/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, 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
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 <cstring>
+#include <atomic>
+#include <bitset>
+#include <condition_variable>
+#include <mutex>
+#include <thread>
+#include <vector>
-#include "lock.h"
+#include "material.h"
#include "movepick.h"
+#include "pawns.h"
#include "position.h"
#include "search.h"
+#include "thread_win32.h"
-const int MAX_THREADS = 32;
-const int MAX_ACTIVE_SPLIT_POINTS = 8;
+struct Thread;
+
+const size_t MAX_THREADS = 128;
+const size_t MAX_SPLITPOINTS_PER_THREAD = 8;
+const size_t MAX_SLAVES_PER_SPLITPOINT = 4;
+
+class Spinlock {
+
+ std::atomic_int lock;
+
+public:
+ Spinlock() { lock = 1; } // Init here to workaround a bug with MSVC 2013
+ void acquire() {
+ while (lock.fetch_sub(1, std::memory_order_acquire) != 1)
+ for (int cnt = 0; lock.load(std::memory_order_relaxed) <= 0; ++cnt)
+ if (cnt >= 10000) std::this_thread::yield(); // Be nice to hyperthreading
+ }
+ void release() { lock.store(1, std::memory_order_release); }
+};
+
+
+/// 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 splitPoint has been setup
- SplitPoint* parent;
+ // Const data after split point has been setup
const Position* pos;
+ Search::Stack* ss;
+ Thread* master;
Depth depth;
- bool pvNode;
Value beta;
- int ply;
- int master;
- Move threatMove;
+ int nodeType;
+ bool cutNode;
// Const pointers to shared data
- MovePicker* mp;
- SearchStack* ss;
+ MovePicker* movePicker;
+ SplitPoint* parentSplitPoint;
- // Shared data
- Lock lock;
- volatile int64_t nodes;
+ // Shared variable data
+ Spinlock spinlock;
+ 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 betaCutoff;
- volatile int slaves[MAX_THREADS];
+ volatile bool cutoff;
};
-// ThreadState type is used to represent thread's current state
-enum ThreadState
-{
- THREAD_INITIALIZING, // thread is initializing itself
- THREAD_SEARCHING, // thread is performing work
- THREAD_AVAILABLE, // thread is waiting for work
- 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
+
+/// 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;
+ Mutex mutex;
+ Spinlock spinlock;
+ ConditionVariable sleepCondition;
+ volatile bool exit = false;
};
-struct Thread {
- Lock sleepLock;
- WaitCondition sleepCond;
- volatile ThreadState state;
- SplitPoint* volatile splitPoint;
- volatile int activeSplitPoints;
- SplitPoint splitPoints[MAX_ACTIVE_SPLIT_POINTS];
+
+/// 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 can_join(const SplitPoint* sp) 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;
};
-#endif // !defined(THREAD_H_INCLUDED)
+
+/// MainThread and TimerThread are derived classes used to characterize the two
+/// special threads: the main one and the recurring timer.
+
+struct MainThread : public Thread {
+ virtual void idle_loop();
+ void join();
+ 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
+
+ virtual void idle_loop();
+
+ bool run = false;
+};
+
+
+/// 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.
+
+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.
+
+ MainThread* main() { return static_cast<MainThread*>(at(0)); }
+ void read_uci_options();
+ Thread* available_slave(const SplitPoint* sp) const;
+ void start_thinking(const Position&, const Search::LimitsType&, Search::StateStackPtr&);
+
+ Depth minimumSplitDepth;
+ TimerThread* timer;
+};
+
+extern ThreadPool Threads;
+
+#endif // #ifndef THREAD_H_INCLUDED
projects / stockfish / blobdiff