Add gather_statistics command that allows gathering statistics from a .bin or .binpack file. Initially only support position count.

docs/stats.md

@@ -0,0 +1,15 @@
+# Stats
+
+`gather_statistics` command allows gathering various statistics from a .bin or a .binpack file. The syntax is `gather_statistics (GROUP)* input_file FILENAME`. There can be many groups specified. Any statistic gatherer that belongs to at least one of the specified groups will be used.
+
+Simplest usage: `stockfish.exe gather_statistics all input_file a.binpack`
+
+## Groups
+
+`all`
+
+ - A special group designating all statistics gatherers available.
+
+`position_count`
+
+ - `struct PositionCounter` - the total number of positions in the file.

src/Makefile

@@ -66,7 +66,8 @@ SRCS = benchmark.cpp bitbase.cpp bitboard.cpp endgame.cpp evaluate.cpp main.cpp
 	learn/gensfen_nonpv.cpp \
 	learn/opening_book.cpp \
 	learn/convert.cpp \
-	learn/transform.cpp
+	learn/transform.cpp \
+	learn/stats.cpp
 
 OBJS = $(notdir $(SRCS:.cpp=.o))
 

src/learn/stats.cpp

@@ -0,0 +1,209 @@
+#include "stats.h"
+
+#include "sfen_stream.h"
+#include "packed_sfen.h"
+#include "sfen_writer.h"
+
+#include "thread.h"
+#include "position.h"
+#include "evaluate.h"
+#include "search.h"
+
+#include "nnue/evaluate_nnue.h"
+
+#include <string>
+#include <map>
+#include <iostream>
+#include <cmath>
+#include <algorithm>
+#include <cstdint>
+#include <limits>
+#include <mutex>
+#include <optional>
+
+namespace Learner::Stats
+{
+    struct StatisticGathererBase
+    {
+        virtual void on_position(const Position&) {}
+        virtual void on_move(const Move&) {}
+        virtual void reset() = 0;
+        [[nodiscard]] virtual std::map<std::string, std::string> get_formatted_stats() const = 0;
+    };
+
+    struct PositionCounter : StatisticGathererBase
+    {
+        PositionCounter() :
+            m_num_positions(0)
+        {
+        }
+
+        void on_position(const Position&) override
+        {
+            m_num_positions += 1;
+        }
+
+        void reset() override
+        {
+            m_num_positions = 0;
+        }
+
+        [[nodiscard]] std::map<std::string, std::string> get_formatted_stats() const override
+        {
+            return {
+                { "Number of positions", std::to_string(m_num_positions) }
+            };
+        }
+
+    private:
+        std::uint64_t m_num_positions;
+    };
+
+    struct StatisticGathererFactoryBase
+    {
+        [[nodiscard]] virtual std::unique_ptr<StatisticGathererBase> create() const = 0;
+    };
+
+    template <typename T>
+    struct StatisticGathererFactory : StatisticGathererFactoryBase
+    {
+        [[nodiscard]] std::unique_ptr<StatisticGathererBase> create() const override
+        {
+            return std::make_unique<T>();
+        }
+    };
+
+    struct StatisticGathererRegistry
+    {
+        void add_statistic_gatherers_by_group(
+            std::vector<std::unique_ptr<StatisticGathererBase>>& gatherers,
+            const std::string& group) const
+        {
+            auto it = m_gatherers_by_group.find(group);
+            if (it != m_gatherers_by_group.end())
+            {
+                for (auto& factory : it->second)
+                {
+                    gatherers.emplace_back(factory->create());
+                }
+            }
+        }
+
+        template <typename T>
+        void add(const std::string& group)
+        {
+            m_gatherers_by_group[group].emplace_back(std::make_unique<StatisticGathererFactory<T>>());
+
+            // Always add to the special group "all".
+            m_gatherers_by_group["all"].emplace_back(std::make_unique<StatisticGathererFactory<T>>());
+        }
+
+    private:
+        std::map<std::string, std::vector<std::unique_ptr<StatisticGathererFactoryBase>>> m_gatherers_by_group;
+    };
+
+    const auto& get_statistics_gatherers_registry()
+    {
+        static StatisticGathererRegistry s_reg = [](){
+            StatisticGathererRegistry reg;
+
+            reg.add<PositionCounter>("position_count");
+
+            return reg;
+        }();
+
+        return s_reg;
+    }
+
+    void do_gather_statistics(
+        const std::string& filename,
+        std::vector<std::unique_ptr<StatisticGathererBase>>& statistic_gatherers)
+    {
+        Thread* th = Threads.main();
+        Position& pos = th->rootPos;
+        StateInfo si;
+
+        auto in = Learner::open_sfen_input_file(filename);
+
+        auto on_move = [&](Move move) {
+            for (auto&& s : statistic_gatherers)
+            {
+                s->on_move(move);
+            }
+        };
+
+        auto on_position = [&](const Position& position) {
+            for (auto&& s : statistic_gatherers)
+            {
+                s->on_position(position);
+            }
+        };
+
+        if (in == nullptr)
+        {
+            std::cerr << "Invalid input file type.\n";
+            return;
+        }
+
+        uint64_t num_processed = 0;
+        for (;;)
+        {
+            auto v = in->next();
+            if (!v.has_value())
+                break;
+
+            auto& ps = v.value();
+
+            pos.set_from_packed_sfen(ps.sfen, &si, th);
+
+            on_position(pos);
+            on_move((Move)ps.move);
+
+            num_processed += 1;
+            if (num_processed % 1'000'000 == 0)
+            {
+                std::cout << "Processed " << num_processed << " positions.\n";
+            }
+        }
+
+        std::cout << "Finished gathering statistics.\n\n";
+        std::cout << "Results:\n\n";
+
+        for (auto&& s : statistic_gatherers)
+        {
+            for (auto&& [name, value] : s->get_formatted_stats())
+            {
+                std::cout << name << ": " << value << '\n';
+            }
+            std::cout << '\n';
+        }
+    }
+
+    void gather_statistics(std::istringstream& is)
+    {
+        Eval::NNUE::init();
+
+        auto& registry = get_statistics_gatherers_registry();
+
+        std::vector<std::unique_ptr<StatisticGathererBase>> statistic_gatherers;
+
+        std::string input_file;
+
+        while(true)
+        {
+            std::string token;
+            is >> token;
+
+            if (token == "")
+                break;
+
+            if (token == "input_file")
+                is >> input_file;
+            else
+                registry.add_statistic_gatherers_by_group(statistic_gatherers, token);
+        }
+
+        do_gather_statistics(input_file, statistic_gatherers);
+    }
+
+}

src/learn/stats.h

@@ -0,0 +1,12 @@
+#ifndef _STATS_H_
+#define _STATS_H_
+
+#include <sstream>
+
+namespace Learner::Stats {
+
+    void gather_statistics(std::istringstream& is);
+
+}
+
+#endif

src/uci.cpp

@@ -40,6 +40,7 @@
 #include "learn/learn.h"
 #include "learn/convert.h"
 #include "learn/transform.h"
+#include "learn/stats.h"
 
 using namespace std;
 
@@ -349,6 +350,7 @@ void UCI::loop(int argc, char* argv[]) {
       else if (token == "convert_plain") Learner::convert_plain(is);
       else if (token == "convert_bin_from_pgn_extract") Learner::convert_bin_from_pgn_extract(is);
       else if (token == "transform") Learner::transform(is);
+      else if (token == "gather_statistics") Learner::Stats::gather_statistics(is);
 
       // Command to call qsearch(),search() directly for testing
       else if (token == "qsearch") qsearch_cmd(pos);