在另一个 withContext 中调用一个（kotlin 协程）withContext 是否安全？

Question

我有这个简单的代码片段：

fun setMapIcon(bitmapDescriptor: BitmapDescriptor?, 
               coordinateId:Long?, clickListener: (Double,Double) -> Unit ){
    
lifecycleScope.launchWhenStarted {
      
    withContext(Dispatchers.IO){
         //Do some heavy work that needs many variables
         withContext(Dispatchers.Main){ 
            //Publish variables
         }

         //Do more heavy work
         withContext(Dispatchers.Main){ 
            //Publish more variables
            //call `lambda` clickListener
         } 
      }  
}

Answer 1

如果您担心上述代码会导致任何问题，请放心，语义定义明确，它将按预期工作。至于该不该做，developer.android.com有下文

suspend fun fetchDocs() {                      // Dispatchers.Main
    val result = get("developer.android.com")  // Dispatchers.Main
    show(result)                               // Dispatchers.Main
}

suspend fun get(url: String) =                 // Dispatchers.Main
    withContext(Dispatchers.IO) {              // Dispatchers.IO (main-safety block)
        /* perform network IO here */          // Dispatchers.IO (main-safety block)
    }                                          // Dispatchers.Main
}

withContext() does not add extra overhead compared to an equivalent callback-based implementation. Furthermore, it's possible to optimize withContext() calls beyond an equivalent callback-based implementation in some situations. For example, if a function makes ten calls to a network, you can tell Kotlin to switch threads only once by using an outer withContext(). Then, even though the network library uses withContext() multiple times, it stays on the same dispatcher and avoids switching threads.

在另一个 withContext 中调用一个（kotlin 协程）withContext 是否安全？

Is it safe to call a (kotlin coroutine) withContext within another withContext?

kotlin

kotlin-coroutines