Fix K/N EvenLoop.reschedule time conversion

[qurbonzoda]

A "point of time" value was wrongly passed to a function that expects a "duration of time". Additionally, the former was in nanos, while the later in milllis.

[qurbonzoda]

I am not sure what is the correct way to test this fix.

[dkhalanskyjb]

I can think of this simple test:

    /** Tests that the delayed tasks scheduled on a closed `runBlocking` event loop get processed in reasonable time. */
    @Test
    fun testReschedulingDelayedTasks() {
        val job = runBlocking {
            val dispatcher = coroutineContext[ContinuationInterceptor]!!
            GlobalScope.launch(dispatcher) {
                delay(1.milliseconds)
            }
        }
        runBlocking {
            withTimeout(10.seconds) {
                job.join()
            }
        }
    }

This would miss the error in the opposite direction (like immediately executing the tasks instead), but testing that is trickier, so maybe let's leave it at that?

A good file for this test could be kotlinx-coroutines-core/concurrent/test/RunBlockingTest.kt.

[qurbonzoda]

Added the test. It failed before the fix and succeeds now.

[dkhalanskyjb]

I don't think that's quite right.

• EventLoopImplBase.DelayedTask has the nanoTime field that tells us when the task has to run.
• now should already be fairly close to nanoTime(). Passing now is a small optimization to avoid requerying nanoseconds all the time.

So, I think the correct version is

Suggested change

	val delayTimeMillis = delayNanosToMillis(nanoTime() - now)
	val delayTimeMillis = delayNanosToMillis(delayedTask.nanoTime - now)

[qurbonzoda]

You are right. I've applied the change.

[dkhalanskyjb]

I can think of this simple test:

    /** Tests that the delayed tasks scheduled on a closed `runBlocking` event loop get processed in reasonable time. */
    @Test
    fun testReschedulingDelayedTasks() {
        val job = runBlocking {
            val dispatcher = coroutineContext[ContinuationInterceptor]!!
            GlobalScope.launch(dispatcher) {
                delay(1.milliseconds)
            }
        }
        runBlocking {
            withTimeout(10.seconds) {
                job.join()
            }
        }
    }

This would miss the error in the opposite direction (like immediately executing the tasks instead), but testing that is trickier, so maybe let's leave it at that?

A good file for this test could be kotlinx-coroutines-core/concurrent/test/RunBlockingTest.kt.

[dkhalanskyjb]

Thanks!