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
34 const size_t MAX_THREADS = 128;
35 const size_t MAX_SPLITPOINTS_PER_THREAD = 8;
36 const size_t MAX_SLAVES_PER_SPLITPOINT = 4;
38 /// Mutex and ConditionVariable struct are wrappers of the low level locking
39 /// machinery and are modeled after the corresponding C++11 classes.
42 Mutex() { lock_init(l); }
43 ~Mutex() { lock_destroy(l); }
45 void lock() { lock_grab(l); }
46 void unlock() { lock_release(l); }
49 friend struct ConditionVariable;
54 struct ConditionVariable {
55 ConditionVariable() { cond_init(c); }
56 ~ConditionVariable() { cond_destroy(c); }
58 void wait(Mutex& m) { cond_wait(c, m.l); }
59 void wait_for(Mutex& m, int ms) { timed_wait(c, m.l, ms); }
60 void notify_one() { cond_signal(c); }
67 /// SplitPoint struct stores information shared by the threads searching in
68 /// parallel below the same split point. It is populated at splitting time.
72 // Const data after split point has been setup
81 // Const pointers to shared data
82 MovePicker* movePicker;
83 SplitPoint* parentSplitPoint;
85 // Shared variable data
87 std::bitset<MAX_THREADS> slavesMask;
88 volatile bool allSlavesSearching;
89 volatile uint64_t nodes;
91 volatile Value bestValue;
92 volatile Move bestMove;
93 volatile int moveCount;
98 /// ThreadBase struct is the base of the hierarchy from where we derive all the
99 /// specialized thread classes.
103 ThreadBase() : handle(NativeHandle()), exit(false) {}
104 virtual ~ThreadBase() {}
105 virtual void idle_loop() = 0;
107 void wait_for(volatile const bool& b);
110 ConditionVariable sleepCondition;
116 /// Thread struct keeps together all the thread related stuff like locks, state
117 /// and especially split points. We also use per-thread pawn and material hash
118 /// tables so that once we get a pointer to an entry its life time is unlimited
119 /// and we don't have to care about someone changing the entry under our feet.
121 struct Thread : public ThreadBase {
124 virtual void idle_loop();
125 bool cutoff_occurred() const;
126 bool available_to(const Thread* master) const;
128 void split(Position& pos, Search::Stack* ss, Value alpha, Value beta, Value* bestValue, Move* bestMove,
129 Depth depth, int moveCount, MovePicker* movePicker, int nodeType, bool cutNode);
131 SplitPoint splitPoints[MAX_SPLITPOINTS_PER_THREAD];
132 Pawns::Table pawnsTable;
133 Material::Table materialTable;
135 Position* activePosition;
138 SplitPoint* volatile activeSplitPoint;
139 volatile size_t splitPointsSize;
140 volatile bool searching;
144 /// MainThread and TimerThread are derived classes used to characterize the two
145 /// special threads: the main one and the recurring timer.
147 struct MainThread : public Thread {
148 MainThread() : thinking(true) {} // Avoid a race with start_thinking()
149 virtual void idle_loop();
150 volatile bool thinking;
153 struct TimerThread : public ThreadBase {
155 static const int Resolution = 5; // Millisec between two check_time() calls
157 TimerThread() : run(false) {}
158 virtual void idle_loop();
164 /// ThreadPool struct handles all the threads related stuff like init, starting,
165 /// parking and, most importantly, launching a slave thread at a split point.
166 /// All the access to shared thread data is done through this class.
168 struct ThreadPool : public std::vector<Thread*> {
170 void init(); // No c'tor and d'tor, threads rely on globals that should be
171 void exit(); // initialized and are valid during the whole thread lifetime.
173 MainThread* main() { return static_cast<MainThread*>(at(0)); }
174 void read_uci_options();
175 Thread* available_slave(const Thread* master) const;
176 void wait_for_think_finished();
177 void start_thinking(const Position&, const Search::LimitsType&, Search::StateStackPtr&);
179 Depth minimumSplitDepth;
181 ConditionVariable sleepCondition;
185 extern ThreadPool Threads;
187 #endif // #ifndef THREAD_H_INCLUDED