Lua 套接字异步调用 [英] Lua socket asynchronous calls

问题描述

我正在编写一个使用 Lua 套接字与 http 服务器通信的程序.我使用的 API 是socket.http.request"，我发现它是同步的.我的理解是它会等到它得到一些响应或超时.我的理解正确吗?如果是这样，我更愿意使用异步 API.

I am writing a program that uses Lua socket to communicate with a http server. The API that I am using is "socket.http.request", and I have found that it is synchronous. My understanding is that it waits until it gets some response or time outs. Is my understanding correct? If so, I'd prefer to use an asynchronous API.

我还发现了另一个APIsocket.http.request_cb"，它在处理请求时调用回调函数.但是，它似乎在这里不起作用.(此 API 在我使用的版本上不可用.)我在这里使用 Lua 5.1 和 Lua socket 2.0.2.谁能告诉我哪个版本的 Lua 或 Lua socket 有这个 API?

I also found another API "socket.http.request_cb", which calls a call back function when the request is processed. However, it doesn't seem to work here. (This API is not available on the version that I'm using.) I'm using Lua 5.1 and Lua socket 2.0.2 here. Could anyone let me know which version of Lua or Lua socket has this API?

推荐答案

使用 connection:settimeout() 您可以设置连接超时.这在 Lua 套接字的并行下载器示例中使用:

With connection:settimeout() you can set a time out for a connection. This is used in this example of a parallel downloader for Lua Socket:

function download (host, file, port)
    port = port or 80
    print (host, file, port)    
    local connectStatus, myConnection = pcall (socket.connect,host,port)
    if (connectStatus) then
        myConnection:settimeout(0.01) -- do not block you can play with this value
        local count = 0 -- counts number of bytes read
        -- May be easier to do this LuaSocket's HTTP functions
        myConnection:send("GET " .. file .. " HTTP/1.0

")
        local lastStatus = nil
        while true do
            local buffer, status, overflow = receive(myConnection, lastStatus)
            -- If buffer is not null the call was a success (changed in LuaSocket 2.0)
            if (buffer ~= nil) then
                 io.write("+")
                 io.flush()
                 count = count + string.len(buffer)
            else
                print ("
"" .. status .. "" with " .. string.len(overflow) .. " bytes of " .. file)
                io.flush()
                count = count + string.len(overflow)
            end
            if status == "closed" then break end
                lastStatus=status
            end
        myConnection:close()
        print(file, count)
    else
        print("Connection failed with error : " .. myConnection)
        io.flush()
    end
end

threads = {} -- list of all live threads

function get (host, file, port)
    -- create coroutine
    local co = coroutine.create(
        function ()
            download(host, file, port)
        end)
    -- insert it in the 
    table.insert(threads, co)
end

function receive (myConnection, status)
    if status == "timeout" then
        print (myConnection, "Yielding to dispatcher")
        io.flush()
        coroutine.yield(myConnection)
    end
    return myConnection:receive(1024)
end

function dispatcher ()
    while true do
        local n = table.getn(threads)
        if n == 0 then break end -- no more threads to run
        local connections = {}
        for i=1,n do
            print (threads[i], "Resuming")
            io.flush()
            local status, res = coroutine.resume(threads[i])
            if not res then -- thread finished its task?
                table.remove(threads, i)
                break
            else -- timeout
                table.insert(connections, res)
            end
        end
        if table.getn(connections) == n then
            socket.select(connections)
        end
    end
end

host = "www.w3.org"
get(host, "/TR/html401/html40.txt")
get(host,"/TR/2002/REC-xhtml1-20020801/xhtml1.pdf")
get(host,"/TR/REC-html32.html")
get(host,"/TR/2000/REC-DOM-Level-2-Core-20001113/DOM2-Core.txt")
dispatcher()

这篇关于Lua 套接字异步调用的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！