Merge bitcoin/bitcoin#24299: validation, refactor: UnloadBlockIndex and ChainstateManager::Reset thread safety cleanups

ae9ceed validation, refactoring: remove ChainstateManager::Reset() (Jon Atack)
daad009 validation: replace lock with annotation in UnloadBlockIndex() (Jon Atack)

Pull request description:

  Thread safety refactoring seen in #24177:
  - replace re-acquiring lock cs_main with a thread safety annotation in UnloadBlockIndex()
  - remove ChainstateManager::Reset(), as it is currently unused (can be reintroduced in the test utilities if needed for unit testing)

ACKs for top commit:
  laanwj:
    Code review ACK ae9ceed
  vasild:
    ACK ae9ceed
  klementtan:
    crACK ae9ceed

Tree-SHA512: cebb782572997cc2dda01590d6bb6c5e479e8202324d8b6ff459b814ce09e818b996c881736bfebd1b8bf4b6d7a0f79faf3ffea176a4699dd7d7429de2db2d13

Author: laanwj

src/test/util/setup_common.cpp

@@ -180,10 +180,9 @@ ChainTestingSetup::~ChainTestingSetup()
     m_node.banman.reset();
     m_node.addrman.reset();
     m_node.args = nullptr;
-    UnloadBlockIndex(m_node.mempool.get(), *m_node.chainman);
+    WITH_LOCK(::cs_main, UnloadBlockIndex(m_node.mempool.get(), *m_node.chainman));
     m_node.mempool.reset();
     m_node.scheduler.reset();
-    m_node.chainman->Reset();
     m_node.chainman.reset();
 }
 

src/validation.cpp

@@ -4070,7 +4070,7 @@ void CChainState::UnloadBlockIndex()
 // block index state
 void UnloadBlockIndex(CTxMemPool* mempool, ChainstateManager& chainman)
 {
-    LOCK(cs_main);
+    AssertLockHeld(::cs_main);
     chainman.Unload();
     pindexBestHeader = nullptr;
     if (mempool) mempool->clear();
@@ -5056,15 +5056,6 @@ void ChainstateManager::Unload()
     m_best_invalid = nullptr;
 }
 
-void ChainstateManager::Reset()
-{
-    LOCK(::cs_main);
-    m_ibd_chainstate.reset();
-    m_snapshot_chainstate.reset();
-    m_active_chainstate = nullptr;
-    m_snapshot_validated = false;
-}
-
 void ChainstateManager::MaybeRebalanceCaches()
 {
     AssertLockHeld(::cs_main);

src/validation.h

@@ -138,7 +138,7 @@ extern CBlockIndex *pindexBestHeader;
 extern const std::vector<std::string> CHECKLEVEL_DOC;
 
 /** Unload database information */
-void UnloadBlockIndex(CTxMemPool* mempool, ChainstateManager& chainman);
+void UnloadBlockIndex(CTxMemPool* mempool, ChainstateManager& chainman) EXCLUSIVE_LOCKS_REQUIRED(::cs_main);
 /** Run instances of script checking worker threads */
 void StartScriptCheckWorkerThreads(int threads_num);
 /** Stop all of the script checking worker threads */
@@ -991,17 +991,13 @@ class ChainstateManager
     //! Unload block index and chain data before shutdown.
     void Unload() EXCLUSIVE_LOCKS_REQUIRED(::cs_main);
 
-    //! Clear (deconstruct) chainstate data.
-    void Reset();
-
     //! Check to see if caches are out of balance and if so, call
     //! ResizeCoinsCaches() as needed.
     void MaybeRebalanceCaches() EXCLUSIVE_LOCKS_REQUIRED(::cs_main);
 
     ~ChainstateManager() {
         LOCK(::cs_main);
-        UnloadBlockIndex(/* mempool */ nullptr, *this);
-        Reset();
+        UnloadBlockIndex(/*mempool=*/nullptr, *this);
     }
 };