Implement new algo for quorum connections (#2710)

Instead of trying to manually figure out params for different quorum/ring sizes, connect to nodes at indexes (i+2^k)%n where k: 0..floor(log2(n-1))-1, n: size of the quorum/ring

src/chainparams.cpp

@@ -122,8 +122,6 @@ static Consensus::LLMQParams llmq10_60 = {
 
         .signingActiveQuorumCount = 2, // just a few ones to allow easier testing
 
-        .neighborConnections = 2,
-        .diagonalConnections = 2,
         .keepOldConnections = 24,
 };
 
@@ -142,8 +140,6 @@ static Consensus::LLMQParams llmq50_60 = {
 
         .signingActiveQuorumCount = 24, // a full day worth of LLMQs
 
-        .neighborConnections = 2,
-        .diagonalConnections = 2,
         .keepOldConnections = 24,
 };
 
@@ -162,8 +158,6 @@ static Consensus::LLMQParams llmq400_60 = {
 
         .signingActiveQuorumCount = 4, // two days worth of LLMQs
 
-        .neighborConnections = 4,
-        .diagonalConnections = 4,
         .keepOldConnections = 4,
 };
 
@@ -183,8 +177,6 @@ static Consensus::LLMQParams llmq400_85 = {
 
         .signingActiveQuorumCount = 4, // two days worth of LLMQs
 
-        .neighborConnections = 4,
-        .diagonalConnections = 4,
         .keepOldConnections = 4,
 };
 

src/consensus/params.h

@@ -107,14 +107,6 @@ struct LLMQParams {
     // Number of quorums to consider "active" for signing sessions
     int signingActiveQuorumCount;
 
-    // Used for inter-quorum communication. This is the number of deterministic connections built to the clockwise
-    // neighbors on the circle shaped nodes topography
-    int neighborConnections;
-
-    // Used for inter-quorum communication. This is the number of deterministic connections built diagonally to the
-    // member on the circle shaped nodes topography.
-    int diagonalConnections;
-
     // Used for inter-quorum communication. This is the number of quorums for which we should keep old connections. This
     // should be at least as much as the active quorums set.
     int keepOldConnections;

src/llmq/quorums_utils.cpp

@@ -50,26 +50,20 @@ std::set<CService> CLLMQUtils::GetQuorumConnections(Consensus::LLMQType llmqType
     for (size_t i = 0; i < mns.size(); i++) {
         auto& dmn = mns[i];
         if (dmn->proTxHash == forMember) {
-            for (int n = 0; n < params.neighborConnections; n++) {
-                size_t idx = (i + 1 + n) % mns.size();
-                auto& otherDmn = mns[idx];
-                if (otherDmn == dmn) {
-                    continue;
-                }
-                result.emplace(otherDmn->pdmnState->addr);
-            }
-            size_t startIdx = i + mns.size() / 2;
-            startIdx -= (params.diagonalConnections / 2) * params.neighborConnections;
-            startIdx %= mns.size();
-            for (int n = 0; n < params.diagonalConnections; n++) {
-                size_t idx = startIdx + n * params.neighborConnections;
-                idx %= mns.size();
+            // Connect to nodes at indexes (i+2^k)%n, k: 0..floor(log2(n-1))-1, n: size of the quorum/ring
+            int gap = 1;
+            int gap_max = mns.size() - 1;
+            while (gap_max >>= 1) {
+                size_t idx = (i + gap) % mns.size();
                 auto& otherDmn = mns[idx];
                 if (otherDmn == dmn) {
                     continue;
                 }
                 result.emplace(otherDmn->pdmnState->addr);
+                gap <<= 1;
             }
+            // there can be no two members with the same proTxHash, so return early
+            break;
         }
     }
     return result;