Added a test to verify that notifications are working properly

unsupported/test/CMakeLists.txt

@@ -149,6 +149,7 @@ if(EIGEN_TEST_CXX11)
   ei_add_test(cxx11_tensor_argmax)
   ei_add_test(cxx11_tensor_shuffling)
   ei_add_test(cxx11_tensor_striding)
+  ei_add_test(cxx11_tensor_notification "-pthread" "${CMAKE_THREAD_LIBS_INIT}")
   ei_add_test(cxx11_tensor_thread_pool "-pthread" "${CMAKE_THREAD_LIBS_INIT}")
   ei_add_test(cxx11_tensor_ref)
   ei_add_test(cxx11_tensor_random)

unsupported/test/cxx11_tensor_notification.cpp

@@ -0,0 +1,72 @@
+// This file is part of Eigen, a lightweight C++ template library
+// for linear algebra.
+//
+// Copyright (C) 2015 Vijay Vasudevan <vrv@google.com>
+//
+// This Source Code Form is subject to the terms of the Mozilla
+// Public License v. 2.0. If a copy of the MPL was not distributed
+// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#define EIGEN_USE_THREADS
+
+#include <unistd.h>
+#include <malloc.h>
+#include "main.h"
+#include <Eigen/CXX11/Tensor>
+
+namespace {
+
+void WaitAndAdd(Eigen::Notification* n, int* counter) {
+  n->Wait();
+  *counter = *counter + 1;
+}
+
+}  // namespace
+
+static void test_notification_single()
+{
+  ThreadPool thread_pool(1);
+
+  int counter = 0;
+  Eigen::Notification n;
+  std::function<void()> func = std::bind(&WaitAndAdd, &n, &counter);
+  thread_pool.Schedule(func);
+  sleep(1);
+
+  // The thread should be waiting for the notification.
+  VERIFY_IS_EQUAL(counter, 0);
+
+  // Unblock the thread
+  n.Notify();
+
+  sleep(1);
+
+  // Verify the counter has been incremented
+  VERIFY_IS_EQUAL(counter, 1);
+}
+
+// Like test_notification_single() but enqueues multiple threads to
+// validate that all threads get notified by Notify().
+static void test_notification_multiple()
+{
+  ThreadPool thread_pool(1);
+
+  int counter = 0;
+  Eigen::Notification n;
+  std::function<void()> func = std::bind(&WaitAndAdd, &n, &counter);
+  thread_pool.Schedule(func);
+  thread_pool.Schedule(func);
+  thread_pool.Schedule(func);
+  thread_pool.Schedule(func);
+  sleep(1);
+  VERIFY_IS_EQUAL(counter, 0);
+  n.Notify();
+  sleep(1);
+  VERIFY_IS_EQUAL(counter, 4);
+}
+
+void test_cxx11_tensor_notification()
+{
+  CALL_SUBTEST(test_notification_single());
+  CALL_SUBTEST(test_notification_multiple());
+}