Pre-sul, checking for interval to next pending scheduled event was expensive and
iterative, so the service avoided it if the wait was already 0.
With sul though, the internal "check" function also services ripe events and
removes them, and finding the interval to the next one is really cheap.
Rename the "check" function to __lws_sul_service_ripe() to make it clear it's
not just about returning the interval to the next pending one. And call it
regardless of if we already decided we are not going to wait in the poll.
After https://github.com/warmcat/libwebsockets/pull/1745
wsi timeout, wsi hrtimer, sequencer timeout and vh-protocol timer
all now participate on a single sorted us list.
The whole idea of polling wakes is thrown out, poll waits ignore the
timeout field and always use infinite timeouts.
Introduce a public api that can schedule its own callback from the event
loop with us resolution (usually ms is all the platform can do).
Upgrade timeouts and sequencer timeouts to also be able to use us resolution.
Introduce a prepared fakewsi in the pt, so we don't have to allocate
one on the heap when we need it.
Directly handle vh-protocol timer if LWS_MAX_SMP == 1
Adapt service loops and event libs to use microsecond waits
internally, for hrtimer and sequencer. Reduce granularity
according to platform / event lib wait.
Add a helper so there's a single place to extend it.
Until now the uv watcher has been composed in the wsi.
This works fine except in the case of a client wsi that
meets a redirect when the event loop is libuv with its
requirement for handle close via the event loop.
We want to reuse the wsi, since the originator of it has
a copy of the wsi pointer, and we want to conceal the
redirect. Since the redirect is commonly to a different
IP, we want to keep the wsi alive while closing its
socket cleanly. That's not too difficult, unless you are
using uv.
With UV the comoposed watcher is a disaster, since after
the close is requested the wsi will start to reconnect.
We tried to deal with that by copying the uv handle and
freeing it when the handle close finalizes. But it turns
out the handle is in a linked-list scheme in uv.
This patch hopefully finally solves it by giving the uv
handle its own allocation from the start. When we want
to close the socket and reuse the wsi, we simply take
responsibility for freeing the handle and set the wsi
watcher pointer to NULL.
