src/sync-core.cpp - ChronoShare - Gitiles

 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /**
  * Copyright (c) 2013-2017, Regents of the University of California.
  *
  * This file is part of ChronoShare, a decentralized file sharing application over NDN.
  *
  * ChronoShare 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.
  *
  * ChronoShare 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 copies of the GNU General Public License along with
  * ChronoShare, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
  *
  * See AUTHORS.md for complete list of ChronoShare authors and contributors.
  */

 #include "sync-core.hpp"
 #include "sync-state-helper.hpp"
 #include "core/logging.hpp"

 #include <ndn-cxx/util/string-helper.hpp>

 #include <boost/lexical_cast.hpp>

 namespace ndn {
 namespace chronoshare {

 INIT_LOGGER("Sync.Core")

 const int SyncCore::FRESHNESS = 2;
 const std::string SyncCore::RECOVER = "RECOVER";
 const double SyncCore::WAIT = 0.05;
 const double SyncCore::RANDOM_PERCENT = 0.5;

 SyncCore::SyncCore(Face& face, SyncLogPtr syncLog, const Name& userName, const Name& localPrefix,
                    const Name& syncPrefix, const StateMsgCallback& callback,
                    long syncInterestInterval /*= -1.0*/)
   : m_face(face)
   , m_log(syncLog)
   , m_scheduler(m_face.getIoService())
   , m_syncInterestEvent(m_scheduler)
   , m_periodicInterestEvent(m_scheduler)
   , m_localStateDelayedEvent(m_scheduler)
   , m_stateMsgCallback(callback)
   , m_syncPrefix(syncPrefix)
   , m_recoverWaitGenerator(
       new RandomIntervalGenerator(WAIT, RANDOM_PERCENT, RandomIntervalGenerator::Direction::UP))
   , m_syncInterestInterval(syncInterestInterval)
 {
   m_rootDigest = m_log->RememberStateInStateLog();

   m_registeredPrefixId =
     m_face.setInterestFilter(m_syncPrefix, bind(&SyncCore::handleInterest, this, _1, _2),
                              RegisterPrefixSuccessCallback(),
                              bind(&SyncCore::onRegisterFailed, this, _1, _2));

   m_log->UpdateLocalLocator(localPrefix);

   time::seconds interval = time::seconds(
     (m_syncInterestInterval > 0 && m_syncInterestInterval < 30) ? m_syncInterestInterval : 4);

   m_periodicInterestEvent =
     m_scheduler.scheduleEvent(interval, bind(&SyncCore::sendPeriodicSyncInterest, this, interval));

   m_syncInterestEvent =
     m_scheduler.scheduleEvent(time::milliseconds(100), bind(&SyncCore::sendSyncInterest, this));
 }

 void
 SyncCore::sendPeriodicSyncInterest(const time::seconds& interval)
 {
   sendSyncInterest();
   m_periodicInterestEvent =
     m_scheduler.scheduleEvent(interval, bind(&SyncCore::sendPeriodicSyncInterest, this, interval));
 }

 SyncCore::~SyncCore()
 {
   // need to "deregister" closures
   m_face.unsetInterestFilter(m_registeredPrefixId);
 }

 void
 SyncCore::updateLocalState(sqlite3_int64 seqno)
 {
   m_log->UpdateLocalSeqNo(seqno);
   localStateChanged();
 }

 void
 SyncCore::localStateChanged()
 {
   ConstBufferPtr oldDigest = m_rootDigest;
   m_rootDigest = m_log->RememberStateInStateLog();

   _LOG_DEBUG("[" << m_log->GetLocalName() << "] localStateChanged ");
   _LOG_TRACE("[" << m_log->GetLocalName() << "] publishes: oldDigest--" << toHex(*oldDigest)
                  << " newDigest--"
                  << toHex(*m_rootDigest));

   SyncStateMsgPtr msg = m_log->FindStateDifferences(*oldDigest, *m_rootDigest);

   // reply sync Interest with oldDigest as last component

   Name syncName(m_syncPrefix);
   syncName.appendImplicitSha256Digest(oldDigest);

   BufferPtr syncData = serializeGZipMsg(*msg);

   // Create Data packet
   shared_ptr<Data> data = make_shared<Data>();
   data->setName(syncName);
   data->setFreshnessPeriod(time::seconds(FRESHNESS));
   data->setContent(reinterpret_cast<const uint8_t*>(syncData->buf()), syncData->size());
   m_keyChain.sign(*data);
   m_face.put(*data);

   _LOG_TRACE(msg);

   // no hurry in sending out new Sync Interest; if others send the new Sync Interest first, no
   // problem, we know the new root digest already;
   // this is trying to avoid the situation that the order of SyncData and new Sync Interest gets
   // reversed at receivers
   m_syncInterestEvent =
     m_scheduler.scheduleEvent(time::milliseconds(50), bind(&SyncCore::sendSyncInterest, this));


   // sendSyncInterest();
 }

 void
 SyncCore::localStateChangedDelayed()
 {
   // many calls to localStateChangedDelayed within 0.5 second will be suppressed to one
   // localStateChanged calls
   m_localStateDelayedEvent =
     m_scheduler.scheduleEvent(time::milliseconds(500), bind(&SyncCore::localStateChanged, this));
 }

 // ------------------------------------------------------------------------------------ send &
 // handle interest

 void
 SyncCore::sendSyncInterest()
 {
   Name syncInterest(m_syncPrefix);
   //  syncInterest.append(name::Component(*m_rootDigest));
   syncInterest.appendImplicitSha256Digest(m_rootDigest);

   _LOG_DEBUG("[" << m_log->GetLocalName() << "] >>> send SYNC Interest for " << toHex(*m_rootDigest)
                  << ": "
                  << syncInterest);

   Interest interest(syncInterest);
   if (m_syncInterestInterval > 0 && m_syncInterestInterval < 30) {
     interest.setInterestLifetime(time::seconds(m_syncInterestInterval));
   }

   m_face.expressInterest(interest, bind(&SyncCore::handleSyncData, this, _1, _2),
                          bind(&SyncCore::handleSyncInterestTimeout, this, _1));

   // // if there is a pending syncSyncInterest task, reschedule it to be m_syncInterestInterval seconds
   // // from now
   // // if no such task exists, it will be added
   // m_scheduler->rescheduleTask(m_sendSyncInterestTask);
 }

 void
 SyncCore::recover(ConstBufferPtr digest)
 {
   if (!(*digest == *m_rootDigest) && m_log->LookupSyncLog(*digest) <= 0) {
     _LOG_TRACE(m_log->GetLocalName() << ", Recover for received_Digest " << toHex(*digest));
     // unfortunately we still don't recognize this digest
     // append the unknown digest
     Name recoverInterest(m_syncPrefix);
     recoverInterest.append(RECOVER).appendImplicitSha256Digest(digest);

     _LOG_DEBUG("[" << m_log->GetLocalName() << "] >>> send RECOVER Interests for " << toHex(*digest));

     m_face.expressInterest(recoverInterest,
                            bind(&SyncCore::handleRecoverData, this, _1, _2),
                            bind(&SyncCore::handleRecoverInterestTimeout, this, _1));
   }
   else {
     // we already learned the digest; cheers!
   }
 }

 void
 SyncCore::handleInterest(const InterestFilter& filter, const Interest& interest)
 {
   Name name = interest.getName();
   _LOG_DEBUG("[" << m_log->GetLocalName() << "] <<<< handleInterest with Name: " << name);
   int size = name.size();
   int prefixSize = m_syncPrefix.size();
   if (size == prefixSize + 1) {
     // this is normal sync interest
     handleSyncInterest(name);
   }
   else if (size == prefixSize + 2 && name.get(m_syncPrefix.size()).toUri() == RECOVER) {
     // this is recovery interest
     handleRecoverInterest(name);
   }
 }

 void
 SyncCore::handleSyncInterest(const Name& name)
 {
   _LOG_DEBUG("[" << m_log->GetLocalName() << "] <<<<< handle SYNC Interest with Name: " << name);

   ConstBufferPtr digest = make_shared<Buffer>(name.get(-1).value(), name.get(-1).value_size());
   if (*digest == *m_rootDigest) {
     // we have the same digest; nothing needs to be done
     _LOG_TRACE("same as root digest: " << toHex(*digest));
     return;
   }
   else if (m_log->LookupSyncLog(*digest) > 0) {
     // we know something more
     _LOG_TRACE("found digest in sync log");
     SyncStateMsgPtr msg = m_log->FindStateDifferences(*digest, *m_rootDigest);

     BufferPtr syncData = serializeGZipMsg(*msg);
     shared_ptr<Data> data = make_shared<Data>();
     data->setName(name);
     data->setFreshnessPeriod(time::seconds(FRESHNESS));
     data->setContent(reinterpret_cast<const uint8_t*>(syncData->buf()), syncData->size());
     m_keyChain.sign(*data);
     m_face.put(*data);

     _LOG_TRACE(m_log->GetLocalName() << " publishes: " << toHex(*digest) << " my_rootDigest:"
                                      << toHex(*m_rootDigest));
     _LOG_TRACE(msg);
   }
   else {
     // we don't recognize the digest, send recover Interest if still don't know the digest after a
     // randomized wait period
     double wait = m_recoverWaitGenerator->nextInterval();
     _LOG_TRACE(m_log->GetLocalName() << ", my_rootDigest: " << toHex(*m_rootDigest)
                                      << ", received_Digest: "
                                      << toHex(*digest));
     _LOG_TRACE("recover task scheduled after wait: " << wait);

     // @todo Figure out how to cancel scheduled events when class is destroyed
     m_scheduler.scheduleEvent(time::milliseconds(static_cast<int>(wait * 1000)),
                               bind(&SyncCore::recover, this, digest));
   }
 }

 void
 SyncCore::handleRecoverInterest(const Name& name)
 {
   _LOG_DEBUG("[" << m_log->GetLocalName() << "] <<<<< handle RECOVER Interest with name " << name);

   ConstBufferPtr digest = make_shared<Buffer>(name.get(-1).value(), name.get(-1).value_size());
   // this is the digest unkonwn to the sender of the interest
   _LOG_DEBUG("rootDigest: " << toHex(*digest));
   if (m_log->LookupSyncLog(*digest) > 0) {
     _LOG_DEBUG("Find in our sync_log! " << toHex(*digest));
     // we know the digest, should reply everything and the newest thing, but not the digest!!! This
     // is important
     unsigned char _origin = 0;
     BufferPtr origin = make_shared<Buffer>(_origin);
     //    std::cout << "size of origin " << origin->size() << std::endl;
     SyncStateMsgPtr msg = m_log->FindStateDifferences(*origin, *m_rootDigest);

     BufferPtr syncData = serializeGZipMsg(*msg);
     shared_ptr<Data> data = make_shared<Data>();
     data->setName(name);
     data->setFreshnessPeriod(time::seconds(FRESHNESS));
     data->setContent(reinterpret_cast<const uint8_t*>(syncData->buf()), syncData->size());
     m_keyChain.sign(*data);
     m_face.put(*data);

     _LOG_TRACE("[" << m_log->GetLocalName() << "] publishes " << toHex(*digest)
                    << " FindStateDifferences(0, m_rootDigest/"
                    << toHex(*m_rootDigest)
                    << ")");
     _LOG_TRACE(msg);
   }
   else {
     // we don't recognize this digest, can not help
     _LOG_DEBUG("we don't recognize this digest, can not help");
   }
 }

 void
 SyncCore::handleSyncInterestTimeout(const Interest& interest)
 {
   // sync interest will be resent by scheduler
 }

 void
 SyncCore::handleRecoverInterestTimeout(const Interest& interest)
 {
   // We do not re-express recovery interest for now
   // if difference is not resolved, the sync interest will trigger
   // recovery anyway; so it's not so important to have recovery interest
   // re-expressed
 }

 void
 SyncCore::handleSyncData(const Interest& interest, Data& data)
 {
   _LOG_DEBUG("[" << m_log->GetLocalName() << "] <<<<< receive SYNC DATA with interest: "
                  << interest.toUri());

   const Block& content = data.getContent();
   // suppress recover in interest - data out of order case
   if (data.getContent().value() && content.size() > 0) {
     handleStateData(Buffer(content.value(), content.value_size()));
   }
   else {
     _LOG_ERROR("Got sync DATA with empty content");
   }

   // resume outstanding sync interest
   m_syncInterestEvent =
     m_scheduler.scheduleEvent(time::milliseconds(0), bind(&SyncCore::sendSyncInterest, this));
 }

 void
 SyncCore::handleRecoverData(const Interest& interest, Data& data)
 {
   _LOG_DEBUG("[" << m_log->GetLocalName() << "] <<<<< receive RECOVER DATA with interest: "
                  << interest.toUri());
   // cout << "handle recover data" << end;
   const Block& content = data.getContent();
   if (content.value() && content.size() > 0) {
     handleStateData(Buffer(content.value(), content.value_size()));
   }
   else {
     _LOG_ERROR("Got recovery DATA with empty content");
   }

   m_syncInterestEvent =
     m_scheduler.scheduleEvent(time::milliseconds(0), bind(&SyncCore::sendSyncInterest, this));
 }

 void
 SyncCore::handleStateData(const Buffer& content)
 {
   SyncStateMsgPtr msg = deserializeGZipMsg<SyncStateMsg>(content);
   if (!(msg)) {
     // ignore misformed SyncData
     _LOG_ERROR("Misformed SyncData");
     return;
   }

   _LOG_TRACE("[" << m_log->GetLocalName() << "]"
                  << " receives Msg ");
   _LOG_TRACE(msg);
   int size = msg->state_size();
   int index = 0;
   while (index < size) {
     SyncState state = msg->state(index);
     std::string devStr = state.name();
     Name deviceName(Block((const unsigned char*)devStr.c_str(), devStr.size()));
     if (state.type() == SyncState::UPDATE) {
       sqlite3_int64 seqno = state.seq();
       m_log->UpdateDeviceSeqNo(deviceName, seqno);
       if (state.has_locator()) {
         std::string locStr = state.locator();
         Name locatorName(Block((const unsigned char*)locStr.c_str(), locStr.size()));
         m_log->UpdateLocator(deviceName, locatorName);

         _LOG_TRACE("self: " << m_log->GetLocalName() << ", device: " << deviceName << " < == > "
                             << locatorName);
       }
     }
     else {
       _LOG_ERROR("Receive SYNC DELETE, but we don't support it yet");
       deregister(deviceName);
     }
     index++;
   }

   // find the actuall difference and invoke callback on the actual difference
   ConstBufferPtr oldDigest = m_rootDigest;
   m_rootDigest = m_log->RememberStateInStateLog();
   // get diff with both new SeqNo and old SeqNo
   SyncStateMsgPtr diff = m_log->FindStateDifferences(*oldDigest, *m_rootDigest, true);

   if (diff->state_size() > 0) {
     m_stateMsgCallback(diff);
   }
 }

 void
 SyncCore::deregister(const Name& name)
 {
   // Do nothing for now
   // TODO: handle deregistering
 }

 sqlite3_int64
 SyncCore::seq(const Name& name)
 {
   return m_log->SeqNo(name);
 }

 } // namespace chronoshare
 } // namespace ndn
	/* -- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -- */
	/**
	* Copyright (c) 2013-2017, Regents of the University of California.
	*
	* This file is part of ChronoShare, a decentralized file sharing application over NDN.
	*
	* ChronoShare 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.
	*
	* ChronoShare 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 copies of the GNU General Public License along with
	* ChronoShare, e.g., in COPYING.md file. If not, see <http://www.gnu.org/licenses/>.
	*
	* See AUTHORS.md for complete list of ChronoShare authors and contributors.
	*/

	#include "sync-core.hpp"
	#include "sync-state-helper.hpp"
	#include "core/logging.hpp"

	#include <ndn-cxx/util/string-helper.hpp>

	#include <boost/lexical_cast.hpp>

	namespace ndn {
	namespace chronoshare {

	INIT_LOGGER("Sync.Core")

	const int SyncCore::FRESHNESS = 2;
	const std::string SyncCore::RECOVER = "RECOVER";
	const double SyncCore::WAIT = 0.05;
	const double SyncCore::RANDOM_PERCENT = 0.5;

	SyncCore::SyncCore(Face& face, SyncLogPtr syncLog, const Name& userName, const Name& localPrefix,
	const Name& syncPrefix, const StateMsgCallback& callback,
	long syncInterestInterval /= -1.0/)
	: m_face(face)
	, m_log(syncLog)
	, m_scheduler(m_face.getIoService())
	, m_syncInterestEvent(m_scheduler)
	, m_periodicInterestEvent(m_scheduler)
	, m_localStateDelayedEvent(m_scheduler)
	, m_stateMsgCallback(callback)
	, m_syncPrefix(syncPrefix)
	, m_recoverWaitGenerator(
	new RandomIntervalGenerator(WAIT, RANDOM_PERCENT, RandomIntervalGenerator::Direction::UP))
	, m_syncInterestInterval(syncInterestInterval)
	{
	m_rootDigest = m_log->RememberStateInStateLog();

	m_registeredPrefixId =
	m_face.setInterestFilter(m_syncPrefix, bind(&SyncCore::handleInterest, this, _1, _2),
	RegisterPrefixSuccessCallback(),
	bind(&SyncCore::onRegisterFailed, this, _1, _2));

	m_log->UpdateLocalLocator(localPrefix);

	time::seconds interval = time::seconds(
	(m_syncInterestInterval > 0 && m_syncInterestInterval < 30) ? m_syncInterestInterval : 4);

	m_periodicInterestEvent =
	m_scheduler.scheduleEvent(interval, bind(&SyncCore::sendPeriodicSyncInterest, this, interval));

	m_syncInterestEvent =
	m_scheduler.scheduleEvent(time::milliseconds(100), bind(&SyncCore::sendSyncInterest, this));
	}

	void
	SyncCore::sendPeriodicSyncInterest(const time::seconds& interval)
	{
	sendSyncInterest();
	m_periodicInterestEvent =
	m_scheduler.scheduleEvent(interval, bind(&SyncCore::sendPeriodicSyncInterest, this, interval));
	}

	SyncCore::~SyncCore()
	{
	// need to "deregister" closures
	m_face.unsetInterestFilter(m_registeredPrefixId);
	}

	void
	SyncCore::updateLocalState(sqlite3_int64 seqno)
	{
	m_log->UpdateLocalSeqNo(seqno);
	localStateChanged();
	}

	void
	SyncCore::localStateChanged()
	{
	ConstBufferPtr oldDigest = m_rootDigest;
	m_rootDigest = m_log->RememberStateInStateLog();

	_LOG_DEBUG("[" << m_log->GetLocalName() << "] localStateChanged ");
	_LOG_TRACE("[" << m_log->GetLocalName() << "] publishes: oldDigest--" << toHex(*oldDigest)
	<< " newDigest--"
	<< toHex(*m_rootDigest));

	SyncStateMsgPtr msg = m_log->FindStateDifferences(oldDigest, m_rootDigest);

	// reply sync Interest with oldDigest as last component

	Name syncName(m_syncPrefix);
	syncName.appendImplicitSha256Digest(oldDigest);

	BufferPtr syncData = serializeGZipMsg(*msg);

	// Create Data packet
	shared_ptr<Data> data = make_shared<Data>();
	data->setName(syncName);
	data->setFreshnessPeriod(time::seconds(FRESHNESS));
	data->setContent(reinterpret_cast<const uint8_t*>(syncData->buf()), syncData->size());
	m_keyChain.sign(*data);
	m_face.put(*data);

	_LOG_TRACE(msg);

	// no hurry in sending out new Sync Interest; if others send the new Sync Interest first, no
	// problem, we know the new root digest already;
	// this is trying to avoid the situation that the order of SyncData and new Sync Interest gets
	// reversed at receivers
	m_syncInterestEvent =
	m_scheduler.scheduleEvent(time::milliseconds(50), bind(&SyncCore::sendSyncInterest, this));


	// sendSyncInterest();
	}

	void
	SyncCore::localStateChangedDelayed()
	{
	// many calls to localStateChangedDelayed within 0.5 second will be suppressed to one
	// localStateChanged calls
	m_localStateDelayedEvent =
	m_scheduler.scheduleEvent(time::milliseconds(500), bind(&SyncCore::localStateChanged, this));
	}

	// ------------------------------------------------------------------------------------ send &
	// handle interest

	void
	SyncCore::sendSyncInterest()
	{
	Name syncInterest(m_syncPrefix);
	// syncInterest.append(name::Component(*m_rootDigest));
	syncInterest.appendImplicitSha256Digest(m_rootDigest);

	_LOG_DEBUG("[" << m_log->GetLocalName() << "] >>> send SYNC Interest for " << toHex(*m_rootDigest)
	<< ": "
	<< syncInterest);

	Interest interest(syncInterest);
	if (m_syncInterestInterval > 0 && m_syncInterestInterval < 30) {
	interest.setInterestLifetime(time::seconds(m_syncInterestInterval));
	}

	m_face.expressInterest(interest, bind(&SyncCore::handleSyncData, this, _1, _2),
	bind(&SyncCore::handleSyncInterestTimeout, this, _1));

	// // if there is a pending syncSyncInterest task, reschedule it to be m_syncInterestInterval seconds
	// // from now
	// // if no such task exists, it will be added
	// m_scheduler->rescheduleTask(m_sendSyncInterestTask);
	}

	void
	SyncCore::recover(ConstBufferPtr digest)
	{
	if (!(digest == m_rootDigest) && m_log->LookupSyncLog(*digest) <= 0) {
	_LOG_TRACE(m_log->GetLocalName() << ", Recover for received_Digest " << toHex(*digest));
	// unfortunately we still don't recognize this digest
	// append the unknown digest
	Name recoverInterest(m_syncPrefix);
	recoverInterest.append(RECOVER).appendImplicitSha256Digest(digest);

	_LOG_DEBUG("[" << m_log->GetLocalName() << "] >>> send RECOVER Interests for " << toHex(*digest));

	m_face.expressInterest(recoverInterest,
	bind(&SyncCore::handleRecoverData, this, _1, _2),
	bind(&SyncCore::handleRecoverInterestTimeout, this, _1));
	}
	else {
	// we already learned the digest; cheers!
	}
	}

	void
	SyncCore::handleInterest(const InterestFilter& filter, const Interest& interest)
	{
	Name name = interest.getName();
	_LOG_DEBUG("[" << m_log->GetLocalName() << "] <<<< handleInterest with Name: " << name);
	int size = name.size();
	int prefixSize = m_syncPrefix.size();
	if (size == prefixSize + 1) {
	// this is normal sync interest
	handleSyncInterest(name);
	}
	else if (size == prefixSize + 2 && name.get(m_syncPrefix.size()).toUri() == RECOVER) {
	// this is recovery interest
	handleRecoverInterest(name);
	}
	}

	void
	SyncCore::handleSyncInterest(const Name& name)
	{
	_LOG_DEBUG("[" << m_log->GetLocalName() << "] <<<<< handle SYNC Interest with Name: " << name);

	ConstBufferPtr digest = make_shared<Buffer>(name.get(-1).value(), name.get(-1).value_size());
	if (digest == m_rootDigest) {
	// we have the same digest; nothing needs to be done
	_LOG_TRACE("same as root digest: " << toHex(*digest));
	return;
	}
	else if (m_log->LookupSyncLog(*digest) > 0) {
	// we know something more
	_LOG_TRACE("found digest in sync log");
	SyncStateMsgPtr msg = m_log->FindStateDifferences(digest, m_rootDigest);

	BufferPtr syncData = serializeGZipMsg(*msg);
	shared_ptr<Data> data = make_shared<Data>();
	data->setName(name);
	data->setFreshnessPeriod(time::seconds(FRESHNESS));
	data->setContent(reinterpret_cast<const uint8_t*>(syncData->buf()), syncData->size());
	m_keyChain.sign(*data);
	m_face.put(*data);

	_LOG_TRACE(m_log->GetLocalName() << " publishes: " << toHex(*digest) << " my_rootDigest:"
	<< toHex(*m_rootDigest));
	_LOG_TRACE(msg);
	}
	else {
	// we don't recognize the digest, send recover Interest if still don't know the digest after a
	// randomized wait period
	double wait = m_recoverWaitGenerator->nextInterval();
	_LOG_TRACE(m_log->GetLocalName() << ", my_rootDigest: " << toHex(*m_rootDigest)
	<< ", received_Digest: "
	<< toHex(*digest));
	_LOG_TRACE("recover task scheduled after wait: " << wait);

	// @todo Figure out how to cancel scheduled events when class is destroyed
	m_scheduler.scheduleEvent(time::milliseconds(static_cast<int>(wait * 1000)),
	bind(&SyncCore::recover, this, digest));
	}
	}

	void
	SyncCore::handleRecoverInterest(const Name& name)
	{
	_LOG_DEBUG("[" << m_log->GetLocalName() << "] <<<<< handle RECOVER Interest with name " << name);

	ConstBufferPtr digest = make_shared<Buffer>(name.get(-1).value(), name.get(-1).value_size());
	// this is the digest unkonwn to the sender of the interest
	_LOG_DEBUG("rootDigest: " << toHex(*digest));
	if (m_log->LookupSyncLog(*digest) > 0) {
	_LOG_DEBUG("Find in our sync_log! " << toHex(*digest));
	// we know the digest, should reply everything and the newest thing, but not the digest!!! This
	// is important
	unsigned char _origin = 0;
	BufferPtr origin = make_shared<Buffer>(_origin);
	// std::cout << "size of origin " << origin->size() << std::endl;
	SyncStateMsgPtr msg = m_log->FindStateDifferences(origin, m_rootDigest);

	BufferPtr syncData = serializeGZipMsg(*msg);
	shared_ptr<Data> data = make_shared<Data>();
	data->setName(name);
	data->setFreshnessPeriod(time::seconds(FRESHNESS));
	data->setContent(reinterpret_cast<const uint8_t*>(syncData->buf()), syncData->size());
	m_keyChain.sign(*data);
	m_face.put(*data);

	_LOG_TRACE("[" << m_log->GetLocalName() << "] publishes " << toHex(*digest)
	<< " FindStateDifferences(0, m_rootDigest/"
	<< toHex(*m_rootDigest)
	<< ")");
	_LOG_TRACE(msg);
	}
	else {
	// we don't recognize this digest, can not help
	_LOG_DEBUG("we don't recognize this digest, can not help");
	}
	}

	void
	SyncCore::handleSyncInterestTimeout(const Interest& interest)
	{
	// sync interest will be resent by scheduler
	}

	void
	SyncCore::handleRecoverInterestTimeout(const Interest& interest)
	{
	// We do not re-express recovery interest for now
	// if difference is not resolved, the sync interest will trigger
	// recovery anyway; so it's not so important to have recovery interest
	// re-expressed
	}

	void
	SyncCore::handleSyncData(const Interest& interest, Data& data)
	{
	_LOG_DEBUG("[" << m_log->GetLocalName() << "] <<<<< receive SYNC DATA with interest: "
	<< interest.toUri());

	const Block& content = data.getContent();
	// suppress recover in interest - data out of order case
	if (data.getContent().value() && content.size() > 0) {
	handleStateData(Buffer(content.value(), content.value_size()));
	}
	else {
	_LOG_ERROR("Got sync DATA with empty content");
	}

	// resume outstanding sync interest
	m_syncInterestEvent =
	m_scheduler.scheduleEvent(time::milliseconds(0), bind(&SyncCore::sendSyncInterest, this));
	}

	void
	SyncCore::handleRecoverData(const Interest& interest, Data& data)
	{
	_LOG_DEBUG("[" << m_log->GetLocalName() << "] <<<<< receive RECOVER DATA with interest: "
	<< interest.toUri());
	// cout << "handle recover data" << end;
	const Block& content = data.getContent();
	if (content.value() && content.size() > 0) {
	handleStateData(Buffer(content.value(), content.value_size()));
	}
	else {
	_LOG_ERROR("Got recovery DATA with empty content");
	}

	m_syncInterestEvent =
	m_scheduler.scheduleEvent(time::milliseconds(0), bind(&SyncCore::sendSyncInterest, this));
	}

	void
	SyncCore::handleStateData(const Buffer& content)
	{
	SyncStateMsgPtr msg = deserializeGZipMsg<SyncStateMsg>(content);
	if (!(msg)) {
	// ignore misformed SyncData
	_LOG_ERROR("Misformed SyncData");
	return;
	}

	_LOG_TRACE("[" << m_log->GetLocalName() << "]"
	<< " receives Msg ");
	_LOG_TRACE(msg);
	int size = msg->state_size();
	int index = 0;
	while (index < size) {
	SyncState state = msg->state(index);
	std::string devStr = state.name();
	Name deviceName(Block((const unsigned char*)devStr.c_str(), devStr.size()));
	if (state.type() == SyncState::UPDATE) {
	sqlite3_int64 seqno = state.seq();
	m_log->UpdateDeviceSeqNo(deviceName, seqno);
	if (state.has_locator()) {
	std::string locStr = state.locator();
	Name locatorName(Block((const unsigned char*)locStr.c_str(), locStr.size()));
	m_log->UpdateLocator(deviceName, locatorName);

	_LOG_TRACE("self: " << m_log->GetLocalName() << ", device: " << deviceName << " < == > "
	<< locatorName);
	}
	}
	else {
	_LOG_ERROR("Receive SYNC DELETE, but we don't support it yet");
	deregister(deviceName);
	}
	index++;
	}

	// find the actuall difference and invoke callback on the actual difference
	ConstBufferPtr oldDigest = m_rootDigest;
	m_rootDigest = m_log->RememberStateInStateLog();
	// get diff with both new SeqNo and old SeqNo
	SyncStateMsgPtr diff = m_log->FindStateDifferences(oldDigest, m_rootDigest, true);

	if (diff->state_size() > 0) {
	m_stateMsgCallback(diff);
	}
	}

	void
	SyncCore::deregister(const Name& name)
	{
	// Do nothing for now
	// TODO: handle deregistering
	}

	sqlite3_int64
	SyncCore::seq(const Name& name)
	{
	return m_log->SeqNo(name);
	}

	} // namespace chronoshare
	} // namespace ndn