core: add a facility to execute functions on the RIB io_service

refs #4279

Change-Id: I29222053348e5d1737d47c85a59d29280b4b791b
diff --git a/tests/rib-io-fixture.hpp b/tests/rib-io-fixture.hpp
new file mode 100644
index 0000000..e89ba44
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+++ b/tests/rib-io-fixture.hpp
@@ -0,0 +1,100 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2014-2018,  Regents of the University of California,
+ *                           Arizona Board of Regents,
+ *                           Colorado State University,
+ *                           University Pierre & Marie Curie, Sorbonne University,
+ *                           Washington University in St. Louis,
+ *                           Beijing Institute of Technology,
+ *                           The University of Memphis.
+ *
+ * This file is part of NFD (Named Data Networking Forwarding Daemon).
+ * See AUTHORS.md for complete list of NFD authors and contributors.
+ *
+ * NFD is free software: you can redistribute it and/or modify it under the terms
+ * of the GNU General Public License as published by the Free Software Foundation,
+ * either version 3 of the License, or (at your option) any later version.
+ *
+ * NFD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+ * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+ * PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * NFD, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef NFD_TESTS_RIB_IO_FIXTURE_HPP
+#define NFD_TESTS_RIB_IO_FIXTURE_HPP
+
+#include "tests/test-common.hpp"
+#include <boost/thread.hpp>
+#include <condition_variable>
+#include <mutex>
+
+namespace nfd {
+namespace tests {
+
+/** \brief a base test fixture that provides both main and RIB io_service
+ */
+class RibIoFixture: public virtual BaseFixture
+{
+protected:
+  RibIoFixture();
+
+  ~RibIoFixture();
+
+protected:
+  /** \brief Poll main and RIB thread io_service to process all pending I/O events
+   *
+   * This call will execute all pending I/O events, including events that are posted
+   * inside the processing event, i.e., main and RIB thread io_service will be polled
+   * repeatedly until all pending events are processed.
+   *
+   *  \note Must be called from the main thread
+   */
+  void
+  poll();
+
+protected:
+  /** \brief pointer to global RIB io_service
+   */
+  boost::asio::io_service* g_ribIo = nullptr;
+
+  /** \brief global RIB thread
+   */
+  boost::thread g_ribThread;
+
+private:
+  bool m_shouldStopRibIo = false;
+  bool m_shouldPollRibIo = false;
+  std::mutex m_ribPollMutex;
+  std::condition_variable m_ribPollStartCv;
+  std::condition_variable m_ribPollEndCv;
+};
+
+/** \brief RibIoFixture that also overrides steady clock and system clock
+ */
+class RibIoTimeFixture : public RibIoFixture, public UnitTestTimeFixture
+{
+protected:
+  using UnitTestTimeFixture::advanceClocks;
+
+  /** \brief advance steady and system clocks in the main and RIB threads
+   *
+   *  Clocks are advanced in increments of \p tick for \p total time.
+   *  The last increment might be shorter than \p tick.
+   *  After each tick, the main and RIB thread io_service is polled to process pending I/O events.
+   *
+   *  Exceptions thrown during I/O events are propagated to the caller.
+   *  Clock advancing would stop in case of an exception.
+   *
+   *  \note Must be called from the main thread
+   */
+  void
+  advanceClocks(time::nanoseconds tick, time::nanoseconds total) override;
+};
+
+} // namespace tests
+} // namespace nfd
+
+#endif // NFD_TESTS_RIB_IO_FIXTURE_HPP