/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
- Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2009 Marco Costalba
+ Copyright (C) 2004-2021 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
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
-
-#if !defined(THREAD_H_INCLUDED)
+#ifndef THREAD_H_INCLUDED
#define THREAD_H_INCLUDED
+#include <atomic>
+#include <condition_variable>
+#include <mutex>
+#include <thread>
+#include <vector>
-////
-//// Includes
-////
-
-#include <cstring>
-
-#include "lock.h"
+#include "material.h"
#include "movepick.h"
+#include "pawns.h"
#include "position.h"
#include "search.h"
+#include "thread_win32_osx.h"
+
+namespace Stockfish {
+
+/// 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 Thread {
+
+ 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();
+ size_t id() const { return idx; }
+
+ 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 trend;
+};
-////
-//// Constants and variables
-////
+/// MainThread is a derived class specific for main thread
-const int MAX_THREADS = 8;
-const int ACTIVE_SPLIT_POINTS_MAX = 8;
+struct MainThread : public Thread {
+ using Thread::Thread;
-////
-//// Types
-////
+ void search() override;
+ void check_time();
-struct SplitPoint {
+ double previousTimeReduction;
+ Value bestPreviousScore;
+ Value iterValue[4];
+ int callsCnt;
+ bool stopOnPonderhit;
+ std::atomic_bool ponder;
+};
- // Const data after splitPoint has been setup
- SplitPoint* parent;
- const Position* pos;
- bool pvNode;
- Depth depth;
- Value beta;
- int ply, master, slaves[MAX_THREADS];
- SearchStack sstack[MAX_THREADS][PLY_MAX_PLUS_2];
- // Const pointers to shared data
- MovePicker* mp;
- SearchStack* parentSstack;
+/// 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.
- // Shared data
- Lock lock;
- volatile Value alpha;
- volatile Value bestValue;
- volatile int moves;
- volatile int cpus;
- volatile bool stopRequest;
-};
+struct ThreadPool : public std::vector<Thread*> {
-// ThreadState type is used to represent thread's current state
+ void start_thinking(Position&, StateListPtr&, const Search::LimitsType&, bool = false);
+ void clear();
+ void set(size_t);
-enum ThreadState
-{
- THREAD_SEARCHING, // thread is performing work
- THREAD_AVAILABLE, // thread is polling for work
- THREAD_SLEEPING, // we are not thinking, so thread is sleeping
- THREAD_BOOKED, // other thread (master) has booked us as a slave
- THREAD_WORKISWAITING, // master has ordered us to start
- THREAD_TERMINATED // we are quitting and thread is terminated
-};
+ 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;
+
+private:
+ StateListPtr setupStates;
-struct Thread {
- SplitPoint* splitPoint;
- volatile int activeSplitPoints;
- uint64_t nodes;
- uint64_t betaCutOffs[2];
- volatile bool printCurrentLineRequest;
- volatile ThreadState state;
- unsigned char pad[64]; // set some distance among local data for each thread
+ uint64_t accumulate(std::atomic<uint64_t> Thread::* member) const {
+
+ uint64_t sum = 0;
+ for (Thread* th : *this)
+ sum += (th->*member).load(std::memory_order_relaxed);
+ return sum;
+ }
};
+extern ThreadPool Threads;
+
+} // namespace Stockfish
-#endif // !defined(THREAD_H_INCLUDED)
+#endif // #ifndef THREAD_H_INCLUDED