From 31e40a494d554a7c386be6d7cf269bded7d686bf Mon Sep 17 00:00:00 2001
From: furszy <matiasfurszyfer@protonmail.com>
Date: Fri, 3 Dec 2021 10:56:54 -0300
Subject: [PATCH] Budget sync: Remove useless extra item sync p2p msgs
 roundtrip (no need to broadcast an inv if the peer is asking for the item
 directly..) and stop walking through the two maps (budgets and proposals),
 locking their mutexes, when the peer is requesting a single proposal/budfin.

---
 src/budget/budgetmanager.cpp | 35 +++++++++++++++++++++++++++++++++--
 1 file changed, 33 insertions(+), 2 deletions(-)

diff --git a/src/budget/budgetmanager.cpp b/src/budget/budgetmanager.cpp
index a6bb7bd39b30c..18e765ed73b25 100644
--- a/src/budget/budgetmanager.cpp
+++ b/src/budget/budgetmanager.cpp
@@ -1327,15 +1327,46 @@ void CBudgetManager::SetSynced(bool synced)
     }
 }
 
+template<typename Map, typename Item>
+static bool relayItemIfFound(const uint256& itemHash, CNode* pfrom, RecursiveMutex& cs, Map& map, bool fPartial, const char* type)
+{
+    CNetMsgMaker msgMaker(pfrom->GetSendVersion());
+    LOCK(cs);
+    const auto& it = map.find(itemHash);
+    if (it == map.end()) return false;
+    Item* item = &(it->second);
+    if (!item->IsValid()) return true; // don't broadcast invalid items
+    g_connman->PushMessage(pfrom, msgMaker.Make(type, item->GetBroadcast()));
+    int nInvCount = 1;
+    item->SyncVotes(pfrom, fPartial, nInvCount);
+    LogPrint(BCLog::MNBUDGET, "%s: single %s sent %d items\n", __func__, type, nInvCount);
+    return true;
+}
+
 void CBudgetManager::Sync(CNode* pfrom, const uint256& nProp, bool fPartial)
 {
+    // Single item request
+    if (!nProp.IsNull()) {
+        // Try first to relay a proposal
+        if (relayItemIfFound<std::map<uint256, CBudgetProposal>, CBudgetProposal>(nProp, pfrom, cs_proposals, mapProposals, fPartial, NetMsgType::BUDGETPROPOSAL)) {
+            return;
+        }
+        // Try now to relay a finalization
+        if (relayItemIfFound<std::map<uint256, CFinalizedBudget>, CFinalizedBudget>(nProp, pfrom, cs_budgets, mapFinalizedBudgets, fPartial, NetMsgType::FINALBUDGET)) {
+            return;
+        }
+        LogPrint(BCLog::MNBUDGET, "%s: single request budget item not found\n", __func__);
+        return;
+    }
+
+    // Full budget sync request.
     CNetMsgMaker msgMaker(pfrom->GetSendVersion());
     int nInvCount = 0;
     {
         LOCK(cs_proposals);
         for (auto& it: mapProposals) {
             CBudgetProposal* pbudgetProposal = &(it.second);
-            if (pbudgetProposal && pbudgetProposal->IsValid() && (nProp.IsNull() || it.first == nProp)) {
+            if (pbudgetProposal && pbudgetProposal->IsValid()) {
                 pfrom->PushInventory(CInv(MSG_BUDGET_PROPOSAL, it.second.GetHash()));
                 nInvCount++;
                 pbudgetProposal->SyncVotes(pfrom, fPartial, nInvCount);
@@ -1350,7 +1381,7 @@ void CBudgetManager::Sync(CNode* pfrom, const uint256& nProp, bool fPartial)
         LOCK(cs_budgets);
         for (auto& it: mapFinalizedBudgets) {
             CFinalizedBudget* pfinalizedBudget = &(it.second);
-            if (pfinalizedBudget && pfinalizedBudget->IsValid() && (nProp.IsNull() || it.first == nProp)) {
+            if (pfinalizedBudget && pfinalizedBudget->IsValid()) {
                 pfrom->PushInventory(CInv(MSG_BUDGET_FINALIZED, it.second.GetHash()));
                 nInvCount++;
                 pfinalizedBudget->SyncVotes(pfrom, fPartial, nInvCount);