Lua - 使用队列链接协程

使用 Queue 可以大大简化协程的链接，并使它们变得松耦合。一个协程可以将消息发送到队列，而另一个协程可以在队列上等待以读取消息并相应地采取行动。

示例 - 使用队列进行链接

队列将作为协程之间消息的通道，如下所示：

定义队列以及发送/接收操作

-- queue as empty table
local queue = {}

-- send message will add a message to the queue
function send(message)
   table.insert(queue, message)
end

-- to receive a message from Queue
function receive()
   -- if queue has message
   if #queue > 0 then
      -- remove first entry and return the same  
      return table.remove(queue, 1)
   end
   -- yield the current coroutine if queue is empty
   return coroutine.yield() 
end

创建生产者和消费者协程函数

function Producer()
   print("Producer Coroutine started")
   send("Message 1 from producer")
   coroutine.yield() -- yield the producer coroutine
   send("Message 2 from producer")
   print("Producer Coroutine finished")
end

function Consumer()
   print("Consumer started")
   local msg = receive() -- receive a message from queue
   print("Consumer received:", msg)
   coroutine.yield()  -- yield the consumer coroutine
   msg = receive()  -- receive a message from queue
   print("Consumer received:", msg)
   print("Consumer Coroutine finished")
end

创建生产者和消费者协程并启动它们

-- create producer
producer = coroutine.create(Producer)
-- create consumer
consumer = coroutine.create(Consumer)

-- start producer
coroutine.resume(producer)
-- start consumer
coroutine.resume(consumer)
-- resume producer
coroutine.resume(producer)
-- resume consumer
coroutine.resume(consumer)

完整示例 - 链接协程

main.lua

-- queue as empty table
local queue = {}

-- send message will add a message to the queue
function send(message)
   table.insert(queue, message)
end

-- to receive a message from Queue
function receive()
   -- if queue has message
   if #queue > 0 then
      -- remove first entry and return the same  
      return table.remove(queue, 1)
   end
   -- yield the current coroutine if queue is empty
   return coroutine.yield() 
end

function Producer()
   print("Producer Coroutine started")
   send("Message 1 from producer")
   coroutine.yield() -- yield the producer coroutine
   send("Message 2 from producer")
   print("Producer Coroutine finished")
end

function Consumer()
   print("Consumer started")
   local msg = receive() -- receive a message from queue
   print("Consumer received:", msg)
   coroutine.yield()  -- yield the consumer coroutine
   msg = receive()  -- receive a message from queue
   print("Consumer received:", msg)
   print("Consumer Coroutine finished")
end

-- create producer
producer = coroutine.create(Producer)
-- create consumer
consumer = coroutine.create(Consumer)

-- start producer
coroutine.resume(producer)
-- start consumer
coroutine.resume(consumer)
-- resume producer
coroutine.resume(producer)
-- resume consumer
coroutine.resume(consumer)

输出

运行上述代码时，将得到以下输出−

Producer Coroutine started
Consumer started
Consumer received:	Message 1 from producer
Producer Coroutine finished
Consumer received:	Message 2 from producer
Consumer Coroutine finished

解释

• 这里 send() 函数将消息发送到队列。

• receive() 函数从队列检索消息，如果队列为空则让协程 yield。

• Producer 和 Consumer 协程通过队列进行通信。