try spacing path building out more wide in time so that intros don't die in the same small interval

include/llarp/pathset.hpp

@@ -51,6 +51,9 @@ namespace llarp
       virtual void
       HandlePathBuildTimeout(Path* path);
 
+      bool
+      GetNewestIntro(service::Introduction& intro) const;
+
       void
       AddPath(Path* path);
 
@@ -124,10 +127,12 @@ namespace llarp
       SelectHop(llarp_nodedb* db, const RouterContact& prev, RouterContact& cur,
                 size_t hop) = 0;
 
+     protected:
+      size_t m_NumPaths;
+
      private:
       typedef std::pair< RouterID, PathID_t > PathInfo_t;
       typedef std::map< PathInfo_t, Path* > PathMap_t;
-      size_t m_NumPaths;
       PathMap_t m_Paths;
     };
 

llarp/pathset.cpp

@@ -190,6 +190,24 @@ namespace llarp
       llarp::LogInfo("path ", p->Name(), " has timed out");
     }
 
+    bool
+    PathSet::GetNewestIntro(service::Introduction& intro) const
+    {
+      bool found = false;
+      auto itr   = m_Paths.begin();
+      while(itr != m_Paths.end())
+      {
+        if(itr->second->IsReady()
+           && itr->second->intro.expiresAt > intro.expiresAt)
+        {
+          intro = itr->second->intro;
+          found = true;
+        }
+        ++itr;
+      }
+      return found;
+    }
+
     Path*
     PathSet::PickRandomEstablishedPath() const
     {

llarp/service/endpoint.cpp

@@ -1343,7 +1343,21 @@ namespace llarp
     {
       if(markedBad)
         return false;
-      return path::Builder::ShouldBuildMore();
+      bool should = path::Builder::ShouldBuildMore();
+      // determinte newest intro
+      Introduction intro;
+      if(!GetNewestIntro(intro))
+        return should;
+
+      auto now = llarp_time_now_ms();
+      // time from now that the newest intro expires at
+      auto dlt = now < intro.expiresAt ? intro.expiresAt - now : 0;
+      return should ||  // try spacing tunnel builds out evenly in time
+          (dlt
+           && (dlt < (DEFAULT_PATH_LIFETIME / 2)
+               && NumInStatus(path::ePathBuilding)
+                   < m_NumPaths)  // try not to overload with builds
+           && dlt > buildIntervalLimit);
     }
 
     /// send on an established convo tag
@@ -1371,6 +1385,7 @@ namespace llarp
         // shift intro
         if(!MarkCurrentIntroBad(now))
         {
+          UpdateIntroSet();
           llarp::LogError("dropping message, no path after shifting intros");
           return;
         }