path: root/contrib/libs/libevent/evport.c

/* 
 * Submitted by David Pacheco (dp.spambait@gmail.com) 
 * 
 * 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 "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 */