/* Copyright libuv contributors. All rights reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to
* deal in the Software without restriction, including without limitation the
* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
#include "uv.h"
#include "internal.h"
#include <errno.h>
#include <sys/epoll.h>
int uv__epoll_init(uv_loop_t* loop) {
int fd;
fd = epoll_create1(O_CLOEXEC);
/* epoll_create1() can fail either because it's not implemented (old kernel)
* or because it doesn't understand the O_CLOEXEC flag.
*/
if (fd == -1 && (errno == ENOSYS || errno == EINVAL)) {
fd = epoll_create(256);
if (fd != -1)
uv__cloexec(fd, 1);
}
loop->backend_fd = fd;
if (fd == -1)
return UV__ERR(errno);
return 0;
}
void uv__platform_invalidate_fd(uv_loop_t* loop, int fd) {
struct epoll_event* events;
struct epoll_event dummy;
uintptr_t i;
uintptr_t nfds;
assert(loop->watchers != NULL);
assert(fd >= 0);
events = (struct epoll_event*) loop->watchers[loop->nwatchers];
nfds = (uintptr_t) loop->watchers[loop->nwatchers + 1];
if (events != NULL)
/* Invalidate events with same file descriptor */
for (i = 0; i < nfds; i++)
if (events[i].data.fd == fd)
events[i].data.fd = -1;
/* Remove the file descriptor from the epoll.
* This avoids a problem where the same file description remains open
* in another process, causing repeated junk epoll events.
*
* We pass in a dummy epoll_event, to work around a bug in old kernels.
*/
if (loop->backend_fd >= 0) {
/* Work around a bug in kernels 3.10 to 3.19 where passing a struct that
* has the EPOLLWAKEUP flag set generates spurious audit syslog warnings.
*/
memset(&dummy, 0, sizeof(dummy));
epoll_ctl(loop->backend_fd, EPOLL_CTL_DEL, fd, &dummy);
}
}
int uv__io_check_fd(uv_loop_t* loop, int fd) {
struct epoll_event e;
int rc;
memset(&e, 0, sizeof(e));
e.events = POLLIN;
e.data.fd = -1;
rc = 0;
if (epoll_ctl(loop->backend_fd, EPOLL_CTL_ADD, fd, &e))
if (errno != EEXIST)
rc = UV__ERR(errno);
if (rc == 0)
if (epoll_ctl(loop->backend_fd, EPOLL_CTL_DEL, fd, &e))
abort();
return rc;
}
void uv__io_poll(uv_loop_t* loop, int timeout) {
/* A bug in kernels < 2.6.37 makes timeouts larger than ~30 minutes
* effectively infinite on 32 bits architectures. To avoid blocking
* indefinitely, we cap the timeout and poll again if necessary.
*
* Note that "30 minutes" is a simplification because it depends on
* the value of CONFIG_HZ. The magic constant assumes CONFIG_HZ=1200,
* that being the largest value I have seen in the wild (and only once.)
*/
static const int max_safe_timeout = 1789569;
static int no_epoll_pwait_cached;
static int no_epoll_wait_cached;
int no_epoll_pwait;
int no_epoll_wait;
struct epoll_event events[1024];
struct epoll_event* pe;
struct epoll_event e;
int real_timeout;
QUEUE* q;
uv__io_t* w;
sigset_t sigset;
uint64_t sigmask;
uint64_t base;
int have_signals;
int nevents;
int count;
int nfds;
int fd;
int op;
int i;
int user_timeout;
int reset_timeout;
if (loop->nfds == 0) {
assert(QUEUE_EMPTY(&loop->watcher_queue));
return;
}
memset(&e, 0, sizeof(e));
while (!QUEUE_EMPTY(&loop->watcher_queue)) {
q = QUEUE_HEAD(&loop->watcher_queue);
QUEUE_REMOVE(q);
QUEUE_INIT(q);
w = QUEUE_DATA(q, uv__io_t, watcher_queue);
assert(w->pevents != 0);
assert(w->fd >= 0);
assert(w->fd < (int) loop->nwatchers);
e.events = w->pevents;
e.data.fd = w->fd;
if (w->events == 0)
op = EPOLL_CTL_ADD;
else
op = EPOLL_CTL_MOD;
/* XXX Future optimization: do EPOLL_CTL_MOD lazily if we stop watching
* events, skip the syscall and squelch the events after epoll_wait().
*/
if (epoll_ctl(loop->backend_fd, op, w->fd, &e)) {
if (errno != EEXIST)
abort();
assert(op == EPOLL_CTL_ADD);
/* We've reactivated a file descriptor that's been watched before. */
if (epoll_ctl(loop->backend_fd, EPOLL_CTL_MOD, w->fd, &e))
abort();
}
w->events = w->pevents;
}
sigmask = 0;
if (loop->flags & UV_LOOP_BLOCK_SIGPROF) {
sigemptyset(&sigset);
sigaddset(&sigset, SIGPROF);
sigmask |= 1 << (SIGPROF - 1);
}
assert(timeout >= -1);
base = loop->time;
count = 48; /* Benchmarks suggest this gives the best throughput. */
real_timeout = timeout;
if (uv__get_internal_fields(loop)->flags & UV_METRICS_IDLE_TIME) {
reset_timeout = 1;
user_timeout = timeout;
timeout = 0;
} else {
reset_timeout = 0;
user_timeout = 0;
}
/* You could argue there is a dependency between these two but
* ultimately we don't care about their ordering with respect
* to one another. Worst case, we make a few system calls that
* could have been avoided because another thread already knows
* they fail with ENOSYS. Hardly the end of the world.
*/
no_epoll_pwait = uv__load_relaxed(&no_epoll_pwait_cached);
no_epoll_wait = uv__load_relaxed(&no_epoll_wait_cached);
for (;;) {
/* Only need to set the provider_entry_time if timeout != 0. The function
* will return early if the loop isn't configured with UV_METRICS_IDLE_TIME.
*/
if (timeout != 0)
uv__metrics_set_provider_entry_time(loop);
/* See the comment for max_safe_timeout for an explanation of why
* this is necessary. Executive summary: kernel bug workaround.
*/
if (sizeof(int32_t) == sizeof(long) && timeout >= max_safe_timeout)
timeout = max_safe_timeout;
if (sigmask != 0 && no_epoll_pwait != 0)
if (pthread_sigmask(SIG_BLOCK, &sigset, NULL))
abort();
if (no_epoll_wait != 0 || (sigmask != 0 && no_epoll_pwait == 0)) {
nfds = epoll_pwait(loop->backend_fd,
events,
ARRAY_SIZE(events),
timeout,
&sigset);
if (nfds == -1 && errno == ENOSYS) {
uv__store_relaxed(&no_epoll_pwait_cached, 1);
no_epoll_pwait = 1;
}
} else {
nfds = epoll_wait(loop->backend_fd,
events,
ARRAY_SIZE(events),
timeout);
if (nfds == -1 && errno == ENOSYS) {
uv__store_relaxed(&no_epoll_wait_cached, 1);
no_epoll_wait = 1;
}
}
if (sigmask != 0 && no_epoll_pwait != 0)
if (pthread_sigmask(SIG_UNBLOCK, &sigset, NULL))
abort();
/* Update loop->time unconditionally. It's tempting to skip the update when
* timeout == 0 (i.e. non-blocking poll) but there is no guarantee that the
* operating system didn't reschedule our process while in the syscall.
*/
SAVE_ERRNO(uv__update_time(loop));
if (nfds == 0) {
assert(timeout != -1);
if (reset_timeout != 0) {
timeout = user_timeout;
reset_timeout = 0;
}
if (timeout == -1)
continue;
if (timeout == 0)
return;
/* We may have been inside the system call for longer than |timeout|
* milliseconds so we need to update the timestamp to avoid drift.
*/
goto update_timeout;
}
if (nfds == -1) {
if (errno == ENOSYS) {
/* epoll_wait() or epoll_pwait() failed, try the other system call. */
assert(no_epoll_wait == 0 || no_epoll_pwait == 0);
continue;
}
if (errno != EINTR)
abort();
if (reset_timeout != 0) {
timeout = user_timeout;
reset_timeout = 0;
}
if (timeout == -1)
continue;
if (timeout == 0)
return;
/* Interrupted by a signal. Update timeout and poll again. */
goto update_timeout;
}
have_signals = 0;
nevents = 0;
{
/* Squelch a -Waddress-of-packed-member warning with gcc >= 9. */
union {
struct epoll_event* events;
uv__io_t* watchers;
} x;
x.events = events;
assert(loop->watchers != NULL);
loop->watchers[loop->nwatchers] = x.watchers;
loop->watchers[loop->nwatchers + 1] = (void*) (uintptr_t) nfds;
}
for (i = 0; i < nfds; i++) {
pe = events + i;
fd = pe->data.fd;
/* Skip invalidated events, see uv__platform_invalidate_fd */
if (fd == -1)
continue;
assert(fd >= 0);
assert((unsigned) fd < loop->nwatchers);
w = loop->watchers[fd];
if (w == NULL) {
/* File descriptor that we've stopped watching, disarm it.
*
* Ignore all errors because we may be racing with another thread
* when the file descriptor is closed.
*/
epoll_ctl(loop->backend_fd, EPOLL_CTL_DEL, fd, pe);
continue;
}
/* Give users only events they're interested in. Prevents spurious
* callbacks when previous callback invocation in this loop has stopped
* the current watcher. Also, filters out events that users has not
* requested us to watch.
*/
pe->events &= w->pevents | POLLERR | POLLHUP;
/* Work around an epoll quirk where it sometimes reports just the
* EPOLLERR or EPOLLHUP event. In order to force the event loop to
* move forward, we merge in the read/write events that the watcher
* is interested in; uv__read() and uv__write() will then deal with
* the error or hangup in the usual fashion.
*
* Note to self: happens when epoll reports EPOLLIN|EPOLLHUP, the user
* reads the available data, calls uv_read_stop(), then sometime later
* calls uv_read_start() again. By then, libuv has forgotten about the
* hangup and the kernel won't report EPOLLIN again because there's
* nothing left to read. If anything, libuv is to blame here. The
* current hack is just a quick bandaid; to properly fix it, libuv
* needs to remember the error/hangup event. We should get that for
* free when we switch over to edge-triggered I/O.
*/
if (pe->events == POLLERR || pe->events == POLLHUP)
pe->events |=
w->pevents & (POLLIN | POLLOUT | UV__POLLRDHUP | UV__POLLPRI);
if (pe->events != 0) {
/* Run signal watchers last. This also affects child process watchers
* because those are implemented in terms of signal watchers.
*/
if (w == &loop->signal_io_watcher) {
have_signals = 1;
} else {
uv__metrics_update_idle_time(loop);
w->cb(loop, w, pe->events);
}
nevents++;
}
}
if (reset_timeout != 0) {
timeout = user_timeout;
reset_timeout = 0;
}
if (have_signals != 0) {
uv__metrics_update_idle_time(loop);
loop->signal_io_watcher.cb(loop, &loop->signal_io_watcher, POLLIN);
}
loop->watchers[loop->nwatchers] = NULL;
loop->watchers[loop->nwatchers + 1] = NULL;
if (have_signals != 0)
return; /* Event loop should cycle now so don't poll again. */
if (nevents != 0) {
if (nfds == ARRAY_SIZE(events) && --count != 0) {
/* Poll for more events but don't block this time. */
timeout = 0;
continue;
}
return;
}
if (timeout == 0)
return;
if (timeout == -1)
continue;
update_timeout:
assert(timeout > 0);
real_timeout -= (loop->time - base);
if (real_timeout <= 0)
return;
timeout = real_timeout;
}
}