Trying to write a lua server...

[i_love2d_you]

Hi! This question isn't specific to LOVE, but I'm not sure where else to look.

I've been trying to do some basic networking in lua with luasocket.

I have a basic server set up, but I can't figure out how settimeout() works.

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function Server:run()
    print("Running.")
    self.running = true
    while self.running do
        if self.client == nil then
            print("Waiting for client.")
            self.client = self.server:accept()
            print("Client connected.")
            self.client:settimeout(10)
        end
        local line, err = self.client:receive()
        if err then
            print("Error: " .. err)
        elseif line == "quit" then
            print("Quitting.")
            self.client:close()
            self.running = false        
        else
            print("Received: " .. line)
        end
    end
    self:terminate()
end

I expect the program to get to self.client:receive() and then wait there until it either gets a message from the client or times out after 10 seconds. However, this is not the behaviour I experience.

Instead, I just get a constant spamming of the error message "Error: timeout" as though the program is not waiting at all.

[Positive07]

...

I expect the program to get to self.client:receive() and then wait there until it either gets a message from the client or times out after 10 seconds. However, this is not the behaviour I experience.

Instead, I just get a constant spamming of the error message "Error: timeout" as though the program is not waiting at all.

Well luasocket tries to receive, and after 10 seconds it timesout... so that's an error in the reception right? luasocket returns "false" followed by the error message... and the error was "timeout", so in your code you do:

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local line, err = self.client:receive()
        if err then
            print("Error: " .. err)
        elseif line == "quit" then
            print("Quitting.")
            self.client:close()
            self.running = false        
        else
            print("Received: " .. line)
        end
    end

err has a value ("timeout") so the first part executes and prints "Error: timeout". Is that your problem?
You can just ignore timeout errors by doing

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local line, err = self.client:receive()
        if err and err ~= "timeout" then
            print("Error: " .. err)
        elseif line == "quit" then
            print("Quitting.")
            self.client:close()
            self.running = false        
        else
            print("Received: " .. line)
        end
    end

Also I dont recommend setting the timeout of the client but the server instead so I would do

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self.server:settimeout(10)

I hope that helps you.

[i_love2d_you]

Thanks for the reply, but I'm not sure I follow.

When I call this line:

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local line, err = self.client:receive()

I expect it to wait 10 seconds before it times out. But it doesn't. It doesn't wait any time at all.

The guide on their site says to use client:settimeout(). Setting server:settimeout() did nothing for me (it never times out).

[Positive07]

I have a question, is this timeout needed? your code doesnt quit when it times out, it tries to receive again.
After it timesout it prints the error and then "while self.running do" will be true so it will do everything again.
So if timeout does nothing more than a print you can just ignore it...

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if err and err ~= "timeout" then

If you are doing this with love you can implement your own timeout using dt/love.timer.getDelta()

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love.update = function (dt)
   time = time or 0 + dt
        if time < 10 do
             self.client:receive()
        else
             print ("Error: timeout")
        end
end

or something like that

[bartbes]

I would like to mention you're checking for errors wrong, you should check the truthiness of line, not of err. That said, unless luasocket is acting really weirdly, that shouldn't matter.