Face*
AsfStrategy::getBestFaceForForwarding(const fib::Entry& fibEntry, const Interest& interest,
const Face& inFace)
{
NFD_LOG_TRACE("Looking for best face for " << fibEntry.getPrefix());
typedef std::function<bool(const FaceStats&, const FaceStats&)> FaceStatsPredicate;
typedef std::set<FaceStats, FaceStatsPredicate> FaceStatsSet;
FaceStatsSet rankedFaces(
[] (const FaceStats& lhs, const FaceStats& rhs) -> bool {
// Sort by RTT and then by cost
double lhsValue = getValueForSorting(lhs);
double rhsValue = getValueForSorting(rhs);
if (lhsValue < rhsValue) {
return true;
}
else if (lhsValue == rhsValue) {
return lhs.cost < rhs.cost;
}
else {
return false;
}
});
for (const fib::NextHop& hop : fibEntry.getNextHops()) {
Face& hopFace = hop.getFace();
if (hopFace.getId() == inFace.getId() || wouldViolateScope(inFace, interest, hopFace)) {
continue;
}
FaceInfo* info = m_measurements.getFaceInfo(fibEntry, interest, hopFace);
if (info == nullptr) {
FaceStats stats = {&hopFace,
RttStats::RTT_NO_MEASUREMENT,
RttStats::RTT_NO_MEASUREMENT,
hop.getCost()};
rankedFaces.insert(stats);
}
else {
FaceStats stats = {&hopFace, info->getRtt(), info->getSrtt(), hop.getCost()};
rankedFaces.insert(stats);
}
}
FaceStatsSet::iterator it = rankedFaces.begin();
if (it != rankedFaces.end()) {
return it->face;
}
else {
return nullptr;
}
}
Face*
ProbingModule::getFaceToProbe(const Face& inFace,
const Interest& interest,
const fib::Entry& fibEntry,
const Face& faceUsed)
{
FaceInfoFacePairSet rankedFaces(
[] (const auto& pairLhs, const auto& pairRhs) -> bool {
// Sort by RTT
// If a face has timed-out, rank it behind non-timed-out faces
FaceInfo& lhs = *pairLhs.first;
FaceInfo& rhs = *pairRhs.first;
return (!lhs.isTimeout() && rhs.isTimeout()) ||
(lhs.isTimeout() == rhs.isTimeout() && lhs.getSrtt() < rhs.getSrtt());
});
// Put eligible faces into rankedFaces. If a face does not have an RTT measurement,
// immediately pick the face for probing
for (const fib::NextHop& hop : fibEntry.getNextHops()) {
Face& hopFace = hop.getFace();
// Don't send probe Interest back to the incoming face or use the same face
// as the forwarded Interest or use a face that violates scope
if (hopFace.getId() == inFace.getId() || hopFace.getId() == faceUsed.getId() ||
wouldViolateScope(inFace, interest, hopFace)) {
continue;
}
FaceInfo* info = m_measurements.getFaceInfo(fibEntry, interest, hopFace.getId());
// If no RTT has been recorded, probe this face
if (info == nullptr || !info->hasSrttMeasurement()) {
return &hopFace;
}
// Add FaceInfo to container sorted by RTT
rankedFaces.insert({info, &hopFace});
}
if (rankedFaces.empty()) {
// No Face to probe
return nullptr;
}
return getFaceBasedOnProbability(rankedFaces);
}
void
BestRouteStrategyBase::afterReceiveInterest(const Face& inFace, const Interest& interest,
const shared_ptr<pit::Entry>& pitEntry)
{
if (hasPendingOutRecords(*pitEntry)) {
// not a new Interest, don't forward
return;
}
const fib::Entry& fibEntry = this->lookupFib(*pitEntry);
for (const auto& nexthop : fibEntry.getNextHops()) {
Face& outFace = nexthop.getFace();
if (!wouldViolateScope(inFace, interest, outFace) &&
canForwardToLegacy(*pitEntry, outFace)) {
this->sendInterest(pitEntry, outFace, interest);
return;
}
}
this->rejectPendingInterest(pitEntry);
}