So the `Thread.sleep` isn't blocking its suspendin...

# vertx

[asad.awadia]

So the Thread.sleep isn't blocking its suspending the coroutine?

[dave08]

Run an asynchronous [block] on a worker threads and awaits the result.
*
* The [block] is executed and should return an object or throw an exception.
*
* - when an object is returned, it is returned from the awaitBlocking call
* - when an exception is thrown, it is thrown from the awaitBlocking call
*
*

* val s = awaitBlocking {
 *   Thread.sleep(1000)
 *   "some-string"
 * }
 *

*
* The coroutine will be suspend until the block is executed, this action do not block vertx's eventLoop.
*

From the function docs... it blocks its thread in a worker thread, it just doesn't block the event loop. Of course, it's always better to use delay for that, only non-async long running computations should be run on workers

[dave08]

What 'will be suspend' means is on the event loop, but the actual operation is blocking the worker with the sleep

[asad.awadia]

so the 'move' from event loop to worker thread is done under the hood?

[dave08]

Here's the implementation

suspend fun <T> awaitBlocking(block: () -> T) : T {
  return awaitResult<T> { handler ->
    val ctx = Vertx.currentContext()
    ctx.executeBlocking<T>({ fut ->
      fut.complete(block())
    }, { ar ->
      handler.handle(ar)
    })
  }
}

[dave08]

From https://github.com/vert-x3/vertx-lang-kotlin/blob/master/vertx-lang-kotlin-coroutines/src/main/kotlin/io/vertx/kotlin/coroutines/VertxCoroutine.kt