validation: do not wipe utxo cache for stats/scans/snapshots

src/bitcoin-chainstate.cpp

@@ -290,7 +290,7 @@ epilogue:
         LOCK(cs_main);
         for (Chainstate* chainstate : chainman.GetAll()) {
             if (chainstate->CanFlushToDisk()) {
-                chainstate->ForceFlushStateToDisk();
+                chainstate->ForceFlushStateToDisk(/*wipe_cache=*/true);
                 chainstate->ResetCoinsViews();
             }
         }

src/init.cpp

@@ -328,7 +328,7 @@ void Shutdown(NodeContext& node)
         LOCK(cs_main);
         for (Chainstate* chainstate : node.chainman->GetAll()) {
             if (chainstate->CanFlushToDisk()) {
-                chainstate->ForceFlushStateToDisk();
+                chainstate->ForceFlushStateToDisk(/*wipe_cache=*/true);
             }
         }
     }
@@ -354,7 +354,7 @@ void Shutdown(NodeContext& node)
         LOCK(cs_main);
         for (Chainstate* chainstate : node.chainman->GetAll()) {
             if (chainstate->CanFlushToDisk()) {
-                chainstate->ForceFlushStateToDisk();
+                chainstate->ForceFlushStateToDisk(/*wipe_cache=*/true);
                 chainstate->ResetCoinsViews();
             }
         }

src/rpc/blockchain.cpp

@@ -976,7 +976,7 @@ static RPCHelpMan gettxoutsetinfo()
     NodeContext& node = EnsureAnyNodeContext(request.context);
     ChainstateManager& chainman = EnsureChainman(node);
     Chainstate& active_chainstate = chainman.ActiveChainstate();
-    active_chainstate.ForceFlushStateToDisk();
+    active_chainstate.ForceFlushStateToDisk(/*wipe_cache=*/false);
 
     CCoinsView* coins_view;
     BlockManager* blockman;
@@ -2279,7 +2279,7 @@ static RPCHelpMan scantxoutset()
             ChainstateManager& chainman = EnsureChainman(node);
             LOCK(cs_main);
             Chainstate& active_chainstate = chainman.ActiveChainstate();
-            active_chainstate.ForceFlushStateToDisk();
+            active_chainstate.ForceFlushStateToDisk(/*wipe_cache=*/false);
             pcursor = CHECK_NONFATAL(active_chainstate.CoinsDB().Cursor());
             tip = CHECK_NONFATAL(active_chainstate.m_chain.Tip());
         }
@@ -2727,7 +2727,7 @@ UniValue CreateUTXOSnapshot(
         //
         LOCK(::cs_main);
 
-        chainstate.ForceFlushStateToDisk();
+        chainstate.ForceFlushStateToDisk(/*wipe_cache=*/false);
 
         maybe_stats = GetUTXOStats(&chainstate.CoinsDB(), chainstate.m_blockman, CoinStatsHashType::HASH_SERIALIZED, node.rpc_interruption_point);
         if (!maybe_stats) {

src/test/fuzz/utxo_total_supply.cpp

@@ -77,9 +77,9 @@ FUZZ_TARGET(utxo_total_supply)
         tx.vin.emplace_back(txo.first);
         tx.vout.emplace_back(txo.second.nValue, txo.second.scriptPubKey); // "Forward" coin with no fee
     };
-    const auto UpdateUtxoStats = [&]() {
+    const auto UpdateUtxoStats = [&](bool wipe_cache) {
         LOCK(chainman.GetMutex());
-        chainman.ActiveChainstate().ForceFlushStateToDisk();
+        chainman.ActiveChainstate().ForceFlushStateToDisk(/*wipe_cache=*/wipe_cache);
         utxo_stats = std::move(
             *Assert(kernel::ComputeUTXOStats(kernel::CoinStatsHashType::NONE, &chainman.ActiveChainstate().CoinsDB(), chainman.m_blockman, {})));
         // Check that miner can't print more money than they are allowed to
@@ -89,7 +89,7 @@ FUZZ_TARGET(utxo_total_supply)
 
     // Update internal state to chain tip
     StoreLastTxo();
-    UpdateUtxoStats();
+    UpdateUtxoStats(/*wipe_cache=*/fuzzed_data_provider.ConsumeBool());
     assert(ActiveHeight() == 0);
     // Get at which height we duplicate the coinbase
     // Assuming that the fuzzer will mine relatively short chains (less than 200 blocks), we want the duplicate coinbase to be not too high.
@@ -114,7 +114,7 @@ FUZZ_TARGET(utxo_total_supply)
     circulation += GetBlockSubsidy(ActiveHeight(), Params().GetConsensus());
 
     assert(ActiveHeight() == 1);
-    UpdateUtxoStats();
+    UpdateUtxoStats(/*wipe_cache=*/fuzzed_data_provider.ConsumeBool());
     current_block = PrepareNextBlock();
     StoreLastTxo();
 
@@ -153,7 +153,7 @@ FUZZ_TARGET(utxo_total_supply)
                     circulation += GetBlockSubsidy(ActiveHeight(), Params().GetConsensus());
                 }
 
-                UpdateUtxoStats();
+                UpdateUtxoStats(/*wipe_cache=*/fuzzed_data_provider.ConsumeBool());
 
                 if (!was_valid) {
                     // utxo stats must not change

src/test/validation_chainstatemanager_tests.cpp

@@ -372,7 +372,7 @@ struct SnapshotTestSetup : TestChain100Setup {
         {
             for (Chainstate* cs : chainman.GetAll()) {
                 LOCK(::cs_main);
-                cs->ForceFlushStateToDisk();
+                cs->ForceFlushStateToDisk(/*wipe_cache=*/true);
             }
             // Process all callbacks referring to the old manager before wiping it.
             m_node.validation_signals->SyncWithValidationInterfaceQueue();

src/validation.cpp

@@ -2869,7 +2869,7 @@ bool Chainstate::FlushStateToDisk(
         // It's been very long since we flushed the cache. Do this infrequently, to optimize cache usage.
         bool fPeriodicFlush = mode == FlushStateMode::PERIODIC && nNow > m_last_flush + DATABASE_FLUSH_INTERVAL;
         // Combine all conditions that result in a full cache flush.
-        fDoFullFlush = (mode == FlushStateMode::ALWAYS) || fCacheLarge || fCacheCritical || fPeriodicFlush || fFlushForPrune;
+        fDoFullFlush = (mode == FlushStateMode::FORCE_FLUSH) || (mode == FlushStateMode::FORCE_SYNC) || fCacheLarge || fCacheCritical || fPeriodicFlush || fFlushForPrune;
         // Write blocks and block index to disk.
         if (fDoFullFlush || fPeriodicWrite) {
             // Ensure we can write block index
@@ -2917,7 +2917,7 @@ bool Chainstate::FlushStateToDisk(
                 return FatalError(m_chainman.GetNotifications(), state, _("Disk space is too low!"));
             }
             // Flush the chainstate (which may refer to block index entries).
-            const auto empty_cache{(mode == FlushStateMode::ALWAYS) || fCacheLarge || fCacheCritical};
+            const auto empty_cache{(mode == FlushStateMode::FORCE_FLUSH) || fCacheLarge || fCacheCritical};
             if (empty_cache ? !CoinsTip().Flush() : !CoinsTip().Sync()) {
                 return FatalError(m_chainman.GetNotifications(), state, _("Failed to write to coin database."));
             }
@@ -2941,10 +2941,10 @@ bool Chainstate::FlushStateToDisk(
     return true;
 }
 
-void Chainstate::ForceFlushStateToDisk()
+void Chainstate::ForceFlushStateToDisk(bool wipe_cache)
 {
     BlockValidationState state;
-    if (!this->FlushStateToDisk(state, FlushStateMode::ALWAYS)) {
+    if (!this->FlushStateToDisk(state, wipe_cache ? FlushStateMode::FORCE_FLUSH : FlushStateMode::FORCE_SYNC)) {
         LogPrintf("%s: failed to flush state (%s)\n", __func__, state.ToString());
     }
 }
@@ -5569,7 +5569,7 @@ bool Chainstate::ResizeCoinsCaches(size_t coinstip_size, size_t coinsdb_size)
         ret = FlushStateToDisk(state, FlushStateMode::IF_NEEDED);
     } else {
         // Otherwise, flush state to disk and deallocate the in-memory coins map.
-        ret = FlushStateToDisk(state, FlushStateMode::ALWAYS);
+        ret = FlushStateToDisk(state, FlushStateMode::FORCE_FLUSH);
     }
     return ret;
 }
@@ -6038,7 +6038,7 @@ util::Result<void> ChainstateManager::PopulateAndValidateSnapshot(
         // returns in `ActivateSnapshot()`, when `MaybeRebalanceCaches()` is
         // called, since we've added a snapshot chainstate and therefore will
         // have to downsize the IBD chainstate, which will result in a call to
-        // `FlushStateToDisk(ALWAYS)`.
+        // `FlushStateToDisk(FORCE_FLUSH)`.
     }
 
     assert(index);
@@ -6138,7 +6138,7 @@ SnapshotCompletionResult ChainstateManager::MaybeCompleteSnapshotValidation()
     assert(this->GetAll().size() == 2);
 
     CCoinsViewDB& ibd_coins_db = m_ibd_chainstate->CoinsDB();
-    m_ibd_chainstate->ForceFlushStateToDisk();
+    m_ibd_chainstate->ForceFlushStateToDisk(/*wipe_cache=*/true);
 
     const auto& maybe_au_data = m_options.chainparams.AssumeutxoForHeight(curr_height);
     if (!maybe_au_data) {

src/validation.h

@@ -448,7 +448,8 @@ enum class FlushStateMode {
     NONE,
     IF_NEEDED,
     PERIODIC,
-    ALWAYS
+    FORCE_SYNC,
+    FORCE_FLUSH,
 };
 
 /**
@@ -678,7 +679,7 @@ public:
         int nManualPruneHeight = 0);
 
     //! Unconditionally flush all changes to disk.
-    void ForceFlushStateToDisk();
+    void ForceFlushStateToDisk(bool wipe_cache);
 
     //! Prune blockfiles from the disk if necessary and then flush chainstate changes
     //! if we pruned.

test/functional/interface_usdt_utxocache.py

@@ -100,7 +100,8 @@ FLUSHMODE_NAME = {
     0: "NONE",
     1: "IF_NEEDED",
     2: "PERIODIC",
-    3: "ALWAYS",
+    3: "FORCE_SYNC",
+    4: "FORCE_FLUSH",
 }
 
 
@@ -368,8 +369,8 @@ class UTXOCacheTracepointTest(BitcoinTestFramework):
         # A node shutdown causes two flushes. One that flushes UTXOS_IN_CACHE
         # UTXOs and one that flushes 0 UTXOs. Normally the 0-UTXO-flush is the
         # second flush, however it can happen that the order changes.
-        expected_flushes.append({"mode": "ALWAYS", "for_prune": False, "size": UTXOS_IN_CACHE})
-        expected_flushes.append({"mode": "ALWAYS", "for_prune": False, "size": 0})
+        expected_flushes.append({"mode": "FORCE_FLUSH", "for_prune": False, "size": UTXOS_IN_CACHE})
+        expected_flushes.append({"mode": "FORCE_FLUSH", "for_prune": False, "size": 0})
         self.stop_node(0)
 
         bpf.perf_buffer_poll(timeout=200)