diff --git a/src/detail/face-impl.hpp b/src/detail/face-impl.hpp
index cb5b3bc..fb6642a 100644
--- a/src/detail/face-impl.hpp
+++ b/src/detail/face-impl.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /**
- * Copyright (c) 2013-2014 Regents of the University of California.
+ * Copyright (c) 2013-2015 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,9 +27,11 @@
 
 #include "registered-prefix.hpp"
 #include "pending-interest.hpp"
+#include "container-with-on-empty-signal.hpp"
 
 #include "../util/scheduler.hpp"
 #include "../util/config-file.hpp"
+#include "../util/signal.hpp"
 
 #include "../transport/transport.hpp"
 #include "../transport/unix-transport.hpp"
@@ -43,14 +45,26 @@
 class Face::Impl : noncopyable
 {
 public:
-  typedef std::list<shared_ptr<PendingInterest> > PendingInterestTable;
+  typedef ContainerWithOnEmptySignal<shared_ptr<PendingInterest>> PendingInterestTable;
   typedef std::list<shared_ptr<InterestFilterRecord> > InterestFilterTable;
-  typedef std::list<shared_ptr<RegisteredPrefix> > RegisteredPrefixTable;
+  typedef ContainerWithOnEmptySignal<shared_ptr<RegisteredPrefix>> RegisteredPrefixTable;
 
   explicit
   Impl(Face& face)
     : m_face(face)
+    , m_scheduler(m_face.getIoService())
+    , m_processEventsTimeoutEvent(m_scheduler)
   {
+    auto postOnEmptyPitOrNoRegisteredPrefixes = [this] {
+      this->m_face.getIoService().post(bind(&Impl::onEmptyPitOrNoRegisteredPrefixes, this));
+      // without this extra "post", transport can get paused (-async_read) and then resumed
+      // (+async_read) from within onInterest/onData callback.  After onInterest/onData
+      // finishes, there is another +async_read with the same memory block.  A few of such
+      // async_read duplications can cause various effects and result in segfault.
+    };
+
+    m_pendingInterestTable.onEmpty.connect(postOnEmptyPitOrNoRegisteredPrefixes);
+    m_registeredPrefixTable.onEmpty.connect(postOnEmptyPitOrNoRegisteredPrefixes);
   }
 
   /////////////////////////////////////////////////////////////////////////////////////////////////
@@ -59,49 +73,34 @@
   void
   satisfyPendingInterests(Data& data)
   {
-    for (PendingInterestTable::iterator i = m_pendingInterestTable.begin();
-         i != m_pendingInterestTable.end();
-         )
-      {
-        if ((*i)->getInterest()->matchesData(data))
-          {
-            // Copy pointers to the objects and remove the PIT entry before calling the callback.
-            OnData onData = (*i)->getOnData();
-            shared_ptr<const Interest> interest = (*i)->getInterest();
+    for (auto entry = m_pendingInterestTable.begin(); entry != m_pendingInterestTable.end(); ) {
+      if ((*entry)->getInterest().matchesData(data)) {
+        shared_ptr<PendingInterest> matchedEntry = *entry;
 
-            PendingInterestTable::iterator next = i;
-            ++next;
-            m_pendingInterestTable.erase(i);
-            i = next;
+        entry = m_pendingInterestTable.erase(entry);
 
-            if (static_cast<bool>(onData)) {
-              onData(*interest, data);
-            }
-          }
-        else
-          ++i;
+        matchedEntry->invokeDataCallback(data);
       }
+      else
+        ++entry;
+    }
   }
 
   void
   processInterestFilters(Interest& interest)
   {
-    for (InterestFilterTable::iterator i = m_interestFilterTable.begin();
-         i != m_interestFilterTable.end();
-         ++i)
-      {
-        if ((*i)->doesMatch(interest.getName()))
-          {
-            (**i)(interest);
-          }
+    for (const auto& filter : m_interestFilterTable) {
+      if (filter->doesMatch(interest.getName())) {
+        filter->invokeInterestCallback(interest);
       }
+    }
   }
 
   /////////////////////////////////////////////////////////////////////////////////////////////////
   /////////////////////////////////////////////////////////////////////////////////////////////////
 
   void
-  ensureConnected(bool wantResume = true)
+  ensureConnected(bool wantResume)
   {
     if (!m_face.m_transport->isConnected())
       m_face.m_transport->connect(m_face.m_ioService,
@@ -115,26 +114,22 @@
   asyncExpressInterest(const shared_ptr<const Interest>& interest,
                        const OnData& onData, const OnTimeout& onTimeout)
   {
-    this->ensureConnected();
+    this->ensureConnected(true);
 
-    m_pendingInterestTable.push_back(make_shared<PendingInterest>(interest, onData, onTimeout));
+    auto entry =
+      m_pendingInterestTable.insert(make_shared<PendingInterest>(interest,
+                                                                 onData, onTimeout,
+                                                                 ref(m_scheduler))).first;
+    (*entry)->setDeleter([this, entry] { m_pendingInterestTable.erase(entry); });
 
-    if (!interest->getLocalControlHeader().empty(nfd::LocalControlHeader::ENCODE_NEXT_HOP))
-      {
-        // encode only NextHopFaceId towards the forwarder
-        m_face.m_transport->send(interest->getLocalControlHeader()
-                                   .wireEncode(*interest, nfd::LocalControlHeader::ENCODE_NEXT_HOP),
-                                 interest->wireEncode());
-      }
-    else
-      {
-        m_face.m_transport->send(interest->wireEncode());
-      }
-
-    if (!m_pitTimeoutCheckTimerActive) {
-      m_pitTimeoutCheckTimerActive = true;
-      m_pitTimeoutCheckTimer->expires_from_now(time::milliseconds(100));
-      m_pitTimeoutCheckTimer->async_wait(bind(&Impl::checkPitExpire, this));
+    if (!interest->getLocalControlHeader().empty(nfd::LocalControlHeader::ENCODE_NEXT_HOP)) {
+      // encode only NextHopFaceId towards the forwarder
+      m_face.m_transport->send(interest->getLocalControlHeader()
+                               .wireEncode(*interest, nfd::LocalControlHeader::ENCODE_NEXT_HOP),
+                               interest->wireEncode());
+    }
+    else {
+      m_face.m_transport->send(interest->wireEncode());
     }
   }
 
@@ -147,19 +142,17 @@
   void
   asyncPutData(const shared_ptr<const Data>& data)
   {
-    this->ensureConnected();
+    this->ensureConnected(true);
 
-    if (!data->getLocalControlHeader().empty(nfd::LocalControlHeader::ENCODE_CACHING_POLICY))
-      {
-        m_face.m_transport->send(
-          data->getLocalControlHeader().wireEncode(*data,
-                                                   nfd::LocalControlHeader::ENCODE_CACHING_POLICY),
-          data->wireEncode());
-      }
-    else
-      {
-        m_face.m_transport->send(data->wireEncode());
-      }
+    if (!data->getLocalControlHeader().empty(nfd::LocalControlHeader::ENCODE_CACHING_POLICY)) {
+      m_face.m_transport->send(
+        data->getLocalControlHeader().wireEncode(*data,
+                                                 nfd::LocalControlHeader::ENCODE_CACHING_POLICY),
+        data->wireEncode());
+    }
+    else {
+      m_face.m_transport->send(data->wireEncode());
+    }
   }
 
   /////////////////////////////////////////////////////////////////////////////////////////////////
@@ -215,7 +208,7 @@
   afterPrefixRegistered(const shared_ptr<RegisteredPrefix>& registeredPrefix,
                         const RegisterPrefixSuccessCallback& onSuccess)
   {
-    m_registeredPrefixTable.push_back(registeredPrefix);
+    m_registeredPrefixTable.insert(registeredPrefix);
 
     if (static_cast<bool>(registeredPrefix->getFilter())) {
       // it was a combined operation
@@ -268,75 +261,32 @@
   {
     m_registeredPrefixTable.erase(item);
 
-    if (!m_pitTimeoutCheckTimerActive && m_registeredPrefixTable.empty())
-      {
-        m_face.m_transport->pause();
-        if (!m_ioServiceWork) {
-          m_processEventsTimeoutTimer->cancel();
-        }
-      }
-
     if (static_cast<bool>(onSuccess)) {
       onSuccess();
     }
   }
 
-  /////////////////////////////////////////////////////////////////////////////////////////////////
-  /////////////////////////////////////////////////////////////////////////////////////////////////
-
   void
-  checkPitExpire()
+  onEmptyPitOrNoRegisteredPrefixes()
   {
-    // Check for PIT entry timeouts.
-    time::steady_clock::TimePoint now = time::steady_clock::now();
-
-    PendingInterestTable::iterator i = m_pendingInterestTable.begin();
-    while (i != m_pendingInterestTable.end())
-      {
-        if ((*i)->isTimedOut(now))
-          {
-            // Save the PendingInterest and remove it from the PIT.  Then call the callback.
-            shared_ptr<PendingInterest> pendingInterest = *i;
-
-            i = m_pendingInterestTable.erase(i);
-
-            pendingInterest->callTimeout();
-          }
-        else
-          ++i;
-      }
-
-    if (!m_pendingInterestTable.empty()) {
-      m_pitTimeoutCheckTimerActive = true;
-
-      m_pitTimeoutCheckTimer->expires_from_now(time::milliseconds(100));
-      m_pitTimeoutCheckTimer->async_wait(bind(&Impl::checkPitExpire, this));
-    }
-    else {
-      m_pitTimeoutCheckTimerActive = false;
-
-      if (m_registeredPrefixTable.empty()) {
-        m_face.m_transport->pause();
-        if (!m_ioServiceWork) {
-          m_processEventsTimeoutTimer->cancel();
-        }
+    if (m_pendingInterestTable.empty() && m_registeredPrefixTable.empty()) {
+      m_face.m_transport->pause();
+      if (!m_ioServiceWork) {
+        m_processEventsTimeoutEvent.cancel();
       }
     }
   }
 
 private:
   Face& m_face;
+  util::Scheduler m_scheduler;
+  util::scheduler::ScopedEventId m_processEventsTimeoutEvent;
 
   PendingInterestTable m_pendingInterestTable;
   InterestFilterTable m_interestFilterTable;
   RegisteredPrefixTable m_registeredPrefixTable;
 
-  ConfigFile m_config;
-
-  shared_ptr<boost::asio::io_service::work> m_ioServiceWork; // if thread needs to be preserved
-  shared_ptr<monotonic_deadline_timer> m_pitTimeoutCheckTimer;
-  bool m_pitTimeoutCheckTimerActive;
-  shared_ptr<monotonic_deadline_timer> m_processEventsTimeoutTimer;
+  unique_ptr<boost::asio::io_service::work> m_ioServiceWork; // if thread needs to be preserved
 
   friend class Face;
 };