Don't run into session timeout when sig shares come in slow

Instead of just tracking when the first share was received, we now also
track when the last (non-duplicate) share was received. Sessios will now
timeout 5 minutes after the first share arrives, or 1 minute after the last
one arrived.

src/llmq/quorums_signing_shares.cpp

@@ -567,7 +567,16 @@ void CSigSharesManager::ProcessSigShare(NodeId nodeId, const CSigShare& sigShare
         }
 
         sigSharesToAnnounce.Add(sigShare.GetKey(), true);
-        firstSeenForSessions.emplace(sigShare.GetSignHash(), GetTimeMillis());
+
+        auto it = timeSeenForSessions.find(sigShare.GetSignHash());
+        if (it == timeSeenForSessions.end()) {
+            auto t = GetTimeMillis();
+            // insert first-seen and last-seen time
+            timeSeenForSessions.emplace(sigShare.GetSignHash(), std::make_pair(t, t));
+        } else {
+            // update last-seen time
+            it->second.second = GetTimeMillis();
+        }
 
         if (!quorumNodes.empty()) {
             // don't announce and wait for other nodes to request this share and directly send it to them
@@ -968,11 +977,12 @@ void CSigSharesManager::Cleanup()
 
         // Remove sessions which timed out
         std::unordered_set<uint256> timeoutSessions;
-        for (auto& p : firstSeenForSessions) {
+        for (auto& p : timeSeenForSessions) {
             auto& signHash = p.first;
-            int64_t time = p.second;
+            int64_t firstSeenTime = p.second.first;
+            int64_t lastSeenTime = p.second.second;
 
-            if (now - time >= SIGNING_SESSION_TIMEOUT) {
+            if (now - firstSeenTime >= SESSION_TOTAL_TIMEOUT || now - lastSeenTime >= SESSION_NEW_SHARES_TIMEOUT) {
                 timeoutSessions.emplace(signHash);
             }
         }
@@ -1054,7 +1064,7 @@ void CSigSharesManager::RemoveSigSharesForSession(const uint256& signHash)
     sigSharesRequested.EraseAllForSignHash(signHash);
     sigSharesToAnnounce.EraseAllForSignHash(signHash);
     sigShares.EraseAllForSignHash(signHash);
-    firstSeenForSessions.erase(signHash);
+    timeSeenForSessions.erase(signHash);
 }
 
 void CSigSharesManager::RemoveBannedNodeStates()

src/llmq/quorums_signing_shares.h

@@ -334,7 +334,8 @@ class CSigSharesNodeState
 
 class CSigSharesManager : public CRecoveredSigsListener
 {
-    static const int64_t SIGNING_SESSION_TIMEOUT = 60 * 1000;
+    static const int64_t SESSION_NEW_SHARES_TIMEOUT = 60 * 1000;
+    static const int64_t SESSION_TOTAL_TIMEOUT = 5 * 60 * 1000;
     static const int64_t SIG_SHARE_REQUEST_TIMEOUT = 5 * 1000;
 
 private:
@@ -344,7 +345,9 @@ class CSigSharesManager : public CRecoveredSigsListener
     CThreadInterrupt workInterrupt;
 
     SigShareMap<CSigShare> sigShares;
-    std::unordered_map<uint256, int64_t> firstSeenForSessions;
+
+    // stores time of first and last receivedSigShare. Used to detect timeouts
+    std::unordered_map<uint256, std::pair<int64_t, int64_t>> timeSeenForSessions;
 
     std::unordered_map<NodeId, CSigSharesNodeState> nodeStates;
     SigShareMap<std::pair<NodeId, int64_t>> sigSharesRequested;