/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
- Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2014 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2004-2020 The Stockfish developers (see AUTHORS file)
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
#ifndef THREAD_H_INCLUDED
#define THREAD_H_INCLUDED
+#include <atomic>
+#include <condition_variable>
+#include <mutex>
+#include <thread>
#include <vector>
#include "material.h"
#include "pawns.h"
#include "position.h"
#include "search.h"
+#include "thread_win32_osx.h"
-const int MAX_THREADS = 64; // Because SplitPoint::slavesMask is a uint64_t
-const int MAX_SPLITPOINTS_PER_THREAD = 8;
-struct Mutex {
- Mutex() { lock_init(l); }
- ~Mutex() { lock_destroy(l); }
+/// 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.
- void lock() { lock_grab(l); }
- void unlock() { lock_release(l); }
+class Thread {
-private:
- friend struct ConditionVariable;
-
- Lock l;
-};
-
-struct ConditionVariable {
- ConditionVariable() { cond_init(c); }
- ~ConditionVariable() { cond_destroy(c); }
-
- void wait(Mutex& m) { cond_wait(c, m.l); }
- void wait_for(Mutex& m, int ms) { timed_wait(c, m.l, ms); }
- void notify_one() { cond_signal(c); }
+ std::mutex mutex;
+ std::condition_variable cv;
+ size_t idx;
+ bool exit = false, searching = true; // Set before starting std::thread
+ NativeThread stdThread;
+
+public:
+ explicit Thread(size_t);
+ virtual ~Thread();
+ virtual void search();
+ void clear();
+ void idle_loop();
+ void start_searching();
+ void wait_for_search_finished();
-private:
- WaitCondition c;
+ Pawns::Table pawnsTable;
+ Material::Table materialTable;
+ size_t pvIdx, pvLast;
+ uint64_t ttHitAverage;
+ int selDepth, nmpMinPly;
+ Color nmpColor;
+ std::atomic<uint64_t> nodes, tbHits, bestMoveChanges;
+
+ Position rootPos;
+ StateInfo rootState;
+ Search::RootMoves rootMoves;
+ Depth rootDepth, completedDepth;
+ CounterMoveHistory counterMoves;
+ ButterflyHistory mainHistory;
+ LowPlyHistory lowPlyHistory;
+ CapturePieceToHistory captureHistory;
+ ContinuationHistory continuationHistory[2][2];
+ Score contempt;
};
-struct Thread;
-
-struct SplitPoint {
-
- // Const data after split point has been setup
- const Position* pos;
- const Search::Stack* ss;
- Thread* masterThread;
- Depth depth;
- Value beta;
- int nodeType;
- bool cutNode;
-
- // Const pointers to shared data
- MovePicker* movePicker;
- SplitPoint* parentSplitPoint;
-
- // Shared data
- Mutex mutex;
- volatile uint64_t slavesMask;
- volatile int64_t nodes;
- volatile Value alpha;
- volatile Value bestValue;
- volatile Move bestMove;
- volatile int moveCount;
- volatile bool cutoff;
-};
+/// MainThread is a derived class specific for main thread
-/// ThreadBase struct is the base of the hierarchy from where we derive all the
-/// specialized thread classes.
+struct MainThread : public Thread {
-struct ThreadBase {
+ using Thread::Thread;
- ThreadBase() : exit(false) {}
- virtual ~ThreadBase() {}
- virtual void idle_loop() = 0;
- void notify_one();
- void wait_for(volatile const bool& b);
+ void search() override;
+ void check_time();
- Mutex mutex;
- ConditionVariable sleepCondition;
- NativeHandle handle;
- volatile bool exit;
+ double previousTimeReduction;
+ Value bestPreviousScore;
+ Value iterValue[4];
+ int callsCnt;
+ bool stopOnPonderhit;
+ std::atomic_bool ponder;
};
-/// 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;
+/// 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.
- template <bool Fake>
- void split(Position& pos, const 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];
- Material::Table materialTable;
- Endgames endgames;
- Pawns::Table pawnsTable;
- Position* activePosition;
- size_t idx;
- int maxPly;
- SplitPoint* volatile activeSplitPoint;
- volatile int splitPointsSize;
- volatile bool searching;
-};
-
-
-/// MainThread and TimerThread are derived classes used to characterize the two
-/// special threads: the main one and the recurring timer.
+struct ThreadPool : public std::vector<Thread*> {
-struct MainThread : public Thread {
- MainThread() : thinking(true) {} // Avoid a race with start_thinking()
- virtual void idle_loop();
- volatile bool thinking;
-};
+ void start_thinking(Position&, StateListPtr&, const Search::LimitsType&, bool = false);
+ void clear();
+ void set(size_t);
-struct TimerThread : public ThreadBase {
- TimerThread() : run(false) {}
- virtual void idle_loop();
- bool run;
- static const int Resolution = 5; // msec between two check_time() calls
-};
+ 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); }
+ Thread* get_best_thread() const;
+ void start_searching();
+ void wait_for_search_finished() const;
+ std::atomic_bool stop, increaseDepth;
-/// 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.
+private:
+ StateListPtr setupStates;
-struct ThreadPool : public std::vector<Thread*> {
+ uint64_t accumulate(std::atomic<uint64_t> Thread::* member) const {
- void init(); // No c'tor and d'tor, threads rely on globals that should
- void exit(); // be initialized and are valid during the whole thread lifetime.
-
- MainThread* main() { return static_cast<MainThread*>((*this)[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&,
- const std::vector<Move>&, Search::StateStackPtr&);
-
- bool sleepWhileIdle;
- Depth minimumSplitDepth;
- size_t maxThreadsPerSplitPoint;
- Mutex mutex;
- ConditionVariable sleepCondition;
- TimerThread* timer;
+ uint64_t sum = 0;
+ for (Thread* th : *this)
+ sum += (th->*member).load(std::memory_order_relaxed);
+ return sum;
+ }
};
extern ThreadPool Threads;