[ONOS-6267] Detect and complete blocked futures on I/O threads.

Change-Id: I0488dc5096f9e610b97405ad05c02d0ff3854b5f
diff --git a/utils/misc/src/test/java/org/onlab/util/BestEffortSerialExecutorTest.java b/utils/misc/src/test/java/org/onlab/util/BestEffortSerialExecutorTest.java
deleted file mode 100644
index 39a1f87..0000000
--- a/utils/misc/src/test/java/org/onlab/util/BestEffortSerialExecutorTest.java
+++ /dev/null
@@ -1,71 +0,0 @@
-/*
- * Copyright 2017-present Open Networking Laboratory
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package org.onlab.util;
-
-import java.util.concurrent.CompletableFuture;
-import java.util.concurrent.CountDownLatch;
-import java.util.concurrent.ExecutionException;
-import java.util.concurrent.Executor;
-import java.util.concurrent.TimeUnit;
-import java.util.concurrent.TimeoutException;
-
-import org.junit.Test;
-
-import static org.junit.Assert.assertEquals;
-
-/**
- * Best effort serial executor test.
- */
-public class BestEffortSerialExecutorTest {
-
-    @Test
-    public void testSerialExecution() throws Throwable {
-        Executor executor = new BestEffortSerialExecutor(SharedExecutors.getPoolThreadExecutor());
-        CountDownLatch latch = new CountDownLatch(2);
-        executor.execute(latch::countDown);
-        executor.execute(latch::countDown);
-        latch.await();
-        assertEquals(0, latch.getCount());
-    }
-
-    @Test
-    public void testBlockedExecution() throws Throwable {
-        Executor executor = new BestEffortSerialExecutor(SharedExecutors.getPoolThreadExecutor());
-        CountDownLatch latch = new CountDownLatch(3);
-        executor.execute(() -> {
-            try {
-                Thread.sleep(2000);
-                latch.countDown();
-            } catch (InterruptedException e) {
-            }
-        });
-        Thread.sleep(10);
-        executor.execute(() -> {
-            try {
-                new CompletableFuture<>().get(2, TimeUnit.SECONDS);
-            } catch (InterruptedException | ExecutionException | TimeoutException e) {
-                latch.countDown();
-            }
-        });
-        Thread.sleep(10);
-        executor.execute(latch::countDown);
-        latch.await(1, TimeUnit.SECONDS);
-        assertEquals(2, latch.getCount());
-        latch.await(3, TimeUnit.SECONDS);
-        assertEquals(0, latch.getCount());
-    }
-
-}
diff --git a/utils/misc/src/test/java/org/onlab/util/BlockingAwareFutureTest.java b/utils/misc/src/test/java/org/onlab/util/BlockingAwareFutureTest.java
new file mode 100644
index 0000000..6a72b58
--- /dev/null
+++ b/utils/misc/src/test/java/org/onlab/util/BlockingAwareFutureTest.java
@@ -0,0 +1,79 @@
+/*
+ * Copyright 2017-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onlab.util;
+
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.Executor;
+import java.util.concurrent.TimeUnit;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+/**
+ * Blocking-aware future test.
+ */
+public class BlockingAwareFutureTest {
+
+    /**
+     * Tests normal callback execution.
+     */
+    @Test
+    public void testNonBlockingThread() throws Exception {
+        CompletableFuture<String> future = new CompletableFuture<>();
+        Executor executor = SharedExecutors.getPoolThreadExecutor();
+        BlockingAwareFuture<String> blockingFuture =
+                (BlockingAwareFuture<String>) Tools.orderedFuture(future, new OrderedExecutor(executor), executor);
+        CountDownLatch latch = new CountDownLatch(1);
+        blockingFuture.thenRun(() -> latch.countDown());
+        executor.execute(() -> future.complete("foo"));
+        latch.await(5, TimeUnit.SECONDS);
+        assertEquals(0, latch.getCount());
+        assertEquals("foo", blockingFuture.join());
+        assertFalse(blockingFuture.isBlocked());
+    }
+
+    /**
+     * Tests blocking an ordered thread.
+     */
+    @Test
+    public void testBlockingThread() throws Exception {
+        CompletableFuture<String> future = new CompletableFuture<>();
+        Executor executor = SharedExecutors.getPoolThreadExecutor();
+        BlockingAwareFuture<String> blockingFuture =
+                (BlockingAwareFuture<String>) Tools.orderedFuture(future, new OrderedExecutor(executor), executor);
+        CountDownLatch latch = new CountDownLatch(2);
+        CompletableFuture<String> wrappedFuture = blockingFuture.thenApply(v -> {
+            assertEquals("foo", v);
+            latch.countDown();
+            return v;
+        });
+        wrappedFuture.thenRun(() -> latch.countDown());
+        executor.execute(() -> wrappedFuture.join());
+        Thread.sleep(100);
+        assertTrue(blockingFuture.isBlocked());
+        future.complete("foo");
+        latch.await(5, TimeUnit.SECONDS);
+        assertEquals(0, latch.getCount());
+        assertEquals("foo", blockingFuture.join());
+        assertEquals("foo", wrappedFuture.join());
+        assertFalse(blockingFuture.isBlocked());
+    }
+
+}
diff --git a/utils/misc/src/test/java/org/onlab/util/SerialExecutorTest.java b/utils/misc/src/test/java/org/onlab/util/OrderedExecutorTest.java
similarity index 87%
rename from utils/misc/src/test/java/org/onlab/util/SerialExecutorTest.java
rename to utils/misc/src/test/java/org/onlab/util/OrderedExecutorTest.java
index 140ce1f..b73fc56 100644
--- a/utils/misc/src/test/java/org/onlab/util/SerialExecutorTest.java
+++ b/utils/misc/src/test/java/org/onlab/util/OrderedExecutorTest.java
@@ -23,13 +23,13 @@
 import static org.junit.Assert.assertEquals;
 
 /**
- * Serial executor test.
+ * Ordered executor test.
  */
-public class SerialExecutorTest {
+public class OrderedExecutorTest {
 
     @Test
     public void testSerialExecution() throws Throwable {
-        Executor executor = new SerialExecutor(SharedExecutors.getPoolThreadExecutor());
+        Executor executor = new OrderedExecutor(SharedExecutors.getPoolThreadExecutor());
         CountDownLatch latch = new CountDownLatch(2);
         executor.execute(latch::countDown);
         executor.execute(latch::countDown);