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(shè)計為消費者驅(qū)動的設(shè)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)
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
......
