Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2015-2019 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
#define THREAD_H_INCLUDED
#include <atomic>
-#include <bitset>
#include <condition_variable>
#include <mutex>
#include <thread>
#include "pawns.h"
#include "position.h"
#include "search.h"
-
-struct Thread;
-
-const size_t MAX_THREADS = 128;
-const size_t MAX_SPLITPOINTS_PER_THREAD = 8;
-const size_t MAX_SLAVES_PER_SPLITPOINT = 4;
-
-/// SplitPoint struct stores information shared by the threads searching in
-/// parallel below the same split point. It is populated at splitting time.
-
-struct SplitPoint {
-
- // Const data after split point has been setup
- const Position* pos;
- Search::Stack* ss;
- Thread* master;
- Depth depth;
- Value beta;
- int nodeType;
- bool cutNode;
-
- // Const pointers to shared data
- MovePicker* movePicker;
- SplitPoint* parentSplitPoint;
-
- // Shared variable data
- std::mutex mutex;
- std::bitset<MAX_THREADS> slavesMask;
- volatile bool allSlavesSearching;
- volatile uint64_t nodes;
- volatile Value alpha;
- volatile Value bestValue;
- volatile Move bestMove;
- volatile int moveCount;
- volatile bool cutoff;
-};
+#include "thread_win32_osx.h"
-/// Spinlock class wraps low level atomic operations to provide spin lock functionality
+/// Thread class keeps together all the thread-related stuff. We use
+/// per-thread pawn and material hash tables so that once we get a
+/// pointer to an entry its life time is unlimited and we don't have
+/// to care about someone changing the entry under our feet.
-class Spinlock {
+class Thread {
- std::atomic_flag lock;
+ Mutex mutex;
+ ConditionVariable cv;
+ size_t idx;
+ bool exit = false, searching = true; // Set before starting std::thread
+ NativeThread stdThread;
public:
- Spinlock() { std::atomic_flag_clear(&lock); }
- void acquire() { while (lock.test_and_set(std::memory_order_acquire)) {} }
- void release() { lock.clear(std::memory_order_release); }
-};
-
-
-/// ThreadBase struct is the base of the hierarchy from where we derive all the
-/// specialized thread classes.
-
-struct ThreadBase {
-
- virtual ~ThreadBase() = default;
- virtual void idle_loop() = 0;
- void notify_one();
- void wait_for(volatile const bool& b);
-
- std::thread nativeThread;
- std::mutex mutex;
- std::condition_variable sleepCondition;
- volatile bool exit = false;
-};
-
+ explicit Thread(size_t);
+ virtual ~Thread();
+ virtual void search();
+ void clear();
+ void idle_loop();
+ void start_searching();
+ void wait_for_search_finished();
+ int best_move_count(Move move);
-/// Thread struct keeps together all the thread related stuff like locks, state
-/// and especially split points. We also use per-thread pawn and material hash
-/// tables so that once we get a pointer to an entry its life time is unlimited
-/// and we don't have to care about someone changing the entry under our feet.
-
-struct Thread : public ThreadBase {
-
- Thread();
- virtual void idle_loop();
- bool cutoff_occurred() const;
- bool available_to(const Thread* master) const;
-
- void split(Position& pos, Search::Stack* ss, Value alpha, Value beta, Value* bestValue, Move* bestMove,
- Depth depth, int moveCount, MovePicker* movePicker, int nodeType, bool cutNode);
-
- SplitPoint splitPoints[MAX_SPLITPOINTS_PER_THREAD];
Pawns::Table pawnsTable;
Material::Table materialTable;
- Endgames endgames;
- Position* activePosition;
- size_t idx;
- int maxPly;
- SplitPoint* volatile activeSplitPoint;
- volatile size_t splitPointsSize;
- volatile bool searching;
+ size_t pvIdx, pvLast, shuffleExts;
+ int selDepth, nmpMinPly;
+ Color nmpColor;
+ std::atomic<uint64_t> nodes, tbHits, bestMoveChanges;
+
+ Position rootPos;
+ Search::RootMoves rootMoves;
+ Depth rootDepth, completedDepth;
+ CounterMoveHistory counterMoves;
+ ButterflyHistory mainHistory;
+ CapturePieceToHistory captureHistory;
+ ContinuationHistory continuationHistory;
+ Score contempt;
};
-/// MainThread and TimerThread are derived classes used to characterize the two
-/// special threads: the main one and the recurring timer.
+/// MainThread is a derived class specific for main thread
struct MainThread : public Thread {
- virtual void idle_loop();
- volatile bool thinking = true; // Avoid a race with start_thinking()
-};
-
-struct TimerThread : public ThreadBase {
- static const int Resolution = 5; // Millisec between two check_time() calls
+ using Thread::Thread;
- virtual void idle_loop();
+ void search() override;
+ void check_time();
- bool run = false;
+ double previousTimeReduction;
+ Value previousScore;
+ int callsCnt;
+ bool stopOnPonderhit;
+ std::atomic_bool ponder;
};
-/// ThreadPool struct handles all the threads related stuff like init, starting,
-/// parking and, most importantly, launching a slave thread at a split point.
-/// All the access to shared thread data is done through this class.
+/// ThreadPool struct handles all the threads-related stuff like init, starting,
+/// parking and, most importantly, launching a thread. All the access to threads
+/// is done through this class.
struct ThreadPool : public std::vector<Thread*> {
- void init(); // No c'tor and d'tor, threads rely on globals that should be
- void exit(); // initialized and are valid during the whole thread lifetime.
+ void start_thinking(Position&, StateListPtr&, const Search::LimitsType&, bool = false);
+ void clear();
+ void set(size_t);
+
+ MainThread* main() const { return static_cast<MainThread*>(front()); }
+ uint64_t nodes_searched() const { return accumulate(&Thread::nodes); }
+ uint64_t tb_hits() const { return accumulate(&Thread::tbHits); }
+
+ std::atomic_bool stop;
+
+private:
+ StateListPtr setupStates;
- MainThread* main() { return static_cast<MainThread*>(at(0)); }
- void read_uci_options();
- Thread* available_slave(const Thread* master) const;
- void wait_for_think_finished();
- void start_thinking(const Position&, const Search::LimitsType&, Search::StateStackPtr&);
+ uint64_t accumulate(std::atomic<uint64_t> Thread::* member) const {
- Depth minimumSplitDepth;
- std::mutex mutex;
- std::condition_variable sleepCondition;
- TimerThread* timer;
+ uint64_t sum = 0;
+ for (Thread* th : *this)
+ sum += (th->*member).load(std::memory_order_relaxed);
+ return sum;
+ }
};
extern ThreadPool Threads;
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