net.server: Fall back to default backend from libevent instead of always select
Fixes that selecting libevent when unavaibalbe would fall back to select
instead of epoll, even if that's available.
This way, we only have to update it in once place when choosing a new
default.
local data = {}
local getinfo = debug.getinfo;
local function linehook(ev, li)
local S = getinfo(2, "S");
if S and S.source and S.source:match"^@" then
local file = S.source:sub(2);
local lines = data[file];
if not lines then
lines = {};
data[file] = lines;
for line in io.lines(file) do
lines[#lines+1] = line;
end
end
io.stderr:write(ev, " ", file, " ", li, " ", lines[li], "\n");
end
end
debug.sethook(linehook, "l");