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This commit is contained in:
Marc Alexander Lehmann 2007-12-13 16:52:50 +00:00
parent 3eb9561b0a
commit 3dbd4efbf1
1 changed files with 70 additions and 16 deletions
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86
ev_epoll.c
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@ -29,23 +29,64 @@
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* general notes about epoll:
*
* a) epoll silently removes fds from the fd set. as nothing tells us
* that an fd has been removed otherwise, we have to continually
* "rearm" fds that we suspect *might* have changed (same
* problem with kqueue, but much less costly there).
* b) the fact that ADD != MOD creates a lot of extra syscalls due to a)
* and seems not to have any advantage.
* c) the inability to handle fork or file descriptors (think dup)
* limits the applicability over poll, so this is not a generic
* poll replacement.
*
* lots of "weird code" and complication handling in this file is due
* to these design problems with epoll, as we try very hard to avoid
* epoll_ctl syscalls for common usage patterns.
*/
#include <sys/epoll.h>
static void
epoll_modify (EV_P_ int fd, int oev, int nev)
{
int mode = nev ? oev ? EPOLL_CTL_MOD : EPOLL_CTL_ADD : EPOLL_CTL_DEL;
struct epoll_event ev;
ev.data.u64 = fd; /* use u64 to fully initialise the struct, for nicer strace etc. */
ev.events =
(nev & EV_READ ? EPOLLIN : 0)
| (nev & EV_WRITE ? EPOLLOUT : 0);
if (expect_false (epoll_ctl (backend_fd, mode, fd, &ev)))
if (errno != ENOENT /* on ENOENT the fd went away, so try to do the right thing */
|| (nev && epoll_ctl (backend_fd, EPOLL_CTL_ADD, fd, &ev)))
fd_kill (EV_A_ fd);
/*
* we handle EPOLL_CTL_DEL by ignoring it here
* on the assumption that the fd is gone anyways
* if that is wrong, we have to handle the spurious
* event in epoll_poll.
*/
if (!nev)
return;
ev.data.u64 = fd; /* use u64 to fully initialise the struct, for nicer strace etc. */
ev.events = (nev & EV_READ ? EPOLLIN : 0)
| (nev & EV_WRITE ? EPOLLOUT : 0);
if (expect_true (!epoll_ctl (backend_fd, oev ? EPOLL_CTL_MOD : EPOLL_CTL_ADD, fd, &ev)))
return;
if (expect_true (errno == ENOENT))
{
/* on ENOENT the fd went away, so try to do the right thing */
if (!nev)
return;
if (!epoll_ctl (backend_fd, EPOLL_CTL_ADD, fd, &ev))
return;
}
else if (expect_true (errno == EEXIST))
{
/* on EEXIST we ignored a previous DEL */
if (!epoll_ctl (backend_fd, EPOLL_CTL_MOD, fd, &ev))
return;
}
fd_kill (EV_A_ fd);
}
static void
@ -63,12 +104,25 @@ epoll_poll (EV_P_ ev_tstamp timeout)
}
for (i = 0; i < eventcnt; ++i)
fd_event (
EV_A_
epoll_events [i].data.u64,
(epoll_events [i].events & (EPOLLOUT | EPOLLERR | EPOLLHUP) ? EV_WRITE : 0)
| (epoll_events [i].events & (EPOLLIN | EPOLLERR | EPOLLHUP) ? EV_READ : 0)
);
{
struct epoll_event *ev = epoll_events + i;
int fd = ev->data.u64;
int got = (ev->events & (EPOLLOUT | EPOLLERR | EPOLLHUP) ? EV_WRITE : 0)
| (ev->events & (EPOLLIN | EPOLLERR | EPOLLHUP) ? EV_READ : 0);
int want = anfds [fd].events;
if (expect_false (got & ~want))
{
/* we received an event but are not interested in it, try mod or del */
ev->events = (want & EV_READ ? EPOLLIN : 0)
| (want & EV_WRITE ? EPOLLOUT : 0);
epoll_ctl (backend_fd, want ? EPOLL_CTL_MOD : EPOLL_CTL_DEL, fd, ev);
}
fd_event (EV_A_ fd, got);
}
/* if the receive array was full, increase its size */
if (expect_false (eventcnt == epoll_eventmax))