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Copy pathev_epoll.c
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413 lines (346 loc) · 9.77 KB
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/*
* FD polling functions for Linux epoll
*
* Copyright 2000-2014 Willy Tarreau <w@1wt.eu>
*
* 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/epoll.h>
#include <sys/time.h>
#include <sys/types.h>
#include <haproxy/activity.h>
#include <haproxy/api.h>
#include <haproxy/clock.h>
#include <haproxy/fd.h>
#include <haproxy/global.h>
#include <haproxy/signal.h>
#include <haproxy/ticks.h>
#include <haproxy/task.h>
#include <haproxy/tools.h>
/* private data */
static THREAD_LOCAL struct epoll_event *epoll_events = NULL;
static int epoll_fd[MAX_THREADS] __read_mostly; // per-thread epoll_fd
#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).
*/
static void __fd_clo(int fd)
{
if (unlikely(fdtab[fd].state & FD_CLONED)) {
unsigned long m = _HA_ATOMIC_LOAD(&polled_mask[fd].poll_recv) | _HA_ATOMIC_LOAD(&polled_mask[fd].poll_send);
int tgrp = fd_tgid(fd);
struct epoll_event ev;
int i;
if (!m)
return;
/* since FDs may only be shared per group and are only closed
* once entirely reset, it should never happen that we have to
* close an FD for another group, unless we're stopping from the
* wrong thread or during startup, which is what we're checking
* for. Regardless, it is not a problem to do so.
*/
if (unlikely(!(global.mode & MODE_STARTING))) {
CHECK_IF(tgid != tgrp && !thread_isolated());
}
for (i = ha_tgroup_info[tgrp-1].base; i < ha_tgroup_info[tgrp-1].base + ha_tgroup_info[tgrp-1].count; i++)
if (m & ha_thread_info[i].ltid_bit)
epoll_ctl(epoll_fd[i], EPOLL_CTL_DEL, fd, &ev);
}
}
static void _update_fd(int fd)
{
int en, opcode;
struct epoll_event ev = { };
ulong pr, ps;
en = fdtab[fd].state;
pr = _HA_ATOMIC_LOAD(&polled_mask[fd].poll_recv);
ps = _HA_ATOMIC_LOAD(&polled_mask[fd].poll_send);
/* Try to force EPOLLET on FDs that support it */
if (fdtab[fd].state & FD_ET_POSSIBLE) {
/* already done ? */
if (pr & ps & ti->ltid_bit)
return;
/* enable ET polling in both directions */
_HA_ATOMIC_OR(&polled_mask[fd].poll_recv, ti->ltid_bit);
_HA_ATOMIC_OR(&polled_mask[fd].poll_send, ti->ltid_bit);
opcode = EPOLL_CTL_ADD;
ev.events = EPOLLIN | EPOLLRDHUP | EPOLLOUT | EPOLLET;
goto done;
}
/* if we're already polling or are going to poll for this FD and it's
* neither active nor ready, force it to be active so that we don't
* needlessly unsubscribe then re-subscribe it.
*/
if (!(en & (FD_EV_READY_R | FD_EV_SHUT_R | FD_EV_ERR_RW | FD_POLL_ERR)) &&
((en & FD_EV_ACTIVE_W) || ((ps | pr) & ti->ltid_bit)))
en |= FD_EV_ACTIVE_R;
if ((ps | pr) & ti->ltid_bit) {
if (!(fdtab[fd].thread_mask & ti->ltid_bit) || !(en & FD_EV_ACTIVE_RW)) {
/* fd removed from poll list */
opcode = EPOLL_CTL_DEL;
if (pr & ti->ltid_bit)
_HA_ATOMIC_AND(&polled_mask[fd].poll_recv, ~ti->ltid_bit);
if (ps & ti->ltid_bit)
_HA_ATOMIC_AND(&polled_mask[fd].poll_send, ~ti->ltid_bit);
}
else {
if (((en & FD_EV_ACTIVE_R) != 0) == ((pr & ti->ltid_bit) != 0) &&
((en & FD_EV_ACTIVE_W) != 0) == ((ps & ti->ltid_bit) != 0))
return;
if (en & FD_EV_ACTIVE_R) {
if (!(pr & ti->ltid_bit))
_HA_ATOMIC_OR(&polled_mask[fd].poll_recv, ti->ltid_bit);
} else {
if (pr & ti->ltid_bit)
_HA_ATOMIC_AND(&polled_mask[fd].poll_recv, ~ti->ltid_bit);
}
if (en & FD_EV_ACTIVE_W) {
if (!(ps & ti->ltid_bit))
_HA_ATOMIC_OR(&polled_mask[fd].poll_send, ti->ltid_bit);
} else {
if (ps & ti->ltid_bit)
_HA_ATOMIC_AND(&polled_mask[fd].poll_send, ~ti->ltid_bit);
}
/* fd status changed */
opcode = EPOLL_CTL_MOD;
}
}
else if ((fdtab[fd].thread_mask & ti->ltid_bit) && (en & FD_EV_ACTIVE_RW)) {
/* new fd in the poll list */
opcode = EPOLL_CTL_ADD;
if (en & FD_EV_ACTIVE_R)
_HA_ATOMIC_OR(&polled_mask[fd].poll_recv, ti->ltid_bit);
if (en & FD_EV_ACTIVE_W)
_HA_ATOMIC_OR(&polled_mask[fd].poll_send, ti->ltid_bit);
}
else {
return;
}
/* construct the epoll events based on new state */
if (en & FD_EV_ACTIVE_R)
ev.events |= EPOLLIN | EPOLLRDHUP;
if (en & FD_EV_ACTIVE_W)
ev.events |= EPOLLOUT;
done:
ev.data.fd = fd;
epoll_ctl(epoll_fd[tid], opcode, fd, &ev);
}
/*
* Linux epoll() poller
*/
static void _do_poll(struct poller *p, int exp, int wake)
{
int status;
int fd;
int count;
int updt_idx;
int wait_time;
int old_fd;
/* first, scan the update list to find polling changes */
for (updt_idx = 0; updt_idx < fd_nbupdt; updt_idx++) {
fd = fd_updt[updt_idx];
if (!fd_grab_tgid(fd, tgid)) {
/* was reassigned */
activity[tid].poll_drop_fd++;
continue;
}
_HA_ATOMIC_AND(&fdtab[fd].update_mask, ~ti->ltid_bit);
if (fdtab[fd].owner)
_update_fd(fd);
else
activity[tid].poll_drop_fd++;
fd_drop_tgid(fd);
}
fd_nbupdt = 0;
/* Scan the shared update list */
for (old_fd = fd = update_list[tgid - 1].first; fd != -1; fd = fdtab[fd].update.next) {
if (fd == -2) {
fd = old_fd;
continue;
}
else if (fd <= -3)
fd = -fd -4;
if (fd == -1)
break;
if (!fd_grab_tgid(fd, tgid)) {
/* was reassigned */
activity[tid].poll_drop_fd++;
continue;
}
if (!(fdtab[fd].update_mask & ti->ltid_bit)) {
fd_drop_tgid(fd);
continue;
}
done_update_polling(fd);
if (fdtab[fd].owner)
_update_fd(fd);
else
activity[tid].poll_drop_fd++;
fd_drop_tgid(fd);
}
thread_idle_now();
thread_harmless_now();
/* Now let's wait for polled events. */
wait_time = wake ? 0 : compute_poll_timeout(exp);
clock_entering_poll();
do {
int timeout = (global.tune.options & GTUNE_BUSY_POLLING) ? 0 : wait_time;
status = epoll_wait(epoll_fd[tid], epoll_events, global.tune.maxpollevents, timeout);
clock_update_local_date(timeout, status);
if (status) {
activity[tid].poll_io++;
break;
}
if (timeout || !wait_time)
break;
if (tick_isset(exp) && tick_is_expired(exp, now_ms))
break;
} while (1);
clock_update_global_date();
fd_leaving_poll(wait_time, status);
/* process polled events */
for (count = 0; count < status; count++) {
unsigned int n, e;
e = epoll_events[count].events;
fd = epoll_events[count].data.fd;
if ((e & EPOLLRDHUP) && !(cur_poller.flags & HAP_POLL_F_RDHUP))
_HA_ATOMIC_OR(&cur_poller.flags, HAP_POLL_F_RDHUP);
#ifdef DEBUG_FD
_HA_ATOMIC_INC(&fdtab[fd].event_count);
#endif
n = ((e & EPOLLIN) ? FD_EV_READY_R : 0) |
((e & EPOLLOUT) ? FD_EV_READY_W : 0) |
((e & EPOLLRDHUP) ? FD_EV_SHUT_R : 0) |
((e & EPOLLHUP) ? FD_EV_SHUT_RW : 0) |
((e & EPOLLERR) ? FD_EV_ERR_RW : 0);
fd_update_events(fd, n);
}
/* the caller will take care of cached events */
}
static int init_epoll_per_thread()
{
epoll_events = calloc(1, sizeof(struct epoll_event) * global.tune.maxpollevents);
if (epoll_events == NULL)
goto fail_alloc;
if (MAX_THREADS > 1 && tid) {
epoll_fd[tid] = epoll_create(global.maxsock + 1);
if (epoll_fd[tid] < 0)
goto fail_fd;
}
/* we may have to unregister some events initially registered on the
* original fd when it was alone, and/or to register events on the new
* fd for this thread. Let's just mark them as updated, the poller will
* do the rest.
*/
fd_reregister_all(tgid, ti->ltid_bit);
return 1;
fail_fd:
free(epoll_events);
fail_alloc:
return 0;
}
static void deinit_epoll_per_thread()
{
if (MAX_THREADS > 1 && tid)
close(epoll_fd[tid]);
ha_free(&epoll_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.
*/
static int _do_init(struct poller *p)
{
p->private = NULL;
epoll_fd[tid] = epoll_create(global.maxsock + 1);
if (epoll_fd[tid] < 0)
goto fail_fd;
hap_register_per_thread_init(init_epoll_per_thread);
hap_register_per_thread_deinit(deinit_epoll_per_thread);
return 1;
fail_fd:
p->pref = 0;
return 0;
}
/*
* Termination of the epoll() poller.
* Memory is released and the poller is marked as unselectable.
*/
static void _do_term(struct poller *p)
{
if (epoll_fd[tid] >= 0) {
close(epoll_fd[tid]);
epoll_fd[tid] = -1;
}
p->private = NULL;
p->pref = 0;
}
/*
* Check that the poller works.
* Returns 1 if OK, otherwise 0.
*/
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.
*/
static int _do_fork(struct poller *p)
{
if (epoll_fd[tid] >= 0)
close(epoll_fd[tid]);
epoll_fd[tid] = epoll_create(global.maxsock + 1);
if (epoll_fd[tid] < 0)
return 0;
return 1;
}
/*
* Registers the poller.
*/
static void _do_register(void)
{
struct poller *p;
int i;
if (nbpollers >= MAX_POLLERS)
return;
for (i = 0; i < MAX_THREADS; i++)
epoll_fd[i] = -1;
p = &pollers[nbpollers++];
p->name = "epoll";
p->pref = 300;
p->flags = HAP_POLL_F_ERRHUP; // note: RDHUP might be dynamically added
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;
}
INITCALL0(STG_REGISTER, _do_register);
/*
* Local variables:
* c-indent-level: 8
* c-basic-offset: 8
* End:
*/
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