External poll support generates a lot of messages on a busy system
for no value unless you're one of the few people using it. It's
not recommended for new users and is there for backwards compatibility.
Make it not built by default and selectable by cmake option.
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
lws_dll2 removes the downsides of lws_dll and adds new features like a
running member count and explicit owner type... it's cleaner and more
robust (eg, nodes know their owner, so they can casually switch between
list owners and remove themselves without the code knowing the owner).
This deprecates lws_dll, but since it's public it allows it to continue
to be built for 4.0 release if you give cmake LWS_WITH_DEPRECATED_LWS_DLL.
All remaining internal users of lws_dll are migrated to lws_dll2.
The logic in the loops for insertion and deletion from the
mini, forced to non ulimit max fds in the pt mode was not
quite right.
It showed up in hard to reproduce problem with the ws client
spam test that uses the mini mode, on travis. This should
fix the root cause.
An lws context usually contains a processwide fd -> wsi lookup table.
This allows any possible fd returned by a *nix type OS to be immediately
converted to a wsi just by indexing an array of struct lws * the size of
the highest possible fd, as found by ulimit -n or similar.
This works modestly for Linux type systems where the default ulimit -n for
a process is 1024, it means a 4KB or 8KB lookup table for 32-bit or
64-bit systems.
However in the case your lws usage is much simpler, like one outgoing
client connection and no serving, this represents increasing waste. It's
made much worse if the system has a much larger default ulimit -n, eg 1M,
the table is occupying 4MB or 8MB, of which you will only use one.
Even so, because lws can't be sure the OS won't return a socket fd at any
number up to (ulimit -n - 1), it has to allocate the whole lookup table
at the moment.
This patch looks to see if the context creation info is setting
info->fd_limit_per_thread... if it leaves it at the default 0, then
everything is as it was before this patch. However if finds that
(info->fd_limit_per_thread * actual_number_of_service_threads) where
the default number of service threads is 1, is less than the fd limit
set by ulimit -n, lws switches to a slower lookup table scheme, which
only allocates the requested number of slots. Lookups happen then by
iterating the table and comparing rather than indexing the array
directly, which is obviously somewhat of a performance hit.
However in the case where you know lws will only have a very few wsi
maximum, this method can very usefully trade off speed to be able to
avoid the allocation sized by ulimit -n.
minimal examples for client that can make use of this are also modified
by this patch to use the smaller context allocations.
