我正在研究面向过程的编程课程中的一个项目。
我试图在协程中启动两个对象(生产者和消费者),然后让生产者消费。然后我告诉主函数等待协程完成 Job.join()。但是,这似乎不起作用。因为 invokeOnCompletion 函数是在生产/消费周期开始之前执行的。我在下面包含了代码和输出,希望有任何输入。
这是面向过程的编程课程中的项目。最终目标是生成多个对象实例并让它们使用通道进行通信。我以前从未在 kotlin 中编写过代码,也从未使用过协程。这甚至可能吗,还是我误解了协程?
class Producer(val idvar: Int) {
var resource: Int = 10
init {
println("${idvar} was created.")
}
suspend fun getConsumed(channel: Channel<Int>) = produce<Int> {
println("Someone is trying to consume me...")
while(true) {
channel.send(1)
resource--
println("I have ${resource} things left.")
if(resource <= 0) {
break
}
var sleep = ((Random().nextDouble())*1000).toLong()
println("sleeping for ${sleep} ms")
delay(1000)
}
println("I'm used up! I have ${resource} resources.")
}
}
class Consumer() {
var resource: Int = 0
suspend fun consume(producer: Producer?, channel: Channel<Int>) = produce<Int> {
println("Trying to consume producer: ${producer?.resource}")
producer?.getConsumed(channel)
while(true) {
var recv = channel.receive()
if(recv == 0) break
resource += recv
}
println("Consumed in total: " + resource)
}
}
fun main(args: Array<String>) = runBlocking<Unit> {
val prodJob = launch {
var prodObj: Producer = Producer(1)
var consumObj: Consumer = Consumer()
val chan = Channel<Int>()
consumObj.consume(prodObj, chan)
// Why does this println print before the above line is complete?
println("Comsumption done.")
}
// invokeOnCompletion is executed before production/consumption is done?
prodJob.invokeOnCompletion { println("Consumption is done?") }
// Main could do other stuff here.
// Since prodJob is regarded as complete, main joins instantly.
prodJob.join()
println("Joined...")
}
输出是:
1 was created.
Comsumption done.
Trying to consume producer: 10
Consumption is done?
Someone is trying to consume me...
I have 9 things left.
sleeping for 310 ms
Joined...