Signed-off-by: Avi Kivity <avi@cloudius-systems.com>

Signed-off-by: Avi Kivity <avi@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

To prevent leaks when a file is close()d without an EPOLL_CTL_DEL,
record epoll registrations in the file structure and remove them
when the file is destroyed.

Signed-off-by: Avi Kivity <avi@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Holding filerefs causes close() to be delayed indefinitly in case
the user "forgets" to EPOLL_CTL_DEL the file before close().

Signed-off-by: Avi Kivity <avi@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Instead of using file descriptors and poll(), use do_poll().  This allows
us to get rid of user supplied fds early, which is important as fd lifetime
is decoupled from epoll lifetime.

Signed-off-by: Avi Kivity <avi@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Ignoring EPOLLET will generate more wakeups, but should work with most
applications.

Signed-off-by: Avi Kivity <avi@cloudius-systems.com>

It's a superset of epoll_create(), so implement the latter in terms of the
former.

Signed-off-by: Avi Kivity <avi@cloudius-systems.com>

Added Cloudius copyright statement to core/*.

poll.cc already had a BSD copyright statement, I believe this is a mistake
(I think Guy wrote this code from scratch), but not wanting to rush to a
conclusion I'm leaving both copyright statements and we should address this
issue later.

We can't include osv/poll.h from osv/file.h. It's not needed there,
and causes a mess now that I added a use of BSD's "struct mtx" to
poll.h (because it turns out we have code using <osv/file.h> and using
the name "mtx" for something else).

After removing the unneeded include of <osv/poll.h> from osv/file.h,
we need to add include <sys/poll.h> to a few additional source files
(note include of sys/poll.h, not osv/poll.h).

Replace debug() messages in epoll with useful tracepoints.

epoll and poll() use different event names (e.g., EPOLLIN vs. POLLIN),
but in practice the bits are identical. Make this conversion more
explicit, and add static_assert()s that the bits are indeed identical.

We still have dynamic assert() that the bits we don't support -
EPOLLET (for edge triggered behavior) and EPOLLONESHOT - aren't
used.

This patch only makes the code cleaner, but doesn't change anything
in its behavior.`

The "events", not "revents", field of the poll structure needs to be set
before calling poll().

This is an epoll_*() implementation which calls poll() to do the real work.
This is of course a terrible implementation, which makes epoll() less
efficient, instead of more efficient, then poll(). However, it allows me
to progress with running Jetty in parallel with perfecting epoll.