (associated) {
               if (!FDI_HAS_EVENTS(fdi) &&
                   port_dissociate(evpd->ed_port, PORT_SOURCE_FD, fd) == -1) {
                       /*
                        * Ignore EBADFD error the fd could have been closed
                        * before event_del() was called.
                        */
                       if (errno != EBADFD) {
                               event_warn("port_dissociate");
                               return (-1);
                       }
               } else {
                       if (FDI_HAS_EVENTS(fdi)) {
                               return (reassociate(evpd, fdi, fd));
                       }
               }
       } else {
               if ((fdi->fdi_what & (EV_READ|EV_WRITE)) == 0) {
                       const int i = fdi->pending_idx_plus_1 - 1;
                       EVUTIL_ASSERT(evpd->ed_pending[i] == fd);
                       evpd->ed_pending[i] = -1;
                       fdi->pending_idx_plus_1 = 0;
               }
       }
       return 0;
}


static void
evport_dealloc(struct event_base *base)
{
       struct evport_data *evpd = base->evbase;

       evsig_dealloc_(base);

       close(evpd->ed_port);

       if (evpd->ed_pending)
               mm_free(evpd->ed_pending);
       if (evpd->ed_pevtlist)
               mm_free(evpd->ed_pevtlist);

       mm_free(evpd);
}

#endif /* EVENT__HAVE_EVENT_PORTS */

You are viewing proxied material from ftp.icm.edu.pl. The copyright of proxied material belongs to its original authors. Any comments or complaints in relation to proxied material should be directed to the original authors of the content concerned. Please see the disclaimer for more details.