Refactor global variables

This aims to remove some of the annoying global structure which Stockfish has. Overall there is no major elo regression to be expected. Non regression SMP STC (paused, early version): https://tests.stockfishchess.org/tests/view/65983d7979aa8af82b9608f1 LLR: 0.23 (-2.94,2.94) <-1.75,0.25> Total: 76232 W: 19035 L: 19096 D: 38101 Ptnml(0-2): 92, 8735, 20515, 8690, 84 Non regression STC (early version): https://tests.stockfishchess.org/tests/view/6595b3a479aa8af82b95da7f LLR: 2.93 (-2.94,2.94) <-1.75,0.25> Total: 185344 W: 47027 L: 46972 D: 91345 Ptnml(0-2): 571, 21285, 48943, 21264, 609 Non regression SMP STC: https://tests.stockfishchess.org/tests/view/65a0715c79aa8af82b96b7e4 LLR: 2.94 (-2.94,2.94) <-1.75,0.25> Total: 142936 W: 35761 L: 35662 D: 71513 Ptnml(0-2): 209, 16400, 38135, 16531, 193 These global structures/variables add hidden dependencies and allow data to be mutable from where it shouldn't it be (i.e. options). They also prevent Stockfish from internal selfplay, which would be a nice thing to be able to do, i.e. instantiate two Stockfish instances and let them play against each other. It will also allow us to make Stockfish a library, which can be easier used on other platforms. For consistency with the old search code, `thisThread` has been kept, even though it is not strictly necessary anymore. This the first major refactor of this kind (in recent time), and future changes are required, to achieve the previously described goals. This includes cleaning up the dependencies, transforming the network to be self contained and coming up with a plan to deal with proper tablebase memory management (see comments for more information on this). The removal of these global structures has been discussed in parts with Vondele and Sopel. closes official-stockfish#4968 No functional change
windfishballad · Jan 23, 2024 · 60c5294 · 60c5294
1 parent 3a63835
commit 60c5294
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Showing 27 changed files with 1,175 additions and 976 deletions.
diff --git a/src/Makefile b/src/Makefile
@@ -63,7 +63,7 @@ HEADERS = benchmark.h bitboard.h evaluate.h misc.h movegen.h movepick.h \
 		nnue/layers/sqr_clipped_relu.h nnue/nnue_accumulator.h nnue/nnue_architecture.h \
 		nnue/nnue_common.h nnue/nnue_feature_transformer.h position.h \
 		search.h syzygy/tbprobe.h thread.h thread_win32_osx.h timeman.h \
-		tt.h tune.h types.h uci.h
+		tt.h tune.h types.h uci.h ucioption.h 
 
 OBJS = $(notdir $(SRCS:.cpp=.o))
 

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
@@ -25,6 +25,7 @@
 #include <fstream>
 #include <iomanip>
 #include <iostream>
+#include <optional>
 #include <sstream>
 #include <unordered_map>
 #include <vector>
@@ -34,9 +35,10 @@
 #include "nnue/evaluate_nnue.h"
 #include "nnue/nnue_architecture.h"
 #include "position.h"
-#include "thread.h"
+#include "search.h"
 #include "types.h"
 #include "uci.h"
+#include "ucioption.h"
 
 // Macro to embed the default efficiently updatable neural network (NNUE) file
 // data in the engine binary (using incbin.h, by Dale Weiler).
@@ -62,10 +64,6 @@ namespace Stockfish {
 
 namespace Eval {
 
-std::unordered_map<NNUE::NetSize, EvalFile> EvalFiles = {
-  {NNUE::Big, {"EvalFile", EvalFileDefaultNameBig, "None"}},
-  {NNUE::Small, {"EvalFileSmall", EvalFileDefaultNameSmall, "None"}}};
-
 
 // Tries to load a NNUE network at startup time, or when the engine
 // receives a UCI command "setoption name EvalFile value nn-[a-z0-9]{12}.nnue"
@@ -74,38 +72,45 @@ std::unordered_map<NNUE::NetSize, EvalFile> EvalFiles = {
 // network may be embedded in the binary), in the active working directory and
 // in the engine directory. Distro packagers may define the DEFAULT_NNUE_DIRECTORY
 // variable to have the engine search in a special directory in their distro.
-void NNUE::init() {
+NNUE::EvalFiles NNUE::load_networks(const std::string& rootDirectory,
+                                    const OptionsMap&  options,
+                                    NNUE::EvalFiles    evalFiles) {
 
-    for (auto& [netSize, evalFile] : EvalFiles)
+    for (auto& [netSize, evalFile] : evalFiles)
     {
         // Replace with
-        // Options[evalFile.option_name]
+        // options[evalFile.optionName]
         // once fishtest supports the uci option EvalFileSmall
         std::string user_eval_file =
-          netSize == Small ? evalFile.default_name : Options[evalFile.option_name];
+          netSize == Small ? evalFile.defaultName : options[evalFile.optionName];
 
         if (user_eval_file.empty())
-            user_eval_file = evalFile.default_name;
+            user_eval_file = evalFile.defaultName;
 
 #if defined(DEFAULT_NNUE_DIRECTORY)
-        std::vector<std::string> dirs = {"<internal>", "", CommandLine::binaryDirectory,
+        std::vector<std::string> dirs = {"<internal>", "", rootDirectory,
                                          stringify(DEFAULT_NNUE_DIRECTORY)};
 #else
-        std::vector<std::string> dirs = {"<internal>", "", CommandLine::binaryDirectory};
+        std::vector<std::string> dirs = {"<internal>", "", rootDirectory};
 #endif
 
         for (const std::string& directory : dirs)
         {
-            if (evalFile.selected_name != user_eval_file)
+            if (evalFile.current != user_eval_file)
             {
                 if (directory != "<internal>")
                 {
                     std::ifstream stream(directory + user_eval_file, std::ios::binary);
-                    if (NNUE::load_eval(user_eval_file, stream, netSize))
-                        evalFile.selected_name = user_eval_file;
+                    auto          description = NNUE::load_eval(stream, netSize);
+
+                    if (description.has_value())
+                    {
+                        evalFile.current        = user_eval_file;
+                        evalFile.netDescription = description.value();
+                    }
                 }
 
-                if (directory == "<internal>" && user_eval_file == evalFile.default_name)
+                if (directory == "<internal>" && user_eval_file == evalFile.defaultName)
                 {
                     // C++ way to prepare a buffer for a memory stream
                     class MemoryBuffer: public std::basic_streambuf<char> {
@@ -124,28 +129,36 @@ void NNUE::init() {
                     (void) gEmbeddedNNUESmallEnd;
 
                     std::istream stream(&buffer);
-                    if (NNUE::load_eval(user_eval_file, stream, netSize))
-                        evalFile.selected_name = user_eval_file;
+                    auto         description = NNUE::load_eval(stream, netSize);
+
+                    if (description.has_value())
+                    {
+                        evalFile.current        = user_eval_file;
+                        evalFile.netDescription = description.value();
+                    }
                 }
             }
         }
     }
+
+    return evalFiles;
 }
 
 // Verifies that the last net used was loaded successfully
-void NNUE::verify() {
+void NNUE::verify(const OptionsMap&                                        options,
+                  const std::unordered_map<Eval::NNUE::NetSize, EvalFile>& evalFiles) {
 
-    for (const auto& [netSize, evalFile] : EvalFiles)
+    for (const auto& [netSize, evalFile] : evalFiles)
     {
         // Replace with
-        // Options[evalFile.option_name]
+        // options[evalFile.optionName]
         // once fishtest supports the uci option EvalFileSmall
         std::string user_eval_file =
-          netSize == Small ? evalFile.default_name : Options[evalFile.option_name];
+          netSize == Small ? evalFile.defaultName : options[evalFile.optionName];
         if (user_eval_file.empty())
-            user_eval_file = evalFile.default_name;
+            user_eval_file = evalFile.defaultName;
 
-        if (evalFile.selected_name != user_eval_file)
+        if (evalFile.current != user_eval_file)
         {
             std::string msg1 =
               "Network evaluation parameters compatible with the engine must be available.";
@@ -155,7 +168,7 @@ void NNUE::verify() {
                                "including the directory name, to the network file.";
             std::string msg4 = "The default net can be downloaded from: "
                                "https://tests.stockfishchess.org/api/nn/"
-                             + evalFile.default_name;
+                             + evalFile.defaultName;
             std::string msg5 = "The engine will be terminated now.";
 
             sync_cout << "info string ERROR: " << msg1 << sync_endl;
@@ -183,7 +196,7 @@ int Eval::simple_eval(const Position& pos, Color c) {
 
 // Evaluate is the evaluator for the outer world. It returns a static evaluation
 // of the position from the point of view of the side to move.
-Value Eval::evaluate(const Position& pos) {
+Value Eval::evaluate(const Position& pos, const Search::Worker& workerThread) {
 
     assert(!pos.checkers());
 
@@ -204,7 +217,7 @@ Value Eval::evaluate(const Position& pos) {
         Value nnue = smallNet ? NNUE::evaluate<NNUE::Small>(pos, true, &nnueComplexity)
                               : NNUE::evaluate<NNUE::Big>(pos, true, &nnueComplexity);
 
-        int optimism = pos.this_thread()->optimism[stm];
+        int optimism = workerThread.optimism[stm];
 
         // Blend optimism and eval with nnue complexity and material imbalance
         optimism += optimism * (nnueComplexity + std::abs(simpleEval - nnue)) / 512;
@@ -227,16 +240,16 @@ Value Eval::evaluate(const Position& pos) {
 // a string (suitable for outputting to stdout) that contains the detailed
 // descriptions and values of each evaluation term. Useful for debugging.
 // Trace scores are from white's point of view
-std::string Eval::trace(Position& pos) {
+std::string Eval::trace(Position& pos, Search::Worker& workerThread) {
 
     if (pos.checkers())
         return "Final evaluation: none (in check)";
 
     // Reset any global variable used in eval
-    pos.this_thread()->bestValue       = VALUE_ZERO;
-    pos.this_thread()->rootSimpleEval  = VALUE_ZERO;
-    pos.this_thread()->optimism[WHITE] = VALUE_ZERO;
-    pos.this_thread()->optimism[BLACK] = VALUE_ZERO;
+    workerThread.iterBestValue   = VALUE_ZERO;
+    workerThread.rootSimpleEval  = VALUE_ZERO;
+    workerThread.optimism[WHITE] = VALUE_ZERO;
+    workerThread.optimism[BLACK] = VALUE_ZERO;
 
     std::stringstream ss;
     ss << std::showpoint << std::noshowpos << std::fixed << std::setprecision(2);
@@ -249,7 +262,7 @@ std::string Eval::trace(Position& pos) {
     v = pos.side_to_move() == WHITE ? v : -v;
     ss << "NNUE evaluation        " << 0.01 * UCI::to_cp(v) << " (white side)\n";
 
-    v = evaluate(pos);
+    v = evaluate(pos, workerThread);
     v = pos.side_to_move() == WHITE ? v : -v;
     ss << "Final evaluation       " << 0.01 * UCI::to_cp(v) << " (white side)";
     ss << " [with scaled NNUE, ...]";

diff --git a/src/evaluate.h b/src/evaluate.h
@@ -27,36 +27,46 @@
 namespace Stockfish {
 
 class Position;
+class OptionsMap;
+
+namespace Search {
+class Worker;
+}
 
 namespace Eval {
 
-std::string trace(Position& pos);
+std::string trace(Position& pos, Search::Worker& workerThread);
 
 int   simple_eval(const Position& pos, Color c);
-Value evaluate(const Position& pos);
+Value evaluate(const Position& pos, const Search::Worker& workerThread);
 
 // The default net name MUST follow the format nn-[SHA256 first 12 digits].nnue
 // for the build process (profile-build and fishtest) to work. Do not change the
 // name of the macro, as it is used in the Makefile.
 #define EvalFileDefaultNameBig "nn-baff1edbea57.nnue"
 #define EvalFileDefaultNameSmall "nn-baff1ede1f90.nnue"
 
+struct EvalFile {
+    // UCI option name
+    std::string optionName;
+    // Default net name, will use one of the macros above
+    std::string defaultName;
+    // Selected net name, either via uci option or default
+    std::string current;
+    // Net description extracted from the net file
+    std::string netDescription;
+};
+
 namespace NNUE {
 
 enum NetSize : int;
 
-void init();
-void verify();
+using EvalFiles = std::unordered_map<Eval::NNUE::NetSize, EvalFile>;
 
-}  // namespace NNUE
+EvalFiles load_networks(const std::string&, const OptionsMap&, EvalFiles);
+void      verify(const OptionsMap&, const EvalFiles&);
 
-struct EvalFile {
-    std::string option_name;
-    std::string default_name;
-    std::string selected_name;
-};
-
-extern std::unordered_map<NNUE::NetSize, EvalFile> EvalFiles;
+}  // namespace NNUE
 
 }  // namespace Eval
 

diff --git a/src/main.cpp b/src/main.cpp
@@ -16,15 +16,13 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#include <cstddef>
 #include <iostream>
+#include <unordered_map>
 
 #include "bitboard.h"
 #include "evaluate.h"
 #include "misc.h"
 #include "position.h"
-#include "search.h"
-#include "thread.h"
 #include "tune.h"
 #include "types.h"
 #include "uci.h"
@@ -35,17 +33,16 @@ int main(int argc, char* argv[]) {
 
     std::cout << engine_info() << std::endl;
 
-    CommandLine::init(argc, argv);
-    UCI::init(Options);
-    Tune::init();
     Bitboards::init();
     Position::init();
-    Threads.set(size_t(Options["Threads"]));
-    Search::clear();  // After threads are up
-    Eval::NNUE::init();
 
-    UCI::loop(argc, argv);
+    UCI uci(argc, argv);
+
+    Tune::init(uci.options);
+
+    uci.evalFiles = Eval::NNUE::load_networks(uci.workingDirectory(), uci.options, uci.evalFiles);
+
+    uci.loop();
 
-    Threads.set(0);
     return 0;
 }
diff --git a/src/misc.cpp b/src/misc.cpp
@@ -721,17 +721,13 @@ void bindThisThread(size_t idx) {
     #define GETCWD getcwd
 #endif
 
-namespace CommandLine {
-
-std::string argv0;             // path+name of the executable binary, as given by argv[0]
-std::string binaryDirectory;   // path of the executable directory
-std::string workingDirectory;  // path of the working directory
-
-void init([[maybe_unused]] int argc, char* argv[]) {
+CommandLine::CommandLine(int _argc, char** _argv) :
+    argc(_argc),
+    argv(_argv) {
     std::string pathSeparator;
 
     // Extract the path+name of the executable binary
-    argv0 = argv[0];
+    std::string argv0 = argv[0];
 
 #ifdef _WIN32
     pathSeparator = "\\";
@@ -766,7 +762,4 @@ void init([[maybe_unused]] int argc, char* argv[]) {
         binaryDirectory.replace(0, 1, workingDirectory);
 }
 
-
-}  // namespace CommandLine
-
 }  // namespace Stockfish
diff --git a/src/misc.h b/src/misc.h
@@ -176,12 +176,17 @@ namespace WinProcGroup {
 void bindThisThread(size_t idx);
 }
 
-namespace CommandLine {
-void init(int argc, char* argv[]);
 
-extern std::string binaryDirectory;   // path of the executable directory
-extern std::string workingDirectory;  // path of the working directory
-}
+struct CommandLine {
+   public:
+    CommandLine(int, char**);
+
+    int    argc;
+    char** argv;
+
+    std::string binaryDirectory;   // path of the executable directory
+    std::string workingDirectory;  // path of the working directory
+};
 
 }  // namespace Stockfish