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Added forward server.
This commit is contained in:
Diego Nehab
parent
7350bad6f4
commit
b18021e22d
229
samples/forward.lua
Normal file
229
samples/forward.lua
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-- load our favourite library
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local socket = require"socket"
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-- timeout before an inactive thread is kicked
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local TIMEOUT = 10
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-- local address to bind to
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local ihost, iport = arg[1] or "localhost", arg[2] or 8080
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-- address to forward all data to
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local ohost, oport = arg[3] or "localhost", arg[4] or 3128
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-- creates a new set data structure
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function newset()
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local reverse = {}
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local set = {}
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return setmetatable(set, {__index = {
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insert = function(set, value)
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if not reverse[value] then
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table.insert(set, value)
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reverse[value] = table.getn(set)
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end
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end,
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remove = function(set, value)
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local index = reverse[value]
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if index then
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reverse[value] = nil
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local top = table.remove(set)
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if top ~= value then
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reverse[top] = index
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set[index] = top
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end
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end
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end
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}})
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end
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local receiving = newset()
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local sending = newset()
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local context = {}
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-- starts a non-blocking connect
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function nconnect(host, port)
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local peer, err = socket.tcp()
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if not peer then return nil, err end
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peer:settimeout(0)
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local ret, err = peer:connect(host, port)
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if ret then return peer end
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if err ~= "timeout" then
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peer:close()
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return nil, err
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end
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return peer
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end
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-- gets rid of a client
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function kick(who)
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if who == server then error("FUDEU") end
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if context[who] then
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sending:remove(who)
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receiving:remove(who)
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context[who] = nil
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who:close()
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end
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end
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-- decides what to do with a thread based on coroutine return
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function route(who, status, what)
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print(who, status, what)
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if status and what then
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if what == "receiving" then receiving:insert(who) end
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if what == "sending" then sending:insert(who) end
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else kick(who) end
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end
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-- loops accepting connections and creating new threads to deal with them
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function accept(server)
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while true do
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print(server, "accepting a new client")
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-- accept a new connection and start a new coroutine to deal with it
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local client = server:accept()
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if client then
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-- start a new connection, non-blockingly, to the forwarding address
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local peer = nconnect(ohost, oport)
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if peer then
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context[client] = {
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last = socket.gettime(),
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thread = coroutine.create(forward),
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peer = peer,
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}
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-- make sure peer will be tested for writing in the next select
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-- round, which means the connection attempt has finished
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sending:insert(peer)
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context[peer] = {
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peer = client,
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thread = coroutine.create(check),
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last = socket.gettime()
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}
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-- put both in non-blocking mode
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client:settimeout(0)
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peer:settimeout(0)
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else
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-- otherwise just dump the client
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client:close()
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end
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end
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-- tell scheduler we are done for now
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coroutine.yield("receiving")
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end
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end
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-- forwards all data arriving to the appropriate peer
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function forward(who)
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while true do
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print(who, "getting data")
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-- try to read as much as possible
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local data, rec_err, partial = who:receive("*a")
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-- if we had an error other than timeout, abort
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if rec_err and rec_err ~= "timeout" then return error(rec_err) end
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-- if we got a timeout, we probably have partial results to send
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data = data or partial
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print(who, " got ", string.len(data))
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-- renew our timestamp so scheduler sees we are active
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context[who].last = socket.gettime()
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-- forward what we got right away
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local peer = context[who].peer
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while true do
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-- tell scheduler we need to wait until we can send something
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coroutine.yield("sending")
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local ret, snd_err
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local start = 0
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print(who, "sending data")
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ret, snd_err, start = peer:send(data, start+1)
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if ret then break
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elseif snd_err ~= "timeout" then return error(snd_err) end
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-- renew our timestamp so scheduler sees we are active
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context[who].last = socket.gettime()
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end
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-- if we are done receiving, we are done with this side of the
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-- connection
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if not rec_err then return nil end
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-- otherwise tell schedule we have to wait for more data to arrive
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coroutine.yield("receiving")
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end
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end
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-- checks if a connection completed successfully and if it did, starts
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-- forwarding all data
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function check(who)
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local ret, err = who:connected()
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if ret then
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print(who, "connection completed")
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receiving:insert(context[who].peer)
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context[who].last = socket.gettime()
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print(who, "yielding until there is input data")
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coroutine.yield("receiving")
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return forward(who)
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else return error(err) end
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end
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-- initializes the forward server
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function init()
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-- socket sets to test for events
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-- create our server socket
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server = assert(socket.bind(ihost, iport))
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server:settimeout(0.1) -- we don't want to be killed by bad luck
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-- we initially
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receiving:insert(server)
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context[server] = { thread = coroutine.create(accept) }
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end
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-- loop waiting until something happens, restarting the thread to deal with
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-- what happened, and routing it to wait until something else happens
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function go()
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while true do
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print("will select for readability")
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for i,v in ipairs(receiving) do
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print(i, v)
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end
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print("will select for writability")
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for i,v in ipairs(sending) do
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print(i, v)
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end
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-- check which sockets are interesting and act on them
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readable, writable = socket.select(receiving, sending, 3)
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print("returned as readable")
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for i,v in ipairs(readable) do
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print(i, v)
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end
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print("returned as writable")
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for i,v in ipairs(writable) do
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print(i, v)
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end
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-- for all readable connections, resume its thread and route it
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for _, who in ipairs(readable) do
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receiving:remove(who)
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if context[who] then
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route(who, coroutine.resume(context[who].thread, who))
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end
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end
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-- for all writable connections, do the same
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for _, who in ipairs(writable) do
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sending:remove(who)
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if context[who] then
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route(who, coroutine.resume(context[who].thread, who))
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end
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end
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-- put all inactive threads in death row
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local now = socket.gettime()
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local deathrow
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for who, data in pairs(context) do
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if data.last then
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print("hung for" , now - data.last, who)
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if now - data.last > TIMEOUT then
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-- only create table if someone is doomed
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deathrow = deathrow or {}
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deathrow[who] = true
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end
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end
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end
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-- finally kick everyone in deathrow
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if deathrow then
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print("in death row")
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for i,v in pairs(deathrow) do
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print(i, v)
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end
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for who in pairs(deathrow) do kick(who) end
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end
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end
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end
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go(init())
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