Coroutines As Connection Handlers

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This shows the basic scaffolding one might use for handling multiple sockets (e.g. TCP or otherwise) via coroutines. (The actual socket code is omitted for brevity.) To avoid writing this scaffolding you might alternately use the Copas library as shown in CopasExample.

function read()

    return coroutine.yield()

end



function write_socket(socket, data)

    print("i'm writing to socket " .. socket .. ": " .. data)

end



function connection_handler(socket)

    write_socket(socket, "hi!")

    local input = read()

    write_socket(socket, "the input was: " .. input)

    local input = read()

    write_socket(socket, "even more input was: " .. input)

    if socket == 2 then

       error("example error in socket 2")

    end

end



function create_connection_handler(socket)

    local handler = coroutine.create(connection_handler)

    coroutine.resume(handler, socket)

    return handler

end



connections = {}



function accept_connection(socket)

    print("accepted socket " .. socket)

    connections[socket] = create_connection_handler(socket)

end



function close_connection(socket)

    connections[socket] = nil

    -- close your socket here

    print("socket " .. socket .. " closed")

end



function handle_socket_data(socket, data)

    local ok, msg = coroutine.resume(connections[socket], data)

    if not ok then

        print("the handler for socket " .. socket .. " failed: " .. msg)

        close_connection(socket)

    elseif ok and coroutine.status(connections[socket]) == "dead" then

        print("the handler for socket " .. socket .. " finished")

        close_connection(socket)

    end

end



-- In a real application, these will be created after you 

-- accept()ed a new connection

accept_connection(1)

accept_connection(2)

accept_connection(3)



-- In a real application, you'll use some dispatcher to read 

-- data from sockets and then call handle_socket_data.



-- Data on socket 1

handle_socket_data(1, "here is some data")



-- Data on socket 2

handle_socket_data(2, "here is data for socket 2")



-- More Data on socket 1

handle_socket_data(1, "wow. more data")



-- hm. socket 3 was closed by the user

close_connection(3)



-- Data on socket 2

handle_socket_data(2, "ok. enough :)")

Coroutines As Connection Handlers

See Also