Merge bitcoin/bitcoin#30466: refactor: Make m_last_notified_header private

fa92705 refactor: Make m_last_notified_header private (MarcoFalke)

Pull request description:

  Seems brittle to expose mutable fields public.

  Fix it by making it private.

  Fixes bitcoin/bitcoin#30425 (comment)

ACKs for top commit:
  dergoegge:
    utACK fa92705

Tree-SHA512: d9841c42571144ced0edeaa4bb1d96a177a011dca37c8342c66513477c37278602a1b88beb93068b94fc4443b1552c8fc9f98bcf0bda7d0fc101e61e90c33944

Author: fanquake

src/validation.cpp

@@ -3405,24 +3405,24 @@ static SynchronizationState GetSynchronizationState(bool init, bool blockfiles_i
     return SynchronizationState::INIT_DOWNLOAD;
 }
 
-static bool NotifyHeaderTip(ChainstateManager& chainman) LOCKS_EXCLUDED(cs_main)
+bool ChainstateManager::NotifyHeaderTip()
 {
     bool fNotify = false;
     bool fInitialBlockDownload = false;
     CBlockIndex* pindexHeader = nullptr;
     {
-        LOCK(cs_main);
-        pindexHeader = chainman.m_best_header;
+        LOCK(GetMutex());
+        pindexHeader = m_best_header;
 
-        if (pindexHeader != chainman.m_last_notified_header) {
+        if (pindexHeader != m_last_notified_header) {
             fNotify = true;
-            fInitialBlockDownload = chainman.IsInitialBlockDownload();
-            chainman.m_last_notified_header = pindexHeader;
+            fInitialBlockDownload = IsInitialBlockDownload();
+            m_last_notified_header = pindexHeader;
         }
     }
-    // Send block tip changed notifications without cs_main
+    // Send block tip changed notifications without the lock held
     if (fNotify) {
-        chainman.GetNotifications().headerTip(GetSynchronizationState(fInitialBlockDownload, chainman.m_blockman.m_blockfiles_indexed), pindexHeader->nHeight, pindexHeader->nTime, false);
+        GetNotifications().headerTip(GetSynchronizationState(fInitialBlockDownload, m_blockman.m_blockfiles_indexed), pindexHeader->nHeight, pindexHeader->nTime, false);
     }
     return fNotify;
 }
@@ -4378,7 +4378,7 @@ bool ChainstateManager::ProcessNewBlockHeaders(const std::vector<CBlockHeader>&
             }
         }
     }
-    if (NotifyHeaderTip(*this)) {
+    if (NotifyHeaderTip()) {
         if (IsInitialBlockDownload() && ppindex && *ppindex) {
             const CBlockIndex& last_accepted{**ppindex};
             int64_t blocks_left{(NodeClock::now() - last_accepted.Time()) / GetConsensus().PowTargetSpacing()};
@@ -4549,7 +4549,7 @@ bool ChainstateManager::ProcessNewBlock(const std::shared_ptr<const CBlock>& blo
         }
     }
 
-    NotifyHeaderTip(*this);
+    NotifyHeaderTip();
 
     BlockValidationState state; // Only used to report errors, not invalidity - ignore it
     if (!ActiveChainstate().ActivateBestChain(state, block)) {
@@ -5126,7 +5126,7 @@ void ChainstateManager::LoadExternalBlockFile(
                     }
                 }
 
-                NotifyHeaderTip(*this);
+                NotifyHeaderTip();
 
                 if (!blocks_with_unknown_parent) continue;
 
@@ -5152,7 +5152,7 @@ void ChainstateManager::LoadExternalBlockFile(
                         }
                         range.first++;
                         blocks_with_unknown_parent->erase(it);
-                        NotifyHeaderTip(*this);
+                        NotifyHeaderTip();
                     }
                 }
             } catch (const std::exception& e) {

src/validation.h

@@ -906,6 +906,11 @@ class ChainstateManager
 
     CBlockIndex* m_best_invalid GUARDED_BY(::cs_main){nullptr};
 
+    /** The last header for which a headerTip notification was issued. */
+    CBlockIndex* m_last_notified_header GUARDED_BY(GetMutex()){nullptr};
+
+    bool NotifyHeaderTip() LOCKS_EXCLUDED(GetMutex());
+
     //! Internal helper for ActivateSnapshot().
     //!
     //! De-serialization of a snapshot that is created with
@@ -1063,9 +1068,6 @@ class ChainstateManager
     /** Best header we've seen so far (used for getheaders queries' starting points). */
     CBlockIndex* m_best_header GUARDED_BY(::cs_main){nullptr};
 
-    /** The last header for which a headerTip notification was issued. */
-    CBlockIndex* m_last_notified_header GUARDED_BY(::cs_main){nullptr};
-
     //! The total number of bytes available for us to use across all in-memory
     //! coins caches. This will be split somehow across chainstates.
     int64_t m_total_coinstip_cache{0};