Merge bitcoin/bitcoin#26762: bugfix: Make CCheckQueue RAII-styled (attempt 2)

5b3ea5fa2e refactor: Move `{MAX,DEFAULT}_SCRIPTCHECK_THREADS` constants (Hennadii Stepanov)
6e17b31680 refactor: Make `CCheckQueue` non-copyable and non-movable explicitly (Hennadii Stepanov)
8111e74653 refactor: Drop unneeded declaration (Hennadii Stepanov)
9cf89f7a5b refactor: Make `CCheckQueue` constructor start worker threads (Hennadii Stepanov)
d03eaacbcf Make `CCheckQueue` destructor stop worker threads (Hennadii Stepanov)
be4ff3060b Move global `scriptcheckqueue` into `ChainstateManager` class (Hennadii Stepanov)

Pull request description:

  This PR:
  - makes `CCheckQueue` RAII-styled
  - gets rid of the global `scriptcheckqueue`
  - fixes https://github.com/bitcoin/bitcoin/issues/25448

  The previous attempt was in https://github.com/bitcoin/bitcoin/pull/18731.

ACKs for top commit:
  martinus:
    ACK 5b3ea5fa2e
  achow101:
    ACK 5b3ea5fa2e
  TheCharlatan:
    ACK 5b3ea5fa2e

Tree-SHA512: 45cca846e7ed107e3930149f0b616ddbaf2648d6cde381f815331b861b5d67ab39e154883ae174b8abb1dae485bc904318c50c51e5d6b46923d89de51c5eadb0

src/validation.h

@@ -13,6 +13,7 @@
 #include <arith_uint256.h>
 #include <attributes.h>
 #include <chain.h>
+#include <checkqueue.h>
 #include <kernel/chain.h>
 #include <consensus/amount.h>
 #include <deploymentstatus.h>
@@ -65,10 +66,6 @@ namespace util {
 class SignalInterrupt;
 } // namespace util
 
-/** Maximum number of dedicated script-checking threads allowed */
-static const int MAX_SCRIPTCHECK_THREADS = 15;
-/** -par default (number of script-checking threads, 0 = auto) */
-static const int DEFAULT_SCRIPTCHECK_THREADS = 0;
 /** Block files containing a block-height within MIN_BLOCKS_TO_KEEP of ActiveChain().Tip() will not be pruned. */
 static const unsigned int MIN_BLOCKS_TO_KEEP = 288;
 static const signed int DEFAULT_CHECKBLOCKS = 6;
@@ -98,11 +95,6 @@ extern uint256 g_best_block;
 /** Documentation for argument 'checklevel'. */
 extern const std::vector<std::string> CHECKLEVEL_DOC;
 
-/** Run instances of script checking worker threads */
-void StartScriptCheckWorkerThreads(int threads_num);
-/** Stop all of the script checking worker threads */
-void StopScriptCheckWorkerThreads();
-
 CAmount GetBlockSubsidy(int nHeight, const Consensus::Params& consensusParams);
 
 bool FatalError(kernel::Notifications& notifications, BlockValidationState& state, const std::string& strMessage, const bilingual_str& userMessage = {});
@@ -926,6 +918,9 @@ private:
         return cs && !cs->m_disabled;
     }
 
+    //! A queue for script verifications that have to be performed by worker threads.
+    CCheckQueue<CScriptCheck> m_script_check_queue;
+
 public:
     using Options = kernel::ChainstateManagerOpts;
 
@@ -1276,6 +1271,8 @@ public:
     //! nullopt.
     std::optional<int> GetSnapshotBaseHeight() const EXCLUSIVE_LOCKS_REQUIRED(::cs_main);
 
+    CCheckQueue<CScriptCheck>& GetCheckQueue() { return m_script_check_queue; }
+
     ~ChainstateManager();
 };