face: Stop using shared_ptr to manage acceptors

This commit also includes a major cleanup of all channels.

Change-Id: I10db9709e0cba6a0691a86482c60b5dbb2956f68
Refs: #2613
diff --git a/daemon/face/unix-stream-channel.cpp b/daemon/face/unix-stream-channel.cpp
index d64f333..52df192 100644
--- a/daemon/face/unix-stream-channel.cpp
+++ b/daemon/face/unix-stream-channel.cpp
@@ -1,11 +1,12 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /**
- * Copyright (c) 2014  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
+ * Copyright (c) 2014-2015,  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.
@@ -20,9 +21,10 @@
  *
  * 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/>.
- **/
+ */
 
 #include "unix-stream-channel.hpp"
+#include "unix-stream-face.hpp"
 #include "core/global-io.hpp"
 
 #include <boost/filesystem.hpp>
@@ -35,23 +37,22 @@
 using namespace boost::asio::local;
 
 UnixStreamChannel::UnixStreamChannel(const unix_stream::Endpoint& endpoint)
-  : m_endpoint(endpoint)
-  , m_isListening(false)
+  : m_acceptor(getGlobalIoService())
+  , m_endpoint(endpoint)
 {
-  setUri(FaceUri(endpoint));
+  setUri(FaceUri(m_endpoint));
 }
 
 UnixStreamChannel::~UnixStreamChannel()
 {
-  if (m_isListening)
-    {
-      // use the non-throwing variants during destruction
-      // and ignore any errors
-      boost::system::error_code error;
-      m_acceptor->close(error);
-      NFD_LOG_TRACE("[" << m_endpoint << "] Removing socket file");
-      boost::filesystem::remove(m_endpoint.path(), error);
-    }
+  if (isListening()) {
+    // use the non-throwing variants during destruction
+    // and ignore any errors
+    boost::system::error_code error;
+    m_acceptor.close(error);
+    NFD_LOG_DEBUG("[" << m_endpoint << "] Removing socket file");
+    boost::filesystem::remove(m_endpoint.path(), error);
+  }
 }
 
 void
@@ -59,7 +60,7 @@
                           const ConnectFailedCallback& onAcceptFailed,
                           int backlog/* = acceptor::max_connections*/)
 {
-  if (m_isListening) {
+  if (isListening()) {
     NFD_LOG_WARN("[" << m_endpoint << "] Already listening");
     return;
   }
@@ -69,78 +70,73 @@
   fs::path socketPath(m_endpoint.path());
   fs::file_type type = fs::symlink_status(socketPath).type();
 
-  if (type == fs::socket_file)
-    {
-      boost::system::error_code error;
-      stream_protocol::socket socket(getGlobalIoService());
-      socket.connect(m_endpoint, error);
-      NFD_LOG_TRACE("[" << m_endpoint << "] connect() on existing socket file returned: "
-                    + error.message());
-      if (!error)
-        {
-          // someone answered, leave the socket alone
-          throw Error("Socket file at " + m_endpoint.path()
-                      + " belongs to another NFD process");
-        }
-      else if (error == boost::system::errc::connection_refused ||
-               error == boost::system::errc::timed_out)
-        {
-          // no one is listening on the remote side,
-          // we can safely remove the socket file
-          NFD_LOG_INFO("[" << m_endpoint << "] Removing stale socket file");
-          fs::remove(socketPath);
-        }
+  if (type == fs::socket_file) {
+    boost::system::error_code error;
+    stream_protocol::socket socket(getGlobalIoService());
+    socket.connect(m_endpoint, error);
+    NFD_LOG_TRACE("[" << m_endpoint << "] connect() on existing socket file returned: "
+                  + error.message());
+    if (!error) {
+      // someone answered, leave the socket alone
+      throw Error("Socket file at " + m_endpoint.path()
+                  + " belongs to another NFD process");
     }
-  else if (type != fs::file_not_found)
-    {
-      throw Error(m_endpoint.path() + " already exists and is not a socket file");
+    else if (error == boost::asio::error::connection_refused ||
+             error == boost::asio::error::timed_out) {
+      // no one is listening on the remote side,
+      // we can safely remove the stale socket
+      NFD_LOG_DEBUG("[" << m_endpoint << "] Removing stale socket file");
+      fs::remove(socketPath);
     }
+  }
+  else if (type != fs::file_not_found) {
+    throw Error(m_endpoint.path() + " already exists and is not a socket file");
+  }
 
-  m_acceptor = make_shared<stream_protocol::acceptor>(ref(getGlobalIoService()));
-  m_acceptor->open();
-  m_acceptor->bind(m_endpoint);
-  m_acceptor->listen(backlog);
-  m_isListening = true;
+  m_acceptor.open();
+  m_acceptor.bind(m_endpoint);
+  m_acceptor.listen(backlog);
 
-  if (::chmod(m_endpoint.path().c_str(), 0666) < 0)
-    {
-      throw Error("Failed to chmod() socket file at " + m_endpoint.path());
-    }
+  if (::chmod(m_endpoint.path().c_str(), 0666) < 0) {
+    throw Error("chmod(" + m_endpoint.path() + ") failed: " + std::strerror(errno));
+  }
 
-  shared_ptr<stream_protocol::socket> clientSocket =
-    make_shared<stream_protocol::socket>(ref(getGlobalIoService()));
-
-  m_acceptor->async_accept(*clientSocket,
-                           bind(&UnixStreamChannel::handleSuccessfulAccept, this,
-                                boost::asio::placeholders::error, clientSocket,
-                                onFaceCreated, onAcceptFailed));
+  // start accepting connections
+  accept(onFaceCreated, onAcceptFailed);
 }
 
 void
-UnixStreamChannel::handleSuccessfulAccept(const boost::system::error_code& error,
-                                          const shared_ptr<stream_protocol::socket>& socket,
-                                          const FaceCreatedCallback& onFaceCreated,
-                                          const ConnectFailedCallback& onAcceptFailed)
+UnixStreamChannel::accept(const FaceCreatedCallback &onFaceCreated,
+                          const ConnectFailedCallback &onAcceptFailed)
+{
+  auto socket = make_shared<stream_protocol::socket>(ref(getGlobalIoService()));
+
+  m_acceptor.async_accept(*socket,
+                          bind(&UnixStreamChannel::handleAccept, this,
+                               boost::asio::placeholders::error,
+                               socket, onFaceCreated, onAcceptFailed));
+}
+
+void
+UnixStreamChannel::handleAccept(const boost::system::error_code& error,
+                                const shared_ptr<stream_protocol::socket>& socket,
+                                const FaceCreatedCallback& onFaceCreated,
+                                const ConnectFailedCallback& onAcceptFailed)
 {
   if (error) {
-    if (error == boost::system::errc::operation_canceled) // when socket is closed by someone
+    if (error == boost::asio::error::operation_aborted) // when the socket is closed by someone
       return;
 
-    NFD_LOG_DEBUG("[" << m_endpoint << "] Connection failed: " << error.message());
-    onAcceptFailed("Connection failed: " + error.message());
+    NFD_LOG_DEBUG("[" << m_endpoint << "] Accept failed: " << error.message());
+    if (onAcceptFailed)
+      onAcceptFailed(error.message());
     return;
   }
 
-  NFD_LOG_DEBUG("[" << m_endpoint << "] << Incoming connection");
-
-  shared_ptr<stream_protocol::socket> clientSocket =
-    make_shared<stream_protocol::socket>(ref(getGlobalIoService()));
+  NFD_LOG_DEBUG("[" << m_endpoint << "] Incoming connection");
 
   // prepare accepting the next connection
-  m_acceptor->async_accept(*clientSocket,
-                           bind(&UnixStreamChannel::handleSuccessfulAccept, this,
-                                boost::asio::placeholders::error, clientSocket,
-                                onFaceCreated, onAcceptFailed));
+  accept(onFaceCreated, onAcceptFailed);
 
   shared_ptr<UnixStreamFace> face = make_shared<UnixStreamFace>(socket);
   onFaceCreated(face);