Properly report exception in future builders if thrown exception is racing with external cancellation or completion

Author: qwwdfsad

integration/kotlinx-coroutines-guava/src/ListenableFuture.kt

@@ -70,7 +70,9 @@ private class ListenableFutureCoroutine<T>(
     }
 
     override fun onCompletedExceptionally(exception: Throwable) {
-        completion.setException(exception)
+        if (!completion.setException(exception)) {
+            handleCoroutineException(parentContext, exception, this)
+        }
     }
 }
 

integration/kotlinx-coroutines-guava/test/ListenableFutureTest.kt

@@ -300,6 +300,22 @@ class ListenableFutureTest : TestBase() {
         finish(3)
     }
 
+    @Test
+    fun testExceptionOnExternalCancellation() = runTest(expected = {it is TestException}) {
+        expect(1)
+        val result = future(Dispatchers.Unconfined) {
+            try {
+                delay(Long.MAX_VALUE)
+            } finally {
+                expect(2)
+                throw TestException()
+            }
+        }
+
+        result.cancel(true)
+        finish(3)
+    }
+
     private inline fun <reified T: Throwable> ListenableFuture<*>.checkFutureException(vararg suppressed: KClass<out Throwable>) {
         val e = assertFailsWith<ExecutionException> { get() }
         val cause = e.cause!!

integration/kotlinx-coroutines-jdk8/src/future/Future.kt

@@ -58,7 +58,9 @@ private class CompletableFutureCoroutine<T>(
     }
 
     override fun onCompletedExceptionally(exception: Throwable) {
-        completion.completeExceptionally(exception)
+        if (!completion.completeExceptionally(exception)) {
+            handleCoroutineException(parentContext, exception, this)
+        }
     }
 }
 

integration/kotlinx-coroutines-jdk8/test/future/FutureTest.kt

@@ -411,6 +411,22 @@ class FutureTest : TestBase() {
         finish(3)
     }
 
+    @Test
+    fun testExceptionOnExternalCompletion() = runTest(expected = {it is TestException}) {
+        expect(1)
+        val result = future(Dispatchers.Unconfined) {
+            try {
+                delay(Long.MAX_VALUE)
+            } finally {
+                expect(2)
+                throw TestException()
+            }
+        }
+
+        result.complete(Unit)
+        finish(3)
+    }
+
     private inline fun <reified T: Throwable> CompletableFuture<*>.checkFutureException(vararg suppressed: KClass<out Throwable>) {
         val e = assertFailsWith<ExecutionException> { get() }
         val cause = e.cause!!