Lua編程示例（八）：生產(chǎn)者-消費者問題

更新時間：2015年07月09日 10:51:36 投稿：junjie

這篇文章主要介紹了Lua編程示例（八）：生產(chǎn)者-消費者問題,本文直接給出實例代碼,需要的朋友可以參考下

這個問題是比較經(jīng)典的啦，基本所有語言的多線程都會涉及到，但是沒想到Lua的這個這么復雜抓狂
看了好長時間才算看明白，先上個邏輯圖：

開始時調(diào)用消費者，當消費者需要值時，再調(diào)用生產(chǎn)者生產(chǎn)值，生產(chǎn)者生產(chǎn)值后停止，直到消費者再次請求。設計為消費者驅(qū)動的設計。
圖畫的不太好，可以先將Filter遮住，它是過濾器對兩個程序之間傳遞的信息進行處理。去掉Filter邏輯就更清晰些了，就是兩個“線程”（其實是兩個協(xié)同程序）互相調(diào)用。resume回到y(tǒng)ield處開始，支持嵌套，返回到棧頂?shù)膟ield位置。yield是非阻塞的“線程同步”。這到有點像linux里的管道通信。

 function receive(prod)
 print("receive is called")
 local status,value = coroutine.resume(prod)
 return value
end

function send(x,prod)
 print("send is called")
 return coroutine.yield(x)
end

function producer()
 return coroutine.create(function ()
 print("producer is called")
 while true do
 print("producer run again")
  local x = io.read()
  send(x)
 end
 end)
end

function filter(prod)
 return coroutine.create(function ()
 for line = 1,1000 do
  print("enter fliter "..line)
  local x = receive(prod)
  print("receive in filter finished")
  x= string.format("%5d %s",line,x)
  send(x,prod)
 end
 end)
end

function consumer(prod)
 print("consumer is called")
 while true do
 print("consumer run again")
 local x = receive(prod)
 print("retrun customer")
 io.write(x,"\n")
 end
end

p = producer()
f=filter(p)
consumer(f)

運行結(jié)果：

consumer is called
consumer run again
receive is called
enter fliter 1
receive is called
producer is called
producer run again
fsy
send is called
receive in filter finished
send is called
retrun customer
  1 fsy
consumer run again
receive is called
enter fliter 2
receive is called
producer run again
gaga
send is called
receive in filter finished
send is called
retrun customer
  2 gaga
consumer run again
receive is called
enter fliter 3
receive is called
producer run again
......

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