ieee80211: drop StationLabelCache, resolve station labels on demand

The cache class wrapped a single call to
L3AddressResolver::findHostWithMacAddress() in a per-receiver memoization
map that every emitting component had to own and thread through as a
parameter. The label derivation now lives in
IRateSelection::getStationLabel() and runs on demand: Dcf, Hcf and
RateControlBase lose their cache members, and emitDatarateSelected()
loses its extra parameter.

Uncached, the resolver sweeps the network's interface tables once per
emitted label instead of at most once per receiver. datarateChanged only
fires when a rate control module changes its decision, so it is
unaffected in practice. datarateSelected fires for every transmitted
frame, so the label is now only computed when the signal has listeners;
with result recording off, transmitting costs nothing extra.

Author: adamgeorge309

src/inet/linklayer/ieee80211/mac/common/StationLabelCache.cc

@@ -7,25 +7,44 @@
 
 #include "inet/linklayer/ieee80211/mac/contract/IRateSelection.h"
 
+#include "inet/networklayer/common/L3AddressResolver.h"
+
 namespace inet {
 namespace ieee80211 {
 
 using namespace inet::physicallayer;
 
 simsignal_t IRateSelection::datarateSelectedSignal = cComponent::registerSignal("datarateSelected");
 
-void IRateSelection::emitDatarateSelected(cComponent *emitter, StationLabelCache& stationLabels, const Ptr<const Ieee80211MacHeader>& header, const IIeee80211Mode *mode)
+void IRateSelection::emitDatarateSelected(cComponent *emitter, const Ptr<const Ieee80211MacHeader>& header, const IIeee80211Mode *mode)
 {
     double rate = mode->getDataMode()->getNetBitrate().get<bps>();
     auto dataHeader = dynamicPtrCast<const Ieee80211DataHeader>(header);
-    if (dataHeader != nullptr && !dataHeader->getReceiverAddress().isMulticast()) {
-        cNamedObject details(stationLabels.getLabel(dataHeader->getReceiverAddress()).c_str());
+    // resolving the station label sweeps the network, so skip it if nothing listens anyway
+    if (dataHeader != nullptr && !dataHeader->getReceiverAddress().isMulticast() && emitter->mayHaveListeners(datarateSelectedSignal)) {
+        cNamedObject details(getStationLabel(dataHeader->getReceiverAddress()).c_str());
         emitter->emit(datarateSelectedSignal, rate, &details);
     }
     else
         emitter->emit(datarateSelectedSignal, rate);
 }
 
+std::string IRateSelection::getStationLabel(const MacAddress& receiver)
+{
+    // resolve the receiver MAC to the network node that owns it; fall back to the MAC
+    if (cModule *node = L3AddressResolver().findHostWithMacAddress(receiver)) {
+        // the path relative to the network, so that nodes of the same name in different
+        // subnetworks get different labels; for a node directly under the network this
+        // is just its name
+        std::string label = node->getFullPath();
+        std::string networkPrefix = std::string(node->getSimulation()->getSystemModule()->getFullName()) + ".";
+        if (label.compare(0, networkPrefix.length(), networkPrefix) == 0)
+            label.erase(0, networkPrefix.length());
+        return label;
+    }
+    return receiver.str();
+}
+
 } // namespace ieee80211
 } // namespace inet
 

src/inet/linklayer/ieee80211/mac/common/StationLabelCache.h

@@ -10,7 +10,6 @@
 
 #include "inet/common/packet/Packet.h"
 #include "inet/linklayer/ieee80211/mac/Ieee80211Frame_m.h"
-#include "inet/linklayer/ieee80211/mac/common/StationLabelCache.h"
 #include "inet/physicallayer/wireless/ieee80211/mode/IIeee80211Mode.h"
 #include "inet/physicallayer/wireless/ieee80211/mode/Ieee80211ModeSet.h"
 
@@ -34,7 +33,14 @@ class INET_API IRateSelection
     // rate, so the label always names the station whose rate is reported. Control, management and
     // group-addressed frames carry no per-station data rate and are emitted without details: the
     // aggregate datarateSelected statistic still records them, a bar chart ignores them.
-    static void emitDatarateSelected(cComponent *emitter, StationLabelCache& stationLabels, const Ptr<const Ieee80211MacHeader>& header, const physicallayer::IIeee80211Mode *mode);
+    static void emitDatarateSelected(cComponent *emitter, const Ptr<const Ieee80211MacHeader>& header, const physicallayer::IIeee80211Mode *mode);
+
+    // The label identifying a station in a per-station signal emission: it names the details
+    // object emitted with the value, which a demux() result filter and the statistic bar chart
+    // visualizer key their per-station series on. The receiver's network node path relative to
+    // the network if the MAC address can be resolved (just the node name unless the node is
+    // nested in a subnetwork), otherwise the MAC address string.
+    static std::string getStationLabel(const MacAddress& receiver);
 
   public:
     virtual ~IRateSelection() {}

src/inet/linklayer/ieee80211/mac/contract/IRateSelection.cc

@@ -102,7 +102,7 @@ void Dcf::transmitControlResponseFrame(Packet *responsePacket, const Ptr<const I
     else
         throw cRuntimeError("Unknown received frame type");
     RateSelection::setFrameMode(responsePacket, responseHeader, responseMode);
-    IRateSelection::emitDatarateSelected(this, stationLabels, responseHeader, responseMode);
+    IRateSelection::emitDatarateSelected(this, responseHeader, responseMode);
     EV_DEBUG << "Datarate for " << responsePacket->getName() << " is set to " << responseMode->getDataMode()->getNetBitrate() << ".\n";
     tx->transmitFrame(responsePacket, responseHeader, modeSet->getSifsTime(), this);
     delete responsePacket;
@@ -166,7 +166,7 @@ void Dcf::transmitFrame(Packet *packet, simtime_t ifs)
     const auto& header = packet->peekAtFront<Ieee80211MacHeader>();
     auto mode = rateSelection->computeMode(packet, header);
     RateSelection::setFrameMode(packet, header, mode);
-    IRateSelection::emitDatarateSelected(this, stationLabels, header, mode);
+    IRateSelection::emitDatarateSelected(this, header, mode);
     EV_DEBUG << "Datarate for " << packet->getName() << " is set to " << mode->getDataMode()->getNetBitrate() << ".\n";
     auto pendingPacket = channelAccess->getInProgressFrames()->getPendingFrameFor(packet);
     auto duration = originatorProtectionMechanism->computeDurationField(packet, header, pendingPacket, pendingPacket == nullptr ? nullptr : pendingPacket->peekAtFront<Ieee80211DataOrMgmtHeader>());

src/inet/linklayer/ieee80211/mac/contract/IRateSelection.h

@@ -50,8 +50,6 @@ class INET_API Dcf : public ICoordinationFunction, public IFrameSequenceHandler:
     ITx *tx = nullptr;
 
     IRateSelection *rateSelection = nullptr;
-    // Names the station a datarateSelected value belongs to (see ~IRateSelection::emitDatarateSelected)
-    StationLabelCache stationLabels;
 
     // Channel access method
     Dcaf *channelAccess = nullptr;

src/inet/linklayer/ieee80211/mac/coordinationfunction/Dcf.cc

@@ -668,7 +668,7 @@ void Hcf::transmitFrame(Packet *packet, simtime_t ifs)
         }
         auto mode = rateSelection->computeMode(packet, header, txop);
         setFrameMode(packet, header, mode);
-        IRateSelection::emitDatarateSelected(this, stationLabels, header, mode);
+        IRateSelection::emitDatarateSelected(this, header, mode);
         EV_DEBUG << "Datarate for " << packet->getName() << " is set to " << mode->getDataMode()->getNetBitrate() << ".\n";
         if (txop->getProtectionMechanism() == TxopProcedure::ProtectionMechanism::SINGLE_PROTECTION) {
             auto pendingPacket = channelOwner->getInProgressFrames()->getPendingFrameFor(packet);
@@ -703,7 +703,7 @@ void Hcf::transmitControlResponseFrame(Packet *responsePacket, const Ptr<const I
     else
         throw cRuntimeError("Unknown received frame type");
     setFrameMode(responsePacket, responseHeader, responseMode);
-    IRateSelection::emitDatarateSelected(this, stationLabels, responseHeader, responseMode);
+    IRateSelection::emitDatarateSelected(this, responseHeader, responseMode);
     EV_DEBUG << "Datarate for " << responsePacket->getName() << " is set to " << responseMode->getDataMode()->getNetBitrate() << ".\n";
     tx->transmitFrame(responsePacket, responseHeader, modeSet->getSifsTime(), this);
     delete responsePacket;

src/inet/linklayer/ieee80211/mac/coordinationfunction/Dcf.h

@@ -64,8 +64,6 @@ class INET_API Hcf : public ICoordinationFunction, public IFrameSequenceHandler:
     ITx *tx = nullptr;
 
     IQosRateSelection *rateSelection = nullptr;
-    // Names the station a datarateSelected value belongs to (see ~IRateSelection::emitDatarateSelected)
-    StationLabelCache stationLabels;
 
     // Channel Access Methods
     Edca *edca = nullptr;

src/inet/linklayer/ieee80211/mac/coordinationfunction/Hcf.cc

@@ -9,6 +9,7 @@
 
 #include "inet/common/ModuleAccess.h"
 #include "inet/common/Simsignals.h"
+#include "inet/linklayer/ieee80211/mac/contract/IRateSelection.h"
 
 namespace inet {
 namespace ieee80211 {
@@ -55,7 +56,7 @@ void RateControlBase::emitDatarateChangedSignal(const MacAddress& receiver, cons
     if (receiver.isBroadcast() || receiver.isMulticast())
         emit(datarateChangedSignal, rate.get());
     else {
-        cNamedObject details(stationLabel(receiver).c_str());
+        cNamedObject details(IRateSelection::getStationLabel(receiver).c_str());
         emit(datarateChangedSignal, rate.get(), &details);
     }
 }

src/inet/linklayer/ieee80211/mac/coordinationfunction/Hcf.h

@@ -8,12 +8,8 @@
 #ifndef __INET_RATECONTROLBASE_H
 #define __INET_RATECONTROLBASE_H
 
-#include <map>
-#include <string>
-
 #include "inet/linklayer/common/MacAddress.h"
 #include "inet/linklayer/ieee80211/mac/common/ModeSetListener.h"
-#include "inet/linklayer/ieee80211/mac/common/StationLabelCache.h"
 #include "inet/linklayer/ieee80211/mac/contract/IRateControl.h"
 
 namespace inet {
@@ -24,9 +20,6 @@ class INET_API RateControlBase : public ModeSetListener, public IRateControl
   public:
     static simsignal_t datarateChangedSignal;
 
-  protected:
-    StationLabelCache stationLabels; // cache of receiver MAC -> demux label (peer node name)
-
   protected:
     virtual int numInitStages() const override { return NUM_INIT_STAGES; }
     virtual void initialize(int stage) override;
@@ -36,9 +29,6 @@ class INET_API RateControlBase : public ModeSetListener, public IRateControl
     virtual MacAddress getReceiverAddress(Packet *frame) const;
     // The mode a newly seen station starts from: the initialRate parameter, or the fastest mandatory mode.
     virtual const physicallayer::IIeee80211Mode *getInitialMode();
-    // The demux label identifying a receiver in the per-station datarate statistic: the receiver's
-    // network node name if it can be resolved, otherwise the MAC address string. Cached per receiver.
-    virtual const std::string& stationLabel(const MacAddress& receiver) { return stationLabels.getLabel(receiver); }
     // Emits datarateChanged with the receiver as a named details object, so a demux(datarateChanged)
     // result filter can record a separate data-rate vector per station. The aggregate datarateChanged
     // statistic ignores the details and is therefore unchanged. Group-addressed receivers are emitted