I'm confused by ev_io_modify as it does seem to allow changing the events
the io watcher gets called for, however the backend is still waking up
for the events I've removed and running 100% CPU since they don't
go away.
So I'm not sure when anyone would use ev_io_modify....
This is Linux (debian 11 bullseye) libev4:amd64 1:4.33-1.
I have some code which is the minimal start of a TCP server.
It successfully uses an io watcher on event EV_READ to get control when
there is a pending connection so it can do the accept.
After the accept, the callback routine creates a new io watcher for this
new connection with callback routine io_cb for events EV_READ | EV_WRITE.
When io_cb gets control it has nothing to send so it uses ev_io_modify
to turn off EV_WRITE:
ev_io_modify(w, w->events & ~EV_WRITE);
This works in that it doesn't get called anymore for EV_WRITE events,
however an strace shows the program is still issuing poll for both
and continually waking up for the POLLOUT events (100% CPU):
I'm sure I'm misunderstanding something here...
below:
fd 3 is server socket for listen,
fd 4 is the TCP connection
20:45:37.959358 bind(3, {sa_family=AF_INET, sin_port=htons(9000),
sin_addr=inet_addr("0.0.0.0")}, 16) = 0
20:45:37.959409 write(2, "server_addr.sin_addr.s_addr 0000"..., 37) = 37
20:45:37.959465 listen(3, 3) = 0
20:45:37.959715 write(2, "makesock complete, nap 0x55e8934"..., 43) = 43
20:45:37.959778 poll([{fd=3, events=POLLIN}], 1, 59743) = 1 ([{fd=3,
revents=POLLIN}])
20:45:43.768122 write(2, "accept_cb fd 3 data 0x55e8934456"..., 35) = 35
20:45:43.768315 accept(3, {sa_family=AF_INET, sin_port=htons(41458),
sin_addr=inet_addr("127.0.0.1")}, [16]) = 4
20:45:43.768535 write(2, "accept fd 4 client_addr_len orig"..., 43) = 43
20:45:43.768664 write(2, "client IP 127.0.0.1 port 41458\n", 31) = 31
20:45:43.768725 poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN|POLLOUT}], 2,
59743) = 1 ([{fd=4, revents=POLLOUT}])
20:45:43.768792 write(2, "io_cb: w 0x55e893445cd0 revents "..., 46) = 46
20:45:43.768868 write(2, "send_do: w 0x55e893445cd0 revent"..., 36) = 36
20:45:43.768954 write(2, "w->events 3 ~EV_WRITE fffffffd r"..., 40) = 40
20:45:43.769033 write(2, "send_do: removing EV_WRITE\n", 27) = 27
20:45:43.769083 poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN|POLLOUT}], 2,
59743) = 1 ([{fd=4, revents=POLLOUT}])
20:45:43.769130 poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN|POLLOUT}], 2,
59743) = 1 ([{fd=4, revents=POLLOUT}])
20:45:43.769170 poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN|POLLOUT}], 2,
59743) = 1 ([{fd=4, revents=POLLOUT}])
20:45:43.769207 poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN|POLLOUT}], 2,
59743) = 1 ([{fd=4, revents=POLLOUT}])
20:45:43.769241 poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN|POLLOUT}], 2,
59743) = 1 ([{fd=4, revents=POLLOUT}])
_______________________________________________
libev mailing list
[email protected]
http://lists.schmorp.de/mailman/listinfo/libev
