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/* ae.c module for illumos event ports.
* Copyright (c) 2012, Joyent, Inc. All rights reserved.
* Released under the BSD license. See the COPYING file for more info. */
#include <assert.h>
#include <errno.h>
#include <port.h>
#include <poll.h>
#include <sys/types.h>
#include <sys/time.h>
#include <stdio.h>
static int evport_debug = 0;
/*
* This file implements the ae API using event ports, present on Solaris-based
* systems since Solaris 10. Using the event port interface, we associate file
* descriptors with the port. Each association also includes the set of poll(2)
* events that the consumer is interested in (e.g., POLLIN and POLLOUT).
*
* There's one tricky piece to this implementation: when we return events via
* aeApiPoll, the corresponding file descriptors become dissociated from the
* port. This is necessary because poll events are level-triggered, so if the
* fd didn't become dissociated, it would immediately fire another event since
* the underlying state hasn't changed yet. We must reassociate the file
* descriptor, but only after we know that our caller has actually read from it.
* The ae API does not tell us exactly when that happens, but we do know that
* it must happen by the time aeApiPoll is called again. Our solution is to
* keep track of the last fds returned by aeApiPoll and reassociate them next
* time aeApiPoll is invoked.
*
* To summarize, in this module, each fd association is EITHER (a) represented
* only via the in-kernel assocation OR (b) represented by pending_fds and
* pending_masks. (b) is only true for the last fds we returned from aeApiPoll,
* and only until we enter aeApiPoll again (at which point we restore the
* in-kernel association).
*/
#define MAX_EVENT_BATCHSZ 512
typedef struct aeApiState {
int portfd; /* event port */
int npending; /* # of pending fds */
int pending_fds[MAX_EVENT_BATCHSZ]; /* pending fds */
int pending_masks[MAX_EVENT_BATCHSZ]; /* pending fds' masks */
} aeApiState;
static int aeApiCreate(aeEventLoop *eventLoop) {
int i;
aeApiState *state = zmalloc(sizeof(aeApiState));
if (!state) return -1;
state->portfd = port_create();
if (state->portfd == -1) {
zfree(state);
return -1;
}
state->npending = 0;
for (i = 0; i < MAX_EVENT_BATCHSZ; i++) {
state->pending_fds[i] = -1;
state->pending_masks[i] = AE_NONE;
}
eventLoop->apidata = state;
return 0;
}
static void aeApiFree(aeEventLoop *eventLoop) {
aeApiState *state = eventLoop->apidata;
close(state->portfd);
zfree(state);
}
static int aeApiLookupPending(aeApiState *state, int fd) {
int i;
for (i = 0; i < state->npending; i++) {
if (state->pending_fds[i] == fd)
return (i);
}
return (-1);
}
/*
* Helper function to invoke port_associate for the given fd and mask.
*/
static int aeApiAssociate(const char *where, int portfd, int fd, int mask) {
int events = 0;
int rv, err;
if (mask & AE_READABLE)
events |= POLLIN;
if (mask & AE_WRITABLE)
events |= POLLOUT;
if (evport_debug)
fprintf(stderr, "%s: port_associate(%d, 0x%x) = ", where, fd, events);
rv = port_associate(portfd, PORT_SOURCE_FD, fd, events,
(void *)(uintptr_t)mask);
err = errno;
if (evport_debug)
fprintf(stderr, "%d (%s)\n", rv, rv == 0 ? "no error" : strerror(err));
if (rv == -1) {
fprintf(stderr, "%s: port_associate: %s\n", where, strerror(err));
if (err == EAGAIN)
fprintf(stderr, "aeApiAssociate: event port limit exceeded.");
}
return rv;
}
static int aeApiAddEvent(aeEventLoop *eventLoop, int fd, int mask) {
aeApiState *state = eventLoop->apidata;
int fullmask, pfd;
if (evport_debug)
fprintf(stderr, "aeApiAddEvent: fd %d mask 0x%x\n", fd, mask);
/*
* Since port_associate's "events" argument replaces any existing events, we
* must be sure to include whatever events are already associated when
* we call port_associate() again.
*/
fullmask = mask | eventLoop->events[fd].mask;
pfd = aeApiLookupPending(state, fd);
if (pfd != -1) {
/*
* This fd was recently returned from aeApiPoll. It should be safe to
* assume that the consumer has processed that poll event, but we play
* it safer by simply updating pending_mask. The fd will be
* reassociated as usual when aeApiPoll is called again.
*/
if (evport_debug)
fprintf(stderr, "aeApiAddEvent: adding to pending fd %d\n", fd);
state->pending_masks[pfd] |= fullmask;
return 0;
}
return (aeApiAssociate("aeApiAddEvent", state->portfd, fd, fullmask));
}
static void aeApiDelEvent(aeEventLoop *eventLoop, int fd, int mask) {
aeApiState *state = eventLoop->apidata;
int fullmask, pfd;
if (evport_debug)
fprintf(stderr, "del fd %d mask 0x%x\n", fd, mask);
pfd = aeApiLookupPending(state, fd);
if (pfd != -1) {
if (evport_debug)
fprintf(stderr, "deleting event from pending fd %d\n", fd);
/*
* This fd was just returned from aeApiPoll, so it's not currently
* associated with the port. All we need to do is update
* pending_mask appropriately.
*/
state->pending_masks[pfd] &= ~mask;
if (state->pending_masks[pfd] == AE_NONE)
state->pending_fds[pfd] = -1;
return;
}
/*
* The fd is currently associated with the port. Like with the add case
* above, we must look at the full mask for the file descriptor before
* updating that association. We don't have a good way of knowing what the
* events are without looking into the eventLoop state directly. We rely on
* the fact that our caller has already updated the mask in the eventLoop.
*/
fullmask = eventLoop->events[fd].mask;
if (fullmask == AE_NONE) {
/*
* We're removing *all* events, so use port_dissociate to remove the
* association completely. Failure here indicates a bug.
*/
if (evport_debug)
fprintf(stderr, "aeApiDelEvent: port_dissociate(%d)\n", fd);
if (port_dissociate(state->portfd, PORT_SOURCE_FD, fd) != 0) {
perror("aeApiDelEvent: port_dissociate");
abort(); /* will not return */
}
} else if (aeApiAssociate("aeApiDelEvent", state->portfd, fd,
fullmask) != 0) {
/*
* ENOMEM is a potentially transient condition, but the kernel won't
* generally return it unless things are really bad. EAGAIN indicates
* we've reached an resource limit, for which it doesn't make sense to
* retry (counterintuitively). All other errors indicate a bug. In any
* of these cases, the best we can do is to abort.
*/
abort(); /* will not return */
}
}
static int aeApiPoll(aeEventLoop *eventLoop, struct timeval *tvp) {
aeApiState *state = eventLoop->apidata;
struct timespec timeout, *tsp;
int mask, i;
uint_t nevents;
port_event_t event[MAX_EVENT_BATCHSZ];
/*
* If we've returned fd events before, we must reassociate them with the
* port now, before calling port_get(). See the block comment at the top of
* this file for an explanation of why.
*/
for (i = 0; i < state->npending; i++) {
if (state->pending_fds[i] == -1)
/* This fd has since been deleted. */
continue;
if (aeApiAssociate("aeApiPoll", state->portfd,
state->pending_fds[i], state->pending_masks[i]) != 0) {
/* See aeApiDelEvent for why this case is fatal. */
abort();
}
state->pending_masks[i] = AE_NONE;
state->pending_fds[i] = -1;
}
state->npending = 0;
if (tvp != NULL) {
timeout.tv_sec = tvp->tv_sec;
timeout.tv_nsec = tvp->tv_usec * 1000;
tsp = &timeout;
} else {
tsp = NULL;
}
/*
* port_getn can return with errno == ETIME having returned some events (!).
* So if we get ETIME, we check nevents, too.
*/
nevents = 1;
if (port_getn(state->portfd, event, MAX_EVENT_BATCHSZ, &nevents,
tsp) == -1 && (errno != ETIME || nevents == 0)) {
if (errno == ETIME || errno == EINTR)
return 0;
/* Any other error indicates a bug. */
perror("aeApiPoll: port_get");
abort();
}
state->npending = nevents;
for (i = 0; i < nevents; i++) {
mask = 0;
if (event[i].portev_events & POLLIN)
mask |= AE_READABLE;
if (event[i].portev_events & POLLOUT)
mask |= AE_WRITABLE;
eventLoop->fired[i].fd = event[i].portev_object;
eventLoop->fired[i].mask = mask;
if (evport_debug)
fprintf(stderr, "aeApiPoll: fd %d mask 0x%x\n",
(int)event[i].portev_object, mask);
state->pending_fds[i] = event[i].portev_object;
state->pending_masks[i] = (uintptr_t)event[i].portev_user;
}
return nevents;
}
static char *aeApiName(void) {
return "evport";
}
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