face: support permanent persistency in TcpTransport

refs #3167

Change-Id: I217c5f0fe0dfbbd759861ee262920cc03394b0ed
diff --git a/daemon/face/tcp-transport.cpp b/daemon/face/tcp-transport.cpp
index 4af12f9..f217bb0 100644
--- a/daemon/face/tcp-transport.cpp
+++ b/daemon/face/tcp-transport.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /**
- * Copyright (c) 2014-2015,  Regents of the University of California,
+ * Copyright (c) 2014-2016,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -28,11 +28,16 @@
 namespace nfd {
 namespace face {
 
-NFD_LOG_INCLASS_TEMPLATE_SPECIALIZATION_DEFINE(StreamTransport, TcpTransport::protocol,
-                                               "TcpTransport");
+NFD_LOG_INCLASS_TEMPLATE_SPECIALIZATION_DEFINE(StreamTransport, TcpTransport::protocol, "TcpTransport");
+
+time::milliseconds TcpTransport::s_initialReconnectWait = time::seconds(1);
+time::milliseconds TcpTransport::s_maxReconnectWait = time::minutes(5);
+float TcpTransport::s_reconnectWaitMultiplier = 2.0f;
 
 TcpTransport::TcpTransport(protocol::socket&& socket, ndn::nfd::FacePersistency persistency)
   : StreamTransport(std::move(socket))
+  , m_remoteEndpoint(m_socket.remote_endpoint())
+  , m_nextReconnectWait(s_initialReconnectWait)
 {
   this->setLocalUri(FaceUri(m_socket.local_endpoint()));
   this->setRemoteUri(FaceUri(m_socket.remote_endpoint()));
@@ -53,11 +58,108 @@
 void
 TcpTransport::beforeChangePersistency(ndn::nfd::FacePersistency newPersistency)
 {
-  if (newPersistency == ndn::nfd::FACE_PERSISTENCY_PERMANENT) {
-    BOOST_THROW_EXCEPTION(
-      std::invalid_argument("TcpTransport does not support FACE_PERSISTENCY_PERMANENT"));
+  // if persistency is changing from permanent to any other value
+  if (this->getPersistency() == ndn::nfd::FACE_PERSISTENCY_PERMANENT) {
+    if (this->getState() == TransportState::DOWN) {
+      // non-permanent transport cannot be in DOWN state, so fail hard
+      this->setState(TransportState::FAILED);
+      doClose();
+    }
   }
 }
 
+void
+TcpTransport::handleError(const boost::system::error_code& error)
+{
+  if (this->getPersistency() == ndn::nfd::FACE_PERSISTENCY_PERMANENT) {
+    NFD_LOG_FACE_TRACE("TCP socket error: " << error.message());
+    this->setState(TransportState::DOWN);
+
+    // cancel all outstanding operations
+    boost::system::error_code error;
+    m_socket.cancel(error);
+
+    // do this asynchronously because there could be some callbacks still pending
+    getGlobalIoService().post([this] { reconnect(); });
+  }
+  else {
+    StreamTransport::handleError(error);
+  }
+}
+
+void
+TcpTransport::reconnect()
+{
+  NFD_LOG_FACE_TRACE(__func__);
+
+  if (getState() == TransportState::CLOSING ||
+      getState() == TransportState::FAILED ||
+      getState() == TransportState::CLOSED) {
+    // transport is shutting down, don't attempt to reconnect
+    return;
+  }
+
+  BOOST_ASSERT(getPersistency() == ndn::nfd::FACE_PERSISTENCY_PERMANENT);
+  BOOST_ASSERT(getState() == TransportState::DOWN);
+
+  // recreate the socket
+  m_socket = protocol::socket(m_socket.get_io_service());
+  this->resetReceiveBuffer();
+  this->resetSendQueue();
+
+  m_reconnectEvent = scheduler::schedule(m_nextReconnectWait,
+                                         [this] { handleReconnectTimeout(); });
+  m_socket.async_connect(m_remoteEndpoint,
+                         [this] (const boost::system::error_code& error) { handleReconnect(error); });
+}
+
+void
+TcpTransport::handleReconnect(const boost::system::error_code& error)
+{
+  if (getState() == TransportState::CLOSING ||
+      getState() == TransportState::FAILED ||
+      getState() == TransportState::CLOSED ||
+      error == boost::asio::error::operation_aborted) {
+    // transport is shutting down, abort the reconnection attempt and ignore any errors
+    return;
+  }
+
+  if (error) {
+    NFD_LOG_FACE_TRACE("Reconnection attempt failed: " << error.message());
+    return;
+  }
+
+  m_reconnectEvent.cancel();
+  m_nextReconnectWait = s_initialReconnectWait;
+
+  this->setLocalUri(FaceUri(m_socket.local_endpoint()));
+  NFD_LOG_FACE_TRACE("TCP connection reestablished");
+  this->setState(TransportState::UP);
+  this->startReceive();
+}
+
+void
+TcpTransport::handleReconnectTimeout()
+{
+  // abort the reconnection attempt
+  boost::system::error_code error;
+  m_socket.close(error);
+
+  // exponentially back off the reconnection timer
+  m_nextReconnectWait =
+      std::min(time::duration_cast<time::milliseconds>(m_nextReconnectWait * s_reconnectWaitMultiplier),
+               s_maxReconnectWait);
+
+  // do this asynchronously because there could be some callbacks still pending
+  getGlobalIoService().post([this] { reconnect(); });
+}
+
+void
+TcpTransport::doClose()
+{
+  m_reconnectEvent.cancel();
+  StreamTransport::doClose();
+}
+
 } // namespace face
 } // namespace nfd