Rework stats to store handles to the counters

src/Conn.h

@@ -132,6 +132,17 @@ public:
 	analyzer::Analyzer* FindAnalyzer(const char* name);	// find first in tree.
 
 	TransportProto ConnTransport() const { return proto; }
+	std::string TransportIdentifier() const override
+		{
+		if ( proto == TRANSPORT_TCP )
+			return "tcp";
+		else if ( proto == TRANSPORT_UDP )
+			return "udp";
+		else if ( proto == TRANSPORT_ICMP )
+			return "icmp";
+		else
+			return "unknown";
+		}
 
 	// FIXME: Now this is in Analyzer and should eventually be removed here.
 	//

src/Session.h

@@ -191,6 +191,12 @@ public:
 	 */
 	void DeleteTimer(double t);
 
+	/**
+	 * Returns a string representation of the transport protocol referenced by the
+	 * session. This is used by SessionManager for statistics.
+	 */
+	virtual std::string TransportIdentifier() const = 0;
+
 protected:
 
 	friend class detail::SessionTimer;
@@ -239,7 +245,6 @@ protected:
 	unsigned int is_active:1;
 	unsigned int record_packets:1, record_contents:1;
 	unsigned int record_current_packet:1, record_current_content:1;
-
 };
 
 namespace detail {

src/SessionManager.cc

@@ -36,13 +36,6 @@ zeek::SessionManager*& zeek::sessions = zeek::session_mgr;
 
 namespace zeek {
 
-SessionManager::SessionManager()
-	: stats(telemetry_mgr->GaugeFamily("zeek", "session_stats",
-	                                   {"tcp", "udp", "icmp"},
-	                                   "Zeek Session Stats", "1", false))
-	{
-	}
-
 SessionManager::~SessionManager()
 	{
 	Clear();
@@ -361,17 +354,9 @@ void SessionManager::Remove(Session* s)
 		if ( session_map.erase(key) == 0 )
 			reporter->InternalWarning("connection missing");
 		else
-			switch ( c->ConnTransport() ) {
-			case TRANSPORT_TCP:
-				stats.GetOrAdd({{"tcp", "num_conns"}}).Dec();
-				break;
-			case TRANSPORT_UDP:
-				stats.GetOrAdd({{"udp", "num_conns"}}).Dec();
-				break;
-			case TRANSPORT_ICMP:
-				stats.GetOrAdd({{"icmp", "num_conns"}}).Dec();
-				break;
-			case TRANSPORT_UNKNOWN: break;
+			{
+			if ( auto* stat_block = stats.GetCounters(c->TransportIdentifier()) )
+				stat_block->num.Dec();
 			}
 
 		s->ClearKey();
@@ -425,17 +410,20 @@ void SessionManager::Clear()
 
 void SessionManager::GetStats(SessionStats& s)
 	{
-	s.max_TCP_conns = stats.GetOrAdd({{"tcp", "max_conns"}}).Value();
-	s.num_TCP_conns = stats.GetOrAdd({{"tcp", "num_conns"}}).Value();
-	s.cumulative_TCP_conns = stats.GetOrAdd({{"tcp", "cumulative_conns"}}).Value();
+	auto* tcp_stats = stats.GetCounters("tcp");
+	s.max_TCP_conns = tcp_stats->max;
+	s.num_TCP_conns = tcp_stats->num.Value();
+	s.cumulative_TCP_conns = tcp_stats->total.Value();
 
-	s.max_UDP_conns = stats.GetOrAdd({{"udp", "max_conns"}}).Value();
-	s.num_UDP_conns = stats.GetOrAdd({{"udp", "num_conns"}}).Value();
-	s.cumulative_UDP_conns = stats.GetOrAdd({{"udp", "cumulative_conns"}}).Value();
+	auto* udp_stats = stats.GetCounters("udp");
+	s.max_UDP_conns = udp_stats->max;
+	s.num_UDP_conns = udp_stats->num.Value();
+	s.cumulative_UDP_conns = udp_stats->total.Value();
 
-	s.max_ICMP_conns = stats.GetOrAdd({{"icmp", "max_conns"}}).Value();
-	s.num_ICMP_conns = stats.GetOrAdd({{"icmp", "num_conns"}}).Value();
-	s.cumulative_ICMP_conns = stats.GetOrAdd({{"icmp", "cumulative_conns"}}).Value();
+	auto* icmp_stats = stats.GetCounters("icmp");
+	s.max_ICMP_conns = icmp_stats->max;
+	s.num_ICMP_conns = icmp_stats->num.Value();
+	s.cumulative_ICMP_conns = icmp_stats->total.Value();
 
 	s.num_fragments = detail::fragment_mgr->Size();
 	s.max_fragments = detail::fragment_mgr->MaxFragments();
@@ -649,31 +637,15 @@ void SessionManager::InsertSession(detail::SessionKey key, Session* session)
 	key.CopyData();
 	session_map.insert_or_assign(std::move(key), session);
 
-	std::string protocol;
-	switch ( static_cast<Connection*>(session)->ConnTransport() )
-		{
-		case TRANSPORT_TCP:
-			protocol = "tcp";
-			break;
-		case TRANSPORT_UDP:
-			protocol = "udp";
-			break;
-		case TRANSPORT_ICMP:
-			protocol = "icmp";
-			break;
-		default:
-			break;
-		}
+	std::string protocol = session->TransportIdentifier();
 
-	if ( ! protocol.empty() )
+	if ( auto* stat_block = stats.GetCounters(protocol) )
 		{
-		auto max = stats.GetOrAdd({{protocol, "max_conns"}});
-		auto num = stats.GetOrAdd({{protocol, "num_conns"}});
-		num.Inc();
+		stat_block->num.Inc();
+		stat_block->total.Inc();
 
-		stats.GetOrAdd({{protocol, "cumulative_conns"}}).Inc();
-		if ( num.Value() > max.Value() )
-			max.Inc();
+		if ( stat_block->num.Value() > stat_block->max )
+			stat_block->max++;
 		}
 	}
 

src/SessionManager.h

@@ -9,7 +9,7 @@
 #include "zeek/Frag.h"
 #include "zeek/NetVar.h"
 #include "zeek/analyzer/protocol/tcp/Stats.h"
-#include "zeek/telemetry/Gauge.h"
+#include "zeek/telemetry/Manager.h"
 #include "zeek/Hash.h"
 #include "zeek/Session.h"
 
@@ -42,7 +42,7 @@ struct SessionStats {
 
 class SessionManager final {
 public:
-	SessionManager();
+	SessionManager() = default;
 	~SessionManager();
 
 	void Done();	// call to drain events before destructing
@@ -141,6 +141,59 @@ public:
 
 private:
 
+	class StatBlocks {
+
+	public:
+
+		struct Block {
+			telemetry::IntGauge num;
+			telemetry::IntCounter total;
+			size_t max = 0;
+
+			Block(telemetry::IntGaugeFamily num_family,
+			      telemetry::IntCounterFamily total_family,
+			      std::string protocol) : num(num_family.GetOrAdd({{"protocol", protocol}})),
+			                              total(total_family.GetOrAdd({{"protocol", protocol}}))
+				{
+				}
+			};
+
+		using BlockMap = std::map<std::string, Block>;
+
+		BlockMap::iterator InitCounters(std::string protocol)
+			{
+			telemetry::IntGaugeFamily num_family = telemetry_mgr->GaugeFamily(
+				"zeek", "open-sessions", {"protocol"}, "Active Zeek Sessions");
+			telemetry::IntCounterFamily total_family = telemetry_mgr->CounterFamily(
+				"zeek", "sessions", {"protocol"},
+				"Total number of sessions", "1", true);
+
+			auto [it, inserted] = entries.insert(
+				{protocol, Block{num_family, total_family, protocol}});
+
+			if ( inserted )
+				return it;
+
+			return entries.end();
+			}
+
+		Block* GetCounters(std::string protocol)
+			{
+			auto it = entries.find(protocol);
+			if ( it == entries.end() )
+				it = InitCounters(protocol);
+
+			if ( it != entries.end() )
+				return &(it->second);
+
+			return nullptr;
+			}
+
+	private:
+
+		BlockMap entries;
+	};
+
 	using SessionMap = std::map<detail::SessionKey, Session*>;
 
 	Connection* NewConn(const detail::ConnIDKey& k, double t, const ConnID* id,
@@ -177,7 +230,7 @@ private:
 	void InsertSession(detail::SessionKey key, Session* session);
 
 	SessionMap session_map;
-	telemetry::IntGaugeFamily stats;
+	StatBlocks stats;
 };
 
 // Manager for the currently active sessions.