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https://github.com/opelly27/Stockfish.git
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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 https://github.com/official-stockfish/Stockfish/pull/4968 No functional change
This commit is contained in:
Disservin
+149
-6
@@ -19,19 +19,37 @@
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#ifndef SEARCH_H_INCLUDED
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#define SEARCH_H_INCLUDED
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#include <atomic>
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#include <cassert>
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#include <cstddef>
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#include <cstdint>
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#include <memory>
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#include <vector>
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#include "misc.h"
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#include "movepick.h"
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#include "position.h"
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#include "timeman.h"
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#include "types.h"
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namespace Stockfish {
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class Position;
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// Different node types, used as a template parameter
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enum NodeType {
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NonPV,
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PV,
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Root
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};
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class TranspositionTable;
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class ThreadPool;
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class OptionsMap;
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class UCI;
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namespace Search {
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// Called at startup to initialize various lookup tables, after program startup
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void init(int);
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// Stack struct keeps track of the information we need to remember from nodes
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// shallower and deeper in the tree during the search. Each search thread has
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@@ -61,7 +79,7 @@ struct RootMove {
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explicit RootMove(Move m) :
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pv(1, m) {}
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bool extract_ponder_from_tt(Position& pos);
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bool extract_ponder_from_tt(const TranspositionTable& tt, Position& pos);
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bool operator==(const Move& m) const { return pv[0] == m; }
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// Sort in descending order
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bool operator<(const RootMove& m) const {
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@@ -85,7 +103,6 @@ using RootMoves = std::vector<RootMove>;
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// LimitsType struct stores information sent by GUI about available time to
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// search the current move, maximum depth/time, or if we are in analysis mode.
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struct LimitsType {
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// Init explicitly due to broken value-initialization of non POD in MSVC
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@@ -103,10 +120,136 @@ struct LimitsType {
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int64_t nodes;
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};
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extern LimitsType Limits;
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void init();
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void clear();
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// The UCI stores the uci options, thread pool, and transposition table.
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// This struct is used to easily forward data to the Search::Worker class.
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struct SharedState {
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SharedState(const OptionsMap& o, ThreadPool& tp, TranspositionTable& t) :
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options(o),
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threads(tp),
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tt(t) {}
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const OptionsMap& options;
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ThreadPool& threads;
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TranspositionTable& tt;
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};
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class Worker;
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// Null Object Pattern, implement a common interface
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// for the SearchManagers. A Null Object will be given to
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// non-mainthread workers.
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class ISearchManager {
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public:
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virtual ~ISearchManager() {}
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virtual void check_time(Search::Worker&) = 0;
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};
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// SearchManager manages the search from the main thread. It is responsible for
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// keeping track of the time, and storing data strictly related to the main thread.
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class SearchManager: public ISearchManager {
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public:
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void check_time(Search::Worker& worker) override;
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Stockfish::TimeManagement tm;
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int callsCnt;
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std::atomic_bool ponder;
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double previousTimeReduction;
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Value bestPreviousScore;
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Value bestPreviousAverageScore;
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Value iterValue[4];
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bool stopOnPonderhit;
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size_t id;
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};
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class NullSearchManager: public ISearchManager {
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public:
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void check_time(Search::Worker&) override {}
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};
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// Search::Worker is the class that does the actual search.
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// It is instantiated once per thread, and it is responsible for keeping track
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// of the search history, and storing data required for the search.
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class Worker {
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public:
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Worker(SharedState&, std::unique_ptr<ISearchManager>, size_t);
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// Reset histories, usually before a new game
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void clear();
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// Called when the program receives the UCI 'go'
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// command. It searches from the root position and outputs the "bestmove".
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void start_searching();
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bool is_mainthread() const { return thread_idx == 0; }
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// Public because evaluate uses this
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Value iterBestValue, optimism[COLOR_NB];
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Value rootSimpleEval;
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// Public because they need to be updatable by the stats
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CounterMoveHistory counterMoves;
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ButterflyHistory mainHistory;
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CapturePieceToHistory captureHistory;
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ContinuationHistory continuationHistory[2][2];
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PawnHistory pawnHistory;
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CorrectionHistory correctionHistory;
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private:
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void iterative_deepening();
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// Main search function for both PV and non-PV nodes
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template<NodeType nodeType>
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Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode);
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// Quiescence search function, which is called by the main search
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template<NodeType nodeType>
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Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth = 0);
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Depth reduction(bool i, Depth d, int mn, int delta) {
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int reductionScale = reductions[d] * reductions[mn];
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return (reductionScale + 1346 - int(delta) * 896 / int(rootDelta)) / 1024
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+ (!i && reductionScale > 880);
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}
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// Get a pointer to the search manager, only allowed to be called by the
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// main thread.
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SearchManager* main_manager() const {
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assert(thread_idx == 0);
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return static_cast<SearchManager*>(manager.get());
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}
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LimitsType limits;
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size_t pvIdx, pvLast;
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std::atomic<uint64_t> nodes, tbHits, bestMoveChanges;
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int selDepth, nmpMinPly;
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Position rootPos;
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StateInfo rootState;
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RootMoves rootMoves;
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Depth rootDepth, completedDepth;
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Value rootDelta;
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size_t thread_idx;
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// Reductions lookup table initialized at startup
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int reductions[MAX_MOVES]; // [depth or moveNumber]
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// The main thread has a SearchManager, the others have a NullSearchManager
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std::unique_ptr<ISearchManager> manager;
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const OptionsMap& options;
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ThreadPool& threads;
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TranspositionTable& tt;
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friend class Stockfish::ThreadPool;
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friend class Stockfish::UCI;
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friend class SearchManager;
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};
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} // namespace Search
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