validation: sync utxo state after block sync

Github-Pull: #15218
Rebased-From: 2626a8a1a2b5697572925c356c77d1dde449f7ab

src/init.cpp

@@ -140,6 +140,9 @@ static constexpr bool DEFAULT_REST_ENABLE{false};
 static constexpr bool DEFAULT_I2P_ACCEPT_INCOMING{true};
 static constexpr bool DEFAULT_STOPAFTERBLOCKIMPORT{false};
 
+//! Check if initial sync is done with no change in block height or queued downloads every 30s
+static constexpr auto SYNC_CHECK_INTERVAL{30s};
+
 #ifdef WIN32
 // Win32 LevelDB doesn't use filedescriptors, and the ones used for
 // accessing block files don't count towards the fd_set size limit
@@ -1064,6 +1067,44 @@ bool AppInitLockDataDirectory()
     return true;
 }
 
+/**
+ * Once initial block sync is finished and no change in block height or queued downloads,
+ * sync utxo state to protect against data loss
+ */
+static void SyncCoinsTipAfterChainSync(const NodeContext& node)
+{
+    LOCK(node.chainman->GetMutex());
+    if (node.chainman->IsInitialBlockDownload()) {
+        LogPrintfCategory(BCLog::COINDB, "Node is still in IBD, rescheduling chainstate disk sync...\n");
+        node.scheduler->scheduleFromNow([&node] {
+            SyncCoinsTipAfterChainSync(node);
+        }, SYNC_CHECK_INTERVAL);
+        return;
+    }
+
+    static auto last_chain_height{-1};
+    const auto current_height{node.chainman->ActiveHeight()};
+    if (last_chain_height != current_height) {
+        LogPrintfCategory(BCLog::COINDB, "Chain height updated since last check, rescheduling chainstate disk sync...\n");
+        last_chain_height = current_height;
+        node.scheduler->scheduleFromNow([&node] {
+            SyncCoinsTipAfterChainSync(node);
+        }, SYNC_CHECK_INTERVAL);
+        return;
+    }
+
+    if (node.peerman->GetNumberOfPeersWithValidatedDownloads() > 0) {
+        LogPrintfCategory(BCLog::COINDB, "Still downloading blocks from peers, rescheduling chainstate disk sync...\n");
+        node.scheduler->scheduleFromNow([&node] {
+            SyncCoinsTipAfterChainSync(node);
+        }, SYNC_CHECK_INTERVAL);
+        return;
+    }
+
+    LogPrintfCategory(BCLog::COINDB, "Finished syncing to tip, syncing chainstate to disk\n");
+    node.chainman->ActiveChainstate().CoinsTip().Sync();
+}
+
 bool AppInitInterfaces(NodeContext& node)
 {
     node.chain = node.init->makeChain();
@@ -1923,6 +1964,10 @@ bool AppInitMain(NodeContext& node, interfaces::BlockAndHeaderTipInfo* tip_info)
     StartupNotify(args);
 #endif
 
+    node.scheduler->scheduleFromNow([&node] {
+        SyncCoinsTipAfterChainSync(node);
+    }, SYNC_CHECK_INTERVAL);
+
     return true;
 }
 

src/net_processing.cpp

@@ -518,6 +518,7 @@ public:
                         const std::chrono::microseconds time_received, const std::atomic<bool>& interruptMsgProc) override
         EXCLUSIVE_LOCKS_REQUIRED(!m_peer_mutex, !m_recent_confirmed_transactions_mutex, !m_most_recent_block_mutex, !m_headers_presync_mutex, g_msgproc_mutex);
     void UpdateLastBlockAnnounceTime(NodeId node, int64_t time_in_seconds) override;
+    int GetNumberOfPeersWithValidatedDownloads() const override EXCLUSIVE_LOCKS_REQUIRED(::cs_main);
 
 private:
     /** Consider evicting an outbound peer based on the amount of time they've been behind our tip */
@@ -1713,6 +1714,12 @@ bool PeerManagerImpl::GetNodeStateStats(NodeId nodeid, CNodeStateStats& stats) c
     return true;
 }
 
+int PeerManagerImpl::GetNumberOfPeersWithValidatedDownloads() const
+{
+    AssertLockHeld(m_chainman.GetMutex());
+    return m_peers_downloading_from;
+}
+
 void PeerManagerImpl::AddToCompactExtraTransactions(const CTransactionRef& tx)
 {
     if (m_opts.max_extra_txs <= 0)

src/net_processing.h

@@ -110,6 +110,9 @@ public:
 
     /** This function is used for testing the stale tip eviction logic, see denialofservice_tests.cpp */
     virtual void UpdateLastBlockAnnounceTime(NodeId node, int64_t time_in_seconds) = 0;
+
+    /** Get number of peers from which we're downloading blocks */
+    virtual int GetNumberOfPeersWithValidatedDownloads() const EXCLUSIVE_LOCKS_REQUIRED(::cs_main) = 0;
 };
 
 #endif // BITCOIN_NET_PROCESSING_H