/*
Unix SMB/CIFS implementation.
main select loop and event handling - epoll implementation
Copyright (C) Andrew Tridgell 2003-2005
Copyright (C) Stefan Metzmacher 2005-2009
** NOTE! The following LGPL license applies to the tevent
** library. This does NOT imply that all of Samba is released
** under the LGPL
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 3 of the License, or (at your option) any later version.
This library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, see .
*/
#include "replace.h"
#include "system/filesys.h"
#include "system/select.h"
#include "tevent.h"
#include "tevent_internal.h"
#include "tevent_util.h"
struct epoll_event_context {
/* a pointer back to the generic event_context */
struct tevent_context *ev;
/* when using epoll this is the handle from epoll_create */
int epoll_fd;
pid_t pid;
};
/*
called when a epoll call fails, and we should fallback
to using select
*/
static void epoll_panic(struct epoll_event_context *epoll_ev, const char *reason)
{
tevent_debug(epoll_ev->ev, TEVENT_DEBUG_FATAL,
"%s (%s) - calling abort()\n", reason, strerror(errno));
abort();
}
/*
map from TEVENT_FD_* to EPOLLIN/EPOLLOUT
*/
static uint32_t epoll_map_flags(uint16_t flags)
{
uint32_t ret = 0;
if (flags & TEVENT_FD_READ) ret |= (EPOLLIN | EPOLLERR | EPOLLHUP);
if (flags & TEVENT_FD_WRITE) ret |= (EPOLLOUT | EPOLLERR | EPOLLHUP);
return ret;
}
/*
free the epoll fd
*/
static int epoll_ctx_destructor(struct epoll_event_context *epoll_ev)
{
close(epoll_ev->epoll_fd);
epoll_ev->epoll_fd = -1;
return 0;
}
/*
init the epoll fd
*/
static int epoll_init_ctx(struct epoll_event_context *epoll_ev)
{
epoll_ev->epoll_fd = epoll_create(64);
epoll_ev->pid = getpid();
talloc_set_destructor(epoll_ev, epoll_ctx_destructor);
if (epoll_ev->epoll_fd == -1) {
return -1;
}
return 0;
}
static void epoll_add_event(struct epoll_event_context *epoll_ev, struct tevent_fd *fde);
/*
reopen the epoll handle when our pid changes
see http://junkcode.samba.org/ftp/unpacked/junkcode/epoll_fork.c for an
demonstration of why this is needed
*/
static void epoll_check_reopen(struct epoll_event_context *epoll_ev)
{
struct tevent_fd *fde;
if (epoll_ev->pid == getpid()) {
return;
}
close(epoll_ev->epoll_fd);
epoll_ev->epoll_fd = epoll_create(64);
if (epoll_ev->epoll_fd == -1) {
tevent_debug(epoll_ev->ev, TEVENT_DEBUG_FATAL,
"Failed to recreate epoll handle after fork\n");
return;
}
epoll_ev->pid = getpid();
for (fde=epoll_ev->ev->fd_events;fde;fde=fde->next) {
epoll_add_event(epoll_ev, fde);
}
}
#define EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT (1<<0)
#define EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR (1<<1)
#define EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR (1<<2)
/*
add the epoll event to the given fd_event
*/
static void epoll_add_event(struct epoll_event_context *epoll_ev, struct tevent_fd *fde)
{
struct epoll_event event;
if (epoll_ev->epoll_fd == -1) return;
fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
/* if we don't want events yet, don't add an epoll_event */
if (fde->flags == 0) return;
ZERO_STRUCT(event);
event.events = epoll_map_flags(fde->flags);
event.data.ptr = fde;
if (epoll_ctl(epoll_ev->epoll_fd, EPOLL_CTL_ADD, fde->fd, &event) != 0) {
epoll_panic(epoll_ev, "EPOLL_CTL_ADD failed");
}
fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
/* only if we want to read we want to tell the event handler about errors */
if (fde->flags & TEVENT_FD_READ) {
fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
}
}
/*
delete the epoll event for given fd_event
*/
static void epoll_del_event(struct epoll_event_context *epoll_ev, struct tevent_fd *fde)
{
struct epoll_event event;
if (epoll_ev->epoll_fd == -1) return;
fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
/* if there's no epoll_event, we don't need to delete it */
if (!(fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT)) return;
ZERO_STRUCT(event);
event.events = epoll_map_flags(fde->flags);
event.data.ptr = fde;
if (epoll_ctl(epoll_ev->epoll_fd, EPOLL_CTL_DEL, fde->fd, &event) != 0) {
tevent_debug(epoll_ev->ev, TEVENT_DEBUG_FATAL,
"epoll_del_event failed! probable early close bug (%s)\n",
strerror(errno));
}
fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
}
/*
change the epoll event to the given fd_event
*/
static void epoll_mod_event(struct epoll_event_context *epoll_ev, struct tevent_fd *fde)
{
struct epoll_event event;
if (epoll_ev->epoll_fd == -1) return;
fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
ZERO_STRUCT(event);
event.events = epoll_map_flags(fde->flags);
event.data.ptr = fde;
if (epoll_ctl(epoll_ev->epoll_fd, EPOLL_CTL_MOD, fde->fd, &event) != 0) {
epoll_panic(epoll_ev, "EPOLL_CTL_MOD failed");
}
/* only if we want to read we want to tell the event handler about errors */
if (fde->flags & TEVENT_FD_READ) {
fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
}
}
static void epoll_change_event(struct epoll_event_context *epoll_ev, struct tevent_fd *fde)
{
bool got_error = (fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR);
bool want_read = (fde->flags & TEVENT_FD_READ);
bool want_write= (fde->flags & TEVENT_FD_WRITE);
if (epoll_ev->epoll_fd == -1) return;
fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
/* there's already an event */
if (fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT) {
if (want_read || (want_write && !got_error)) {
epoll_mod_event(epoll_ev, fde);
return;
}
/*
* if we want to match the select behavior, we need to remove the epoll_event
* when the caller isn't interested in events.
*
* this is because epoll reports EPOLLERR and EPOLLHUP, even without asking for them
*/
epoll_del_event(epoll_ev, fde);
return;
}
/* there's no epoll_event attached to the fde */
if (want_read || (want_write && !got_error)) {
epoll_add_event(epoll_ev, fde);
return;
}
}
/*
event loop handling using epoll
*/
static int epoll_event_loop(struct epoll_event_context *epoll_ev, struct timeval *tvalp)
{
int ret, i;
#define MAXEVENTS 1
struct epoll_event events[MAXEVENTS];
int timeout = -1;
if (epoll_ev->epoll_fd == -1) return -1;
if (tvalp) {
/* it's better to trigger timed events a bit later than to early */
timeout = ((tvalp->tv_usec+999) / 1000) + (tvalp->tv_sec*1000);
}
if (epoll_ev->ev->signal_events &&
tevent_common_check_signal(epoll_ev->ev)) {
return 0;
}
ret = epoll_wait(epoll_ev->epoll_fd, events, MAXEVENTS, timeout);
if (ret == -1 && errno == EINTR && epoll_ev->ev->signal_events) {
if (tevent_common_check_signal(epoll_ev->ev)) {
return 0;
}
}
if (ret == -1 && errno != EINTR) {
epoll_panic(epoll_ev, "epoll_wait() failed");
return -1;
}
if (ret == 0 && tvalp) {
/* we don't care about a possible delay here */
tevent_common_loop_timer_delay(epoll_ev->ev);
return 0;
}
for (i=0;iadditional_flags |= EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR;
/*
* if we only wait for TEVENT_FD_WRITE, we should not tell the
* event handler about it, and remove the epoll_event,
* as we only report errors when waiting for read events,
* to match the select() behavior
*/
if (!(fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR)) {
epoll_del_event(epoll_ev, fde);
continue;
}
flags |= TEVENT_FD_READ;
}
if (events[i].events & EPOLLIN) flags |= TEVENT_FD_READ;
if (events[i].events & EPOLLOUT) flags |= TEVENT_FD_WRITE;
if (flags) {
fde->handler(epoll_ev->ev, fde, flags, fde->private_data);
break;
}
}
return 0;
}
/*
create a epoll_event_context structure.
*/
static int epoll_event_context_init(struct tevent_context *ev)
{
int ret;
struct epoll_event_context *epoll_ev;
epoll_ev = talloc_zero(ev, struct epoll_event_context);
if (!epoll_ev) return -1;
epoll_ev->ev = ev;
epoll_ev->epoll_fd = -1;
ret = epoll_init_ctx(epoll_ev);
if (ret != 0) {
talloc_free(epoll_ev);
return ret;
}
ev->additional_data = epoll_ev;
return 0;
}
/*
destroy an fd_event
*/
static int epoll_event_fd_destructor(struct tevent_fd *fde)
{
struct tevent_context *ev = fde->event_ctx;
struct epoll_event_context *epoll_ev = NULL;
if (ev) {
epoll_ev = talloc_get_type(ev->additional_data,
struct epoll_event_context);
epoll_check_reopen(epoll_ev);
epoll_del_event(epoll_ev, fde);
}
return tevent_common_fd_destructor(fde);
}
/*
add a fd based event
return NULL on failure (memory allocation error)
*/
static struct tevent_fd *epoll_event_add_fd(struct tevent_context *ev, TALLOC_CTX *mem_ctx,
int fd, uint16_t flags,
tevent_fd_handler_t handler,
void *private_data,
const char *handler_name,
const char *location)
{
struct epoll_event_context *epoll_ev = talloc_get_type(ev->additional_data,
struct epoll_event_context);
struct tevent_fd *fde;
epoll_check_reopen(epoll_ev);
fde = tevent_common_add_fd(ev, mem_ctx, fd, flags,
handler, private_data,
handler_name, location);
if (!fde) return NULL;
talloc_set_destructor(fde, epoll_event_fd_destructor);
epoll_add_event(epoll_ev, fde);
return fde;
}
/*
set the fd event flags
*/
static void epoll_event_set_fd_flags(struct tevent_fd *fde, uint16_t flags)
{
struct tevent_context *ev;
struct epoll_event_context *epoll_ev;
if (fde->flags == flags) return;
ev = fde->event_ctx;
epoll_ev = talloc_get_type(ev->additional_data, struct epoll_event_context);
fde->flags = flags;
epoll_check_reopen(epoll_ev);
epoll_change_event(epoll_ev, fde);
}
/*
do a single event loop using the events defined in ev
*/
static int epoll_event_loop_once(struct tevent_context *ev, const char *location)
{
struct epoll_event_context *epoll_ev = talloc_get_type(ev->additional_data,
struct epoll_event_context);
struct timeval tval;
tval = tevent_common_loop_timer_delay(ev);
if (tevent_timeval_is_zero(&tval)) {
return 0;
}
epoll_check_reopen(epoll_ev);
return epoll_event_loop(epoll_ev, &tval);
}
/*
return on failure or (with 0) if all fd events are removed
*/
static int epoll_event_loop_wait(struct tevent_context *ev, const char *location)
{
struct epoll_event_context *epoll_ev = talloc_get_type(ev->additional_data,
struct epoll_event_context);
while (epoll_ev->ev->fd_events) {
if (epoll_event_loop_once(ev, location) != 0) {
break;
}
}
return 0;
}
static const struct tevent_ops epoll_event_ops = {
.context_init = epoll_event_context_init,
.add_fd = epoll_event_add_fd,
.set_fd_close_fn= tevent_common_fd_set_close_fn,
.get_fd_flags = tevent_common_fd_get_flags,
.set_fd_flags = epoll_event_set_fd_flags,
.add_timer = tevent_common_add_timer,
.add_signal = tevent_common_add_signal,
.loop_once = epoll_event_loop_once,
.loop_wait = epoll_event_loop_wait,
};
bool tevent_epoll_init(void)
{
return tevent_register_backend("epoll", &epoll_event_ops);
}