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ev_epoll.c
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ev_epoll.c
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/*
* FD polling functions for Linux epoll
*
* Copyright 2000-2014 Willy Tarreau <[email protected]>
*
* 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.
*/
#include <unistd.h>
#include <sys/time.h>
#include <sys/types.h>
#include <common/compat.h>
#include <common/config.h>
#include <common/debug.h>
#include <common/epoll.h>
#include <common/standard.h>
#include <common/ticks.h>
#include <common/time.h>
#include <common/tools.h>
#include <types/global.h>
#include <proto/fd.h>
/* private data */
static struct epoll_event *epoll_events;
static int epoll_fd;
/* This structure may be used for any purpose. Warning! do not use it in
* recursive functions !
*/
static struct epoll_event ev;
#ifndef EPOLLRDHUP
/* EPOLLRDHUP was defined late in libc, and it appeared in kernel 2.6.17 */
#define EPOLLRDHUP 0x2000
#endif
/*
* Immediately remove file descriptor from epoll set upon close.
* Since we forked, some fds share inodes with the other process, and epoll may
* send us events even though this process closed the fd (see man 7 epoll,
* "Questions and answers", Q 6).
*/
REGPRM1 static void __fd_clo(int fd)
{
if (unlikely(fdtab[fd].cloned)) {
epoll_ctl(epoll_fd, EPOLL_CTL_DEL, fd, &ev);
}
}
/*
* Linux epoll() poller
*/
REGPRM2 static void _do_poll(struct poller *p, int exp)
{
int status, eo, en;
int fd, opcode;
int count;
int updt_idx;
int wait_time;
/* first, scan the update list to find polling changes */
for (updt_idx = 0; updt_idx < fd_nbupdt; updt_idx++) {
fd = fd_updt[updt_idx];
fdtab[fd].updated = 0;
fdtab[fd].new = 0;
if (!fdtab[fd].owner)
continue;
eo = fdtab[fd].state;
en = fd_compute_new_polled_status(eo);
if ((eo ^ en) & FD_EV_POLLED_RW) {
/* poll status changed */
fdtab[fd].state = en;
if ((en & FD_EV_POLLED_RW) == 0) {
/* fd removed from poll list */
opcode = EPOLL_CTL_DEL;
}
else if ((eo & FD_EV_POLLED_RW) == 0) {
/* new fd in the poll list */
opcode = EPOLL_CTL_ADD;
}
else {
/* fd status changed */
opcode = EPOLL_CTL_MOD;
}
/* construct the epoll events based on new state */
ev.events = 0;
if (en & FD_EV_POLLED_R)
ev.events |= EPOLLIN | EPOLLRDHUP;
if (en & FD_EV_POLLED_W)
ev.events |= EPOLLOUT;
ev.data.fd = fd;
epoll_ctl(epoll_fd, opcode, fd, &ev);
}
}
fd_nbupdt = 0;
/* compute the epoll_wait() timeout */
if (!exp)
wait_time = MAX_DELAY_MS;
else if (tick_is_expired(exp, now_ms))
wait_time = 0;
else {
wait_time = TICKS_TO_MS(tick_remain(now_ms, exp)) + 1;
if (wait_time > MAX_DELAY_MS)
wait_time = MAX_DELAY_MS;
}
/* now let's wait for polled events */
gettimeofday(&before_poll, NULL);
status = epoll_wait(epoll_fd, epoll_events, global.tune.maxpollevents, wait_time);
tv_update_date(wait_time, status);
measure_idle();
/* process polled events */
for (count = 0; count < status; count++) {
unsigned int n;
unsigned int e = epoll_events[count].events;
fd = epoll_events[count].data.fd;
if (!fdtab[fd].owner)
continue;
/* it looks complicated but gcc can optimize it away when constants
* have same values... In fact it depends on gcc :-(
*/
fdtab[fd].ev &= FD_POLL_STICKY;
if (EPOLLIN == FD_POLL_IN && EPOLLOUT == FD_POLL_OUT &&
EPOLLPRI == FD_POLL_PRI && EPOLLERR == FD_POLL_ERR &&
EPOLLHUP == FD_POLL_HUP) {
n = e & (EPOLLIN|EPOLLOUT|EPOLLPRI|EPOLLERR|EPOLLHUP);
}
else {
n = ((e & EPOLLIN ) ? FD_POLL_IN : 0) |
((e & EPOLLPRI) ? FD_POLL_PRI : 0) |
((e & EPOLLOUT) ? FD_POLL_OUT : 0) |
((e & EPOLLERR) ? FD_POLL_ERR : 0) |
((e & EPOLLHUP) ? FD_POLL_HUP : 0);
}
/* always remap RDHUP to HUP as they're used similarly */
if (e & EPOLLRDHUP)
n |= FD_POLL_HUP;
fdtab[fd].ev |= n;
if (n & (FD_POLL_IN | FD_POLL_HUP | FD_POLL_ERR))
fd_may_recv(fd);
if (n & (FD_POLL_OUT | FD_POLL_ERR))
fd_may_send(fd);
}
/* the caller will take care of cached events */
}
/*
* Initialization of the epoll() poller.
* Returns 0 in case of failure, non-zero in case of success. If it fails, it
* disables the poller by setting its pref to 0.
*/
REGPRM1 static int _do_init(struct poller *p)
{
p->private = NULL;
epoll_fd = epoll_create(global.maxsock + 1);
if (epoll_fd < 0)
goto fail_fd;
epoll_events = (struct epoll_event*)
calloc(1, sizeof(struct epoll_event) * global.tune.maxpollevents);
if (epoll_events == NULL)
goto fail_ee;
return 1;
fail_ee:
close(epoll_fd);
epoll_fd = -1;
fail_fd:
p->pref = 0;
return 0;
}
/*
* Termination of the epoll() poller.
* Memory is released and the poller is marked as unselectable.
*/
REGPRM1 static void _do_term(struct poller *p)
{
free(epoll_events);
if (epoll_fd >= 0) {
close(epoll_fd);
epoll_fd = -1;
}
epoll_events = NULL;
p->private = NULL;
p->pref = 0;
}
/*
* Check that the poller works.
* Returns 1 if OK, otherwise 0.
*/
REGPRM1 static int _do_test(struct poller *p)
{
int fd;
fd = epoll_create(global.maxsock + 1);
if (fd < 0)
return 0;
close(fd);
return 1;
}
/*
* Recreate the epoll file descriptor after a fork(). Returns 1 if OK,
* otherwise 0. It will ensure that all processes will not share their
* epoll_fd. Some side effects were encountered because of this, such
* as epoll_wait() returning an FD which was previously deleted.
*/
REGPRM1 static int _do_fork(struct poller *p)
{
if (epoll_fd >= 0)
close(epoll_fd);
epoll_fd = epoll_create(global.maxsock + 1);
if (epoll_fd < 0)
return 0;
return 1;
}
/*
* It is a constructor, which means that it will automatically be called before
* main(). This is GCC-specific but it works at least since 2.95.
* Special care must be taken so that it does not need any uninitialized data.
*/
__attribute__((constructor))
static void _do_register(void)
{
struct poller *p;
if (nbpollers >= MAX_POLLERS)
return;
epoll_fd = -1;
p = &pollers[nbpollers++];
p->name = "epoll";
p->pref = 300;
p->private = NULL;
p->clo = __fd_clo;
p->test = _do_test;
p->init = _do_init;
p->term = _do_term;
p->poll = _do_poll;
p->fork = _do_fork;
}
/*
* Local variables:
* c-indent-level: 8
* c-basic-offset: 8
* End:
*/