操作演示

生产者消费者模型
一个Promise 只有一个future
Promise只能给future确认一次结果

简单上手

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import scala.concurrent.ExecutionContext.Implicits.global

val countDownLatch = new CountDownLatch(1)
val p = Promise[Int]()
val f1 = p.future

// 生产者线程
val t1_provider = new Thread(() => {
TimeUnit.SECONDS.sleep(2)
println("do some thing - provider")
p.success(888) // fature的返回值
// p.failure(new NullPointerException)
println("do some thing - provider")
})
t1_provider.start()
// 消费者线程
val t2_consumer = new Thread(() => {
TimeUnit.SECONDS.sleep(1)
println("do some thing - consumer")
f1.onComplete(zz => zz match {
  case Success(result) => {
    println(s"future result -- ${result}")
    countDownLatch.countDown()
  }
  case Failure(exception) =>
})

println("do some thing - consumer")
})
t2_consumer.start()

countDownLatch.await()
println("main -- done")

运行结果

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do some thing - consumer
do some thing - consumer
do some thing - provider
do some thing - provider
future result -- 888
main -- done