From 38513b6346fb743aa3c34b0daeb10ea81829d3e5 Mon Sep 17 00:00:00 2001
From: Konstantin Akimov <knstqq@gmail.com>
Date: Mon, 23 Jun 2025 14:00:11 +0700
Subject: [PATCH 1/3] perf: temporary cache for consequent calls of
 CDeterministicMNList for historical blocks

It speeds ups blocks's Undo up to 10x. It speeds up RPC `protx diff` up to 9x
---
 src/evo/deterministicmns.cpp | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/evo/deterministicmns.cpp b/src/evo/deterministicmns.cpp
index e3e850bdb9df..17c19fd6bf66 100644
--- a/src/evo/deterministicmns.cpp
+++ b/src/evo/deterministicmns.cpp
@@ -778,6 +778,13 @@ CDeterministicMNList CDeterministicMNManager::GetListForBlockInternal(gsl::not_n
     for (const auto& diffIndex : listDiffIndexes) {
         const auto& diff = mnListDiffsCache.at(diffIndex->GetBlockHash());
         snapshot.ApplyDiff(diffIndex, diff);
+        if (snapshot.GetHeight() % 32 == 0) {
+            // Add this temporary mini-snapshot to cache.
+            // This extra cached mn-list helps to improve performance of GetListForBlock
+            // for close blocks, because in the worst cases each of them requires to retrieve
+            // and apply up to 575 diffs
+            mnListsCache.emplace(snapshot.GetBlockHash(), snapshot);
+        }
     }
 
     if (tipIndex) {

From bfca7268728358477e19e7bb12a16062156dfe44 Mon Sep 17 00:00:00 2001
From: Konstantin Akimov <knstqq@gmail.com>
Date: Mon, 18 Aug 2025 15:13:15 +0700
Subject: [PATCH 2/3] perf: do not create mini-snapshots during re-index

---
 src/evo/deterministicmns.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/evo/deterministicmns.cpp b/src/evo/deterministicmns.cpp
index 17c19fd6bf66..5ec5066b5aef 100644
--- a/src/evo/deterministicmns.cpp
+++ b/src/evo/deterministicmns.cpp
@@ -16,6 +16,7 @@
 #include <consensus/validation.h>
 #include <deploymentstatus.h>
 #include <messagesigner.h>
+#include <node/blockstorage.h>
 #include <script/standard.h>
 #include <stats/client.h>
 #include <uint256.h>
@@ -778,7 +779,7 @@ CDeterministicMNList CDeterministicMNManager::GetListForBlockInternal(gsl::not_n
     for (const auto& diffIndex : listDiffIndexes) {
         const auto& diff = mnListDiffsCache.at(diffIndex->GetBlockHash());
         snapshot.ApplyDiff(diffIndex, diff);
-        if (snapshot.GetHeight() % 32 == 0) {
+        if (!fReindex && snapshot.GetHeight() % 32 == 0) {
             // Add this temporary mini-snapshot to cache.
             // This extra cached mn-list helps to improve performance of GetListForBlock
             // for close blocks, because in the worst cases each of them requires to retrieve

From 366cd2b19d3de1da6c733d9e529ad8040f6d83c6 Mon Sep 17 00:00:00 2001
From: Konstantin Akimov <knstqq@gmail.com>
Date: Mon, 18 Aug 2025 15:20:56 +0700
Subject: [PATCH 3/3] refactor: clarify logic and add a named constant
 MINI_SNAPSHOT_INTERVAL

---
 src/evo/deterministicmns.cpp | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/src/evo/deterministicmns.cpp b/src/evo/deterministicmns.cpp
index 5ec5066b5aef..5353bb83a488 100644
--- a/src/evo/deterministicmns.cpp
+++ b/src/evo/deterministicmns.cpp
@@ -779,11 +779,21 @@ CDeterministicMNList CDeterministicMNManager::GetListForBlockInternal(gsl::not_n
     for (const auto& diffIndex : listDiffIndexes) {
         const auto& diff = mnListDiffsCache.at(diffIndex->GetBlockHash());
         snapshot.ApplyDiff(diffIndex, diff);
-        if (!fReindex && snapshot.GetHeight() % 32 == 0) {
-            // Add this temporary mini-snapshot to cache.
-            // This extra cached mn-list helps to improve performance of GetListForBlock
-            // for close blocks, because in the worst cases each of them requires to retrieve
-            // and apply up to 575 diffs
+
+        static constexpr int MINI_SNAPSHOT_INTERVAL = 32;
+        if (!node::fReindex && snapshot.GetHeight() % MINI_SNAPSHOT_INTERVAL == 0) {
+            // Add this temporary mini-snapshot to the cache.
+            // Persistent masternode list snapshots are stored in evo-db every 576 blocks.
+            // To answer GetListForBlock() between these snapshots, the node must rebuild
+            // state by applying up to 575 diffs from the nearest persistent snapshot.
+            // If GetListForBlock() is called repeatedly in that range, the work multiplies
+            // (up to 575 diffs * number of calls).
+            // Mini-snapshots reduce this overhead by caching intermediate states
+            // every MINI_SNAPSHOT_INTERVAL blocks. Unlike persistent snapshots, these live
+            // only in memory and are cleaned up after a short time by the scheduled cleanup().
+            // There is also separate in-memory caching for the current tip and active quorums,
+            // but this mini-snapshot cache specifically speeds up repeated requests
+            // for nearby historical blocks.
             mnListsCache.emplace(snapshot.GetBlockHash(), snapshot);
         }
     }