Fixed cancellation of runBlocking event loon in the presence of delay (#589)

* Fixed cancellation of runBlocking event loon in the presence of delay

Fixes #586

Author: elizarov

core/kotlinx-coroutines-core/src/EventLoop.kt

@@ -106,7 +106,13 @@ internal abstract class EventLoopBase: CoroutineDispatcher(), Delay, EventLoop {
 
     private val nextTime: Long
         get() {
-            if (!isQueueEmpty) return 0
+            val queue = _queue.value
+            when {
+                queue === null -> {} // empty queue -- proceed
+                queue is Queue<*> -> if (!queue.isEmpty) return 0 // non-empty queue
+                queue === CLOSED_EMPTY -> return Long.MAX_VALUE // no more events -- closed
+                else -> return 0 // non-empty queue
+            }
             val delayed = _delayed.value ?: return Long.MAX_VALUE
             val nextDelayedTask = delayed.peek() ?: return Long.MAX_VALUE
             return (nextDelayedTask.nanoTime - timeSource.nanoTime()).coerceAtLeast(0)

core/kotlinx-coroutines-core/test/RunBlockingTest.kt

@@ -42,7 +42,7 @@ class RunBlockingTest : TestBase() {
             runBlocking(coroutineContext) {
                 expect(3)
                 // still same event loop
-                assertTrue(coroutineContext[ContinuationInterceptor] === outerEventLoop)
+                assertSame(coroutineContext[ContinuationInterceptor], outerEventLoop)
                 yield() // still works
                 expect(4)
             }
@@ -58,7 +58,7 @@ class RunBlockingTest : TestBase() {
         val thread = newSingleThreadContext(name)
         runBlocking(thread) {
             expect(2)
-            assertTrue(coroutineContext[ContinuationInterceptor] === thread)
+            assertSame(coroutineContext[ContinuationInterceptor], thread)
             assertTrue(Thread.currentThread().name.contains(name))
             yield() // should work
             expect(3)
@@ -82,4 +82,25 @@ class RunBlockingTest : TestBase() {
             job.cancelAndJoin()
         }
     }
-}
+
+    @Test
+    fun testCancelWithDelay() {
+        // see https://github.com/Kotlin/kotlinx.coroutines/issues/586
+        try {
+            runBlocking {
+                expect(1)
+                coroutineContext.cancel()
+                expect(2)
+                try {
+                    delay(1)
+                    expectUnreached()
+                } finally {
+                    expect(3)
+                }
+            }
+            expectUnreached()
+        } catch (e: JobCancellationException) {
+            finish(4)
+        }
+    }
+}