2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
4 Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
6 Stockfish is free software: you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation, either version 3 of the License, or
9 (at your option) any later version.
11 Stockfish is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <http://www.gnu.org/licenses/>.
20 #ifndef THREAD_H_INCLUDED
21 #define THREAD_H_INCLUDED
25 #include <condition_variable>
35 #include "thread_win32.h"
39 const size_t MAX_THREADS = 128;
40 const size_t MAX_SPLITPOINTS_PER_THREAD = 8;
41 const size_t MAX_SLAVES_PER_SPLITPOINT = 4;
44 /// SplitPoint struct stores information shared by the threads searching in
45 /// parallel below the same split point. It is populated at splitting time.
49 // Const data after split point has been setup
58 // Const pointers to shared data
59 MovePicker* movePicker;
60 SplitPoint* parentSplitPoint;
62 // Shared variable data
64 std::bitset<MAX_THREADS> slavesMask;
65 volatile bool allSlavesSearching;
66 volatile uint64_t nodes;
68 volatile Value bestValue;
69 volatile Move bestMove;
70 volatile int moveCount;
75 /// ThreadBase struct is the base of the hierarchy from where we derive all the
76 /// specialized thread classes.
80 virtual ~ThreadBase() = default;
81 virtual void idle_loop() = 0;
83 void wait_for(volatile const bool& b);
85 std::thread nativeThread;
87 ConditionVariable sleepCondition;
88 volatile bool exit = false;
92 /// Thread struct keeps together all the thread related stuff like locks, state
93 /// and especially split points. We also use per-thread pawn and material hash
94 /// tables so that once we get a pointer to an entry its life time is unlimited
95 /// and we don't have to care about someone changing the entry under our feet.
97 struct Thread : public ThreadBase {
100 virtual void idle_loop();
101 bool cutoff_occurred() const;
102 bool can_join(const SplitPoint* sp) const;
104 void split(Position& pos, Search::Stack* ss, Value alpha, Value beta, Value* bestValue, Move* bestMove,
105 Depth depth, int moveCount, MovePicker* movePicker, int nodeType, bool cutNode);
107 SplitPoint splitPoints[MAX_SPLITPOINTS_PER_THREAD];
108 Pawns::Table pawnsTable;
109 Material::Table materialTable;
111 Position* activePosition;
114 SplitPoint* volatile activeSplitPoint;
115 volatile size_t splitPointsSize;
116 volatile bool searching;
120 /// MainThread and TimerThread are derived classes used to characterize the two
121 /// special threads: the main one and the recurring timer.
123 struct MainThread : public Thread {
124 virtual void idle_loop();
125 volatile bool thinking = true; // Avoid a race with start_thinking()
128 struct TimerThread : public ThreadBase {
130 static const int Resolution = 5; // Millisec between two check_time() calls
132 virtual void idle_loop();
138 /// ThreadPool struct handles all the threads related stuff like init, starting,
139 /// parking and, most importantly, launching a slave thread at a split point.
140 /// All the access to shared thread data is done through this class.
142 struct ThreadPool : public std::vector<Thread*> {
144 void init(); // No c'tor and d'tor, threads rely on globals that should be
145 void exit(); // initialized and are valid during the whole thread lifetime.
147 MainThread* main() { return static_cast<MainThread*>(at(0)); }
148 void read_uci_options();
149 Thread* available_slave(const SplitPoint* sp) const;
150 void wait_for_think_finished();
151 void start_thinking(const Position&, const Search::LimitsType&, Search::StateStackPtr&);
153 Depth minimumSplitDepth;
154 ConditionVariable sleepCondition;
158 extern ThreadPool Threads;
160 #endif // #ifndef THREAD_H_INCLUDED