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

5b3ea5fa2e7f6dc1c9161ed8b74c9be4bd1e92dd refactor: Move `{MAX,DEFAULT}_SCRIPTCHECK_THREADS` constants (Hennadii Stepanov)
6e17b3168072ab77ed7170ab81327c017877133a refactor: Make `CCheckQueue` non-copyable and non-movable explicitly (Hennadii Stepanov)
8111e74653dc5c93cb510672d99048c3f741d8dc refactor: Drop unneeded declaration (Hennadii Stepanov)
9cf89f7a5b81197e38f58b24be0793b28fe41477 refactor: Make `CCheckQueue` constructor start worker threads (Hennadii Stepanov)
d03eaacbcfb276fb638db1b423113ff43bd7ec41 Make `CCheckQueue` destructor stop worker threads (Hennadii Stepanov)
be4ff3060b7b43b496dfb5a2c02b114b2b717106 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 5b3ea5fa2e7
  achow101:
    ACK 5b3ea5fa2e7f6dc1c9161ed8b74c9be4bd1e92dd
  TheCharlatan:
    ACK 5b3ea5fa2e7f6dc1c9161ed8b74c9be4bd1e92dd

Tree-SHA512: 45cca846e7ed107e3930149f0b616ddbaf2648d6cde381f815331b861b5d67ab39e154883ae174b8abb1dae485bc904318c50c51e5d6b46923d89de51c5eadb0

2 files changed, 18 insertions, 1 deletions

diff --git a/src/node/chainstatemanager_args.cpp b/src/node/chainstatemanager_args.cpp
index 87d9238c18..1cc126cb05 100644
--- a/src/node/chainstatemanager_args.cpp
+++ b/src/node/chainstatemanager_args.cpp
@@ -6,7 +6,8 @@
 
 #include <arith_uint256.h>
 #include <common/args.h>
-#include <kernel/chainstatemanager_opts.h>
+#include <common/system.h>
+#include <logging.h>
 #include <node/coins_view_args.h>
 #include <node/database_args.h>
 #include <tinyformat.h>
@@ -16,6 +17,7 @@
 #include <util/translation.h>
 #include <validation.h>
 
+#include <algorithm>
 #include <chrono>
 #include <string>
 
@@ -41,6 +43,16 @@ util::Result<void> ApplyArgsManOptions(const ArgsManager& args, ChainstateManage
     ReadDatabaseArgs(args, opts.coins_db);
     ReadCoinsViewArgs(args, opts.coins_view);
 
+    int script_threads = args.GetIntArg("-par", DEFAULT_SCRIPTCHECK_THREADS);
+    if (script_threads <= 0) {
+        // -par=0 means autodetect (number of cores - 1 script threads)
+        // -par=-n means "leave n cores free" (number of cores - n - 1 script threads)
+        script_threads += GetNumCores();
+    }
+    // Subtract 1 because the main thread counts towards the par threads.
+    opts.worker_threads_num = std::clamp(script_threads - 1, 0, MAX_SCRIPTCHECK_THREADS);
+    LogPrintf("Script verification uses %d additional threads\n", opts.worker_threads_num);
+
     return {};
 }
 } // namespace node
diff --git a/src/node/chainstatemanager_args.h b/src/node/chainstatemanager_args.h
index 701515953e..b2cdba68b8 100644
--- a/src/node/chainstatemanager_args.h
+++ b/src/node/chainstatemanager_args.h
@@ -10,6 +10,11 @@
 
 class ArgsManager;
 
+/** Maximum number of dedicated script-checking threads allowed */
+static constexpr int MAX_SCRIPTCHECK_THREADS{15};
+/** -par default (number of script-checking threads, 0 = auto) */
+static constexpr int DEFAULT_SCRIPTCHECK_THREADS{0};
+
 namespace node {
 [[nodiscard]] util::Result<void> ApplyArgsManOptions(const ArgsManager& args, ChainstateManager::Options& opts);
 } // namespace node