在kotlin coroutines doc中,它解释了“ runBlocking和coroutineScope之间的差异”:
范围生成器
除了不同构建器提供的协程作用域之外,还可以使用coroutineScope构建器声明自己的作用域。它创建一个协程范围,直到所有启动的子级都完成后才完成。
The main difference between runBlocking and coroutineScope is that the latter does not block the current thread while waiting for all children to complete
。
我不太明白,示例代码显示
import kotlinx.coroutines.*
fun main() = runBlocking { // this: CoroutineScope
launch {
delay(200L)
println("+++Task from runBlocking")
}
coroutineScope { // Creates a coroutine scope
launch {
delay(500L)
println("+++Task from nested launch")
}
delay(100L)
println("+++ Task from coroutine scope") // This line will be printed before the nested launch
}
println("+++ Coroutine scope is over") // This line is not printed until the nested launch completes
}
日志:
2019-05-16 10:47:45.107 12239-12239 +++ before enter runBlocking{}
2019-05-16 10:47:45.219 12239-12239 +++ Task from coroutine scope
2019-05-16 10:47:45.320 12239-12239 +++ Task from runBlocking
2019-05-16 10:47:45.620 12239-12239 +++ Task from nested launch
2019-05-16 10:47:45.621 12239-12239 +++ ---after exit runBlocking{}
并且+++ Task from nested launch
是演出结束后+++ Task from runBlocking
如预期,因为它拥有500L的延迟。
但是,如果launch
在该coroutineScop{}
块之后添加一些其他构建器,则结果令人困惑。
这里launch
在coroutineScop{}
延迟30L和100L之后添加了两个。
我期望看到30L
延迟日志应在之前的300L
延迟日志中显示coroutineScop{}
,但在所有launch
内部日志完成之后才显示coroutineScop{}
fun testCoroutines() {
Log.e("+++", "+++ enter testCoroutines_3")
runBlocking {
launch {
println("+++ start Task from runBlocking, with 200L delay")
delay(200L)
println("+++ end Task from runBlocking, with 200L delay")
}
launch {
println("+++ start Task from runBlocking, with 50L delay")
delay(50L)
println("+++ end Task from runBlocking, with 50L delay")
}
launch {
println("+++ start Task from runBlocking, with 70L delay")
delay(70L)
println("+++ end Task from runBlocking, with 70L delay")
}
coroutineScope {
println("+++ enter Task from coroutineScope")
// Creates a coroutine scope
launch {
Log.v("+++", "+++ === start Task from nested launch, 500L")
delay(500L)
Log.v("+++", "+++ --- end Task from nested launch, 500L")
}
delay(100L)
println("+++ in Task from coroutineScope after delay(100L)")
launch {
Log.v("+++", "+++ === start Task from nested launch, 300L")
delay(300L)
Log.v("+++", "+++ --- end Task from nested launch, 300L")
}
println("+++ --- exit Task from coroutine scope") // This line will be printed before the nested launch
}
launch {
println("+++ start Task from runBlocking, with 30L delay")
delay(30L)
println("+++ end Task from runBlocking, with 30L delay")
}
launch {
println("+++ start Task from runBlocking, with 100L delay")
delay(100L)
println("+++ end Task from runBlocking, with 100L delay")
}
}
Log.e("+++", "--- exit testCoroutines_3 scope is over") // This line is not printed until the nested launch completes
}
日志:
10:35:05.819 4657-4657 +++ enter testCoroutines_3
10:35:05.828 4657-4657 +++ enter Task from coroutineScope
10:35:05.833 4657-4657 +++ start Task from runBlocking, with 200L delay
10:35:05.833 4657-4657 +++ start Task from runBlocking, with 50L delay
10:35:05.833 4657-4657 +++ start Task from runBlocking, with 70L delay
10:35:05.834 4657-4657 +++ === start Task from nested launch, 500L
10:35:05.885 4657-4657 +++ end Task from runBlocking, with 50L delay
10:35:05.905 4657-4657 +++ end Task from runBlocking, with 70L delay
10:35:05.932 4657-4657 +++ in Task from coroutineScope after delay(100L)
10:35:05.933 4657-4657 +++ --- exit Task from coroutine scope
10:35:05.935 4657-4657 +++ === start Task from nested launch, 300L
10:35:06.034 4657-4657 +++ end Task from runBlocking, with 200L delay
10:35:06.235 4657-4657 +++ --- end Task from nested launch, 300L
10:35:06.334 4657-4657 +++ --- end Task from nested launch, 500L
10:35:06.335 4657-4657 +++ start Task from runBlocking, with 30L delay
10:35:06.335 4657-4657 +++ start Task from runBlocking, with 100L delay
10:35:06.366 4657-4657 +++ end Task from runBlocking, with 30L delay
10:35:06.436 4657-4657 +++ end Task from runBlocking, with 100L delay
10:35:06.437 4657-4657--- exit testCoroutines_3 scope is over
我认为至少+++ start Task from runBlocking, with 30L delay
应该在+++ === start Task from nested launch, 500L
之前和之后出现+++ end Task from runBlocking, with 50L delay
,但是不会,毕竟launch
在之后才出现+++ --- end Task from nested launch, 500L
。
coroutineScope
协同程序中的功能是什么?
(我正在使用android应用程序进行测试,只需点击一下按钮即可调用testCoroutines
)
两者都是对的,runBlocking
并且coroutineScope
直到它们中所有的协程都完成后它们才完成。
注意将“直到完成”和“直到阻塞调用线程”区分开。runBlocking
是唯一做后者的人。
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