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-----------------------------------------------------------------------------
-- Select implementation
-- LuaSocket toolkit.
-- Author: Diego Nehab
-- RCS ID: $Id: select.lua,v 1.5 2003/06/26 18:47:47 diego Exp $
-----------------------------------------------------------------------------
----------------------------------------------------------------------
-- Copy fds from tab to set, creating fd_tab association table.
----------------------------------------------------------------------
local function collect_fd(obj_tab, fd_set, fd_tab)
for i, obj in ipairs(obj_tab) do
local fd = obj:fd()
fd_set:set(fd)
fd_tab[fd] = obj
end
return fd_set
end
----------------------------------------------------------------------
-- Copy socks from set to tab, using fd_tab association table.
----------------------------------------------------------------------
local function collect_obj(fd_set, max_fd, obj_tab, fd_tab)
for fd = 0, max_fd do
if fd_set:isset(fd) then
table.insert(obj_tab, fd_tab[fd])
end
end
end
----------------------------------------------------------------------
-- Treat objects with unread buffered data
----------------------------------------------------------------------
local function check_dirty(obj_tab, dirty, fd_tab)
local any = false
for i, obj in ipairs(obj_tab) do
if obj:dirty() then
table.insert(dirty, obj)
fd_tab[obj:fd()] = nil
any = true
end
end
return any
end
----------------------------------------------------------------------
-- Lua select helper
----------------------------------------------------------------------
return function(read_obj_tab, write_obj_tab, timeout,
read_fd_set, write_fd_set, c_select)
local fd_tab = {}
local readable, writable = {}, {}
read_obj_tab = read_obj_tab or {}
write_obj_tab = write_obj_tab or {}
-- build read_fd_set from from read_obj_tab and build write_fd_set
-- from write_obj_tab. create fd_tab mapping fd values to their
-- corresponding objects.
collect_fd(read_obj_tab, read_fd_set, fd_tab)
collect_fd(write_obj_tab, write_fd_set, fd_tab)
-- if there are any sockets being tested for readability that
-- have buffered data unread, move them to readable table and
-- set timeout to 0
local dirty = check_dirty(read_obj_tab, readable, fd_tab)
if dirty then timeout = 0 end
-- compute the maximum fd value
local max_fd = -1
for fd, obj in fd_tab do
if fd > max_fd then
max_fd = fd
end
end
-- call C select
local ret = c_select(max_fd+1, read_fd_set, write_fd_set, timeout)
if ret > 0 then
-- collect readable and writable sockets from fd sets to
-- readable and writable object tables
collect_obj(read_fd_set, max_fd, readable, fd_tab)
collect_obj(write_fd_set, max_fd, writable, fd_tab)
ret = nil
elseif dirty then ret = nil
else ret = "timeout" end
return readable, writable, ret
end
|
