more aggressive path building. (#1423)

* more aggressive path building.

* do more than one in parallel path builds at a time

* correct last commit's logic

* rename numPaths -> numDesiredPaths to clarify intent

* revert string change as it will break a lot

* don't prematurly short circuit on snode builds

Co-authored-by: Thomas Winget <tewinget@gmail.com>

llarp/exit/session.cpp

@@ -58,7 +58,7 @@ namespace llarp
     {
       if (BuildCooldownHit(now))
         return false;
-      const size_t expect = (1 + (numPaths / 2));
+      const size_t expect = (1 + (numDesiredPaths / 2));
       // check 30 seconds into the future and see if we need more paths
       const llarp_time_t future = now + 30s + buildIntervalLimit;
       return NumPathsExistingAt(future) < expect;
@@ -250,7 +250,7 @@ namespace llarp
     bool
     BaseSession::IsReady() const
     {
-      const size_t expect = (1 + (numPaths / 2));
+      const size_t expect = (1 + (numDesiredPaths / 2));
       return AvailablePaths(llarp::path::ePathRoleExit) >= expect;
     }
 
@@ -265,9 +265,9 @@ namespace llarp
     {
       if (BuildCooldownHit(now))
         return false;
-      if (!IsReady())
+      if (IsReady() and NumInStatus(path::ePathBuilding) < numDesiredPaths)
-        return NumInStatus(path::ePathBuilding) < numPaths;
+        return path::Builder::UrgentBuild(now);
-      return path::Builder::UrgentBuild(now);
+      return false;
     }
 
     bool

llarp/path/pathbuilder.cpp

@@ -191,7 +191,7 @@ namespace llarp
     {
       util::StatusObject obj{{"buildStats", m_BuildStats.ExtractStatus()},
                              {"numHops", uint64_t(numHops)},
-                             {"numPaths", uint64_t(numPaths)}};
+                             {"numPaths", uint64_t(numDesiredPaths)}};
       std::transform(
           m_Paths.begin(),
           m_Paths.end(),

llarp/path/pathbuilder.hpp

@@ -44,7 +44,7 @@ namespace llarp
       llarp_time_t buildIntervalLimit = MIN_PATH_BUILD_INTERVAL;
 
       /// construct
-      Builder(AbstractRouter* p_router, size_t numPaths, size_t numHops);
+      Builder(AbstractRouter* p_router, size_t numDesiredPaths, size_t numHops);
 
       virtual ~Builder() = default;
 

llarp/path/pathset.cpp

@@ -11,7 +11,7 @@ namespace llarp
 {
   namespace path
   {
-    PathSet::PathSet(size_t num) : numPaths(num)
+    PathSet::PathSet(size_t num) : numDesiredPaths(num)
     {}
 
     bool
@@ -19,10 +19,10 @@ namespace llarp
     {
       (void)now;
       const auto building = NumInStatus(ePathBuilding);
-      if (building >= numPaths)
+      if (building >= numDesiredPaths)
         return false;
       const auto established = NumInStatus(ePathEstablished);
-      return established < numPaths;
+      return established < numDesiredPaths;
     }
 
     bool

llarp/path/pathset.hpp

@@ -97,8 +97,8 @@ namespace llarp
       /// maximum number of paths a path set can maintain
       static constexpr size_t max_paths = 32;
       /// construct
-      /// @params numPaths the number of paths to maintain
+      /// @params numDesiredPaths the number of paths to maintain
-      PathSet(size_t numPaths);
+      PathSet(size_t numDesiredPaths);
 
       /// get a shared_ptr of ourself
       virtual PathSet_ptr
@@ -296,7 +296,7 @@ namespace llarp
       void
       DownstreamFlush(AbstractRouter* r);
 
-      size_t numPaths;
+      size_t numDesiredPaths;
 
      protected:
       BuildStats m_BuildStats;

llarp/service/endpoint.cpp

@@ -52,7 +52,7 @@ namespace llarp
     Endpoint::Configure(const NetworkConfig& conf, [[maybe_unused]] const DnsConfig& dnsConf)
     {
       if (conf.m_Paths.has_value())
-        numPaths = *conf.m_Paths;
+        numDesiredPaths = *conf.m_Paths;
 
       if (conf.m_Hops.has_value())
         numHops = *conf.m_Hops;
@@ -1231,7 +1231,7 @@ namespace llarp
               return HandleInboundPacket(tag, pkt.ConstBuffer(), eProtocolTrafficV4, 0);
             },
             Router(),
-            numPaths,
+            numDesiredPaths,
             numHops,
             false,
             ShouldBundleRC());
@@ -1466,13 +1466,8 @@ namespace llarp
     bool
     Endpoint::ShouldBuildMore(llarp_time_t now) const
     {
-      if (path::Builder::BuildCooldownHit(now))
+      if (not path::Builder::ShouldBuildMore(now))
         return false;
-
-      size_t numBuilding = NumInStatus(path::ePathBuilding);
-      if (numBuilding > 0)
-        return false;
-
       return ((now - lastBuild) > path::intro_path_spread)
           || NumInStatus(path::ePathEstablished) < path::min_intro_paths;
     }

llarp/service/outbound_context.cpp

@@ -359,11 +359,9 @@ namespace llarp
     bool
     OutboundContext::ShouldBuildMore(llarp_time_t now) const
     {
-      if (markedBad || path::Builder::BuildCooldownHit(now))
+      if (markedBad || not path::Builder::ShouldBuildMore(now))
         return false;
-      const bool canBuild =
+      if (NumInStatus(path::ePathBuilding) >= numDesiredPaths)
-          NumInStatus(path::ePathBuilding) == 0 and path::Builder::ShouldBuildMore(now);
-      if (not canBuild)
         return false;
       llarp_time_t t = 0s;
       ForEachPath([&t](path::Path_ptr path) {